<!--[if gte mso 9]> Normal 0 MicrosoftInternetExplorer4 Hi,

 

We’re seriously considering geothermal, and we’d love some feedback on our particular situation and these potential contractors.

 

Our house is a 1941 brick cape cod with approximately 1400 finished square feet above. We have a basement, half finished, of about 850 square feet (so 425 finished). We’re currently using about 1200 gallons of heating oil per year (about $4000 at today’s prices), plus about $440 in electricity for our window units. We believe, based on these numbers, that the house has basically no insulation. We have no ducts at this point.

 

We’re looking into the Keystone Help Whole House Geothermal Loan program, which would require us to get a HERS energy audit and make other envelope improving fixes like air sealing and insulation.

 

Here is what our potential geothermal contractors have recommended:

 

1)      Says they do about 120 installations/ year.

a.       Recommends 3 ton climatemaster Tranquility 2 stage system, with desuperheater and extra 52 gallon electric water heater, HONEYWELL FAN POWERED HUMIDIFIER

b.      Cost of 17308 PLUS drilling costs of approx 5850, so a total of 23158.

2)      Says they do about 80 installations/ year

a.       Recommends 2 ton Tranquility 27 2 stage system, 10 kw aux heat, Bradford White 50 Gallon Electric Water Heater.

b.      Proposal is not specific about well depth etc

c.       TOTAL cost including drilling, 17880.

3)      Says they do about 75/ year

a.       25 years experience with geothermal

b.      Recommends 2 ton WaterFurnace Envision series 2 speed, desuperheater with 50gallon pre-heat tank, 8kw auxility heater

                                                               i.      2 ton loop, 300’ drilling with 600’ of 1.25” pipe in the ground

c.       Total cost of $19741

4)      Says they do over 50/ year and have over 25/ yrs experience

a.       Says that a load calculation on the house revealed it needed a 6 ton unit, and he didn’t recommend proceeding unless we get increased insulation. He dropped some numbers that don’t make sense to me, but may to you: 24 degree balance point, 2^nd floor needs 12000 CFM.

5)      Says they do about 100/ year.

a.       He did geothermal for a friend of mine, and they are very happy with their system.

b.      Presented me with load calculation documents showing that I probably currently would need a 5 ton unit. It shows a need of 72895 BTU heating and 41349 cooling, which apparently corresponds well with what we’re currently spending.

c.       He recommended only doing geothermal if we can use the audit/ insulation to get down to a 3 ton unit with more like 53806 BTU/heating and 26186/ cooling.

d.      He recommended a 3 ton Waterfurnace #NDV038, 2 stage, with desuperheater and 15kw aux heat; Two 50 gallon water heaters, one as preheat buffer tank

e.       Cost of 20492 plus 3.4 ton of ground source heat exchanger (2- 260) using 1” high density piping; he also provided me with a loop details report, though I’m not sure which if any of those numbers might be useful to you guys

f.        Total cost of $27000

g.       Recommends zoning second floor because it will be tricky to get vents up there and will probably not heat/ cool the same as the 1^st floor (extra $1600)

 

Obviously there’s a great variance in recommendations and costs here, from 17k for a 2 ton to 28k for a 3 ton. The last contractor gave me the most information and generally impressed me with his knowledge and expertise. If costs were equal, I’d certainly go with him. I’m inclined to discount the 2 ton folks because, based on conversations with contractor 5, I wonder if they really listened when I told them we were going through 1200 gallons of oil per year. Apparently, if our load really was 2 tons, we should need a lot less than that.

 

Ideally, we’d get our energy audit and figure out what our new load will be before deciding to do geothermal or not. Unfortunately, that’s not the way this loan works; we need to decide and commit BEFORE the audit, because we have to get a fancier (HERS) audit if we’re doing geothermal. We plan to, at the very least, go ahead and get air sealing and insulation.

 

The reason I want to do this is that we’re spending ridiculous money on oil, and we’re planning to stay in the house long term—probably 20+ years. At our current spending level, we’ll spend 44200 over 10 years. I would rather invest that in geothermal and then pay substantially less in 10 years.

 

I am concerned, however, because if we go with the last contractor and get our additional air sealing/insulation improvements, we may be looking at $35k. At the loan rate of 3.875, this will cost us $350 per month, or 4200/ year. Contractor 5 estimated our new energy costs at $1023/ year. He said this would be quite reliable since his numbers for our current expenses were so dead on, and our friends who had them do their geothermal system are spending about that per year.  We could then deduct tax rebates (which I calculate we’ll only be able to take 7500 of, since our tax liability isn’t very substantial) and various energy rebates/ incentives to hopefully make the cost comparable to what we’re spending now.

 

I’m mainly concerned because it looks like we can do this, but the numbers need to be reliable. If geothermal ends up costing us $2000/ year, so that we’re spending $6200/ year for the loan and the energy costs, we’ll be in trouble. Our margin for error here is small, so while I really want to get away from oil, I’m worried.

 

How likely do you think it is that oil prices will continue to go up, at least pacing with inflation? That makes this a better investment.

How reliable are post- geothermal cost calculations if they do a good load calc?

Should I discount the contractors who recommended 2 ton units?

And any general recommendations you have.

 

In advance, thanks so much for your expertise.

Laura

Sorry laura its late and I don't have time to digest this but my first blush would be closer to 3 tons. i'll weigh in later, but let's make sure everyone who will ponies up their load calcs. throw in closest major city and we can offer more.
j

Thanks for the help, Joe!

We're about 40 minutes from Harrisburg, PA. All our windows are single pane, though we do have storm windows. Also, our oil heat is from hot water radiators.

First off if the load numbers are good the op cost calcs can be reliable.
Have to do the numbers later, but can't belive you have a 72MBH load (do you have glass in your windows?).
Would not discard the 2 ton, but would ask for supporting load calcs.
j

At least get some quotes on more extensive insulation upgrades plus geothermal.

Yes, we do have glass in the windows. However, it's a 1941 house, and I believe that we have no insulation in the walls-- and it would be hard to put insulation in the walls, since it's brick over concrete with, I believe, no more than a 3/4 inch space there, so there would probably never be a ROI on insulating the walls. We have no attic access, but I believe, given the oil $ we're spending, that there's no insulation up there. The one contractor (#5) said that those 72MBH numbers were consonant with what we're actually spending and using-- 1200 gallons of oil per year.

But, it seems like [based on my minimal internet research etc] there's a BIG difference between no insulation and some insulation, so if we could get some stuff in the attic that our numbers could go down significantly.

You may want to try to get hold of Dana1 in this forum (regarding insulation options and value.)

Even 3/4 of foam is far better than nothing. In fact, the first little bit has the highest ROI.

Posted By lgeldred on 17 Aug 2011 09:07 AM
Yes, we do have glass in the windows. However, it's a 1941 house, and I believe that we have no insulation in the walls-- and it would be hard to put insulation in the walls, since it's brick over concrete with, I believe, no more than a 3/4 inch space there, so there would probably never be a ROI on insulating the walls. We have no attic access, but I believe, given the oil $ we're spending, that there's no insulation up there. The one contractor (#5) said that those 72MBH numbers were consonant with what we're actually spending and using-- 1200 gallons of oil per year.

But, it seems like [based on my minimal internet research etc] there's a BIG difference between no insulation and some insulation, so if we could get some stuff in the attic that our numbers could go down significantly.

Is it brick over poured concrete, or is it brick over CMU (concrete blocks, with hollow cores)?

You can't get away with insulating the masonry cavity between the brick & concrete in a PA climate without stressing the brick from freeze/thaw cycles- it'll spall, frost-heave and fail if you do.  But you CAN use non-expanding injection foam in CMU cores.  (eg. CoreFill 500, Tripolymer, etc. google- "non-expanding injection foam" for more.)

Assuming it's a  a 6" CMU wall + brick facing with 3/4" cavity, your wall R-values are probably around R2 (give or take, depending on actual construction.) Your windows + storms are also about R2. A core-fill with non-expanding injection foam would more than double that R to ~R4-5.  If it's an 8" CMU wall you're starting out at around R2.5, and a core fill would bring it up to ~R7-8.

Attic insulation is the easiest & cheapest retrofit you can do for most homes.  Air-seal the heck out of the ceiling, and give it at least a foot of cellulose.

You should also insulate the foundation walls to at least R8 with rigid foam board- preferably unfaced EPS or XPS, not foil or vinyl/poly faced goods, since you want ground moisture to still be able to dry toward the interior rather than forcing it to rise above grade creating spalling & mortar failures there.  To meet code you'd need to put 1/2" gypsum or other fire-rated igntion barrier on the interior. (half-inch OSB usually works, as does

For the kind of money you're talking for geo you might even consider a QuadLock Retro type whole-house retrofit, (even a DIY version) of R18 or more over brick, then heat the place with a much less expensive split-system air source heat pump (mini-split/multi-split).  It'll have nearly the efficiency of geo, but would likely come in at under $10K  now that you've cut the design-day heat load down by 2/3 or so.   The heat loss then would be primarily from the windows & doors, n the walls.  This marketing profile is quite similar to what you're currently facing, only yours is likely worse, since you're starting out around R2 rather than R5. 

There's no rocket science to this- it's pretty straightforward to add exterior foam to buildings using stock rigid foam of the type used under commercial flat roofing rather than QuadLock's slick fastening system.  Material costs on the foam using polyisocyanurate or EPS runs ~10 cents per square foot per-R. (R20 would then run ~$2 per square foot + assembly + finish siding.)  3" of iso is ~R18, 3" of EPS is ~R12, so in some aspects going with iso is easier to assemble when looking at R18+.  Up to about R24 the assembly costs will be about the same whether you're talking  R8 or R18, but as it gets  thicker than 5" or so it becomes more awkward and time consuming.

BTW:  Assuming a design temp of +5F (about the 99th percentile for Harrisburg), and an 80% efficiency boiler (it's probably lower than that for as-used AFUE due to age & oversizing factors) and 5500 base-65F heating degree days:

Out of every gallon of oil you get 0.8x 138,000=

110,400BTUs of heat into the house,

So with 1200 gallons for 5500 HDD (base 65) you're looking at (110,400 x 1200)/5500=

24,087 BTU/HDD

Hourly that works out to ~1000 BTU per degree-hour. 

The difference between 65F (the outdoor HDD base temp) and 5F (the design temp) is only 60F, your 99th percentile design condition heat load is really at most ~60KBTU/hr (=60MBH) not 72.  Heating contractors will often use numbers 5-10F lower than the ASHRAE numbers to build in some margin, but that's generally not necessary, since 10F below the 99% number is a once-a-decade condition, usually only a few hours in duration (and usually hours when most people are still in bed.)

Since your as-used efficiency on the boiler is more likely to be 70-75%, 60KBTU/hr is really an upper bound.   The 97.5th percentile design condition for Harrisburg is +11F, (and perfectly reasonable to use as a design temp) so it's likely you could heat the place comfortably with the house as-is with 50-55KBTU of heating system output.  But that's still more than 4 tons... So 3 tons of geo + some heating strips would get you there, but 2 tons might not even cover the January mean-temp of ~30F, and you'd be using the auxilliary heating strips a lot, which gets expensive.

But for the difference in cost between the 2 & 3 ton geo systems you could almost surely peel a ton or more off the peak load, putting it within the range of a (relatively) cheap-but-efficient mini-split air-source heat pump.

BTW: IF you add exterior foam of R10 or more over the brick, then it's OK to fill the 3/4" cavity with non-expanding injection foam, since the brick face no longer needs to purge rain & dew moisture, and will stay above freezing year round. At 3/4" you're adding nearly R4 to the stackup. If your structural wall is a 6' CMU rather than poured concrete, foaming the cores as well then brings the masonry side up to R7-8 if you also foamed the brick cavity, which means just 2" of exterior iso would then bring you up to ~R20, cutting the heat loss through wall area by about 90%.

Wow, Dana, that's really helpful. Thank you.

Looking down in our basement, it looks like the walls are concrete blocks, not poured concrete-- assuming that continues the same above the foundation level. I've had phone calls with a couple home energy folks in the area, and they'd said that insulating the walls probably wasn't worth it. Is the ROI on non-expanding injection foam in cores reasonable? Certainly no one mentioned R-ETRO as a possibility, and that seems pretty exciting. The house in the project profile even looks a lot like ours.

Whatever we do, we're planning at least to take care of the attic and the foundation walls. I'm talking with a couple home energy/ insulation people about audits and insulation, and their rough estimates have varied from 3-9k, so that's another source of confusion. None of the companies have Angie's List notes either, so I'm not sure how to choose.

Our furnace is 80% efficient; we have it cleaned and tuned up every year. But it's good to have some perspective on the tonnage/ BTU figures. It sounds like the guy who said we needed 6 tons was just crazy. The house is quite small and compact, even if excessively leaky.

Those 1200 gallons are also currently running our hot water heater throughout the year, so it's not pure winter heat. It sounds like some added insulation would probably get us comfortably into 3 ton range. It also sounds like the guys who recommended 2 tons might not have done a proper load calculation for us.

It's amazing to me the range of quotes we've gotten-- from 2 to 6 tons. If supposed experts can't agree on what your house needs, how's your average homeowner supposed to figure it out? That's why I really appreciate you guys providing advice and help.

The mini-split system looks interesting, and no one has mentioned it to us, though I admit to not liking the look of the interior units. Part of the appeal of geothermal is getting ducts added to the house in a tax-advantaged way so that we can have proper air conditioning, which we don't have now (window units). But either way, it's likely to mess up the aesthetics of our 1940s cape cod a bit, so I guess it's a matter of whether we want a couple boxed-out ducts or a couple wall units.

It looks like, if the contractor's projected costs of 1k electric/year hold up, we should be looking at a 10 year ROI for the insulation/geothermal job, which seems reasonable to me since we'd also get ducts and air conditioning out of the deal. When it moves over 10 years, then it seems more questionable.

Insulation- fine. Lest my point be missed however, I don't believe this house has a 72MBH load.
800 SF of lid, insulation or not in the walls, if there is glass in the windows and insulation in the attic I'd SWAG it at 40-50MBH.
I think bidder 3 is one of these guys that puts artificial conditions into his load calcs (i.e. drop design temp by 10.....).
j

I'm pretty sure that there is no insulation currently in the attic, so I think that's a large part of our problem and something easy to fix for our insulation contractor.

I defer to your superior knowledge of insulation, Dana, but I thought the current thinking about cmu is that inserts or core fills are pretty much a waste of money, that the webs of block conduct heat around the insulation and reduce its value. IIRC 2009 IRC effectively shot down core fills.

BTW, Igeldred, energy tax credits carry over, which is to say that you can keep claiming a share of it each year until you have all of it.

Todd, I believe that they're currently slated to roll over through 2016, but not after that. Is that right? We have limited tax liability, so it'll probably take us until 2016 to claim even 7500 worth of credits.

The credits expire in 2016 but, as far as I know, once you claim a credit the money is yours no matter how many years it takes to get it. Gotta say though, that a big loan for geo is risky business if your finances leave little margin for error. Have you explored Pa's weatherization programs? http://www.newpa.com/strengthen-your-community/redeveloping-your-community/housing/weatherization Otherwise, piecemeal is relatively painless. Insulating the attic would make the biggest immediate impact.

Talk about low hanging fruit....no attic insulation? Did 2 and 3 ton bidders plan on adding that?

Even though the furnace is 80% efficent steady-state, it's almost certainly oversized, and only hitting in the mid-70s due to cycling issues. Given that you're heating hot water with oil as well, knock 180-200 annual gallons off for the HW, so it's looking more like 48-50 MBH rather than 60MBH for the as-is condition.

Mini-splits do a great job at air-conditioning, even without ducts, but ductless solutions work best in open-floor plan homes that have at least some insulation, rather than doored-off smaller room setups. The interior units are clearly not designed with US-market aesthetics in mind, but they look a heluva lot better than window-shaker AC units, and don't block your windows either. I've seen some people screen them visually with valances (permenante, or curtain-type) to better match the interior look they were going for. That works, but it can mean having to point the remote control under the valance to get a good link.

toddm: yes, the webbing is a HUGE thermal short, which is why even though those foams run R5/inch and you're putting in a couple of inches, filling the cores only adds R2 to the stackup even though the cores are 3" deep. And it's not cheap- the better money is spent on exterior foam if you can go there. If overall wall thickness is an issue, it may in some cases be worth filling the masonry cavity for the extra R, but I'd get it quoted. The core fill probably only worth it if you're not going to add exterior foam. (It's a VERY expensive R2, to be sure.)

Ok so if 48-50 is as is condition and no attic insulation exists, we might be able to make a good case for 2-3 tons with a modest amount of work.