Can I use my HVAC system to cool HPS lighting?

Hey all,

Fired up my 1KW HPS yesterday for the first time (air-cooled hood, but not vented at this point). My temp-shooter indicated the hood was at 178 degrees. Yikes... and I'll be firing up a second one soon, so need to work the cooling out. Room temps were up over 82 late in the day, and basement temp was up over 75.

So, ok - I need to air-cool the hoods. I've got the bulk of it figured out, the duct runs, a Can Fan 260 cfm fan, etc. But what concerns me is the heated air. Drawing air in from the basement, and exhausting it to same will increase the basement temps. And that same air is used to vent and cool the grow room.

I was walking around, looking this over, when I had an idea. Looking for any downsides to this - please speak up if you see any.

The area where I will set up an intake for light cooling is near a supply duct. The area where I'm thinking to exhaust the heated air is near the main return duct. So I'm thinking I'll splice a wye in the supply line, and run that through the wall and into the first light. Then duct through the second light, the cooling fan, and exhaust the fan to the return duct. In other words, drawing air from and pumping the heat into the HVAC system instead of the basement.

My furnace is on 8 months out of the year. I figure the additional heat will reduce my energy consumption for those 8 months. I run the fan at low speed 7/24 when not heating/cooling to constantly circulate air in the house and keep temps even from room to room. I do see loading the AC system more when it's on, but it's running only 10 or 12 weeks out of the year.

I do see less effective light cooling when the heat is on, as I'll be drawing already heated air into the light hoods. So will this work? Or will I cause HVAC issues drawing and pumping air through it? Thanks for any advice you can offer. :)

I did something very similiar. I had floor HVAC vent/duct in the bedroom...so I used 6 inch dryer vent flex hose running from the floor vent to the area between the canopy of the plants and my 400 watt HPS light. This maintained a temp of 78-82 degrees at the top of the canopy and less than 50% humidity...near ideal...:thumbsup:...and I left the fan running constantly.

Bottomline: the temps would be whatever I set the thermostat at....heat or cooling.

i was similar too dp. ac in with holes cut into duct blowing cold air up and through canopy with just an out sucktion on the lights

you might want a filter or your house may stink if you 4recycle air that way

Thanks for the replies.

I already have a carbon filter and fan for venting and removing odors from the rooms. Was looking at running just the light cooling system via the HVAC. That way the heat from the lights won't be recirculated back into the basement, and thus into the grow room, but instead get circulated throughout the house. Basement stays cooler, so grow room stays cooler.

Drawing the air I'm creating a negative pressure on the supply side, but on the other hand I'm pushing air into the return side, so in theory, at least, there is no gain or loss in the system. However, I'm no HVAC engineer, which is what led me to ask the question.

Any other opinions on this topic are more than welcome. Knowledge is a valuable thing, and it's nice to see people here share what they know. I'm asking questions more that answering at this point, but hope to be able to contribute something back as I learn. Thanks again. :rasta:

Update - it's done. Was a lot of work setting this up, but thus far it's working well. I can put my hand on the glass of the HPS lights - it's warm, but not unbearable. Grow room temps, while slightly higher than with T-5s, are staying under 80 so far.

Let the blooming begin. :rastasmoke:

Quote:

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Originally Posted by cavadge

Update - it's done. Was a lot of work setting this up, but thus far it's working well. I can put my hand on the glass of the HPS lights - it's warm, but not unbearable. Grow room temps, while slightly higher than with T-5s, are staying under 80 so far.

Let the blooming begin. :rastasmoke:

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The only thing I would add is that you will want to keep an eye on your filters in the HVAC to make sure you don't start pulling a bunch of dust and dirt into your lights.:thumbsup: