So I would like to replace my Lennox Completeheat with a ground source geothermal system. I currently have a single completeheat boiler/water heater with 2 air handlers. Home is 4800 sq ft-about 60% above ground single level and 40% basement mostly below grade/no walkout. Climate is eastern Washington state-typical winter day is lows of mid 20s, highs in low 30s and summer hot days run 3 weeks or so of 100-105dF and very dry and then mid 90s for the rest of the heat of summer. First quote: Guy comes out, looks at system, looks at air handlers and A/C units. Doesn't measure anything so clearly doesn't so a manual J. He quotes for 2 5 ton geothermal water-air units and a 3 to water to water for domestic. He also quotes a few odd things like 2 solar water heater panels to dump heat into the ground loop,etc. His bid is $64k Second quote: Very professional team of 2 arrive from Econar dealer. They work together to measure every window, room, etc and do a manual J with a winter design temp of 0dF. They quote a 4 ton and a 3 ton Econar Vara 2 (2 stage units) with desuperheater on largest unit, electric storage tank and 90% efficient gas water heater for about $28k. They want me to bid my own excavation so they don't have to mark it up so add $3k, plus I'd need a couple air cleaners (say Aprilaire 5000 at $500 a piece self acquired) so let's say bid at $32k Third quote: Very professional young man does same as #2, measures each room, windows, etc. Looks at units. His manual-J is done for winter design temperature of 5dF. He quotes single 4 ton unit and tying together the air returns and such. All inclusive with air cleaner and excavation he quotes $28,000. So first guy was a crook, no way I'm going with complex system designed based on no real data (no Manual-J) but I have 2 different guys who claim to have done good, solid manual-J calculations and are apart by 3 tons or the addition of 75% more capacity! Manual-J for the single 4 ton guy was BTU heating 91,293, cooling 39,691 and CFM cooling was 1549. I don't have the other guys numbers House is 4800sq ft. Thoughts?!?

Interestingly, I just spoke with the gentleman who quoted just the 4 ton system. He acknowledged the heat loss calculation was 91,000 BTU and that the 4 ton unit would at best produce 48,000btu heating (at 50dF loop temp) or just 37,500 btu at a more realistic 32dF loop temperature....That is 1/2 to almost just 1/3 of the total heating needs for the house! Doesn't that seem insane?!?

What percent of load is covered by the 4 ton?
If most of your winter days are 20+ degrees then it may be 95% or so (if only 5% of the time you are below 20* and require auxiliary heat).
Doesn't sound insane, you simply percieve the heat pump as satisfying a small fraction of the max load which is different than the discussion of how much of your requirement is handled by the heat pump.
Good luck,
Joe

5 F seems reasonable for eastern Washington. What you really need is BIN data to quantify how often (how many hours per season) temp will be below, say 20.

Give me nearest city and elevation and I'll try to reply with BIN data

Another consideration is cost of power - are you in or near the BPA (Bonneville Power Admin) with its cheapest-in-the-country power? If so, more aux heat use might not be unreasonable to both lower first cost and optimize for summer cooling.

The 4 ton bidder may also have determined that your present ductwork can't support the airflow needed by a 5 or 6 ton unit, in which case he earns my respect. His 4 ton unit might require just $200 or so per year in extra aux power cost, which you get by depositing the savings from going with him in the bank.

I'm not saying his is the best answer, but it COULD be, despite the apparently way shortchanged heating load.

I'm at about 1400ft in 98942

I live near BPA and have fairly low power rates....

The duct system is very large, so I don't think that is the issue, nor did he SAY that is the issue. Also, the quotes are very close (within 5k dollars) for a single 4 ton or dual units at a total of 7 tons which makes me a bit suspicious as I'm not really saving that much money going with the smaller units

The difference is small enough to make the two unit bid quite attractive. I would want to be absolutely certain that the duct work could handle the flow. I'd look at the present A/H blowers, their speed taps, and ESP across them while in operation.

The classic blunder we find time and again is an oversized unit coupled with undersized ductwork.

I'd also want to be sure that the proposed loop field would support 7 tons. Proper design and local references are key.

Bin data: Your location puts you between Yakima and Ellensburg, and slightly higher than both. However my software ony has Bin data for 3 big WA cities. The one likely most resembling your climate is Spokane and its Bin data illustrates our point well: Spokane is both higher, more inland and further north than your area, so its winter is likely more severe.

Spokane - design day temp is 2 degrees - pretty cold. However in a typical winter Bin data shows:

Temperature Range Hours

0-5----- 13
5-10---- 25
10-15-- 101
15-20--223

Total -- 362

So if the system is designed for geo to meet load down to 20, and aux operates at an average of 50 cents per hour all hours below 20F, the additional operating cost is $181 per year. Those are guesses - I'd like Joe to weigh in with his greater experience. However our point is that for less than a couple hundred dollars more in op cost you get a system with thousands lower first cost, quieter operation, and more comfortable summer cooling.

The foregoing is an example, not my actual prediction of the costs or rigorous evaluation of the alternatives - just food for thought on Thanksgiving day and free-and-worth-every-penny-you-paid Internet advice.

I don't have much to add right now except the natural instinct towards bigger is better philosophy can be counter productive in geo.
I don't think you have enough info to make a decision. You need more estimates to try to determine which is the better design.
joe

Interesting. Part of the problem with the installers (particuarly the one listing the very small system) is they didn't really take any time to explain why they felt THEIR quote was the right one. In fact, he knew he was the last guy to provide a quote, and I let him know he was 3 tons smaller than the other guy and just got a 'well, that is what the calculation was' even after he left the manual J final calculations of heating at 91k btu and I had looked up the 4ton Climatemaster and saw best case heat output at just shy of 40k btu with a 32dF loop.

I'm still not certain which is the way to go. I just bought HVAC-Calc personal to run my own calculations and then I can play with design temps based on the data above trying to get a feel for where the design temp break point is from full speed geothermal to heat strip backup.

One issue to ask about, the 4ton plus 3ton Econar dealer is big on horizontal slinky installations and quoted a needed excavation put of 100' by 30' which to me seems awfully small for 7 tons! The 4 ton installer stated quite clearly they had very bad luck with slinky installs here in eastern Washington (soil is rocky clay and VERY dry as we only get 8 inches of rain/yr) and they dug a large pit and did linear runs (but still all in 1 pit, just no slinky overlaps)

Both quoted 750-800ft of tubing/ton.

Thoughts?

Not much can come of dissecting such disparite bids.
We need to narrow down your needs first and go from there.

I asked you once before;
"What percent of load is covered by the 4 ton?"

Engineer made a point about ductwork that you discarded but it is important. Code insists on 6 square inches of return air per thousand btu's on a heat pump. So a Climatemaster 2 stage 4 ton (TTV049) for instance would require 294 sq inches. Not found in the average cold air duct. Since you are combining 2, with the 4 ton this is likely met but with the other systems who knows.
7 tons sounds grossly oversized and would likely pop as 100% of load (aux. required less than 1%).
So far my money is on the 4 ton guy.

Specific, directed questions would be helpful to keep contractors eyes from glazing over.
Organize your thoughts and write a question list to get the answers you really need......
1) How long in geo business.....
2) List of references and credentials
3) manual J load

further down the list
what % of load is covered by geo vs aux.?

further down
How much?

somewhere at the bottom of the list
How many feet of what diameter tube will be in my loopfield?

With so much money at stake folks want to educate themselves on geo. The problem for folks new to this is gleening what's really important. You have inspired a new thread to help with the right questions.

A resource to find qualified installers in your area can be found at the igshpa.
j

I wil definitely ask about the cold air return/ducting question don't get me wrong! But I definitely needed some help understanding the load issue. It was shocking to have the heat loss numbers put before me and then see a system recommended that provided only about 45% of that amount of heat and not have the contractor provide any real explanation as to why (versus a makes sense in my head nearly 100% of heat loss quote at 7 tons)

I bought the personal HVAC-Calc software and am going to run some numbers using varying outside air temps to see where things are really at...

I bought the personal HVAC-Calc software and am going to run some numbers using varying outside air temps to see where things are really at...

Fudge factor is in manual J already. Give honest data and you and you will have a reliable result. Do not add your own fudge factors.
J

Thank you so much Joe and others for the honest replies.

What I had hoped was to not redo the whole calc, but play with design temps to see where the 'break even' 100% geothermal heating point would appear to lie.  $50 to play with the data and get my head around it is definitely worth it.

I also reviewed your 'things to ask' thread which was very helpful.  Thanks!

What I had hoped was to not redo the whole calc, but play with design temps to see where the 'break even' 100% geothermal heating point would appear to lie. $50 to play with the data and get my head around it is definitely worth it.

Then you bought the wrong software. Balance points and percent of load could be gleened as you describe, but it will be quite time consuming. Since all loads have user bias (some guys don't trust their own software). I suggest you re load the house and share that number with us. Then we can pull up balance point and % of load for you.
j

Joe - you've got PM

Thanx Curt,

I ammended my 6 sq inches per ton to the accurate 6 sq inches/thousand btus. My math was right at 294 but....

Engineer also asked why the balance point et al could not be simply drawn from the load calc. In another fingers moving faster than the brain instance, I overstated the complexity of arriving at those numbers with the software mentioned.
More accurately, I first would like to establish concensus about the load. Giving the large number of square feet I could easily imagine a 50kbtu difference in load depending on age of construction insulation etc.
Generating new data from a number that may not be accurate is unhelpful. Once we have a confirmed load, OP may manipulate #'s until stumbling on the right one or give me the load and nearest major city and my load software will produce % of load and balance point, in moments, without having to do the math.

Joe

Joe, the IGHSPA accredited installer that gave me his manual J calcs (and did a very thorough walkthrough/measurement) calculated BTU Heating 91,293 BTU Cooling 39,691 CFM Cooling 1549 and of course quoted a 4 ton unit (combining cool air returns) I'm in Yakima, WA (KYKM) but Spokane would be similar as I'm actually up a bit from Yakima and average 3-4 degrees cooler (honestly, which I know too well as I'm a cherry grower and have to run the wind machine much more in the spring than others in town)

Since you have the software license, confirm the load and then I'll be happy to do the op cost stuff for you.
J

Okay Joe. I have a military commitment starting tomorrow so I'll do the load calc next week when I return and get back to you.

I found 2 additional local contractors I am also going to get bids from (hopefully wife can show them the house while I'm gone)

Thank you.
Be safe.
Joe

So interesting addition. Spoke with the single 4 ton estimate guy and asked what the balance point of the proposed system was. He did a good job and went back and got the numbers for me.

So with his manual J (91k heat loss, 38k gain) in my climate, the 4 ton system had a balance point of 37dF. Now, mind you our typical winter days are typically between 32-35dF and nights between 20-25dF (but this week, every night is below 15dF and some will be down to 8). Basically that means use of resistance heat every night and a lot of days during the winter!

So I guess the 4 ton system is out....At that balance point I think I'd go with a hybrid heat system instead---it likely would cost a lot less to lean that heavily on 96% efficiency gas heat vs electric resistive!