Monday, December 17, 2012

A Unique and Cost Effective Solar Space Heating System

Taylor's space heating system has a couple of unique features that I like and think are worth taking a look at if you are planning a solar space heating system.

He describes the system on his blog here...

One of the unique features is the use of inexpensive pool heating collectors.  He adds polycarbonate glazing to the collectors to get the performance up in the same area as commercial glazed space heating collectors.  The danger here is that if the collectors are stagnated (no flow), the temperatures inside the collector can get high enough to damage the the polypropylene pool heating collector.  To avoid this he fits the glazing with some air leakage paths to bring the stagnation temperatures down.

The glazed pool heating collector.
This is the same idea that I have been looking into on our new inexpensive, off-the-shelf solar water heating system.   I think this idea has a lot of promise for getting solar water and space heating costs down.  But, bear in mind that its still on the experimental side.

The other feature I like in the system is that Taylor uses a commercial off the shelf water to air heat exchanger to distribute the solar heat to the house.

The water to air heat exchanger -- has to be one of the funkiest looking ones ever!
Even with the relatively low temperature hot water that solar heating systems typically provide, these heat exchangers will deliver quite a bit of heat.  On Taylor's system, the airflow through the heat exchanger is driven by a fan that is PV powered.

One thing to bear in mind about heat distribution for solar heating systems is that unless you have an exceptionally well insulated house, or a very large solar collector array, the solar heat will be a supplement that reduces your heating bill, not your only source of heat.  This being the case, the thing you want the heat distribution system to accomplish is to be able to always deliver the solar heat you collect during a day to the house during that day and through the night.  Its not important that the solar heat distribution system be able to supply the whole heat loss of your house on a cold day -- you have a furnace for that.  What's important is that all of the solar heat that you collect gets delivered to the house overnight.  This can make a world of difference in the size of the distribution system needed.

For a ton of other solar space heating systems and ideas go here...

December 17, 2012

Saturday, December 8, 2012

DIY Heat Recovery Ventilator (HRV)

An HRV pulls fresh air into the house and exhausts stale air to the outside.  In the HRV, the fresh and stale air pass through a heat exchanger that recovers most of the heat remaining in the stale air to heat the incoming fresh outside air -- thus providing a significant saving in energy to heat the incoming air.

While I've been looking for material on building an HRV, I've not had much luck in finding anything that appeared to have a chance of working well over time.  This book from William Shurcliff that has a little on a DIY design, but its pretty minimal.

Paul from BC noted the above page and came through with the article below describing an HRV design that uses sheets of Coroplast material for the heat exchanger.  Paul actually built one of these for his own house some time back and it worked well for the time period he was in that house.  It seems to me that the Coroplast has a descent chance of holding up well in the somewhat hostile (wet and even icy) environment inside an HRV heat exchanger.  Thank you Paul for sending this in!

The Coroplast HRV design

Full details on building the Coroplast sheet HRV...

New section on HRV's ...
A completed HRV

December 8, 2012

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