Harvesting Heat

Ok, most doods are concerned with cooling, i'm interested in heat.
In particular adding to passive solar (in my greenhouse.. in winter.. for vegies..)..

So I was considering building an insulated box/es inside the g/house.. say 8' x 2' by 4' tall housing 3 growing totes and pumping water from three more totes under (50 odd gallons) through an bar/heatsink (cobs attached), letting the heat redistribute to the cabinet.

(I guess with an exhaust fan on a thermostat in the cabinet ceiling as well to tick over some fresh air intake)

I have vero 18's & was looking at between 180 and 360w in various cycles, and more than one box like this ^v



Maybe the efficiency of cobs would make this way of gathering heat negligible?

Any thoughts on attaching pvc (gluing) directly to the ends of Al light bars??

I just use a temperature controller. The lights add heat until it gets to 80F, then it kicks the fan on until the temp lowers to 76F, then it turns off and waits for the temp to rise. Even when it's only 60 degrees in my house, I can still keep the tent 76-80 with nothing but the lights/power supplies.

The greenhouse only really reaches ideal temps in mid-summer for a few weeks, i'm usually needing to add heat somehow, even indoors. I use a temp controller to switch my heater..

It's usually a trade off to get enough fresh air growing bigger plants. At the least iv'e got a greenhouse heater bar going 10 mths of the year.. things slow right down outside of summer, winter days 25/40F, may not be worth the effort but storing the heat for some of the day (lights off) could help.. a bit..

Add rocks /stones..............absorb light/heat and release at dusk.

If your greenhouse is too cool for TEN months of the year, something is wrong. I'd start by looking for leaks or better materials for the glazing.

COB style LED lighting is some of the most efficient lighting available- not a lot of heat to recapture there!

However, it can be done; I use water chilling for my whole setup. In the winter, I drag the chiller in from the windowsill and run it in my office/air intake. The chiller rejects the heat removed from the water into the air, which then heats my whole home all winter. In Colorado. I haven't run my furnace in four winters now...

We get (usually) a good crop of tomatoes in the gh, one crop in summer, the greenhouse is ok, good for a few hours of the day but yeah, I guess i mean it's just more typically 70F max and a few degrees short of ideal. Everything is typically small and slow growing (compared to warmer places iv'e lived).

Anyhow.. got paving stones already and just moved a water tank in, was actually mulling over building some compost bins in there. I think your right with Led ttystikk, maybe too efficient to expect much, then water cooling looks easy enough. I'm not sure even 50gal totes of water would be a big enough heat collector though either, pumping heat into the 300g water tank perhaps.. and a few hundred watts of waste heat.

In your situation DE hps sounds like an ideal mate. That spike in th the IR range would actually help keep your canopy warm.

Iv'e found to be always adding heat since HPS days, usually up to a few hundred watts in early veg with not much light running.. but still, LED, it's all far more controllable. The plan is to spread the light over a large area (for veg/green leaf etc) and be able to move light to concentrate for flowering plants. It's more of a 'shed' than greenhouse, solid walls with a clear roof so I plan to further insulate the walls.

It's all interesting to me, there's some innovative people around, just been reading about cheap solar water heating by pumping water through Corflute



Love to heat the entire area (18'x 9') but that can only be a bigger task.

how about some black plastic tubes filled with water? they store a lot of solar energy

Did see a coiled plastic hose setup for a rooftop, preheater for a domestic hot water system.
When I first thought of a heated greenhouse/growhouse I must have been 10, had visions of a tropical oasis in the high 20's.. 80/90F. Iv'e realised that's a bit over the top, can get my cabinet to stay up there but it takes a HPS or equivalent heating watts (almost) in winter (cant have it in the house). It's going to need some careful design to make vegie growing viable in winter months (ie without too much gas or other supp heating). The lighting is there/up to the task and can only get better.

Wow must be nice to live somewhere besides the desert of the southwest were I am.. never seen a heating system ever needed in a grow room in my (desert) life. Always need more refrigeration around here....I would love to live in that type of whether. ..the fact thatthere is two different temperatures between your grow room and the outside environment because of the lights you have introduced makes the possibility OFI ficiently controlling all of the grow rooms temperatures very efficient and easy, you could put your Res outside the room maybe even outside in the natural environment and that would help take the heat out of the water and keep your grow area the right 75 to 78 degrees, an aquarium heater in the res on a thermostat would be perfect.. you lucky lucky bass-turdz offense

sethimus said:

how about some black plastic tubes filled with water? they store a lot of solar energy

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This is a heat generation strategy, not a storage option.

Tazbud said:

Did see a coiled plastic hose setup for a rooftop, preheater for a domestic hot water system.
When I first thought of a heated greenhouse/growhouse I must have been 10, had visions of a tropical oasis in the high 20's.. 80/90F. Iv'e realised that's a bit over the top, can get my cabinet to stay up there but it takes a HPS or equivalent heating watts (almost) in winter (cant have it in the house). It's going to need some careful design to make vegie growing viable in winter months (ie without too much gas or other supp heating). The lighting is there/up to the task and can only get better.

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Look into 'walipini', it's a Lakota word for an earth sheltered greenhouse. I'm not sure where you live but a well designed one off these can grow crops year round with no supplemental heat at most latitudes in the continental US.

Even if you find you can't convert yours, I'm sure you can find some useful tips.

Realclosetgreenz said:

Wow must be nice to live somewhere besides the desert of the southwest were I am.. never seen a heating system ever needed in a grow room in my (desert) life. Always need more refrigeration around here....I would love to live in that type of whether. ..the fact thatthere is two different temperatures between your grow room and the outside environment because of the lights you have introduced makes the possibility OFI ficiently controlling all of the grow rooms temperatures very efficient and easy, you could put your Res outside the room maybe even outside in the natural environment and that would help take the heat out of the water and keep your grow area the right 75 to 78 degrees, an aquarium heater in the res on a thermostat would be perfect.. you lucky lucky bass-turdz offense

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Putting the res outside to freeze won't help him.

Walipini, yeah! or similar concepts, heat generation and storage. Small scale, i'd imagine large would be an advantage. I can see the advantages of Aquaponics here but only really interested in the garden side.

I'm thinking compost heating might be ideal?, pump the warm water (or air) down under compost tubs, maybe a water/air filled 'frame'.. anyhow, cycle it back into reservoir (or air back up through whatever's growing) a vent fan ticking over, maybe some small co2 boost?

ttystikk said:

This is a heat generation strategy, not a storage option.

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you could use water to cool you lights and your greenhouse as a radiator

that would be ideal but it would take much more than a few waste watts , and cost $ to make work

I think your most cost effective move is to better insulate your greenhouse.

I'm not sure about that ttystikk, mass water is a great way to collect heat, the temperature with slow dissipation is cumulative and in a cold grow space heat's just going to waste. While it may only be 50-100W of heat it would make no difference to a green house but a good few degrees in an insulated cabinet. The cost is effectively not much at all.

That said, it was proving difficult to cover the area with a watercooled design, maybe down the track, I did have a simple flood and return square tube in mind with these radial sinks clamped on but it would work better in long bars over a big veg growth area. A big tray shape/tank/ heatsink perhaps?

Anyhow, i went again with a trusty piece o wood, this is the first one, i'll build another. They'll cost around 9c p/h to run / 10sq ft of growing. I doubt there will be much saving in food cost but the point is homegrown/fresh harvest in mid-winter.

Tazbud said:

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whats your fan set up on this?
i have the same heatsinks and and had troubles cooling-about to rebuild