Trying to justify geo cost, looking at all factors

[gregbig2]

I'm thinking about installing geothermal at my house. I've been using this spreadsheet to look at costs of different fuels:
www.eia.gov/neic/experts/heatcalc.xls

My current system is forced air propane and I pay $3 a gallon for propane and 12 cents for electric. So propane shows about $35.58 per million btu and geo @ COP of 4.6 shows $7.90 per million btu. So geothermal would be 4.5 times cheaper. My question is, this spreadsheet doesn't take into account the electricity use of the furnace fan (single speed fan, %92 efficient furnace.) I'm thinking that fan costs me $10 a month to run. So do you factor that in? I mean, that's only probably $50 a year but it's a small factor to consider?

What do you guys think about that spreadsheet from EIA? I know I use at least 700 gallons of propane, so that's about 64 million btus so I should see about $1800 savings per year in heat costs alone, not even including the hot water and a/c savings. Is my logic correct? Is there something I'm missing and maybe I can't rely on that spreadsheet? I have some contractors doing heat/loss calcs , giving me estimates this week.

2400 sq foot home, tight, Allentown, PA.

[Chuck]

Wow! $3 per gallon! We are at $1.90.

It looks like you are close on your figures. You need to change the AFUE to 90 to get an accurate figure for your furnace. I do believe a blower motor is figured into the COP. Usually you will get a package unit and remove your LP furnace completely.

When you say your home is "tight" what do you mean? What kind of leakage rate when tested with a blower door?

[gregbig2]

Oh, how I would love $1.90 propane. I don't understand how it can be that much cheaper in WI than PA. Well, you can see why I want to go geothermal.

You say change to %90 on propane just because %92 isn't really %92? That %92 is only in ideal situations and I'm really only getting %90? But the cop on a geo heat pump of 4.6 really is 4.6? I changed the spreadsheet to %90 for propane and that causes propane to show $50 more per year, just by adjusting by %2. So now I'm over $1800 a year savings.

I meant the fan on the furnace, not the geothermal heat pump. I'm just wondering how much a fan on a propane furnace really costs per month. I know my electric bill seems to drop by $20 in the mild months like June when there's no a/c or heat, so I guess that's a good way to tell how much the fan is costing me. So I can include that amount on my savings. With a geo heat pump, during some cooler months like November, I may not see my electric bill even rise because the geo heat pump will use less electric than my furnace fan did, perhaps?

By tight I mean 2x6 walls so r-19. Probably not really tight, just not really leaky like an old house. House is 9 years old.
Here's results from blower door:
Measured leakage area 1.41 sq feet.
Test data: 50 pa house pressure, 120 pa flow pressure, 1714 cfm.
Avg air change rate: 7.83 per day.
Manual j air change rate: c=135 n=.65 winter = .041 per hour or 128 CFM, summer = .24 per hour or 77cfm.
Constant mechanical whole building ventilation rate = 61cfm.

[SkyHeating]

How many sq feet is the home? Last November we changed out a propane furnace and 10 year old AC for a geo system(5 ton water furnace dual capacity) and the customer has saved about $3,800 a year, but they were also using 1,600 gallons per year. You should have NO problem justifying the geothermal in longevity, added comfort, reduced noise levels, increased home value and of course doing something green. I don't know if your part of the country does vertical or horizontal loops but if they do horizontal check out my YouTube listed below to see some propane to geo change outs and how to put in a ground loop. The most important factor is to find a contractor that knows what they are doing. I have seen 20 years of experience mess up jobs and newer companies get it right so really compare and contrast your dealers and ensure they know their systems. Look for IGSHPA certified installers and as a WaterFurnace dealer I would check their dealer locator. I have represented other brands before and I can tell you that nobody trains and supports their dealer like WaterFurnace.

[gregbig2]

Home is 2350 sq ft. Seems like every contractor so far said they do vertical. Yep, I had a waterfurnace guy here this evening. I'll check out your youtube, thanks. I have an acre lot but every contractor is telling me I don't have enough room for horizontal and vertical is better, but I don't see why they couldn't put in a loop, I have wide open back yard. I have one more guy coming Saturday, his business is all geothermal, will see what he says.
I'm really hoping to get away with 3 tons based on the blower door test and heat/loss calc.
I had one guy tell me 4 tons already, but he also tried to pull a fast one and entered 9 cents/kwh when I know that he knows it's 12.5 cents and hasn't been 9 cents for like 9 years. He was using a online portal to show costs and skipped right through the electric rate section. I had to ask him what he used for kwh. Skum bag.

Also tried to tell me that propane furnaces made when mine was made, around 2003, only last 8-12 years because the government made the manufacturers make them more energy efficient so they used thinner metals, so they only last 8-12 years. Tried to convince me that my furnace only had a couple more years on it to make geothermal look better, again skumbag. I don't think there's any truth to that at all? Furnace should last on average 20 years? Not sure how these guys think they can lie like that. This guy was an igshpa certified installer too.

[SkyHeating]

Vertical certainly is more efficient but in my part of the country cost three times as much as horizontal. I wouldnt worrt about finding a way to fit a horizontal. Just make sure vertical wells are fully grouted and properly spaced. You are also right abiut the furnace with proper maintenance you sgould get 20+ years from it. In my experience and opinion geo is so much better you can replace a 1 year old furnace and ut still makes sense financially.

[arc8]

I don't think conventional furnaces are at 20 years average. Yes they can last 20 or maybe more, but it depends. I believe the average is definitely less than 20 years. Some brands don't last as long as well.

Another thing, I don't think you can get more than a 4 COP in your area, unless your winters are mild. Matter of fact, you might be able to see your contractors Geothermal Calcs that they should have done. That will show you and us alot what your Geo system can do. Ask for it.

I do like Geothermal systems, they are awesome, but sometimes it makes sense to go with the next higher efficient system then the Geo (like Air Source HP).

Your PSC motors (blower) are between 500 to 800 watts. If you know your approximate run time (in hr increments) you can total it up and figure it out.

I hope this helps.

[gregbig2]

Thanks for the feedback. Arc, you said you don't see me getting more than a 4 COP, please explain. I don't understand that. I thought the outside temp was irrelevant with the geothermal since the ground is at a almost constant temp. So why would the COP vary based on climate? Shouldn't the COP only vary based on the temp of the ground/water in the wells?

[SkyHeating]

I thought the outside temp was irrelevant with the geothermal since the ground is at a almost constant temp. So why would the COP vary based on climate? Shouldn't the COP only vary based on the temp of the ground/water in the wells?

the outside temp is mostly irrelevant but as it gets colder your system takes more heat out of the ground so the ground temps will change a few degrees, a knowledgeable contractor should so you expected performance data on loops in your area.

For example, here in Portland Oregon, a loops EWT(entering water temperature) is usually in the low 40 degree range even though our ground is 52-55 year round. When a system is rated for 4.6 COP that is only if the ground water coming in is 50 degrees so at the realistic conditions of 40 degree incoming water your COP will be 4.1 not 4.6. This still makes geothermal much more efficient than any air source below about a 40 degree outside air temperature and in the summer your realistic EERs could be as high as 25 while the best air source I know of is a 14 EER on an 82 degree day. Don't confuse EER with SEER as air source and ground source heat pumps are rated differently.

Air source vs Ground source.
At 47 degree outdoor temp an air source may be a 4.1 cop and the ground source is let's say a 4.3 COP, now as the temperature drops the air source goes from being a 3 ton unit at 47 degrees to only providing 1.5 tons of heat at 17F with a COP of 2.1 while the ground source has now maybe dropped to 4.1 COP but is still providing 3 tons of heating. There is more than just efficiency to look at because if your air source is a 3 ton unit but it can't provide the three tons of heating needed due to outside air temp dropping and it loosing capacity then the air source shuts down, negating any savings and turns on your backup expensive propane furnace and you are back to where you started. I'm sorry ARC8 but air source 9 times out of 10 can't hold a candle to a geothermal system. Arc8 I. An also tell you with over 20,000 gas furnaces installed in my area installed by my company the average life is aout 20 years.

[arc8]

Thanks for the feedback. Arc, you said you don't see me getting more than a 4 COP, please explain. I don't understand that. I thought the outside temp was irrelevant with the geothermal since the ground is at a almost constant temp. So why would the COP vary based on climate? Shouldn't the COP only vary based on the temp of the ground/water in the wells?

Not all ground temp are the same. The northern ground temps are colder than the southern region. It also depend on your water flow, hopefully it's correct when installed, which can be caused by the loopfield design as well. And of course, your space temps also affects the final COP of your system.

If you know which brand and model of equipment, you can find it listed on a performance data on any particular model. Your contractor should be able to show it to you.

[arc8]

Air source vs Ground source.
At 47 degree outdoor temp an air source may be a 4.1 cop and the ground source is let's say a 4.3 COP, now as the temperature drops the air source goes from being a 3 ton unit at 47 degrees to only providing 1.5 tons of heat at 17F with a COP of 2.1 while the ground source has now maybe dropped to 4.1 COP but is still providing 3 tons of heating. There is more than just efficiency to look at because if your air source is a 3 ton unit but it can't provide the three tons of heating needed due to outside air temp dropping and it loosing capacity then the air source shuts down, negating any savings and turns on your backup expensive propane furnace and you are back to where you started. I'm sorry ARC8 but air source 9 times out of 10 can't hold a candle to a geothermal system. Arc8 I. An also tell you with over 20,000 gas furnaces installed in my area installed by my company the average life is aout 20 years.

It's amazing what each area is capable of doing to the equipment minus the other things by the occupants. They must run more than where you are at.

Now about those ASHP. Is that a blank statement across the nation? Around here ASHP can hold water and put out the candle in some instances. I disagree that ASHP's have no competition with Geo's, at least around here they do. Matter of fact, here we usually install plenum heaters, it doesn't matter if it's a Geo or ASHP. We size up systems based on the cooling, not heating; we size systems by the book (ACCA's way).

All and all, if a GEo does not make sense financially (ROI), I usually recommend the second choice ASHP. I wished all could afford a Mercedes, but it is not possible.

[SkyHeating]

I don't see how an air source is close to that of a geo, please explain. Does air source take care of your water heating needs that can be $400-$550 a year with electric or propane? Geo can do some or all of the water heating. Does geo provide constant capacities even in 0f temperatures without backup heat? Yes. Can air source start up with minimal LRA in case of generator operation? No but geo can. In my area and this is not true of all, but a geo can be had for the same and often less after federal tax credit than a two stage or Invertor heat pump. Does air source lose up to half it's efficient at only 17f yes but once again geo may lose 5-10% at most depending on loop.

I didn't realize you were in MN I can see why your furnaces wouldn't last as long but I still see many 40 year old units in my area, very poor efficiency but running yes.

Have you installed geothermal before? I used to do just air source and thought the same things until I really dug deep and had some comparisons from houses with top of the line air source vs even basic geo and the geo in my mild climate usually made sense(biggest restriction is land size) so in colder climates with smaller cooling loads thus according to ACCA more heat strips required the geo took off in average seasonal COP.

[crash11]

Skyheating is right. Geo will always be better..............when installed correctly.

[19characterusername]

First cost and design cost has always been an issue with GSHP. If its cheap and easy to put pipe in the ground where you are, GSHP is great, but you need to make sure you have enough pipe in the ground. That's not easy. You need someone who understands local hydrogeology well.

ASHP performance on an annual basis is worse than GSHP but closer than you'd think. ASHP performance is also easier and cheaper to accurately predict. If you're looking to combine water heating I'd look at Daikin Altherma or the hydronic attachments to mitsubishi's city multi system. Both of those systems have good low ambient performance.

I think something like the Altherma would be a cheap and easy "bolt on" solution to your energy cost issue by adding a hydronic coil to the existing propane furnace system (probably in place of your existing DX cooling coil). On the DHW side you could put the Altherma DHW tank in a preheat position in series with your existing and run your recirc to the Altherma tank if youre not comfortable with peak day performance and want to minimize your capital costs now.

[gregbig2]

Interesting, very interesting. I googled Altherma and it looks like it's a inverter heat pump boiler? I'm trying to understand how that would work with my force air ducts though? Use a water to air heat exchanger? Or would I have to put those fan coil units in each room? Thanks

[gregbig2]

Sorry, I re-read your post and you explained it already, add a hydronic coil to the propane system. So I'd use my existing ducts. I could probably easily add a zone to the basement also with a fan coil. I will contact a local Daikin dealer, thanks.

[19characterusername]

If you went with Mitsubishi, you'd put small DX fan coils in each room and a hydronic heat exchanger on a recirc loop with domestic. They have a product called HydraDan that's just like Altherma but not available in the US.

Make sure you understand how the Altherma system wants to operate on the hydronic side before doing this. It looks more like a commercial two-pipe hydronic system to your terminal equipment, except add on the complexity of DHW priority during both cooling and heating. It will affect the piping layout. Basically you want to keep the tees going off to the Daikin DHW tank close to the hydrobox so that there isn't a big cold slug when it changes over for DHW priority in the summer and a big hot slug when it goes back into cooling once the DHW call is satisfied. Also I would suggest using three port valves on your water to air coils so that you keep a decent mass of water moving through the refrigerant to water heat exchanger. Speaking of those coils, size them based on 105F entering water in heating for best performance.

[SkyHeating]

Maybe your area is much different than mine but an Altherma costs MORE than geothermal where I am and does not receive a tax credit. I can put in a vertical bore or horizontal bore(about $18 per foot in my area to drill) for the cost of an Altherma and still have higher performance. Just something to consider.

[19characterusername]

At nominal 200-250 of borehole ft/ton equipment, that sounds like it would be 20 to 25 k to drill plus equipment and installation less the tax credit. Which isn't bad, I guess. I'm not sure how much Altherma systems are running per ton, and in propane territory you should have lots of skilled people who can make big holes in the ground for a reasonable price. So it's something to consider.

I've dealt with a bunch of site constrained closed loop projects and drilling ends up being expensive and logistically constraining the balance of activities on site. Worse, I've had a bunch of boreholes come up short due to broken drill bits and difficulties getting through frag rock. When you've got lots of space accessible to the drill rig it's easy to just dig another hole if one goes awry or comes up short and the drill rig doesn't hold up other activity.

From a carbon and energy perspective, ground source is hands down the way to go. I've just been burned with drilling issues.

[waterpirate]

The lion share of drilling issues are based in in-experiance. I have taken my share of lumps. When you pile up issues on one site, you are generally asking for it. We counter act nature by talking alot upfront about fall back positions and plan B's on sites where the lot size does not allow any flubb. The other side of that is that you really need to hire a looper that is local. They know when and where to expect what and how to deal with it, or punt.
Eric

Just to stir the money pot a bit. Vertical closed loop resi goes for 6 dollars a foot in my AO.