Boiler Question

[GT Jets]

You know, I don't think it's been mentioned plain and clear but did you ever think that the reason they use electric strip heat in these buildings is because your in a warm climate where heating in high rises is barely needed? These places practically heat themselves to about 50-40 degrees. In Dallas that's about the average winter high.

I could EASILY see the engineers that put these systems together saying that very same thing, and just throwing strip heating in because it's cheapest and will hardly be used anyway.

Up north hydronics and steam is definitely predominant and looks to stay that way for some time.

Nothing is the way it seems. Things do go in and out of fashion. Right now I'd say hydronics and chilled water etc have made a bit of a comeback.

And don't forget alot of decisions are made based strictly on money, cost effectiveness etc. There really is no set date for when anything went in/out of fashion lost/gained popularity etc. Everything is different city to city, building by building.

You seem like you could use some more hands on experience, outside of your home evironment. Things really are a bit different then how your original statements make it sound.

Very eloquent.

Your are correct, however....

He uses the terms "all newer building have strip heat", this is bunk....

He uses the terms "boilers are being phased out due to install costs" again, bunk.

And I totally agree with you, he needs to tour about a half a dozen LEED platinum buildings and get a feel for the direction that the building industry is heading.

That is my argument in it's entirety. BTW, did you see the electrical statistics on the Dallas bank building? Holy crap Batman! In California you could run three city blocks off that badboy...

GT

[MHall]

Hold the phone.. You said "new construction" boss... Check again, 527 Madison is NOT a new building. Since when in 1986 new? it's almost twice as old as you are....

Almost 30 years old is NOT newer., Check into buildings built in the mid 90's on...Using your own criteria, ALL buildings built since then used virtually NO strip heat as their primary heat source.


At what point do you call a building "old".


I can assure you, things have changed dramatically since the mid 1980's.

As I stated earlier anything built 1981 or prior usually has a full central plant system including steam or HW heat provided by boilers, district steam, and heat recovery chillers. Anything built after about 1982/3----to the present seems to utilize electric heat, hence the examples I listed. I could show you brand new properties and you would see DX units and electric heat.

[timmy2734]

As I stated earlier anything built 1981 or prior usually has a full central plant system including steam or HW heat provided by boilers, district steam, and heat recovery chillers. Anything built after about 1982/3----to the present seems to utilize electric heat, hence the examples I listed. I could show you brand new properties and you would see DX units and electric heat.

Dude, once again, you're wrong. I posted about 4 buildings last page, with the oldest being 2008. No electric heat in sight.

The funny part is, that I'm not annoyed one bit nor do I think anyone else is.

[GT Jets]

As I stated earlier anything built 1981 or prior usually has a full central plant system including steam or HW heat provided by boilers, district steam, and heat recovery chillers. Anything built after about 1982/3----to the present seems to utilize electric heat, hence the examples I listed. I could show you brand new properties and you would see DX units and electric heat.

The highlighted area is where you lose me completely... This information is wrong for MOST areas of the country... The DX units you are mentioning are more than likely going to be heatpumps.

Look up FHP (Florida heat pumps) these are water to water heat pumps. Also look up CHP (California heat pumps) these are water to air systems. Both considered DX when loosely translated.

When done correctly, these systems can be crazy efficient and provide an almost perfect environment.

As stated before, you would never get a building permit here in Silicon Valley for all electric heat... Not in a million years. This is why I am so passionate about letting you know that what you are saying is not accurate. If you ever move out of Dallas you will be totally lost.

GT

[MHall]

The highlighted area is where you lose me completely... This information is wrong for MOST areas of the country... The DX units you are mentioning are more than likely going to be heatpumps.

Look up FHP (Florida heat pumps) these are water to water heat pumps. Also look up CHP (California heat pumps) these are water to air systems. Both considered DX when loosely translated.

When done correctly, these systems can be crazy efficient and provide an almost perfect environment.

As stated before, you would never get a building permit here in Silicon Valley for all electric heat... Not in a million years. This is why I am so passionate about letting you know that what you are saying is not accurate. If you ever move out of Dallas you will be totally lost.

GT

What about heat recovery chillers for hot water heating? I am being completely honest, when I say that this application seems quite rare. I have only heard of one building in my area, (and it is an older building), that utilizes this type of system.

[timmy2734]

I've never seen one.... Surely you could use it to preheat your water, but I think that you'd still need a dedicated hw heater.

found some reading material

http://www.mcquay.com/mcquaybiz/lite...er-HeatRec.pdf

http://www.johnsoncontrols.com/conte..._%28510%29.pdf

[GT Jets]

What about heat recovery chillers for hot water heating? I am being completely honest, when I say that this application seems quite rare. I have only heard of one building in my area, (and it is an older building), that utilizes this type of system.

This is actually the beautiful part about WSHP systems, lets say I had twenty heat pumps heating and 15 heat pumps cooling, I would not have to inject any heat nor would I have to reject any heat. I would simply be taking the heat from once space and moving it to another.

I know that is not what you are referring to, but it works out the same.

It is not (as far as I know) a widely used system because of the small window of utilization versus the expense and maintenance involved. You need to have really warm condenser water to be able to get much use out of it, and that takes most modern chillers out of their "comfort level" as far as efficiency. Think about it this way, most newer chillers like the coolest water possible for the condenser (in the low 70's), raising that temperature enough to gain much sensible heat out of it (high 80's) would likely negate any gains from recovering the heat.

Hope I didn't con-volute the crap out of that, I get the feeling I did.

There are chillers specially designed for this use and I don't think the total efficiency is there yet.

What seems to be on the cutting edge these days is in the refrigerant side for economizing with liquid refrigerant. The biggest issue so is the vast quantity of refrigerant required to accomplish it.

GT

[MHall]

This is actually the beautiful part about WSHP systems, lets say I had twenty heat pumps heating and 15 heat pumps cooling, I would not have to inject any heat nor would I have to reject any heat. I would simply be taking the heat from once space and moving it to another.

I know that is not what you are referring to, but it works out the same.

It is not (as far as I know) a widely used system because of the small window of utilization versus the expense and maintenance involved. You need to have really warm condenser water to be able to get much use out of it, and that takes most modern chillers out of their "comfort level" as far as efficiency. Think about it this way, most newer chillers like the coolest water possible for the condenser (in the low 70's), raising that temperature enough to gain much sensible heat out of it (high 80's) would likely negate any gains from recovering the heat.

Hope I didn't con-volute the crap out of that, I get the feeling I did.

There are chillers specially designed for this use and I don't think the total efficiency is there yet.

What seems to be on the cutting edge these days is in the refrigerant side for economizing with liquid refrigerant. The biggest issue so is the vast quantity of refrigerant required to accomplish it.

GT

Thank you for your informative post. I greatly appreciate you taking the time to explain the system’s operation. Tomorrow I will post some more questions.

[GT Jets]

Thank you for your informative post. I greatly appreciate you taking the time to explain the system’s operation. Tomorrow I will post some more questions.

You are very welcome.

Just one last jab before I go do a high intensity light filtering eyelid performance check...

If you have a heat recovery chiller (duplex condenser) you have to have a hydronic heating loop regardless, so technically speaking this would be a great retrofit to an existing building with separate systems. Especially if there is a really consistent load on the chiller (like a manufacturing facility with office space).

GT

[Gus-Herb94]

As I stated earlier anything built 1981 or prior usually has a full central plant system including steam or HW heat provided by boilers, district steam, and heat recovery chillers. Anything built after about 1982/3----to the present seems to utilize electric heat, hence the examples I listed. I could show you brand new properties and you would see DX units and electric heat.

You have said this a couple times but you can't be more specific as to WHERE your referring to? Is this a blanket statement for the whole country or are you referring to your city Dallas? and have you actually seen these electric heat strips your talking about or are you taking somebodies word for it?

I can think of at least one building built before 1981 that does not have a "full central plant" and that would be the Sears tower (Or Willis tower as you probably only know it as at this point). It has water source heat pumps (I haven't seen this for myself, but have heard this from quite a few techs around this area). That was completed in 1973.

[ckartson]

Requirement is based on boiler horsepower. 30 hp and greater. hense the ohio special only 29 hp

[MHall]

I've never seen one.... Surely you could use it to preheat your water, but I think that you'd still need a dedicated hw heater.

found some reading material

http://www.mcquay.com/mcquaybiz/lite...er-HeatRec.pdf

http://www.johnsoncontrols.com/conte..._%28510%29.pdf

My question concerns the operation of heat recovery chillers for hot water space heating. Not domestic hot water.

[timmy2734]

No worries. It is performing the same function though. It's all just going into a heat exchanger.

Have you ever checked out tecogen chillers?