Question about Solar heating and floor vents
odqP3ooSV9
| Posted in Energy Efficiency and Durability on
My new to me home has a solar heating set up under the floor, that vents directly into the crawl space. (3 ft tall)
When the blower turns on, the air in the crawlspace is pushed up through vents in the floor. There is no ductwork connecting the vents to the blower fan. This seems a little bizarre to me, but maybe that is how the system was designed? I don’t know when it was installed, but the house was built in ’78, and the solar tank is under the house, along with the water heater.
My question: Is this a normal set up? If not, what would you suggest as the easiest way to connect ducting from the fan to the vents?
Thanks
Richard
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Replies
Richard,
You aren't providing us enough information.
A lot of experimental designs were used in the 1970s, so anything is possible.
Does your house have solar collectors on the roof or on the lawn? If so, are they solar air collectors or solar hot water collectors?
Or perhaps your crawl space has direct-gain south-facing windows?
We need to know more about your solar heat collection system.
Then we need to know about your heat storage system. You mentioned a "solar tank." Is that a hot water tank? Or is it a bin full of rocks?
Do you have backup heat? Is your backup heat distributed by ductwork or by hydronic pipes?
My house, recently purchased (oakland, CA), was also built in 78. The owner builder was an energy hippie and I have a setup similar to yours. The solar thermal system pumped water into baseboard heaters but the system had been dismantled by the builder's widow. There was a big solar thermal tank under the house which I have since cut a hole into to use as a small storage room. There is a ventilation system similar you yours that supplies cool crawlspace air to the house in the summer. When you open a clerestory window the air rushes in without any fans like you have but unfortunately this lets the heated air out in winter. What the builder back in 78 wasn't aware of was how important air sealing is. While he had the best intentions, the execution was rudimentary. However, as a general contractor myself, this has given me a wonderful hobby as the roof is south facing, the framing is 2x6 24" oc, and there are design elements that are perfect to build on in order to have the house reach it's original intent as a energy wise home. You might want to have an energy oriented contractor try to inspect the home and figure out how it was intended to work while offering suggestions on how to use modern technologies to remediate and build upon these irregularities. Perhaps in your case, like mine, passive solar was the base for the builder's venture which is a blessing when buying a home and not building one yourself.
Martin, the house has collectors on the roof and a storage tank under the floor in the crawl space. The tank is full of "goo" (sellers term, not mine. :) ) The goo gets pumped to the collectors, heated and returned. I have 2 regular light switch type switches on the wall. One turns on the pump, the other the blower. There is a digital readout of the tank temperature, which maxes out at 165 degrees.
House also has a wood burning stove and a heat pump for additional heat. Heat pump uses ductwork in the attic. No windows in the crawlspace, just exterior vents and the vents into the house for the solar..
Mark, thanks for the response, but I live in a very rural area and there is not much to choose from when it comes to contractors.
Thank you both for your responses.
Richard
Richard,
It sounds like your house has a forced-air distribution system. You also have a solar thermal system with solar hot-water collectors on the roof and a water tank in your basement.
There is no reason to have a solar thermal system unless the collected heat can be used. So I have to assume that either (a) the hot water tank provides heat to your domestic hot water system, or (b) the hot water tank provides space heat, or (c) the hot water tank provides heat to your domestic hot water system and also provides space heat.
If (a) is the case, see if there are any pipes that connect your solar storage tank to your hot water heater.
If (b) is the case, there needs to be some way to transfer heat from the solar tank to your house. The most logical method would be a copper heat transfer coil in your hot-air plenum. This copper coil would be connected to a circulator.
If (c) is the case, the solar tank would probably have two heat-exchange coils -- one for domestic hot water, and one for space heat. There would still need to be some mechanism to transfer the heat from the tank to your home's interior.
There is a fourth possibility: the designer just allowed the hot water tank to heat the crawl space air, and pulls air from the crawl space. If that's what you've got, it's a really inefficient system.
If this is hard to figure out, you should call a solar contractor to inspect your system and test the components.