Venting exhaust into AC/heat return

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Heyoka

Active Member
I am wondering if anyone out there has routed your rooms exhaust into the return air duct of your homes central heating/ac system. I was thinking of adding a Y connector to a return air duct so that the exhaust moves through the heating and air system. Naturally the air would pass through a carbon filter before entering the ducts.

I figure this might save a little money by using the the heat from the lamp to heat the house. In addition to using the heat from the lamp to warm the house, routeing through the heating ducts would essentially camoflage the warm air that might be obvious to thermal imaging equipment were it exhausted directly into the attic.

Thoughts? Comments?
 
thelastpirate

thelastpirate

Well-Known Member
Fuck it. I'll try it and let ya know. Right now, I'm venting under the house, using that to keep the pipes from freezing this winter, but using that heat for the inside might be a better idea. I'm just wondering if it will fuck up the suction in the return? If yer Buds are stinky, you'll be spreading that all over the house, keep that in mind.
 
dtankd

dtankd

Well-Known Member
thats what i was thinking...unless u have carbon filter...house gonna smell like Haze :) lol.....
 
Landragon

Landragon

Well-Known Member
I do exactly this. There are numerous things to consider. How large of a house. Houw large and efficient of an a/c and heating system. How many cfm. How many lights. Basically this can be done for two reasons. In wattage:house size ratios where the total room wattage would not overwhelm the house a/c in warm climates, and a ratio favoring higher wattage that can pump enough warm air in the house to not require the heater engaging in cool climates.
 
Z

zor

Active Member
Landragon said:
I do exactly this. There are numerous things to consider. How large of a house. Houw large and efficient of an a/c and heating system. How many cfm. How many lights. Basically this can be done for two reasons. In wattage:house size ratios where the total room wattage would not overwhelm the house a/c in warm climates, and a ratio favoring higher wattage that can pump enough warm air in the house to not require the heater engaging in cool climates.
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i was thinking about going this route as well. Could u describe your setup a bit landdragon?

For instance, would a 8" fan exhausting 2k of lights be to much air flow for the furnace to handle on its return vent?
 
A

Archie22

Active Member
I currently run my flower light into the cold air return in my basement. The fan is probably moving 300+ cfm after considering restrictions. So, far so good. All rooms in the house still pull smoke into the return vents quickly. A few of the return vents closest to the hvac unit still hold an 8.5x11 up against them. I haven't turned on the furnace yet this year. In fact, the 1000w Lumatek on 110% is providing so much heat that I've been keeping my windows cracked to get good Co2 rich air circulating and the temps are still above 66 when ambient is down below 40* in the AM. Another benefit of this is that the run back too the hvac kills the noise a bit by blending it with its own fan noise and the filter media. Also, the whole houses filter media can be had in a carbon version as well and act as a "second scrub".

Unfortunately, I can't comment as to how this would work in the summer long term because I just constructed this new room in early September. I did note that even as ambient temps dipped to 70 my compressor was still working pretty heavily. At this point I'm thinking it should be okay. Yes, it will add significant load to the ac but at least an auxiliary unit won't be required. In the spring I'm going to be adding a reflective tinting to my southern facing windows in an effort to reduce AC load(The entire 95ft back wall of my house faces due south)

Edit: 8" fan exhausting 2k watts could be too much for the condenser to handle in 90 degree ambient temps. That is if the 700+CFM that the 8" is supplying doesn't screw up the flow in the rest of the house. Ultimately is all depends on the size of your houses hvac unit. For comparison, my house is ~3000 hvac'ed sqft and is only three years old and energy star certified. Not directed at anyone in particular, but if your house is 20 years old, has poor insulation and the ac is already cranking for 5 months outta the year I'd say you could push the dwelling into the situation where it will never be able to acheive that 73 degrees your asking for.
 
Z

zor

Active Member
Archie22 said:
I currently run my flower light into the cold air return in my basement. The fan is probably moving 300+ cfm after considering restrictions. So, far so good. All rooms in the house still pull smoke into the return vents quickly. A few of the return vents closest to the hvac unit still hold an 8.5x11 up against them. I haven't turned on the furnace yet this year. In fact, the 1000w Lumatek on 110% is providing so much heat that I've been keeping my windows cracked to get good Co2 rich air circulating and the temps are still above 66 when ambient is down below 40* in the AM. Another benefit of this is that the run back too the hvac kills the noise a bit by blending it with its own fan noise and the filter media. Also, the whole houses filter media can be had in a carbon version as well and act as a "second scrub".

Unfortunately, I can't comment as to how this would work in the summer long term because I just constructed this new room in early September. I did note that even as ambient temps dipped to 70 my compressor was still working pretty heavily. At this point I'm thinking it should be okay. Yes, it will add significant load to the ac but at least an auxiliary unit won't be required. In the spring I'm going to be adding a reflective tinting to my southern facing windows in an effort to reduce AC load(The entire 95ft back wall of my house faces due south)

Edit: 8" fan exhausting 2k watts could be too much for the condenser to handle in 90 degree ambient temps. That is if the 700+CFM that the 8" is supplying doesn't screw up the flow in the rest of the house. Ultimately is all depends on the size of your houses hvac unit. For comparison, my house is ~3000 hvac'ed sqft and is only three years old and energy star certified. Not directed at anyone in particular, but if your house is 20 years old, has poor insulation and the ac is already cranking for 5 months outta the year I'd say you could push the dwelling into the situation where it will never be able to acheive that 73 degrees your asking for.
Click to expand...
Thanks for the info. Personally i was hoping to just exhaust into the cold air return of the furnace during the heating season. But it sounds like your using a 6" fan to extract the heat from a 1000w lumatek and this alone warms up your house enough to not use heat when outside temps are in the 40s.

Seems like it should work then, however, im wondering if there is a limit to the amount of air that can be pushed into the return vent before causing strain on the furnace.
 
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Archie22

Active Member
It won't cause a strain. It will just fuck up the flow from the rest of the return locations. If you pick up with the return off the main trunk instead of the end of the line the air velocity will be higher and will accept the high velocity from the exhaust much easier. IMO.
 
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