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2008Putting in the heat pump moves our source of heat to electricity and away from gas. In June of 2008 we got the last two appliances off gas and shut off the gas meter. The gas service charges were about $35/month so it's nice to see that go.
|So first we had to swap out the washer and dryer. I had to finish the floor under the new machines and change out the previous washer drain standpipe but that just took an afternoon. The washer is a low water use european model made for Sears by Whirlpool in Germany. The dryer is the matching electric model. The drawers under the machines are excellent.|
|Once all the gas appliances are out it is time to shut off the gas. Here is the auspicious day. Note me wearing my Bullfrog Power hat. Now that we are all-electric we can buy green electricity offsets to erase the carbon footprint from our house. Running the geothermal on coal-fired power doesn't actually get you much in the way of carbon savings. We were one of the first users of bullfrog power in Edmonton. www.bullfrogpower.com|
|And here is the gas meter gone. That meter was always in the way on that sidewalk. It was always something I wanted to get rid of - now it's gone. It took about a month for my gas retailer to get all the charges off my bill but that eventually get fixed.|
2007OK, two winters of using the heat pump and no problems yet. Going into winter number three and everything seems to be working nicely. This year I added a programmable thermostat. I set back the heat during the day, our dog doesn't seem to mind and we'll see if it saves any energy.
I also fixed the humidifier. I finally had to wire it directly to the furnace to come on when the furnace came on. It helped to install the thermostat first.
|Here is the new thermostat that went in this year. The last one was not programmable and was very difficult to read. It had white letters on a silver background. I needed my glasses and a strong flashlight to read it even in the daytime. This is the top of the line commercial thermostat and is fully programmable. It has large numbers and a backlight so it is easy to read. Although this thermostat is designed for heat pumps it is normally used on air to air heat pumps. It keeps wanting to call up second stage heat (electric heat) whenever it gets started. I've put an in-line switch into the stage two heat line and switch it off unless it's going to be needed. The only time it would be needed is if the outside temperature goes below -30C for an extended period and the heat pump can't keep up. I don't think we'll ever need this backup heater but it's wired in just in case.|
|I was a bit disappointed with the humidifier that I bought. It requires a temperature of 40C in order to activate the solenoid. Unfortunately the heat pump only manages 38C to the humidifier. So it never worked. Calls to the humidifier company resulted in a pressure switch being sent for another $30. Unfortunately once the pressure switch arrives the instructions say that it is only to turn the humidifier off, not on, and still needs 40C to activate the solenoid. Calls to their engineering guy got me a call back to my office at 6 in the morning (nice one - I said I was in Edmonton). Anyway, I hooked up the solenoid to Y1 on the thermostat wires and now it works perfectly. Too bad the humidifier manufacturer can't add the instructions on how to do this to their manual. It's actually pretty easy to do. Just took me a few minutes with a multimeter to figure out which wires would work. It also helped that I had just installed the new thermostat so I was very familiar with all the thermostat wires. The heat pump manufacturer was very helpful when I called them about the new thermostat and reviewed all the connections with me.
Alas, it didn't work for long. For some reason it is not working again. Haven't had time to investigate the problem yet. Maybe I'll just throw it out and start again.
20062006 So what's it like to live with a geothermal heat pump? We honestly can't tell the difference between the heat pump and our old furnace. They both make about the same amount of noise. They both run for about the same amount of time (at -30C they both run continuously). The fan in the heat pump is much stronger and moves a lot more air so the ducts whistle a bit more. The only noticeable difference is quiet little noise that the heat pump makes after it turns off. If you are standing near the utility room you can hear this faint sound like a jet going overhead on a clear day at 40,000 ft. It fades after about a minute as the compressor settles itself.
The other thing is that we love having air conditioning. Although it's hardly even used it sure is nice to be able to cool the house down on a hot day. The geothermal heat pump is as good an air conditioner as it is a heater. It only takes a minute or two to cool the whole house down. It hasn't contributed noticeably to our heating bill as cooling is used so infrequently here.
I added four thermometers to the heat pump to show me the incoming and outgoing water temp and the incoming and outgoing air temp. I can now explain the heat pump operation a little more clearly. The water circulates to the boreholes at 20 gallons per minute. When the pump is on there is a 2.5C temp drop in the water. This is the heat that the heat pump extracts. This results in about a 20C rise is air temp across the fan at 900 cfm. When air conditioning it is exactly opposite a 2.5C water temp rise results in a 20C air temp drop. Simple.
The main upgrade to the geothermal system in 2006 was to install a Heat Recovery Ventilator so that we could get the fresh air intake needed to complete our permit. While installing the duct work for the HRV I fixed a particularly dangerous piece of ductwork over the stove. The other thing that helped us get our permit was to remove the gas tankless water heater and put in an electric tank. That let us avoid putting in a combustion make up air duct to feed combustion air to the 100,000 BTU gas tankless water heater. Since the idea was to close up the holes in the house putting in a 5" duct for fresh air and combustion make up air was not part of the plan. After all those items were completed we got our heating permit signed off.
I also installed a flow through humidifier. It operates on a temperature rise and the geothermal furnace doesn't generate a large enough temperature rise to activate it. I didn't have time to fix it in 2006, next year.
|After getting the Heat Recovery Ventilator in place we were finally able to get the City to sign off on our heating permit. It also helped that we removed the gas tankless water heater and went with an electric one (didn't need a combustion air duct). Getting that green sticker took a year longer than I expected but it's finally done!|
|Here's another one of those disasters we discovered behind the walls. We had never been able to find out where the exhaust fan for the stove went outside. Opening up a glued-shut panel in the cupboards confirmed our worst fear - it was exhausted into the chimney. This fan powered vent was pushing air into a convection operated chimney for a gas furnace. What idiot did this? Not only that, but the vent pipe had to go through a heat duct first before it went to the chimney. This was one big leak. The blower door test showed air leakage behind this cupboard - it was coming down the chimney - then leaking into the ductwork. Wow! What a carbon monoxide risk. Since the geothermal furnace no longer uses the chimney I just drilled a hole through the other side of the chimney and took the exhaust outside. Then with a lot of effort I sealed the duct work and the exhaust vent so that there are no leaks between the two. In the future I want to fill the chimney with insulation and cap it to keep the drafts out but for now I am much happier to see this duct work all buttoned up. We have left the panel off the cupboard so that we can see the exhaust pipe for periodic inspection.|
|In order to monitor how the heat pump is working I installed four thermometers. These thermometers have thermistors at the end of a cord that I can place away from the read out. There is a thermistor on the incoming and outgoing pipes for the water that circulates to the boreholes out front. That way I can see the incoming and outgoing water temperature. In the picture the incoming water temp (bottom left) is +0.5C while the outgoing water temp (top left) is -1.9C. This is a drop of 2.4C which represents the heat being extracted from the water. The current air inlet temperature (bottom right) is 24.2C and the current air outlet temp (top right) is 41.0C. That essentially how the heat pump works. A 2.5 degree temperature drop in the circulating water results in about a 20C increase in the temperature of the circulating air. Over the winter you can see the incoming water temp decrease during periods of cold weather. When the furnace isn't working for a while the incoming water temp will go up to a high of about 5C. The lowest incoming water temp I've see so far is -0.9C.|
|On the basement wall just outside of the utility room I have this little cluster of controls. The top left sensor is a remote temperature sensor that connects wirelessly to the temperature sensors on the furnace. I can read three of the four temperature sensors. Typically I leave this set to read the incoming water temperature as this is the most important temp to monitor. Then to the right is the Heat Recovery Ventilator control. This control lets you set the ventilator on low, high, or recirculate. I have fan switches at both of the bathrooms that turn the ventilator on low when switched. Finally on the bottom is the control panel for hot water heater. It has a number of settings as it is meant to control a solar hot water system. Right now it just controls the hot water with electric heat.|
|The new heating codes require that there be a fresh air intake to any new furnace that is installed. This was a sticking point between me and the City inspectors. They said to run a 5" duct from outside and connect it to the intake air duct of the furnace. I had two problems with that. First the geothermal heat pump can only manage a 20C temperature rise from the intake to the distribution ducts, and second, I didn't want to put a 5" hole in the side of the house after I had spent all that time plugging all the leaks. After many back-and-forth discussions with the City I decided to put in a Heat Recovery Ventilator (HRV). Then I had to figure out where to put it. It needs two ducts to the outside (intake and exhaust) and two ducts that connect to the inside system. I looked at every joist space in the house before deciding to put it in this closet. It is a very tight fit but we were able to get the ducts to the outside down two open joist spaces.|
|One of the advantages of an HRV is that all the ports are closed when it is not in operation. That limits air leakage. The other is that the incoming air is heated by the outgoing exhaust air so that the temperature of the air supplied to the house is not cold (appears to be only a degree or two below house temp even on a winter day). I put in three air exhaust ducts, one in each bathroom, and one in the main floor hallway. The fresh air is ducted into the return air duct of the furnace. Initially the inspectors wanted me to set the HRV so that it came on with the furnace. After a bit more discussion they let me set it up so that it comes on with the bathroom fan switches. The fan switches in each bathroom turn on the unit. Even though the instructions for the HRV showed this type of bathroom exhaust set up when I talked to the manufacturer they had a fit. I was supposed to buy a much more expensive unit for bathroom exhaust use (but it was too big and wouldn't fit in the closet). They thought it would condense too much water and would damage the unit. At this point I just have a pail under the condensation drain. In a year of use there has not yet been enough condensation to wet the bottom of the bucket. I had to figure out how to set up the bathroom switches myself as the manufacturer's help line wouldn't help. They've since stopped selling HRVs to the public (only available now through heating contractors).|
|The geothermal installer told us we probably wouldn't need a humidifier. The idea is that since there is no more gas combustion going on in the house the air doesn't dry out as much as it did with a gas furnace. After the first winter we found the the air was too dry. We can see it in the wood floors when the humidity gets too low as the wood shrinks and the gaps in the floor open up. So I decided to install a flow through humidifier. It was a tight fit but there was just enough room around the back of the furnace to hang the humidifier on the inlet plenum.|
|Then I used expandable metal duct work to connect the outlet plenum air to the humidifier. Everything was all hooked up and looked really good. So I went to start it up and - nothing. Troubleshooting the unit I find that it is temperature activated. It needs to have 40C at the humidifier to open the soleniod. I do a measurement and find that I can only get 38C at the humidifier. I don't really have time to fix it up this year so I leave it until next year.|
2005The main event this summer was to install a ground source geothermal heat pump in our house. This is a fairly big undertaking. As you can see there are many other activities that had to happen to get this all installed. The first step was to have a heat loss calculation done for our house. This is very important as you need this information to estimate how much heat pump you will need to keep your house warm. The City heating inspectors also want to see this calculation to make sure you don't undersize your heat pump. As a result of our heat loss calculation we decided to add insulation to the main floor and to upgrade some windows and doors and to work at sealing up as much air leakage in the house as we could.
Geothermal heat pumps are something I've been looking at for about 10 years. Recently the prices for these units have come down considerably. Years ago you were lucky if you could find one installer in western Canada, now there are 4 in Edmonton alone. It is becoming very popular.
The thing about a ground source heat pump in a cold climate is that you need to drill deep vertical boreholes to access a large amount of thermal mass in the ground. In warm climates you can trench the pipes 4 ft into the ground, in our climate we needed holes 200 ft deep. Each 200 ft deep hole gives us about 12,000 BTU/hour of heat so we had 4 holes dug to give us about 48,000 BTU/hour of heat. The heat pump is matched to this rating of 48,000 BTU/hour. Since our current furnace is rated at about 60,000 BTU/hour we definately had to improve the insulation and seal the house a bit more securely.
That's enough preamble, let's look at some pictures.
|Here is our little house. It was built in 1949 and sits on small lot only 33 ft wide. We elected to drill the holes in the front yard because our backyard is already landscaped. There was also no good way to get the piping into the house from the back. The four boreholes are going to go right here in front. We took out the tree in the front and killed off all the grass in preparation for drilling.|
|There are few better ways to attract your neighbors attention than to pull a drilling rig into your front lawn. This little unit was just right for drilling 4" wide holes in our small yard.|
|Although it is a small rig it operates just like the big drilling rigs. Lengths of drill stem are screwed together and turned in a constant direction. This twists the drill bit into the ground. The flights bring the muck up from the hole. Water is used as the drilling fluid here. They hooked up our garden hose to the drill and water is pumped down the inside of the drill stem and comes back up the sides on the flights bringing the muck out of the hole.|
|And it brings up a lot of muck. It took two full days to drill the four holes. Our hose ran constantly all the time they were drilling (about 1,500 gallons - a significant expense for water). They pumped the muck into tanks (in the background) and took it away for disposal. The straw bales are used to help keep the muck in place so it doesn't run off the site.|
|Once the holes are dug the ground source pipes are placed in the holes and grouted in place. The pipes are 3/4" polyethylene designed specifically for geothermal use. There are two pipes in each hole with a "u" bend on the bottom. The grout is mixed with water(shown here) so that it becomes a slurry. This is poured down the hole and thickens in place to hold the pipes in the ground and to make a connection between the earth and the geothermal pipes.|
|Here is a completed hole with the pipes grouted in place. At this point the grout is the consistency of a milk shake but will thicken up over the next couple of days eventually becoming a solid underground.|
|This is what we called the "aftermath" of the drilling. We were a bit discouraged at this point as we had no idea how this was going to get cleaned up. Our driller told us he would mix the muck into the ground but we were a bit worried when we saw this.|
|We can see the pattern of the geothermal pipes here. The pipes need to be 10 to 12 feet apart. They also need to be about 10 to 12 feet from sewer or water lines. In operation the geothermal pipes can chill the ground to the point where the ground freezes near the pipes. This presents a risk of freezing to water and sewer lines nearby. In our case we had to move the pipes away from the fence to get further away from the neighbor's sewer and water lines. This left us with only a 30 ft width in our front yard between our neighbor's sewer line and our sewer lines. To make the pipes fit within a 12 ft spacing we had to put them into a parallogram spacing instead of a rectangle. We would have needed 36 ft for a rectangular 12 foot spacing.|
|Our fears about the persistence of muck were cleared up the next day when the geothermal installer returned to install the manifolds. A 5 ft deep trench is dug to connect the four drilled holes and a larger polyethylene pipe joins all the 3/4" pipes together. The idea is to create one inlet pipe and one outlet pipe. The inlet delivers fluid to all the boreholes and the outlet collects all the liquid and delivers it to the heat pump in the house.|
|Here the manifold pipes are in place. After the connections are made they are pressurized with air. While under pressure soapy water is sprayed on the pipes to detect any leaks. A wire is buried with the lines to help locate the pipes later if ever you have to dig in this area. Then every thing is buried.|
|And here we are with the drilling and outside work complete. From here we carried on with landscaping. Go to the landscaping page for more details on that activity.|
|So at the end of all this work all we see are these two manifold pipes at the side of the house. On this old house we had a drain pipe that used to drain the eavestroughs to the drain in the basement. The drain is no longer used but the pipe was still in place. When we removed the pipe we had a clear path from the outside of the house to the furnace room. The manifold pipes are right underneath this access hole.|
|So the pipes from the manifold are connected to pipes that run to the furnace room. This actually happened months later. We had to wait after the drilling was done for the geothermal heat pump to be delivered from the states. That took about 8 weeks. Here the installer is connecting the manifold pipes to the pipes that go into the furnace room.|
|Since these manifold pipes are out of the ground it is best to insulate them. I built a box around the pipes so that I could insulate them a little easier. But since I had this access point to the furnace room I also decided to add a few tricks. I added an electrical outlet to the box and two water taps.|
|We didn't have an electrical outlet in the front of the house before so this is going to be handy. There are also two water taps. One is for the drip irrigation pipes that we ran to the new trees and shrubs and one is for a garden hose out front if we need it. The box is stuffed with insulation and painted to match the front steps.|
|So here is the furnace room in our basement. It is separated from the bathroom by two sliding doors. We removed the doors for the summer for the construction. Here you can see that the new hot water heater is installed and that the new electrical panel for the geothermal heater is in place. You can see more info on these two items on the water heater page and the electrical page. You can also see the construction heater on the floor. We were without heat for about a week during this hook-up and change over process. Fortunately temperatures were mild but we planned for temporary heat just in case.|
|So here the furnace has been removed. The old duct work was attached to the joists in the ceiling so that it didn't fall down when the furnace was pulled out. This leaves the old ducts in place for the new heat pump installation.|
|The new heat pump arrives and gets lowered down the stairs. It is very heavy.|
|Only to find it will not fit through the bathroom door. I hadn't anticipated that the unit would be so big. We were short by about 1/2". We removed the trim on the bathroom door and were able to squeeze it through. The thing that got in the way was the condensate drain on one side. This little fitting stuck out about an inch and got missed on my measurements. We got it in but had to repair the door frame afterwards.|
|Once the unit is in place the pipes are hooked up from outside. They go to a flow center (two pumps that circulate the liquid) and then to the heat pump. At this point the entire piping system is charged. A mixture of water and methanol was used in our system. You need some anti-freeze properties in the liquid since you will be chilling the liquid as it circulates. Once all the piping is charged with liquid the geothermal installer waits until the electricians have had a chance to hook up the unit. In this picture you can see the pipes coming in from outside on the top right of the picture. They come around the back of the heat pump to the flow center on the left. Then the pipes connect from the flow center to the front left of the heat pump.|
|The electricans have finished their hookup so it's time to test the unit. Here the installer checks over the unit in preparation for starting it up.|
|He runs through a series of tests to make sure everything is working properly. Here he is measuring the heat output. Note the pressure guages on the compressor. You'll also note that the duct work is not connected yet. That's OK, you can still test the operation of the unit.|
|Perhaps this is a good place to explain how this work. Liquid is circulated from the ground to a coil in the heat pump (the coil is in the insulation on the right). The compressor extracts heat from the water in the coil and pumps it into the fan chamber. A fan circulates the heat to the house. Water with it's heat removed goes out of the house to the boreholes in the front yard and absorbs heat from the ground (the liquid is colder than the ground). In effect you are trying to chill the ground outside and taking the heat produced and blowing it into the house. It works like a refrigerator. The coils on the back of the fridge give off heat in return for cooling the contents of the fridge. By cooling the ground outside the house we end up heating the air inside the house (like having a big fridge coil giving off lots of heat).|
|One of the last things to do is to connect the new heat pump to the old duct work. We had some repairs to make but otherwise used the existing ducts.|
|A groovy piece of duct work to angle the new heat pump outlet to the old plenum. Note the yellow fabric vibration isolator to reduce noise.|
|So here is the unit all done and ready to operate. The pipes on the right go out to the front yard. The flow center on the left circulates the water to the field. The electrical panel has its own meter to monitor just the geothermal heater so I will be able to do some cost analysis later this year. The tankless water heater is much smaller than the old water heater which makes for quite a bit of room.|
|All done and ready to put the doors back on in the bathroom. The heater is working now. It provides lots of heat and even more air conditioning. It's starting to get cool now and the heater comes on quite regularly. We'll monitor it over this winter to see how it measures up.|
|And finally, the bathroom sliding doors are replaced. Lucy approves!|