Low Temperature Growth Chambers 1

[ChrisConley]

I'm working on a little project where the client would like to hodge together a few growth chambers (rather than purchasing them).

One of the criteria I've been given is to be able to maintain the chamber at 4 deg C (40 deg F) with air at 1 deg C (34 deg F) to prevent freezing the plants.

Within the growth chamber are a number of lights (10 lights at 1000W each), if the lights are on, given the low deltaT I'm working with I end up moving a huge volume of air through a small space (~5300 cfm through an 8x10x10 chamber). The velocity would be the equivalent of standing in an air handler.

The only option I see is to try and supply air below freezing and then induce room air to prevent freezing air from reaching the plants.

Has anyone worked on a similar project? I've already indicated to the client that their criteria may not be possible, but would still like to present them with options.

 

[imok2]

Chris I found this
"Sorry but the most space you should use a 1000w is a 4'x4' area. So two lights = 4'x8' table or 2 4'x4' table. If you put the two 4'x4' tables next to each other or the one 4'x8' table then you could use 3 600w and be using less amps and less electricity but getting the same light and yeilds". at this web sits if your interested. If its true your heat load could be cut 50%

http://www.gardenscure.com/420/lighting/97055-optimal-number-plants-1000w-hps.html

 

[IRstuff]

One option is to use cold filters on the lamps, and wall off the lamps from the main growth chamber. You'd run massive amounts of air through the light chamber, and that could potentially cut considerably the thermal load in the main chamber.

TTFN

FAQ731-376

 

[ChrisConley]

Thanks imok, I unfortunetly have no control over the lighting design, and when it comes to plant biology I'm out of my element.

We looked at using 'ducted' lights, still need a tremendous volume of air in the space. In addition, the rooms are too small for much ductwork.

Thanks for the comments!

 

[AbbyNormal]

sounds like you need walk in cooler equipment

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[SAK9]

One approach would be to design the air distribution system in such a way that most of the heat from the lights can be accounted for in the return air heat gain.I have seen this at work in some manufactirung spaces with large equipment loads.

 

[AbbyNormal]

SAK

you make it sound like UFAD, displaces the heat outof the space

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[walkes]

Hey Chris, we are just finishing off 8 growth rooms with similar characteristics, not as cold as yours though. Is the intent to provide that level of cooling with the lights on? In our situation the cooler setpoint (10 to 14°C) was for a night mode.
Our design was based on two heat pumps, one had the capability of maintaining space temperature with the lights on. The second was to assist in dehumidification and driving the temperature down for night mode.
The air is supplied below the plant tables because the lighting system essentially covers the entire space and is on a winch system to vary the distance of the lamps to the plants. Essentially a displacement type of system, the coil handles most of the load through the return air.
Your situation sounds like you will require some low temp refrigeration though.

Our client revised their requirements such that the temperature was not as critical as the humidity control, so a dessicant type dehumidifier was employed as well.

 

[ChrisConley]

A long talk with the owner resulted in them revising their criteria. My thought was that they were asking for everything they could imagine, and I was right.

The growth chambers have been revised to 15 deg C lights on 10 deg C lights off.

Thanks for the tips everyone.

 

[AbbyNormal]

Moose Jaw Sinsimelian is going to rival British Columbia?

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install

 

[ChrisConley]

Sorry AbbyNormal, I can't make any sense of your post. I even googled Sinsimelian (no results other than a band name of similar spelling).

 

[AbbyNormal]

I was trying to be funny, its sounds like a grow-op

someone even had a grow op forum link up there.

get a lot of hits on yahoo on the mis-spelling

http://en.wikipedia.org/wiki/Cannabis_cultivation

The way we build has a far greater impact on our comfort, energy consumption and IAQ, than any HVAC system we install