Residential Package unit and Chiller speculation

[motoguy128]

I wonder if any of the major mfg's would ever consider modifiying their split systems to be packaged units with split condensers coils only, so you could reheat the air and even do as Ultra-Aire does and use a heat exchanger to increase moisture removal. THen it's jsut a matter of modulating the amount of vapor going ot reheat vs. the condenser coil.... which of course would require EXV's.

Then again, by the time you've done all that, you might as well just buy a chiller, keep your coil 45F and make hot water for reheat. A chiller eliminates the need for a dedicated dehmidifier, since airflow can be independant of system capacity. I know Crazi is on board with chillers for residential use. Though a WHD is still going ot be a little more economical in a small and medium sized home.

[CraziFuzzy]

I wonder if any of the major mfg's would ever consider modifiying their split systems to be packaged units with split condensers coils only, so you could reheat the air and even do as Ultra-Aire does and use a heat exchanger to increase moisture removal. THen it's jsut a matter of modulating the amount of vapor going ot reheat vs. the condenser coil.... which of course would require EXV's.

Then again, by the time you've done all that, you might as well just buy a chiller, keep your coil 45F and make hot water for reheat. A chiller eliminates the need for a dedicated dehmidifier, since airflow can be independant of system capacity. I know Crazi is on board with chillers for residential use. Though a WHD is still going ot be a little more economical in a small and medium sized home.

If packaged units made sense for homes, there's be more of them out there - it is cheaper to make a packaged unit than a split system. They just don't makes sense the way architects design homes in most cases. If that changes, then yes, a split condenser would make for a very good dehumidifier, especially with a smart control, that way it could seemlessly cycle between cooling mode, and dehumidification mode, while working on the same air stream. That said, since architects DO like split systems (because of freedom of placement), that's the same reason I like chilled water.. :-)

Whd's do make sense when moisture removal is all you are looking for. That said, if you are wanting to use chilled water for dehumidification, you don't actually HAVE to use hot water for the reheat, you can actually use the chilled water return as the reheat. With two chilled water coils, and a 3-way solenoid valves, you can switch them from cooling only, to dehumidification without cooling.

I'm still not convinced that chilled water doesn't work in a small/medium sized home. The only reason it doesn't make sense right now is market, not technical. There just isn't enough small chiller systems on the market for their price to drop. You can custom build a small chiller for very cheap - but a mass produced one would be a lot cheaper, and if you subtract the cost of duct installation and go with a couple small fan coils, it is probably not a lot more than a traditional split system. PEX tubing is the key thing that has changed in the market to allow this.

This exact scenario points to the key advantage of hydronic systems. Once the system's head ends are in place (be it a boiler or chiller), all it takes is coils and valves and that cold/hot water can be manipulated in so many different ways that any comfort scenario can be handled easily.

[jtrammel]

In my market package units are very common in residential, probably 50+% of homes have package units

[CraziFuzzy]

In my market package units are very common in residential, probably 50+% of homes have package units

Are those A/C's with gas heat, or heat pump heating? I'm wondering if that is the difference... as I said, around here in SoCal, gas is so cheap, there are very few heat pumps - just about every home has an oversized gas fired furnace, feeding through a split A-coil.

[udarrell]

I get 18,500 Btus of sensible heat gain and 3,500 Btus of latent gain. I like Ruud/Rheem equipment, and when I look at the specs for their hardware a 2-ton unit does look like enough even for the very hot, humid days we get here in Virginia.

At 85-F ambient, 75-IDB & 63F IWB a 2-Ton Goodman 13-SEER with just a piston metering device; at 700-CFM, it gets 20,200 total at an S/T of 0.73, or 14,746 sensible & 5,454 latent.

You need to figure out what the sensible load is at 85-F ambient & how much air infiltration you have; which will also depend on wind conditions & the ambient humidity level at 85-F.

You also need a room stat that will provide some degrees of temp swing for longer runtime periods; indoor fan should cycle off with condenser & you need a TXV metering device on a 2-Ton evaporator.

I also agree in general with Teddy Bear's statements...

[jtrammel]

Are those A/C's with gas heat, or heat pump heating? I'm wondering if that is the difference... as I said, around here in SoCal, gas is so cheap, there are very few heat pumps - just about every home has an oversized gas fired furnace, feeding through a split A-coil.

probably about 60%gas/electric 35% heat pump 5% dual fuel on residential package equipment

[54regcab]

Package units are typical on older homes in our area that didn't have central heat at the time of construction. Package units aren't used on homes made after 1970 or so in our area.

The home chiller is VERY interesting. A few other bonuses are when it comes time for system replacement the indoor units don't have to be replaced at the same time as the outside unit. No ductwork looses. Easy zoning. Easy to heat cool additions w/o new equipment. The same water used to cool the space could be used to heat it. Heat could come from heat pump or gas/oil. Whole home dual fuel becomes easy. Domestic hot water could be provided by chiller. Geothermal/Miniature cooling towers become practical. The advantages go on, it's just a matter of somebody coming up with a cost effective unit in smaller sizes.

[CraziFuzzy]

Package units are typical on older homes in our area that didn't have central heat at the time of construction. Package units aren't used on homes made after 1970 or so in our area.

The home chiller is VERY interesting. A few other bonuses are when it comes time for system replacement the indoor units don't have to be replaced at the same time as the outside unit. No ductwork looses. Easy zoning. Easy to heat cool additions w/o new equipment. The same water used to cool the space could be used to heat it. Heat could come from heat pump or gas/oil. Whole home dual fuel becomes easy. Domestic hot water could be provided by chiller. Geothermal/Miniature cooling towers become practical. The advantages go on, it's just a matter of somebody coming up with a cost effective unit in smaller sizes.

It would take less innovation than you might think. All it takes to turn a conventional outdoor compressor/condenser unit into a chiller is to connect it to a TXV and heat exchanger (either shell and tube, or brazed plate). The chilled water system itself is also not anything new, as cheap fancoils are already made and readily available in sizes small enough match residential uses, including nice small ceiling mount concealed units, that just need power, t-stat, chilled/hot water, and a condensate drain. Circ pumps, expansion tanks, control valves, are already used in hydronic heating systems. Even conventional hot water tanks makes a very good chilled water buffer tank to avoid excessive chiller cycling. Not the easiest retrofit to an existing home, and some of the savings aren't there, but in a new construction, I don't think I would ever have a home built with conventional ducting at this point.

[54regcab]

It would take less innovation than you might think. All it takes to turn a conventional outdoor compressor/condenser unit into a chiller is to connect it to a TXV and heat exchanger (either shell and tube, or brazed plate). The chilled water system itself is also not anything new, as cheap fancoils are already made and readily available in sizes small enough match residential uses, including nice small ceiling mount concealed units, that just need power, t-stat, chilled/hot water, and a condensate drain. Circ pumps, expansion tanks, control valves, are already used in hydronic heating systems. Even conventional hot water tanks makes a very good chilled water buffer tank to avoid excessive chiller cycling. Not the easiest retrofit to an existing home, and some of the savings aren't there, but in a new construction, I don't think I would ever have a home built with conventional ducting at this point.

My wife used to work at a place that manufactured fan coil units. House I was living at didn't have central heat/air. Got a 600CFM "lab unit" for free and hooked it to the existing gas water heater. The unit had a 5 row coil, 2 rows for hot water, 3 rows hooked to a TXV and a 1.5 ton condenser. System was still in service when I sold the house. Front of the coil is VERY easy to get to on these units, making them easy to clean. The guys at my wife's work thought I was nuts, but were surprised when they saw it work. Now if they would only market to residential customers like FirstCO does...

[CraziFuzzy]

My wife used to work at a place that manufactured fan coil units. House I was living at didn't have central heat/air. Got a 600CFM "lab unit" for free and hooked it to the existing gas water heater. The unit had a 5 row coil, 2 rows for hot water, 3 rows hooked to a TXV and a 1.5 ton condenser. System was still in service when I sold the house. Front of the coil is VERY easy to get to on these units, making them easy to clean. The guys at my wife's work thought I was nuts, but were surprised when they saw it work. Now if they would only market to residential customers like FirstCO does...

FirstCo only makes DX cooling coil units, no chilled water. Multiaqua makes some great looking units, including full whole-house 4-pipe air handlers to replace a conventional furnace/a-coil setup. This great thing about that particular unit (CWA4) is that it properly does the chilled water coil first, then the blower, then the hot water coil, allowing for dehumidification via simultaneous cooling and reheat.

[motoguy128]

It would take less innovation than you might think. All it takes to turn a conventional outdoor compressor/condenser unit into a chiller is to connect it to a TXV and heat exchanger (either shell and tube, or brazed plate). The chilled water system itself is also not anything new, as cheap fancoils are already made and readily available in sizes small enough match residential uses, including nice small ceiling mount concealed units, that just need power, t-stat, chilled/hot water, and a condensate drain. Circ pumps, expansion tanks, control valves, are already used in hydronic heating systems. Even conventional hot water tanks makes a very good chilled water buffer tank to avoid excessive chiller cycling. Not the easiest retrofit to an existing home, and some of the savings aren't there, but in a new construction, I don't think I would ever have a home built with conventional ducting at this point.

That's a good point. For R410a, you'd have to get a HE rated for I think around 500psi however... and install the proper PRV if it's rating needs to be lover than the PRV at the compressor.

I wonder if you could even use an indirect tank as the heat exchanger. Then you'd have an evaporator and storage together. It would hurt efficeincy slightly, since you wouldn't have the higher tmep return water ging to the coil first. Although you'd still have soem stratification in hte tank where hte top of hte tank is warmer than the bottom.

[jtrammel]

That's a good point. For R410a, you'd have to get a HE rated for I think around 500psi however... and install the proper PRV if it's rating needs to be lover than the PRV at the compressor.

I wonder if you could even use an indirect tank as the heat exchanger. Then you'd have an evaporator and storage together. It would hurt efficeincy slightly, since you wouldn't have the higher tmep return water ging to the coil first. Although you'd still have soem stratification in hte tank where hte top of hte tank is warmer than the bottom.

Yes, some company makes one, not sure of brand but we installed one at a church for a single fan coil unit when we converted the rest to dx. It was not feasible to get duct to this area and piping was already there. They make the condenser on a stand with the hx and storage tank built into stand, pretty neat set up

[motoguy128]

FirstCo only makes DX cooling coil units, no chilled water. Multiaqua makes some great looking units, including full whole-house 4-pipe air handlers to replace a conventional furnace/a-coil setup. This great thing about that particular unit (CWA4) is that it properly does the chilled water coil first, then the blower, then the hot water coil, allowing for dehumidification via simultaneous cooling and reheat.

Carrier makes commerical air handlers down to 400 CFM nominal and can be had with chilled water and hot water coils. It looks like they have 2 returns, so you can use up to 100% outside air for economizing. The blower looks like it's after both the chilled and hot water coils. http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/39s-3pd.pdf

[CraziFuzzy]

That's a good point. For R410a, you'd have to get a HE rated for I think around 500psi however... and install the proper PRV if it's rating needs to be lover than the PRV at the compressor.

I wonder if you could even use an indirect tank as the heat exchanger. Then you'd have an evaporator and storage together. It would hurt efficeincy slightly, since you wouldn't have the higher tmep return water ging to the coil first. Although you'd still have soem stratification in hte tank where hte top of hte tank is warmer than the bottom.

Standard Refrigeration sells 'chiller kits', which include the shell and tube evaporator, txv, and controls, that can easily be installed to a standard condenser/compressor unit. they are all rated for R-410A pressures. (http://www.stanref.com/pdfs/CBChillerBuilderKitBrochure.pdf). I think Alfa Laval also sells kits based on their brazed plate exchangers as well. Thermal Flow (http://www.thermalflow.net/greenm.htm) market a residential chilled water system no idea on the details though. Unico has started marketing a residential chiller system (calling it UniChiller (http://www.unicosystem.com/Homeowners/OurProductSolutions/ProductListByName/UniChiller.aspx)). Many parts of the market ARE starting to take notice - I think the biggeset thing preventing the spread at THIS point is the lack of chiller/chilled-water knowledge of residential techs.


Carrier makes commerical air handlers down to 400 CFM nominal and can be had with chilled water and hot water coils. It looks like they have 2 returns, so you can use up to 100% outside air for economizing. The blower looks like it's after both the chilled and hot water coils. http://www.docs.hvacpartners.com/idc/groups/public/documents/techlit/39s-3pd.pdf

Of course there are plenty of commercial air handlers using chilled and hot water - the problem is that they are BUILT as commercial units - which means, in most cases, they are way over-built for residential use, and consequently, way too expensive.

[tedkidd]

Right on. The free cooling can double the amount of moisture removed the compressor verses conventional cooling.
The heat is 1050 btus per lbs. of moisture removed + 3414 btus per KW used = btus added to the air. The high efficiency of the deh means less heat added to the space. Keep in mind the heat from the dehu only occurs when the properly set up a/c is cycling on/off. So dehu does not add to the cooling unless reheat is needed to extend a/c dehumidification.
Regards TB

Now I'm feeling completely lost. It'll have to be dummed down for me to understand. Sorry.


I wonder if any of the major mfg's would ever consider modifiying their split systems to be packaged units with split condensers coils only, so you could reheat the air and even do as Ultra-Aire does and use a heat exchanger to increase moisture removal. THen it's jsut a matter of modulating the amount of vapor going ot reheat vs. the condenser coil.... which of course would require EXV's.

Then again, by the time you've done all that, you might as well just buy a chiller, keep your coil 45F and make hot water for reheat. A chiller eliminates the need for a dedicated dehmidifier, since airflow can be independant of system capacity. I know Crazi is on board with chillers for residential use. Though a WHD is still going ot be a little more economical in a small and medium sized home.

I think Climatemaster offers an optional reheat coil.

[motoguy128]

Now I'm feeling completely lost. It'll have to be dummed down for me to understand. Sorry.



You have ot think about surface tmepratures of the coil and heat exchanger. FOr efficeincy, you want a big coil area. But to get low dewpoints, you need a small surface area to get lower coil temps. So you put is a propoertionally larger coil, and you end up with lets say 50F surface temps and 55F air discharge. Efficient, but not a very good dehumidifier. Now, what if you flow that air across a heat exchanger and cool it to 55F. Now you flow the incomming air across that coil first. So now you're dropping the dewpoint of the incomming air. Further, that air is now dryer and cooler, so the evaporator will now be even colder, but you still retain that large surface area. The result is that for the same CFM, you will be able to use an even smaller compressor with the same coil size and achieve the same level of moisture removed.

It's in a sense liek the economizer or the secondary heat exchanger in a condensing boiler or furnace.

[tedkidd]

Air path:

In through HE - the other side of which sees evap exhaust

Precooled air through evap

out he as mentioned above

finally through condensor.

That it?

[motoguy128]

Air path:

In through HE - the other side of which sees evap exhaust

Precooled air through evap

out he as mentioned above

finally through condensor.

That it?

You got it.

Or... you needed the air even more dry without much more energy use, you'd add a dessicant wheel and run the incomming air across the condenser coil first to preheat it and drop the RH, then across the regen side of hte dessicant wheel, then the HE, evap, then the dry/regenerated side of the wheel. That would get your dewpoints around 0-20F. Add heat strips for the regeneration and you can see -60F dewpoints.

[dan sw fl]

Chillers are obviously used EXTENSIVELY in condos / high rises, retail and institutional.

:whistle:

[CraziFuzzy]

Chillers are obviously used EXTENSIVELY in condos / high rises, retail and institutional.

Of course they are. We're talking about smaller scale though - as in the <6 ton level.

[54regcab]

FirstCo only makes DX cooling coil units, no chilled water. Multiaqua makes some great looking units, including full whole-house 4-pipe air handlers to replace a conventional furnace/a-coil setup. This great thing about that particular unit (CWA4) is that it properly does the chilled water coil first, then the blower, then the hot water coil, allowing for dehumidification via simultaneous cooling and reheat.

The ones that my wife's used to sell were configured as 4 pipe units. For DX use they just added a TXV to one set of pipes. No distributors, just 1 circuit.

[motoguy128]

That's a good point, you could use a DX coil for chilled water, but you might have less capacity because of overall pipe size I think.

[CraziFuzzy]

The ones that my wife's used to sell were configured as 4 pipe units. For DX use they just added a TXV to one set of pipes. No distributors, just 1 circuit.

Yeah, I found them on the firstco site. They were listed only in the commercial section, as I should have expected - again, there-in lies the problem...

[jtrammel]

http://www.aquaproducts.us/home/reverse-cycle-chiller.html

[jtrammel]

Yes, some company makes one, not sure of brand but we installed one at a church for a single fan coil unit when we converted the rest to dx. It was not feasible to get duct to this area and piping was already there. They make the condenser on a stand with the hx and storage tank built into stand, pretty neat set up

http://www.aquaproducts.us/chillers/package-chillers.html this is what we installed

[motoguy128]

I think they are stretching with the claim taht it will be more efficient that natural gas heating. How much better COP does the water cooled evap give you? Can you even get 120F water when it's 10F outside?

I thought the advantage of air cooled chillers was having a single central plant along with the dehumidification and building control benefits of chilled water... which is improtant when you are drawing in a lot of outdoor air for ventilation. Not as much the direct energy savings.


The nerd is me really would love to put on of these in when I replace my downstairs system in the next year or two, still install a furnace, but with a hydronic coil and use it as a dual fuel system and use an outdoor reset to adjust the hot water temeprature setpoint for capacity control and maybe even modulate chilled water temperature for humidity control.

I bet I don't even want ot see the prices. I'm guessing a carrier Greenspeed hybrid is looking competitive with it.

[CraziFuzzy]

http://www.aquaproducts.us/home/reverse-cycle-chiller.html

I think, in my case, I'd rather run a water-to-water chiller with an outdoor fan coil for excess heat rejection, than a reversing heat pump type setup. With a water to water, you could run the chiller as necessary to cool the chilled loop and reject to the hot loop, and if the hot loop is over a set temp, run it through the outside coil. This would maximize the ability to recover waste heat from the chiller (and use it for domestic hot water). If hot loop temp is low, it would be supplemented with a high efficiency gas water heater.

With this type of setup, it would be possible to build a 'central plant in a box' type setup, that contained the controls, cold water supply and return, hot water supply and return, and a outdoor (or ground loop) coil supply and return. If gas is an option, it can be installed on the hot loop. In residential uses, I see no reason why you can't use the same loop for heating and domestic, as long as all components are domestic water rated. This type of box can include the pumps, chiller, etc. Accessories such as storage/buffer tanks, etc can be added, as can other items such as solar heat.

There's also no refrigerant work with a box like this. It's a self contained appliance, just like a refrigerator.

[jtrammel]

I think they are stretching with the claim taht it will be more efficient that natural gas heating. How much better COP does the water cooled evap give you? Can you even get 120F water when it's 10F outside?

I thought the advantage of air cooled chillers was having a single central plant along with the dehumidification and building control benefits of chilled water... which is improtant when you are drawing in a lot of outdoor air for ventilation. Not as much the direct energy savings.


The nerd is me really would love to put on of these in when I replace my downstairs system in the next year or two, still install a furnace, but with a hydronic coil and use it as a dual fuel system and use an outdoor reset to adjust the hot water temeprature setpoint for capacity control and maybe even modulate chilled water temperature for humidity control.

I bet I don't even want ot see the prices. I'm guessing a carrier Greenspeed hybrid is looking competitive with it.

I haven't checked it at low temps, it was in ac season when we installed all of the equipment and someone at the church changes filters and cleans coils etc. we havnt been back and it was installed 6 years ago. No complaints of it not meeting the heat/cool demand with no backup heat. It's a 5 ton model that serves 6 small fan coils the rest of church is dx York predators

[jtrammel]

Pricing isn't that bad it's just a heat pump with a pump, tank, and coax hx. It is a small operation right up the road from me in South Carolina

[beenthere]

Made this its own thread in Tech to Tech, since it has little to do with the thread it was in.

[Elfshadow]

I think, in my case, I'd rather run a water-to-water chiller with an outdoor fan coil for excess heat rejection, than a reversing heat pump type setup. With a water to water, you could run the chiller as necessary to cool the chilled loop and reject to the hot loop, and if the hot loop is over a set temp, run it through the outside coil. This would maximize the ability to recover waste heat from the chiller (and use it for domestic hot water). If hot loop temp is low, it would be supplemented with a high efficiency gas water heater.

With this type of setup, it would be possible to build a 'central plant in a box' type setup, that contained the controls, cold water supply and return, hot water supply and return, and a outdoor (or ground loop) coil supply and return. If gas is an option, it can be installed on the hot loop. In residential uses, I see no reason why you can't use the same loop for heating and domestic, as long as all components are domestic water rated. This type of box can include the pumps, chiller, etc. Accessories such as storage/buffer tanks, etc can be added, as can other items such as solar heat.

There's also no refrigerant work with a box like this. It's a self contained appliance, just like a refrigerator.

I know these are commercial but they would be close to what your talking about. They don't have any water tanks though. They actually are pretty small boxes at the lower size, 28x28x19, like I said there are only controls for the refrigerant cycle. These are 410a based off of copeland scrolls. They can be configured for heating, cooling or reversible.

http://www.daikinmcquay.com/mcquaybiz/DocumentStorage/WaterSourceHeatPump/Catalogs/Cat_1107.pdf

[CraziFuzzy]

Waterfurnace (http://www.waterfurnace.com/products.aspx?prd=NSW_Hydronic) also makes some nice water-to-water units, down to I think 1.5 ton, and I think they DO have water temp based controls.

[Dallas Duster]

I wonder if any of the major mfg's would ever consider modifiying their split systems to be packaged units with split condensers coils only, so you could reheat the air and even do as Ultra-Aire does and use a heat exchanger to increase moisture removal. THen it's jsut a matter of modulating the amount of vapor going ot reheat vs. the condenser coil.... which of course would require EXV's.

Then again, by the time you've done all that, you might as well just buy a chiller, keep your coil 45F and make hot water for reheat. A chiller eliminates the need for a dedicated dehmidifier, since airflow can be independant of system capacity. I know Crazi is on board with chillers for residential use. Though a WHD is still going ot be a little more economical in a small and medium sized home.

Have you thought about the maintenance on the water treatment ? I have also thought about this idea and to me this seems to be my gray area as for long term system performance.

[Freightshaker]

It would take less innovation than you might think. All it takes to turn a conventional outdoor compressor/condenser unit into a chiller is to connect it to a TXV and heat exchanger (either shell and tube, or brazed plate). The chilled water system itself is also not anything new, as cheap fancoils are already made and readily available in sizes small enough match residential uses, including nice small ceiling mount concealed units, that just need power, t-stat, chilled/hot water, and a condensate drain. Circ pumps, expansion tanks, control valves, are already used in hydronic heating systems. Even conventional hot water tanks makes a very good chilled water buffer tank to avoid excessive chiller cycling. Not the easiest retrofit to an existing home, and some of the savings aren't there, but in a new construction, I don't think I would ever have a home built with conventional ducting at this point.

We had a little old lady that had a chiller on her house. Her husband that passed away was a retired submariner. When he retired he made their basement into a mock submarine right down to the watertight hatches in all the doorways. For his submarine basement ductwork was not going to fly so he made a chiller. The shell in tube was inside hanging on the wall with a TXV.(it just might have been the smallest chiller barrel I have ever seen) It was hooked to a 5 ton trane outside. She had a boiler for heat of course. This was the sharpest home built systems and worked excellent. When we were done servicing the equipment the fella I was with told her due to the boiler age it might not be a bad idea to have a carbon monoxide detector. She laughed and said, "At my age you look foreword to dying in your sleep. I don't think I will be buying one."

[CraziFuzzy]

Have you thought about the maintenance on the water treatment ? I have also thought about this idea and to me this seems to be my gray area as for long term system performance.

With no leaks, there really is no water treatment costs associated with a chilled water loop. Once chemical is added once, it will stay treated fine for many many years.

[Dallas Duster]

With no leaks, there really is no water treatment costs associated with a chilled water loop. Once chemical is added once, it will stay treated fine for many many years.

Unless there is a small leak somehwere. Hey I like the idea as a whole you could count the bad evap coils on one hand if you did have a leaking coil the water goes down the drain.

[Dallas Duster]

With no leaks, there really is no water treatment costs associated with a chilled water loop. Once chemical is added once, it will stay treated fine for many many years.

Then there is back flow inspection.

[xarralu]

Then there is back flow inspection.

Well, maybe not if you had something like this. (http://axiomind.sasktelwebhosting.com/pdf/MF200.pdf)
I have also looked into different "stuff" for residential use like Absorption Chillers (http://www.roburcorp.com/products/ga-line/) and water-to-water like CraziFuzzy has mentioned. I would like it not only being for humidity control, but also maintaining a set temperature. DX is always going to be a "see-saw" if you want efficiency with it. I would do the same thing that Crazi said earlier in post #27, but at this point I don't think any major mfg. is real close to having a residential chill water rig. I wish someone did, I would be the first in line!

[Dallas Duster]

Well, maybe not if you had something like this. (http://axiomind.sasktelwebhosting.com/pdf/MF200.pdf)
I have also looked into different "stuff" for residential use like Absorption Chillers (http://www.roburcorp.com/products/ga-line/) and water-to-water like CraziFuzzy has mentioned. I would like it not only being for humidity control, but also maintaining a set temperature. DX is always going to be a "see-saw" if you want efficiency with it. I would do the same thing that Crazi said earlier in post #27, but at this point I don't think any major mfg. is real close to having a residential chill water rig. I wish someone did, I would be the first in line!

That seems pretty neat wonder if it cost an arm and a leg but I think that someone already makes a residential chiller.

[xarralu]

Yea I've looked into the usual air cooled equipment, but unless you have a good sized buffer/storage tank your still going to have the temperature swings because your still banging compressors on and off...back to square one. Also, even in "quiet mode" they are still very noisy for a residential area. To answer your question, the absorption chiller is appealing in theory but it is way too expensive upfront. I have contacted that company and for what I could have two 3 ton systems changed out, I could buy the GAHP-AR machine! Mind you, it is very efficient but when do you see your ROI? 10 years? 15 years? Plus, who do you know that can work on an absorption chiller? (not me!)

What I would like to do is make ice with something like this (http://www.ice-energy.com/ice-bear-energy-storage-system). Only problem is they don't sell to the general public, only to utility companies! :censored: I believe with that equipment you could vary your CFM in your AHU without having to worry about freezing your coil and maintain setpoint.

[CraziFuzzy]

That seems pretty neat wonder if it cost an arm and a leg but I think that someone already makes a residential chiller.

It's already been mentioned in this thread, but there ARE actual residential chillers in production. Daikin, MultiAqua, ThermalFlow, Unico and WaterFurnace all make residential grade chiller equipment. Waterfurnace markets theirs as a geothermal water heater, but it is the same thing - you just use the 'chilled water' as the source, and the 'hot water' as the load...

[CraziFuzzy]

Yea I've looked into the usual air cooled equipment, but unless you have a good sized buffer/storage tank your still going to have the temperature swings because your still banging compressors on and off...back to square one. Also, even in "quiet mode" they are still very noisy for a residential area. To answer your question, the absorption chiller is appealing in theory but it is way too expensive upfront. I have contacted that company and for what I could have two 3 ton systems changed out, I could buy the GAHP-AR machine! Mind you, it is very efficient but when do you see your ROI? 10 years? 15 years? Plus, who do you know that can work on an absorption chiller? (not me!)

What I would like to do is make ice with something like this (http://www.ice-energy.com/ice-bear-energy-storage-system). Only problem is they don't sell to the general public, only to utility companies! :censored: I believe with that equipment you could vary your CFM in your AHU without having to worry about freezing your coil and maintain setpoint.

Actually, with a decoupling buffer tank, you don't have to have the temperature swings. The air handler can maintain a nice steady temperature control, and the chiller will cycle as needed to maintain the buffer's charge.

[motoguy128]

Yea I've looked into the usual air cooled equipment, but unless you have a good sized buffer/storage tank your still going to have the temperature swings because your still banging compressors on and off...back to square one. Also, even in "quiet mode" they are still very noisy for a residential area. To answer your question, the absorption chiller is appealing in theory but it is way too expensive upfront. I have contacted that company and for what I could have two 3 ton systems changed out, I could buy the GAHP-AR machine! Mind you, it is very efficient but when do you see your ROI? 10 years? 15 years? Plus, who do you know that can work on an absorption chiller? (not me!)

What I would like to do is make ice with something like this (http://www.ice-energy.com/ice-bear-energy-storage-system). Only problem is they don't sell to the general public, only to utility companies! :censored: I believe with that equipment you could vary your CFM in your AHU without having to worry about freezing your coil and maintain setpoint.

The goal is more for zoning and comfort, not direct energy savings.

The compressor can be 2 stage or use multiple compressors and refrigerant circuits. Very easy to split the heat exchanger into 2 circuits.

Why are they noisy? The condenser shouldn't be any different from a residential condenser. Eveen better, the condenser fan on a unit that generates hot water as well, should have a ECM motor and ramp down based on head pressure. At night in particular, it would be running at a pretty low rate.

We're not talking 150T+ screw machines. Those are very noisy.

+1 on the buffer tank. With just 50 gallons of storage, if you have a building that has a max load of 3 tons, and when at just 1/3 load, 12000 BTU's, with an unloading scroll... so 28000BTU output on low, it would cycle on and off in about 20 minute cycles with a 5-6F temperature swing if I did my math right. Now, let say 6000BTU's are used for hot water dehumidification. Now the condenser fan would just be poking along at maybe 50% speed.

[CraziFuzzy]

The goal is more for zoning and comfort, not direct energy savings.

The compressor can be 2 stage or use multiple compressors and refrigerant circuits. Very easy to split the heat exchanger into 2 circuits.

Why are they noisy? The condenser shouldn't be any different from a residential condenser. Eveen better, the condenser fan on a unit that generates hot water as well, should have a ECM motor and ramp down based on head pressure. At night in particular, it would be running at a pretty low rate.

We're not talking 150T+ screw machines. Those are very noisy.

+1 on the buffer tank. With just 50 gallons of storage, if you have a building that has a max load of 3 tons, and when at just 1/3 load, 12000 BTU's, with an unloading scroll... so 28000BTU output on low, it would cycle on and off in about 20 minute cycles with a 5-6F temperature swing if I did my math right.

Really, the buffer's capability is a function of the system's delta-t between chilled water supply and return. Larger delta-t, the greater amount of cooling the buffer can hold. With oversized coils, you can run with a very large delta-t (20°F+) and get a lot of buffering from your storage. A tall-skinny insulated storage tank would be perfect for this, as it would allow the tank itself to maintain some stratification. cold water at the bottom, warm water at the top. A couple temperature sensors over the length of the tank to determine the thermocline level would be the indicating factor in controlling the chiller's cycling (or staging).

[motoguy128]

So you put the storage on the return side. I'm used to primary/secondary system where the storage is the point where the 2 loops combine together. I figured in this case, the storage woudl be on the supply side and you'd store cold water. I do see how it's better to store return water and create a heat sink and have a wider temperature swing. The downside, is that the RWT would be lower on average at the chiller.

If you have a zone system, you would end up with a primary/secondary set-up anyway, sicne you'd want ot maintain water flow across the chiller, but wouldn't need as much flow to the zones.

Using delta T is a good way to modulate or stage a chiller.

[CraziFuzzy]

So you put the storage on the return side. I'm used to primary/secondary system where the storage is the point where the 2 loops combine together. I figured in this case, the storage would be on the supply side and you'd store cold water. I do see how it's better to store return water and create a heat sink and have a wider temperature swing. The downside, is that the RWT would be lower on average at the chiller.

If you have a zone system, you would end up with a primary/secondary set-up anyway, since you'd want to maintain water flow across the chiller, but wouldn't need as much flow to the zones.

Using delta T is a good way to modulate or stage a chiller.

No, I am talking about the storage being the decoulper between the primary and secondary, just as you describe. I'm just talking about using it as a stratified tank, using the stratification as the indicator of energy storage, and use THAT to stage the chiller.
Example:
314291

[xarralu]

Actually, with a decoupling buffer tank, you don't have to have the temperature swings. The air handler can maintain a nice steady temperature control, and the chiller will cycle as needed to maintain the buffer's charge.

Exactly my point. You just basically said the same thing I did.

[Dallas Duster]

Exactly my point. You just basically said the same thing I did.

But don't you add the need for an extra chilled water pump? I think the important thing to do is keep it simple and straight forward lets not try to over think this. How was your training class?

[xarralu]

The goal is more for zoning and comfort, not direct energy savings. .

Correct, I was referencing the absorption chiller when I said that.


Why are they noisy? The condenser shouldn't be any different from a residential condenser. .

Not the machine that Dallas Duster posted the picture of! It would be too noisy for residential use.

[xarralu]

I just PM'd you Dallas. Without being able to quickly draw it out, I would only use one pump. I would use a three way valve at the chiller and the storage tank and maintain CHW delta T across the FCU(s). Give me a few and I will whip up my drawing

[CraziFuzzy]

While yes, it WOULD work with a single pump, it is not as flexible as a 2 pump system. This difference is even more significant when dealing with multiple 'secondary' zones. So, yes, decoupled would require a different pump, but with the 3-speed pumps on the market not costing much more than a single speed, I think I'd rather run a 3-speed pump on the secondary with a 3-stage t-stat, and no valve at all, than a single pump and 3-way valves. Remember, it's important that the system maximizes the delta-t to maximize the effectiveness of the buffer.

[xarralu]

315761

If was able to do it, this is how my setup would look. Minimal amount of equipment to buy and maintain.

[motoguy128]

I wonder if the buffer tank should move to the retrun side of the chiller, and the chiller draws from the top and loop return is to the top, but the bypass is to the bottom of the tank. That way you get the warmest water to the chiller most of the time even when below minimum load.

I assume to lengthen minimum cycle times you might run the chiller to start at 44-45F and shut off at 40F.

[xarralu]

I see what your saying, but depending on how large the tank is it might take a while before the chiller can catch up, and before you could have a decent enough leaving water temp. With the way I have it drawn out the FCU(s) can have presidence.

If I was able to actually build a system like the way I wanted it, I would want the tanks to be very large (3,000+ gallons total). I have free electricity after 10 pm and I would like to have thermal storage if possible. In the hottest of summers my unit runs 14 hours a day (3 ton unit). So I would need 42 ton/hrs. storage plus be able to recharge the tanks. Just shootin' in the wind I would guess that a 10 ton chiller like this (http://www.multiaqua.com/pdf09/Multiaqua09_MAC120.pdf) that CraziFuzzy had mentioned earlier would work.

Yea, I know I'm dreaming...

[CraziFuzzy]

I've actually figured out that I would only need about 2 tons if running at night, to provide the cooling i need during the day, with about 2500 gallons of storage, but I wouldn't be able to use an off-the-shelf fan coil. I need one with a much larger chilled water coil, to provide full approach to return air temp to maximize the storage capacity. I think that's the primary problem with using that variable primary type system you posted - It is harder to ensure that max delta-t with that setup, and no way to always provide a fixed supply temp, regardless of return temp. You have to have that primary pump and 3-way recirc valve around the chiller, to ensure the outlet temp going to the storage tank is always at your supply setpoint. Running warm water into the cold end of a stratified tank is bad, as it destroys the thermocline, and overall degrades your recovery capability.

[beenthere]

Is that 2500 gallons with or without the A/C also running during the day.

[CraziFuzzy]

Is that 2500 gallons with or without the A/C also running during the day.

For my example, that was enough to keep the chiller OFF during the peak demand period (8 hours a day - 10am to 6pm). Power costs are the same for the other 16 hours of the day, so that was enough. That system i drew up a couple pages ago, that ran the chiller based on storage tank temps, would pretty much start topping off the tank as soon as the peak period ended.

That calc was also based on a chilled water supply temps of 44°F, and a full return temp of 74°F, which is why it would require a large multi-stage coil, but the higher the delta-t, the better stratification you get, and the more storage you can have per gallon.

[Dallas Duster]

Makes me wonder if you read an article in "supply house times" talking about small scale chilled after cooling as a developing market. The article was by John Siegenthaler, P.E..

[CraziFuzzy]

Makes me wonder if you read an article in "supply house times" talking about small scale chilled after cooling as a developing market. The article was by John Siegenthaler, P.E..
I have not, but I'm not surprised to see the article. It IS a natural progression, and a single change that opens up much more opportunities with little extra engineering. Water is the perfect medium for heat transfer in homes, mainly because of it's safety, and, if for no other reason, is already piped to every home. It takes nothing to add on 'extra features' to an established chilled water system. Want to stretch out cycle times? add in some buffering storage. Want to shift loads (something that is a much harder proposition with direct cooling), just add a larger tank. Want to zone? sure, that's simple. Want to expand the system to that new addition? sure, just add another fan-coil there. Did the chiller just die? okay, go to the store and buy another one off the shelf - they are self contained units, not requiring any recovery, charging, vacuum, etc. I know THAT part the residential part of the industry doesn't want, but in the end, it's going to happen.

[xarralu]

I've actually figured out that I would only need about 2 tons if running at night, to provide the cooling i need during the day, with about 2500 gallons of storage...

I was just trying to run some numbers of my own and I was wondering how you can up with your 2,500 mark. The last thing I have run across is this from ASHRAE. (http://www.oeashrae.org/Presentations/2009_10/Thermal_Energy_Storage_Tank_Design.pdf)

All in all I'm coming up with some pretty broad numbers and I was wanting to nail something down.

[motoguy128]

I was just trying to run some numbers of my own and I was wondering how you can up with your 2,500 mark. The last thing I have run across is this from ASHRAE. (http://www.oeashrae.org/Presentations/2009_10/Thermal_Energy_Storage_Tank_Design.pdf)

All in all I'm coming up with some pretty broad numbers and I was wanting to nail something down.

That's a good question. I assume you'd have to know your average heat gain during design conditions. Then you determine what the 24 hour average is and then size your storage so your chiller is sized for hte average load and run continously but you have enough water storage.

Its' just thermal mass. You can accomplish a similar effect if you had enough concrete or masonry walls in a home. This is why IMO, energy efficient structure design needs ot encorporate materials when possible with a lot of thermal mass. SO using ICF's. I've mentioned in another thread, that I think you could easily raise the sill plate up to at least a point level with the bottom of the 1st floor windows. Homes should be 2 story and use stucco, brick or stone on the exterior. Have deep overhangs for shading the building in the summer, and less in the winter, use interior walls (non of this open concept garbage) and use stone, brick or plaster, instead of gypsum for interior walls too. Close cell spray foam of course and unvented attics with cool roofs.

Actually, with enough thermal mass in the structure, the need for water storage could then be sized to target a minimum cycle time at low load conditions.

[CraziFuzzy]

I was just trying to run some numbers of my own and I was wondering how you can up with your 2,500 mark. The last thing I have run across is this from ASHRAE. (http://www.oeashrae.org/Presentations/2009_10/Thermal_Energy_Storage_Tank_Design.pdf)

All in all I'm coming up with some pretty broad numbers and I was wanting to nail something down.

my 2500 gallon number is considerably oversized, but that is for a couple reasons. part of the space has to be taken up by the termocline layer, so not the entire volume of the storage is 'usable'. also, I figured bigger is better, as tanks really aren't THAT expensive in this size range (I was looking at splitting the storage among say 3 separate tanks plumbed in series). My actual 'conservative calc' was based on how much it would take to store 24 hours of the 2 ton chiller's capacity. As such, that's:

24,000 BTU/hr * 24 hr * 1 lb/BTU°F ÷ 8.34 lb/gal ÷ 30°F = 2302 gallons

Previously, I had determined how much it would take to provide absolute worst case cooling on my home for the entire peak power period, which is about 3.5 tons for 8 hours. As such:

42,000 BTU/hr * 8 hr * 1 lb/BTU°F ÷ 8.34 lb/gal ÷ 30°F = 1342 gallons

so if all you are looking to do is shift load from the peak power period (for Time-of-use metering), it doesn't take THAT much of a storage system. It's also something that can easily be expanded upon. Starting with just 500 gallons will minimize the cycling, but adding tanks can seriously start to shift load.

[xarralu]

Great, thanks for the info.

[xarralu]

I know prices can't be posted in the open forum, but I was wondering if anyone has any idea of the cost of the 10 ton multiaqua chiller is? I talked to multiaqua a couple of weeks ago just for them to tell me that Trane is the distributor for their equipment in the Dallas/Fort Worth area. I have called and e-mailed every contact in the D/FW Trane office and still have not heard anything. Good 'ol Trane. Their reputation will never change!!!!