Hi, everyone. I'm new here and this site has been really great for helping me understand ground source heat exchange. Thanks to you all for making this info exchange possible! We have a quote that we think seems pretty good and would be interested on getting your feedback. Our heat load (2700 sq foot house, two story, with only one great room having vaulted ceiling extending to second floor) was estimated at 45,971 btu/hr (based on R16 in walls and R40 in ceiling after the reno is completed in September). We were quoted $34,536.17 for a 5 ton unit (but I thought that we only needed 4 ton based on head load): -vertical bore (.75" in two holes down to around 375', if I recall correctly) -plumb loops in basement -water to air heat pump -new 50 ga water heater (because we will probably need one soon anyway) and new 40ga water heater ( I assume this last one is the desuperheater tank?) -supply ducts to 2nd floor (currently oil forced air has supply and return only to 1st floor) -controls and wiring -warranty 10 years parts and labor. I have been told that the electric strips in unit will kick in when indoor-outdoor temp discrepancy exceeds unit's capacity. (Assumed 65 degree heat load differential.) I'm not worried about that because we also have an amazing wood-burning stove that can heat the house pretty well. Any feedback on what else we should think about or ask about? Thanks! Darryl
What brand model 5 ton? (Affects the cost, and in some ways the performance). Did the installer give you an expected heating load? Did you mention to them you thought you would need a 4 ton? I am in the process of finalizing my quote/install with an installer and there were multiple times (with multiple installers I talked to) where I just had to be upfront and ask the questions that needed to be asked. Price is in line with a quote I got for 5 ton from a Buffalo area installer. And roughly in line with a co-workers install from Rochester. Unless you are sold on your installer I would get another quote or two, if for nothing more than to make sure you still like the first choice. I found I preferred the installer from my second quote, even though I was on the fence about getting the quote at all (the first company "had everything" on paper, but I didn't realize what they were missing until I went looking else ware. End of Rant
They told me my heat load was 45,971 btu/h. That's why I thought I needed 4 ton and not 5. When I asked one of the people working in the quote, he said yes to needing 4 ton. But the quote is for ClimateMaster Tranquility 22, 60 kbtu (5 ton). I have only the one quote because the other business in town that offered ground source heat exchange is no longer offering it. I've been talking to the same installer for two years and I think that things have gone okay. Some communication via email is not very efficient, however. We do better talking face to face. If anyone could suggest an installer in the Twin Tiers, I'd appreciate it. Darryl
I am sure Doc or Joe or someone else will post shortly, but if they calculated your heat load at 46kBTU, I am surprised they are quoting a 5 ton. But I am sure one of the experts will weigh in soon.
The tranquility 22 quoted is the 060 and has stage 2 output of 45.9k btuh. So I am probably confused about something, namely why one person told me I was quoted for a 5 ton unit. I've sent them an email asking to straighten it out. They're good about responding. They've been recommended by others. I attribute my lack of understand to me.
So I noticed that most company state their close loop output at 32 or 35F, which does lower the output some. I believe the WF 5 series 5 ton is ~48kBTU and the 7 series 5 ton is ~51kBTU (this is the only brand I know the data for offhand). So, the Tranquility putting out 46kBTU doesn't seem unreasonable (at colder end of season temperatures). Perhaps going down to a 4 ton would require too much aux heat. then again, if you have alternate heat (wood stove) maybe you should design for less than 65F offset (aka, if your woodstove can handle any nights below 10 degrees, maybe size your system so it only carries the load down to 10F, which would reduce your install cost. However, being as I am a rank amateur, I should stop talking like I know what I am saying.
A careful study of this site will show youthat 5 tons is quite oversized. I would estimate that the 3 ton would actually be the most cost effective and comfortable installation. Download the free GeoDesigner application from climate master, and plug in some numbers. They won't be as good as those produced by someone who knows what they're doing, but could serve to give you a good ballpark and allow you to see the difference in cost and run characteristics between different size units. You will find that a 3 ton does not have a significantly higher running cost compared to a 4 or a 5 ton with your modest loads, even when you consider the higher use of auxiliary heat for the 3 ton. Pocket the savings in decreased installation cost, and enjoy the increased comfort and longevity of a system that does not cycle on and off frequently because it is oversized
birkie, that's an interesting point. The ClimateMaster literature says that 80% of heating and cooling needs are met with stage 1 compressor use (in their 2-stage compressors). So a smaller unit will spend more time in stage 2 than would a larger unit in that same house. If you compare the TZ-060 in stage 1, it generates 37.2k btuh. The TZ-o48 in stage 2 generates 35.6k btuh. But the catch is that the 060 has a COP of 3.9 but the 048 has a COP of 3.7. So when you need at least that latter amount of heat output, it comes from a less efficient system. Of course, one would have to know exact run times and power draw to flesh out this comparison. And one would probably have to know more things about which I am not aware. I would rather invest in the capital than in the operating cost, I think. But there are so many variables in this system to consider.
Hopefully you will find yourself within Doc's reach (Buffalo Geothermal). What you need to understand about design is that the calculated load is the "peak" load. If we look at actual heating hours you will likely find that only a small percent of the time do you exceed 80% of peak load. You will find that most of your heating hours are spent at 50% of peak load or less. First attack the envelope with air sealing or insulation improvements and then look at an actual bin analysis of different units to find the best fit with a modified load. So just to throw a round numbers out if you had 6000 heating hours each year you likely will only have a couple hundred hours over the capacity of a 3 ton unit and of those maybe 1/2 need significant auxiliary contribution. We find that something of that nature uses less than $100 a year in auxiliary. Meanwhile a 4 or a 5 ton unit with little auxiliary use will cycle more frequently and quite possibly have higher operating cost from running larger compressor all the time to avoid a little auxiliary use. So the 5 ton you have been offered most certainly has a higher first cost and likely a higher operating cost than the 4 ton and maybe the 3. Installers who recommend such are generally speaking, not very progressive. Ask them to show you some of their systems in action with monitoring equipment. If they actually do monitor their installs you will likely see systems running well below zero without auxiliary which indicates you are burning way to many kilowatts during the lighter load times.
You can try DOC, but might be a little far for him. I think he is out of the county currently, but not sure. We typically service the Rochester area and 2 hour radius. I was in Orchard Park today for a dig and had to trailer the excavator home tonight..that was a fun trip after a long day...If DOC isn't up for the trip, I am a whore for geothermal and would entertain atleast talking with you via email/phone first to see if it makes sense for a visit?? Also, not sure what driller quoted the job, but can easily get the drilling done in the area for you no problem!
Darryl, I believe we sent you a proposal last Friday. The main point is that you are living in a different climate zone than Buffalo International Airport, where most of the weather data comes from. Unfortunately, none of my customers live at the airport. To give you an example, while the lowest temp in Buffalo this harsh winter was 0.2F (at my house), the coldest we measured via online monitoring in Ellicottville was -16.7F and -15.8F in Franklinville, both which should be 10-15 miles away from you and have the same weather. North Java was the peak with -19.8F this year. If someone did a heat loss with 65F differential (5F design, 99%), that is about 15F short in my book. While you plan to update your insulation, it is still a retrofit which will have higher air infiltration than a new built. For your weather pattern, we came up with a heat loss around 63 KBTU/H at -12F design temp. Thus I would shy away from putting anything but a 5 ton in your house. Now, while the peak load is about 20% higher, the average BIN load is closer to 50% increased, meaning when other systems in Buffalo cycle in 1st stage yours is running constantly in 1st or cycle already in 2nd. Thus the load you put on the loop over the season is significantly higher, something the software does not fully account for. Another point is that the TZ22 has a significantly lower efficiency than units which are $2000 more (WF 5 series, CM TE30). Thus to save 7% of the total upfront cost but making the system 25% less efficient (for the life of the system) does not make much sense to me. Don't get too excited of COP of 1st versus 2nd stage. The difference comes mainly from the difference in entering water temperature (EWT) of 41F in 1st and 32F in 2nd stage according to the rating conditions, when in real life the EWT remains the same (assuming a well designed ground loop), thus the difference between 1st and 2nd stage is much less than the rated COP suggests.
"... 0.75" in two holes down to around 375', if I recall correctly" I had overlooked this one. A 5 ton should have between 12 and 15 gpm water flow, meaning this contractor is pushing down 7.5 GPM down each circuit. This would require an enormous amount of pumping power, making the whole loop field very inefficient. I can only stress this here: Do you pressure drop calcs! 2 boreholes supporting 5 tons should have 1.25" pipe!
