Page 4 of 4

Re: Using sub floor air for cooling?

PostPosted: Tue Sep 20, 2011 6:22 pm
by Gordon-Loomberah
Nice job getting that swamp cooler moved :)

jarbar wrote:Solar panels also reduce considerably the radiant heat from the previously uncovered North roof.

Are you able to quantify that difference? Can you measure the underside of the roof under the middle of the PV array area and under an open area that is also North facing? What insulation is under the tiles?

The small IR remote thermometers sold by Jaycar and others are handly for spot measurements, although they do give incorrect readings on most metal and some other surfaces.

Re: Using sub floor air for cooling?

PostPosted: Tue Sep 20, 2011 6:53 pm
by jarbar
Hi Gordon,
with an electronic temp tester with a bi metal probe the tiles last summer, I'm guessing on the same days as Karen measured 43 deg ambient I registered 65 deg on the uncovered tiles and 35deg on the covered.No insulation behind tiles but glass wool on ceiling probably only about 2.5R value.Brick house built in 1966 with terracotta tiles.Next project will be water cooling of panels using mains and thermostat controlled solenoid draining back to water tanks, cooling house further and increasing PV efficiency. :lol:


Re: Using sub floor air for cooling?

PostPosted: Tue Sep 20, 2011 9:44 pm
by Gordon-Loomberah
You could probably reduce the internal roof space temperature a bit with a layer of foil as an IR barrier under the tiles, but the panels are doing a pretty good job at keeping the heat down already in the covered area..

Re: Using sub floor air for cooling?

PostPosted: Wed Sep 21, 2011 10:19 am
by Clemo
moemoke wrote:As the title says I'm thinking of using the sub floor air to help cool my house down, either this or the wife wants to buy a power hungry air cond :cry: .

You could buy the A/C (happy wife, happy life). Invest a little more in something like a heat wheel to take advantage of the cooler sub floor temperatures and pre-cool the return air, reduce load on ac, reduce running cost, would work well with inverter system. No health risk as you are not using air from sub floor just transferring heat to it.
If you have that much space below the house you may want to consider installing the A/C sub floor as well, this would make the return air pre cooling much more simple (simple is good) and would reduce heat loss through ducting, sub floor systems also work much better/efficient on heating cycle IMO especial if you house has high ceilings.

Anyway you would want a Refrigeration engineer to do the numbers on it first.