Monday, February 12, 2007

Geothermal Heat Pumps: Adventures in Contracting

Getting our geothermal heat pumps was, to say the least, an adventure. The first problem was that neither our builder nor our architect were very familiar with heat pumps. While both very competent individuals, they were always hesitant whenever we brought up ideas with which they were not familiar. If there was something different that we wanted, they always provided the advice that there were cheaper ways or other ways to do what we wanted, and they always deferred to their contacts that they had used. This is a natural reaction for anyone, namely you go with what you know or who you trust. We would get our way only if we kept pressing the matter. On most things, their advice was well-given, but on others, in particular when it came to the heating and cooling systems, their advice was more appropriate for the 1980s and not the coming decades.

With respect to installing the heat pumps, we were on our own and had to take over the contractor's role. I wasn't quite ready for that, and it resulted in some inconvenient delays. The installation in our renovation project had been done to code and standard practices (of course, given how many things go, that is actually a good thing!). What had been installed was a standard heating oil boiler and three air handlers with appropriate duct work. Two of the air handlers were dual zone, so we have five separate zones in our house. The air conditioning wasn't installed as yet, but they would hook right into the air handlers.

We located dealers for both WaterFurnace and Climatemaster from the dealer locator buttons on their website. (As mentioned, we didn't know about the Trane units.) The Climatemaster dealer came out, looked at the house and said no problem. He took a set of house plans and sized a system and then told us that the guy who had sized the original system had shorted us a bit. Looking around the house, he located a good place for the vertical wells in the back, and said we could get in a system. He sent us a quote and said we would need to swap out one of the air handlers for a bigger one to meet the cooling load and that the guy who sized the original system undersized it.

So, now I have two different people giving me two different answers for what the house needs. Being technically inclined, I decided to look into the calculations a bit to see what I came up with. The method for sizing the heating/cooling systems is known as a Manual J calculation. I found software for this at HVAC Computer Systems Ltd. The software for a residential calculation is $49, and given the drawings of the house, the estimate took about one hour including time to change some of the parameters to get an idea of the sensitivity to different assumptions. It was very user-friendly. You can download a demo that gives you an idea of how the software works. If you end up purchasing the software, please let them know where you heard about it.

What I found disagreed with the first two estimates. By my estimate, the original heating/cooling load calculations were high by about 20%, and the new quote I got were about 20% higher than that. After performing the calculation myself, there were clearly many things in this calculation where judgement came in. If the world is ever going to improve its energy efficiency or turn to greener methods, a new look at the Manual J assumptions will probably have to be done. Let's put that firmly on the back-burner and plow forward.

Given the discrepancies, I thought I'd ask the Climatemaster dealer about it. Some of the differences were due to things like the use of shading. In the calculation, you can deduct some of the cooling load if the house is shaded by bushes or trees. Well, we have two trees on our neighbor's property that shade a good portion of the house in the summer afternoons. As mentioned in a prior post, they annoyingly cut into our solar power output. The dealer said that he "never puts shading into the calculation." Hmm... Eventually it dawned on me why he would never put in shading. With houses turning over every 7 years or so, and with people not very literate when it comes to HVAC, making the most conservative assumptions is a good idea. This way you sell a system slightly larger than the code would suggest, and any future changes were bound to be covered pretty well. If a new owner came in a chopped down the tree, the system would still work, and the HVAC company wouldn't have to be bothered in that situation.

The other thing I noticed in the calculation that I'll quickly mention is that putting glass doors on the fireplace are a rather good way to reduce the heating load. Funny how nobody seemed to mention that one or mention about the present insulation in the house. Hmm...

After thinking about it for a couple of days I figured I'd get the opinion from the other dealer. What could it hurt? A second quote is a good idea (and 3 is even better), and I wanted more information.

The WaterFurnace guy came out and gave us a completely different story. He said we'd be wasting our money, we'd never get the well driller in the back yard where we needed to put in the well, and we should have called him at the beginning of the project. He was Mister Negative. I still haven't figured that one out. He clearly didn't want the job. I told him we were still interested in a quote and were very serious about putting in geothermal and weren't just tire kickers. He said to send us the plans and he'd work on it. We did and never heard back from him.

So we didn't get the other Manual J calculation from the Climatemaster dealer, but doubt was put into my mind regarding whether or not the well drilling truck could get into the back yard. After thinking about it for a week, I decided that the best thing to do was to call the drillers and ask them directly. Their guy said "no problem." That taken care of, it was time to make a decision.

As you could probably guess, we chose the Climatemaster system; not because we thought it was particularly better than the WaterFurnace technology, but because the representative for Climatemaster took our project more seriously. With regards to the sizing issue, my reasoning was this. The system was sized for the cooling load, and secondary heating was going to be required anyway. Given our Yankee location, heating needs are about double the cooling needs, so if the heat pumps are sized for the cooling loads and under still under my estimate for the heating loads, then it would probably be okay. I might pay up more in the initial cost but would probably make out in the future. We were also running up against time limits due to issues with the house reconstruction, and a decision had to get done quickly.

The story of our installation has some lessons too. Again, we didn't find a one-stop shop for this. I lined up the well drillers, the heat-pump guys, and I also had to hire the backhoe operator. Not knowing the timing of each or knowing what all needed to get done at the beginning, it took longer just due to scheduling constraints.

Well, the heat pumps have been in use since October, 2006. They've worked well (despite some quibbles with the electronics....maybe another time) and have definitely saved money. When the numbers are all in, I'll post on how they've performed.

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