|Re: Ground Source Heat Pumps||<– Date –> <– Thread –>|
|From: Sharon Villines (sharonsharonvillines.com)|
|Date: Tue, 24 Oct 2017 14:53:15 -0700 (PDT)|
We have ground source heat pumps at Takoma Village in DC and Eastern Village about a mile away has heat pumps. Liberty Village and I think Catoctin Creek Cohousing have ground source heat pumps. I love it. Until you have lived with a ground source heat pump you can’t appreciate how smooth the temperature is. The advice is to set the temperature you want and leave it alone. The temperature range should be set to 1 degree above and 1 degree below the desired temperature. The compressor is designed to run frequently for short periods of time to keep the water in the ground loops moving and the temperatures even. It’s wonderful. I never think about it. Yes, they can go terribly wrong if you don’t have an experienced installer in your area. That is crucial. We had a terrible time at first because we had a totally incompetent installer who I was told was handcuffed and taken off the property. The company went bankrupt before our system was finished. We spent several years fixing it. My HVAC didn’t work at all for 2 years. Finally we discovered that my loops were hooked up to the loops of the HVAC unit above me and they were flowing in fighting directions. It burned out my pump every weeks when it worked at all. Our loops were stored outdoors on the construction site waiting for installation and were filled with rocks and debris. And installed anyway. The flush cart was here a lot until they were cleaned out. Some of the loops were not sealed and never worked. A few years in we found pipes in the basement that just sat there inside a connector. So pay attention to the experience record of your installer. Eastern Village, built a few years later than us, used the best installer in the area. Their system is better designed and they haven’t had any problems that I know of. We have individual loops for each unit that go straight down and back up again. There are seams at the bottom of the loop. In the new technology, like Eastern Village’s, loops are connected to a horizontal loop under the piazza called a manifold that then branches off to the living units. That means if one loop going down to the ideal temperature level fails, it can be closed off and the horizontal loop continues to circulate water from the rest of the loops. There are far fewer loops drilled into the ground. The new technology also uses a continuous loop with no junctures so it is less likely to have a leak. The loop curves naturally to return to the HVAC unit. We also had less expensive HVAC units and have gradually replaced them with the Water Furnace brand. My electric bill went down 10%. My unit is 825 SF with southern exposure. Because it is an end unit, only the floor, ceiling, and one wall are attached. I also use my W/D and dishwasher. I pay $60 a month on a budget plan which equalizes my payments each month. That covers all my electricity including an air purifier that runs constantly. I set the temp at 72-74 in the summer and 68-70 in the winter. One of our residents who didn’t use her washer or dryer or dishwasher, had an electric bill of $18 for many years. If the HVAC is turned down or up for some reason, it should be returned to the normal temperature 2 degrees at a time. The first HVACs to fail here, years before the others, were both in large units that were for sale and had turned down their HVAC. So whenever someone wanted to see the unit, the HVAC was cranked up quickly. Ground source heat pumps heat and cool slowly because the air coming into the room is not as cold or as hot as in conventional systems. It may take an hour or two to warm up or cool down. It isn’t good for the compressor to run continuously. It heats or cools from a fairly constant ground temperature of 57-60, vs an air source heater that heats or cools from air temperature — 20-100. Large units, like our 3 bedroom units, have a larger HVAC with a superheater that heats water. When the HVAC unit in the guest rooms went out, we considered and were advised to put in one of the systems I think Dick is referring to called a “split system.” They went on and on about the costs being the same but the split was easier to install and took up less space. They are often installed in motels that have been renovated because they are easy to install high on the wall. But I ran the numbers on the cost to run both units and it wasn’t even close. We saved 50% on the ground source heat pump. But we already had the loop installed so that would have added to the initial cost. A construction company up the street installed heat pumps for their new four story building. When they installed them, it was predicted that the system would pay for itself in 8 years. When I toured the building about 2 years after the system was installed, the owner said it was going to take a maximum of 6 years and possibly as little as 4 to pay for itself. There are temperature zones where heat pumps are not economical. I don’t know what they are — hotter or colder than DC. My old system had trouble keeping up with temperatures over 80 and under 30, so I had to adjust the desired temperature a few degrees up or down. The Water Furnace hasn’t had a problem. And DC is pretty temperate. I got all this information from research and talking with two engineers who specialized in heat pumps. One talked to me for 2 hours. He had them in both his homes. Even in the cabin in the woods, he sets the temp and leaves it. Never turns it up or down. He kept stressing the importance of keeping the water field moving. When I was researching the best temperature to set the CH at, the other engineer laughed and said the money saved is so small that it isn’t worth the argument — set it at 72 and don’t touch it. (We set it at 74 summer and 70 winter). But it is hard to convince people that this system is not the same as a conventional system and shouldn’t be turned up or down. You can’t experience the evenness of the temperature until you live with it. It’s most like the temperatures in hospitals that are kept a constant temperature with super clean air. And the Water Furnace is all but silent. I never hear it unless I’m standing by it. If you can afford it, and if you have an experienced installer, and if it fits your climate, I highly recommend the ground source heat pumps. It isn’t new technology. It’s been around more than 50 years in residential buildings. Long message again, but it’s an important topic. Sharon ---- Sharon Villines Takoma Village Cohousing, Washington DC http://www.takomavillage.org
- Ground Source Heat Pumps, (continued)
- Ground Source Heat Pumps Thomas Lofft, October 25 2017
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