Thinking about insulating hoods

What have you all used to insulate your hoods? Reflectix looks like the easiest to use non permanent solution but it has no rated R value.

If someone has used reflectix can you give me:
A) Room temp
B) uninsulated hood temp
C) insulated hood temp

The reason I ask is there is another material, a self-stick foil type insulation and the ROI on that is 7 months and it's really hard to get that stuff off once its on.

Is it worth it? Only if you're running a sealed room with A/C and sealed air cooled hoods - otherwise you could just increase air exchange to lower temps.

Lets do some rough calculations

Assume the reflector is 10" high and 21" wide then taking the area for a cylinder of those dimensions and dividing by two = 6.75sqft

BTU = (T2-T1)*sqft/R-value

The hood is currently ~100 degrees (air cooled) and the room is 80, the self stick foil has an R value of 3.

Using those numbers

BTU, uninsulated = (100-80)*6.75 = 135

BTU, insulated = (100-80)*6.75/3 = 45

difference = 90 BTU

Over 1 month of flowering = 90BTU/hour *12hours/day*30 days = 32,400 BTU per light

convert to kW = 32,400BTU * (1/3412.142 BTU/kW) = 9.5kW

assume 10 cents a kilowatt and you have a savings of 9.5*0.10 = 0.95 or roughly a dollar a month

at 20 bucks for enough insulation to do 3 lights that's ~7 dollars per light.

So it's a 7 month ROI on the self-stick foil and then you begin saving ~$1 per month per light.

why not just blow a fan through the hoods and get the hot air out . you can insulate trap the heat and it will sure to melt any thing up or burn . sounds like a bad idea to me. unless your talking about 400 or 250 watt bulbs . any higher for get about it .

lose the hood n go bare bulb

I've seen something like that done with faced fiberglass batting......I've been told by the person who did it as it's kind of a waste of time and the only payoff is in the long - long haul. I don't find that my stringed 1K's have much of a surface temp change from #1 to #4 but you have me interested enough to get out my IFR gun to actually "see". Of course you must run the proper cfm to keep parity between those hoods too. I don't think I would run more then 4 inline with 6 inch line hoods and that's a personal choice.

Still, I'll bet you would be FAR better served by not Having the ballasts in the growing area over trying to insulate the hoods (if their in the grow area). That's the route the fellow I was talking about earlier did and made a far bigger change overall!

They do sell insulating covers for ac hoods you know.

Dr. Who - the ballasts are located outside. Those things crank the heat!

I just thought if it was possible to insulate the hoods for a few bucks and 10-15 minutes of work it might be worth it. I saw some other insulation that was R-12 for wrapping pipes that I quickly crunched the numbers on and it was like a 3 month ROI. Not sure if it was self stick or not though. Faced batting would be WAY too much effort for the R value.

Dbkick, I saw the hood covers but at $50 for one that's somewhere around a 4 year ROI.

if your really looking to insulate these hoods I would try a material calledhttp://www.sonicelectronix.com/index.php/lp/pla-sound-dampening/dyna-10612?utm_medium=cpc&utm_source=bing_pla&utm_campaign=Bing+PLAs&scpid=31&scid=scsho3601383 this will stop the heat its actually for car audio but its used for many purposes it will stick right to the hoods .

Bryan that's a sound barrier material. It has the same drawback as reflectix, no R-value listed.
The formula:

BTU = sqft*(T2-T1)/R-value can be used to estimate the R-value if you rearrange and get:

1) 0=(sqft*(T2-T1)/R)-BTU

Assuming the difference in BTU will account for room temp we can ignore that for now and get:

2) 0=sqft*(T2-T1)/R

set the equation equal to itself for insulated and uninsulated hood and sqft cancelling out because it's the same hood.

3) (Hood temp uninsulated-Room temp w/ uninsulated hood)/R(uninsulated) = (Hood temp insulated-Room temp w/ insulated hood)/R(insulated)

Assuming that R(uninsulated) is 1 we solve for the insulated R.

4) R(insulated)=(Insulated hood IR temp-Room temp w/ insulated hood)/(Uninsulated hood IR temp-Room temp w/ uninsulated hood)

This only works if the A/C doesn't ramp up to handle the higher heat load..if it does you'd need to see the difference in power usage and convert the KWH into BTU and plug that into part one of the break down with sqft cancelling out.

1A) Sqft_of_hood*(Insulated hood IR temp-Room temp w/ insulated hood)/R)-BTU(insulated)=Sqft_of_hood(Uninsulated hood IR temp-Room temp w/ uninsulated hood)/R)-BTU(uninsulated)

Where BTU = KWH*0.000293071 and Sqft_of_hood cancels.

2A) (Insulated hood IR temp-Room temp w/ insulated hood)/R)-KWH*0.000293071(insulated)=(Uninsulated hood IR temp-Room temp w/ uninsulated hood)/R)-KWH*0.000293071(uninsulated)

So you see with an IR gun, thermometer, and kW meter you can determine the R-value your insulation has actually provided.