Solar space heating in Canada

[randen]

I had recieved some requests from some fellow eco-renovators for some more details of our solar install with some pictures. If it may help any others who are thinking of solar space heating we have had some very good results.

Four years ago the decision was made for our family that burning furnace oil was no longer an option for us. The cost sky-rocketed. Our home is 11 yrs old with heated concrete floors. Although the heating method was extremely effiecient we couldn't afford it. We had to find a better way. Some research resulted with Geo-thermal GSHP and some solar hot water information popping up. Only finding one example at the time and many people blogging about solar hot water space heating, it seamed plausible that one could heat their home. Noticing just one sunny day and with our southern exposure the air temp in the house would climb about 4 deg.C. One other trick we had already taken advantage of was utilizing black floor tile to absorb any solar gain thru the windows. And it is amazing in the dead of winter how warm that concrete floor gets with that sunshine. Hey, "this solar heating could work" We fully realized that solar won't supply all our heating requirments so GSHP would be the most economically to operate back-up.

The same time period that the oil prices spiked we found our home needed some major repairs. During the original construction, the stucco was not installed correctly and had become loose. With that the windows and structure had become damaged with moisture and all became rotten. All had to replaced. It was a very expensive and heart-breaking time that our relatively new home needed massive repairs due to ignorant contractors. The only up-side was the installation of solar hot water panels could be done as an integral part of the re-constuction therefore all the tubing could be routed within the insulated wall. It made for a really nice looking install as the solar panels are set into the new stucco/styrofoam.

A Geo-thermal contractor was hired to install the geo-thermal in Sept. 4 yrs back. We removed the chimney and all things related with oil. The oil fired hot water tank was retained and a hole with a 1" pipe fitting was welded into the side to install a heating element. This was to provide domestic hot water for 3 months until the rest of the system was installed.

During that time I had constructed a combination Solar/geo-thermal buffer tank. The tank is actually two tanks one on top of the other sharing a common partition between. The tank has the top portion for domestic hot water with a electric element and copper heat exchanger for the solar input. The bottom tank that shares the partition and has a copper coil for the solar input as well , 6 electrical heating elements (for future wind energy dump) and the input for the GSHP. The really neat thing is the shared partition between the top & bottom tank is: the heat from the GSHP warms the top domestic tank with in-expensive heat. And if need be can be further heated with the electrical element. The tank is made entirely of stainless steel and insulated with 3" of rock wool with a polished stainless jacket. The lower tank recieves the hot water from the GSHP or from the copper solar heat exchanger and circulates it thru the hydronic floor heat.

Randen

[randen]

The installation of the solar collectors started with two purchased panels. (Solcan Canada)(Very Helpfull) They were installed vertically on the exterior wall between the patio doors. After reading about Garys solar shed (Builditsolar) and vertical collectors being a good thing for not collecting too much heat in the summer months and most heat during the winter months with the sun being lower angle, vertical mounted they were. (Thanks Gary Good advice)

The planned solar install was for 240 sqft of collector. I had decided to make my own panels to complete the install. It ended up taking me 3 years to get it all completed with all the other constuction going on. I did it in stages; 1st year 2 panels the results were on a really sunny day I could warm the floor about 2-3 Deg C. 2nd year added 4 more panels and WOW with the six panels we were able to heat the floor through 6 deg C. This would mean again on a really totally sunny day we would have enough heat to warm the concrete floor up and it would keep us warm till the next day to maybe get the next recharge of heat. This would be without any heat input from the GSHP. (FREE HEAT FROM THE SUN) Now the problem was not everyday is totally clear, some clouds do occure. There are some days with some thin high overcast that also reduces our solar gain. One other problem during the 2-3 weeks around summer solstice June 21 We were not always able to collect enough heat for the domestic hot water with the sun being directly overhead. The solution is for the last solar collectors to be able to be tilted. So far this tilted panel is performing exceptionally well. I'm seeing a difference of 10 deg.C. between the vertical and tilted panels.

In true eco-renovator style the panels that I had made were from some recycled materials. As mentioned in some other postings the risers were from the furnace oil supply lines straightened and soldered to copper fin purchased from the scrap yard. The tilting solar panels tempered glass is from the patio doors that had to be replaced. The stainless frame material is also from the scrap-yard.

The temperatures that are in the photos are average. The temps on the fluke multimeter of 53 deg. C.(photo wouldn't fit) are sometimes seen up to 66 deg. These are the glycol temps. from the panels. The temps on the Taylor are the domestic HW and usually finish the day 50+ deg. This would be 250 Ltr (60 gals.) of hot water till the next day. Lots for morning showers.The temps on the Rancor are for the floor heat and depending on the zones requiring heat. The supply temp can be anywere from 28 to 50 deg. (The set temp for the GSHP is 43 deg C) During the depth of winter a floor temp of 32 deg.C. is very nice and over night it may drop as low as 25 deg. C. but still comfortable. That would relate to an air temp 24 to 20 deg.C.

The controls are fairly simple with a differential controller. By about 10 O clock in the morning the pump may start. This signal also operates a timer/relay to open the circuit for the GSHP. This timer is set for 30 min. In the event that a cloud may roll by and the solar circulation pump stops momentarially we wouldn't like the GSHP to start. But 30mins after the sun is no longer producing enough heat the GSHP starts, if there is a requirement from the floor thermostats. But if we have recieved lots of solar heat the floor temps are above the set temps so no requirement for the GSHP to start.

For the last 3 weeks the GSHP has been switched off with the exception of 2-3 days (overcast) both domestic and space heat has been via solar. NICE. If anyone is thinking about solar heating it works. But the key things: The house needs to be very well insulated and air tight. 10-30 % solar collector per sqft. of floor space. For us, concrete floor for heat retention. Other source of heat for back-up is nessisary. DIY is possible with great results.

Randen

[sunspot]

Wow! Nice work. Great write up too. Thanks for taking the time to put that post together.

What size is the rough in plumbing to the collectors?

Thanks, Greg

[Daox]

Very nice write up! Thanks for the info.

What is your home's square footage? How well is it insulated and do you know your ACH?

I'll be installing 200 sq/ft of collector this summer and I've calculated I'll get ~25% (based on past natural gas usage and historical sun information) of my heat in December (worst month) from the solar array. Of course that number will increase as I seal up and insulate the house better. In summer I plan on having more hot water than I know what to do with. I'm planning to mount my collectors at 70 degrees.