Registered: 1359070732 Posts: 2,240
Reply with quote #51
Impressive project ! One way to retain more heat, would be to pull warm air down from the roof apex, to floor level, and get that heat into thermal mass. You could do that in several ways, simplest bean to install a couple of ceiling fans, 3-speed reversible. In pull-down mode, the fans would pull warm air down towards the floor, and that air would then circulate, and in doing so, some of would enter - essentially - cold concrete walls. its heat Alternatively, you could get the same effect but better, by transferring that same heat into the earth floor, by making a subfloor. In this case, you would need a duct, vertical, and a fan, pulling air down from the ridge, and pushing it under the subfloor. Your duct could draw from a ridge plenum, configured at the gable end (above your entrance doors, where the dual square windows are). You would need an additional horizontal duct, say a big plastic pipe, 3 foot in diameter, suspended tight right along the ridge, and connecting with the plenum. This ridge pipe would have open-work ports in its bottom circumference, to let warm air in. The subfloor would be, for example, pressure-treated lumber, and it would be "semi-airtight enough" to make the air stay down, in contact with the *packed* earth (the heat should penetrate into the earth by around 2 or 3 inches, hardly more...). ==================== If I understand right, you are intending installing solar collectors (?) inside the greenhouse, to warm water ? Or are you referring to an external solar collector, additional to the greenhouse, to do this ? If you install a solar collector in the greenhouse, I am not sure how it would work, or whether it would work "well". I know that SolarDan accidentally left a water collector lyng around in his sunspace, and he was surprised to see it getting hot ! All I am saying, is, if it does work, then the energy it uses will be to deduct from the overall energy inside the greenhouse (put otherwise, your hot water will cost you in heated air - the greenhouse will heat water, but its general temp will drop). Perhaps this is your design intent - using water as thermal mass (that is exactly what thermal mass is for ! - absorbing heat, for later release). Hoipe this helps a bit ! G_H __________________
(1) "Heat goes from hot to cold, there is no directional bias" (2) It's wrote, "voilà" unless talking musical instruments...
Registered: 1382751231 Posts: 16
Reply with quote #52
Thank you GH!
I like your heated floor idea. That is simular to what I'm doing for the 30' x 5' x 3' grow bed. 330' of 4" drain pipe snake through that soil/block bed. It has eleven 30' runs from barrel to barrel. I'm installing the 8" circulation fan pulling air up high in the ridge. I just purchased 3 ceiling fans. Each rated for a 20' room. I"m hoping this will bring down the heat as well as limit the condensation from forming on the Solexx. My fish tank walls are 4' off the ground and I was thinking of installing a 2' wide 16" high step the complete length of the greenhouse with cinder blocks and 2 x 12s for the top. I could use your idea to push air through that chamber. This will give me a 24" x 18" air chamber 48' long with half the floor and one wall being the concrete that makes up my tanks. Wouldn't concrete soak up more heat then the soil? Would I be further ahead to fill this air chamber with drain pipes and rock or maybe the use of cinder blocks laid sideways to support the floor would add turbulence to the air and provide more heat sink. If my understanding of heat transfer is correct, turbulence is good. I wasn't sure if I should install the solar collectors inside or outside, but you make a good point. Any heat I gain inside I would be robbing from the greenhouse. So I purchased two 50' black 3/4" hoses today from Lowe's. These are premium black rubber rated to 140 deg with a lifetime guarantee. My idea is to use them in a 8' x 8' or maybe a 4' x 8' solar collector. I'm thinking of nails to hold the hose in place so it doesn't kink. I can easily unwrap it and change out the hose if they spring a leak. Thanks again, Jason
Registered: 1383442590 Posts: 3
Reply with quote #53
I really enjoyed your video on pool heaters. I plan in making one. We live in southwest Florida and the sun here in the winter is still pretty strong. I plan on using 1/2" pipe and what would you recommend for a pump? Thanks and God bless, Richard Dionne
Registered: 1352911502 Posts: 697
Reply with quote #54
I've never built a pool heater (don't even have a pool), so I'm not sure which video you are referring to. Your pump selection will depend on collector size. Generally speaking, the higher the flow rate the better. A good target is .04 to .05 gallons per minute per square foot of collector, or about 1.4 gallons per minute for each 4' X 8' collector. Here is a thorough analysis: http://www.builditsolar.com/References/ColFlowRate.htm __________________ Take care, Scott MD
Registered: 1383442590 Posts: 3
Reply with quote #55
Thank you. Although I have the wrong contact, your information is valuable and I will use it in determining the pump size.
Registered: 1352940256 Posts: 1,060
Reply with quote #56
dionne if you are looking for info on solar heaters for swimming pools the link below is a good place to start:
http://www.builditsolar.com/Projects/PoolHeating/pool_heating.htm __________________ Both temperature rise and airflow are integral to comparing hot air collectors
Registered: 1376748071 Posts: 11
Reply with quote #57
any of you seen this site http://www.heliatos.com/ love the idea of using your own tank no need for big tank any thoughts???? Thanks Dave
Registered: 1353153771 Posts: 1,845
Reply with quote #58
pftg41, I posted about it a while ago, the thing I liked that they did was the little adaptor\exchanger they hooked into the hot water tank drain to heat it up. They sell just that unit by itself for not a bad price, I do not remember what that was but it was around 75 dollars or less. I was more tempted to build my own panels but for an all in one kit it's not bad. That led me down the path of build your own heat exchangers and by the time I got done I decided to stick to air. Dan
Registered: 1376748071 Posts: 11
Reply with quote #59
yeah i'm going to build my collector out of metal studs and metal track with polyiso insulation underneath then do double layer cpvc and fill 1/4 inch void with metal hvac tape i wrote earlier in the thread with super tuff glazing should be very light and of course be metal on the bottom so no need for flashing i liked that adapter to just wanted to know what everybody else thought there heat exchanger look good also not sure how effeint they are tho was hoping for so input thin k i would have to go with closed loop tho as pumps are to expensive for drain back
thanks for your input this place is a gold mine for solar Really Dave
Registered: 1353392169 Posts: 720
Reply with quote #60
The metal studs & trcks does make a nice panel.
I'm currently building a small experimental panel with studs/track & it works well for shallow panels. The CPVC piping is definately easy to work with. I'm not working with Solar DHW, but those units in the link looked interesting. Good luck with your panel.