PLANNING FOR SOLAR HOT WATER & HEATING

     Our crew have now turned their attention to a long list of project parts that need to be done at the church before they begin installing pine panelling on the walls and angled ceiling. With the plumbing and electrical all roughed in, final decisions need to be made in regard to the hot water system.  Donna and I have had a number of discussions, as well, about the heating system. We looked at: forced air oil, which is what is there presently and discounted it immediately for a variety of reasons; wood; propane forced air; solar and have decided that our commitment to the environment should step up here. Since a modern thermal solar system supported by a back-up boiler, can be energy efficient in a super insulated home, that is our direction. 

    There has been a lot of discussion in the “green building” industry, as to the merit of thermal solar vs. photovoltaic (PV).  Some believe that using one of the new air source heat pump water heaters and a PV installation is the more cost efficient of the two. This because, typically, thermal solar systems really only support hot water heating, in some cases providing less than 50% of annual hot water needs. 

Other arguments include the fact that thermal solar requires electricity to operate, pumps can fail, freeze ups have been known to happen and maintenance, including glycol replacement or top-up is needed every few years. While all of these comments have merit, having had both PV and thermal in my previous home, I can state that neither system caused me much grief.  In regard to thermal, I often turned our back-up electric hot water tank off for weeks on end in the summer.

    When we began this project, we set a budget. While adding a solar thermal system will increase that number fairly dramatically, it supports our values; solar energy is clean, environmentally friendly and, by selecting the right system, the use of back-up propane will be greatly reduced. For hot water use alone, a typical thermal solar system can eliminate up to 2 tons of CO2 emissions annually. The catch is simple….it must be the right system.


    Taping into the experience of a close friend who has a commercial system on his roof, I called Paul Zammit at Fall River Restaurant. Paul swears by his solar thermal system for both heat and hot water and has 120 evacuated tubes on the roof of the restaurant and a huge 3000 gallon storage tank. Last Sunday, I was talking to Paul in anticipation of writing this column. It was a grey rainy day and his display control told him his system was operating at 52 degrees Celsius; not bad for an overcast day. A carefully planned system can be very efficient, especially when using propane for cooking, clothes drying and since there will be a back-up generator. A further advantage is that this means that the addition of a back-up on demand hot water unit is possible.

    What goes into a thermal solar system? First there are two kinds of solar collectors, the flat plate panel and the evacuated tubes. Studies show that the flat panels are more durable than the tubes over a longer period of time. While the tubes are known to be more efficient, additional flat plate panels can be added to compensate for this and still be capital cost reasonable. For these reasons, panels have been selected. The next part of the system is the storage tank and these are a dual purpose fixture, having two heat exchanger coils inside the tank. One each for the solar thermal system and for the back-up heat source; in our case a wall hung, on demand boiler. Where we are breaking away from the usual installation is that we also intend to use this system for heating and are discussing the installation of a large, super insulated storage tank to store the hot water from the sun. We are planning an ‘air handler’ connected to our forced air duct system. An air handler is simply a metal cabinet with a radiator that circulates the hot water, utilizing a direct drive fan. In our case it will be a DC fan, which is more energy efficient to operate.

   Installation, whether roof or ground, is a major part of the capital cost. The church is “blessed” with a clear southern landscape. We are going to mount our panels on a ground based frame and we have come to this decision for four reasons: 1) The church roof is metal and I am not comfortable with holes in an older metal roof; 2) The circa 1894 building might have needed some structural upgrades to accommodate the added weight; 3) While the pitch of the roof is good, a ground based frame will allow me to change the solar angle from summer to winter, increasing the efficiency of the system; 4) Lastly, it will allow us to clear the snow off and also keep the panels clean, again an efficiency benefit.

   One of the federal agencies that I have excellent relations with is CMHC and the folks there have produced a Performance Directory on Solar Thermal Systems. Unlike some government information, this directory was updated less than 6 months ago. It lists off the Solar Systems that are CSA Standard F379 approved and it also shows the annual performance rating for each system.  Based on this document, found at www.canmetenergy.nrcan.gc.ca/renewables/solar-thermal/publications/1343 we have narrowed our search to two companies, EnerWorks, a Canadian company and Viessman, which has a worldwide reputation for quality. This selection process is far from over, but we now have a clear path as to where we are going and what we need. In future columns you will get to see the actual system as it’s installed. 

Oh, and, while the original budget called for an Elmira wood cookstove  that would have cost about $10,000 installed, Donna has decided on a Heartland 5100 all propane unit she found on Kijiji for $500.  The difference will go to the thermal system. 

    If you wish to update yourself on our project or if it’s your first look, please go to www.alltechgreenchurch.ca to follow our progress.