1500 W heater fan in joists/ceiling
darrel
| Posted in Energy, Heating & Insulation on
I bought a GE bath exhaust fan/heater fan combo. The documentation is thin, to say the least (basically says mount to joists, exhaust).
I’m a bit concerned as it seems as if I’m putting a giant, un-insulated toaster in my joists and then closing it all up. Am I paranoid, or is there more to mounting a heater of this sort than the documentation is indicating? If I mount it as is, I maybe have a 1″ clearing on the sides and top of the fixture. Do I insulate this? Leave it open? The fixture is just a sheet metal box, so I’m a bit concerned of heat build up in the joist bay. Above the joists are toungue-and-groove sub-floor and then the crawl space (which I will then cover with fiberglass insulation in this area.)
Replies
DARREL,
The installation instructions although "thin" are from the mfr. modify those instructions and who becomes responsible?
If trapping heat is a concern, wouldn't you want to cut a hole in the flooring and not insulate around that opening?
If I cut out the floor above it and around it, then I have a giant hole in my crawlspace where any heat that was in the bathroom to begin with there will just go to heat my crawlspace. ;o)I guess my question is are these heater fans normally installed this way...inside a closed ceiling?The instructions appear to be generic enough to apply to any bath fan, not necessarily a heater fan.Or, maybe I'm just being paranoid, and this is a perfectly acceptable way to install it?
Check to see if there is a thermo-couple on the outside case. Like in recessed lights these will shut off if you install the wrong type or Wattage bulb in them....its usually an inch long with two wires attached. Is this UL approved.
I will check. I assume it is UL approved (It's a GE fan sold at the big-box home store) but, yea, one should never assume... ;o)I just found it odd to have a 'toaster' in the ceiling with nothing more than a piece of sheet metal to 'insulate' it. But, now that I think about it, the heater won't work unless the heater fan is also running, so perhaps there's enough air flow that it never really becomes a fire hazard.
A thermo-couple is used to generate a small voltage. It used in measurements and as pilot safties on gas eqiupment. It is not used for on can lights.What you are talking about is a type of thermostat. Called a thermo-cut off.However, I suspect that they are not used on heaters.Many heating devices (an dryer is one) have thermo links or fusible link. If the unit over its it will melt and the unit nees to be disasembled to replace it. You have to know what to look for to find it.
well, so much for assuming...I can't find a UL stamp/sticker anywhere on this device.The clearance issue is exactly what I'm worried about. The instructions make no mention of any clearance specifications. It *does* say "not to install this in a ceiling thermally insulated to a value greater than r-40"...so maybe that's all there is to it.Ah...wait a minute...here's the spec's on the fan: http://64.233.187.104/search?q=cache:EJTSf72vLOwJ:www.geindustrial.com/products/specs/bfretail/e-det369.pdf+bflh85l&hl=en&client=firefox-aThis did NOT come with the fan, but I found it on GE's web site."Designed for ceilings insulated to R-40 with at least 6” clearance"UGH! WHY isn't this in the documentation? (Rhetorical question...just ranting... ;o)OK, well, I guess that answer it, I need 6" clearance. Seeing as how the unit is 6" tall, I suppose that means one needs 12" joists. Not going to happen in this old house, alas. Looks like we'll have to skip the heat in our bath for now. ;o)
This is why lots of bathrooms have drop ceilings.
Well, we've lived with a cold bathroom for 5 years. We can stand a couple more. Hopefully the new (and smaller) window + better insulation will make things bearable until we sell and let the next owners figure out how to heat the space. ;o)
I was thinking that you were trying to let some of that heat escape since your opening has so little clearance .As far as my experience with these fans, I have installed only a few , but they were in exposed attics & some had insulation laid around them , If you asked me to install that fan in your house, I would decline. How much peace of mind are you comfortable with?Put a regular fan in the ceiling and install a baseboard heater next to the ..............(fill in the blank)"
well, I talked with the electrician a bit and he had no issues with these types of fans.So, I think I'm going to go the route of lowering the celing (going to fur it out with 2x4s) which will give me the 6" clearance, plus add a layer of sheet metal to the space as an added peace-of-mind.That will give me a 6" airspace, subfloor, and likely a chunk of fiberglass insulation above that around the duct.And we'll see what happens. ;o)
that 'll work"
In theory the thing is UL approved and all that, and is safe to put anywhere so long as installation instructions are followed (including any clearances).
If you're paranoid (always a good idea), securely tack a piece of sheet metal in the joist bay, running 6" or so beyond the unit in both directions and bending down in a U to cover the sides of the joists. This should roughly double your margin of safety should the unit overheat or throw sparks into the joist bay.