Cohousing-L Mailing List: Re: Ground Source Heat Pumps

[Sharon Villines (sharon]

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
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Sharon Villines
Takoma Village Cohousing, Washington DC
http://www.takomavillage.org