Author Topic: Electric ceiling heater / building code question  (Read 11242 times)

Spork

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Electric ceiling heater / building code question
« on: December 20, 2013, 01:00:07 PM »
We heat almost exclusively with a wood stove.  The end result is that the area furthest from the heat source (which is on a northeast corner) is hard to keep warm.  The bad news is: this is the master bathroom.  Morning showers can be chilly.

Last winter I installed this ceiling heater.  From the description, I think it is sized well to the room... but ... it takes FOREVER for it to heat the room up.  It's a 240v / 2000w heater and a little ceramic floor heater that is 120v/1000w does a much better job.   

The obvious answer is "just use the floor heater, dummy."   But I'd like to sort out why the original heater isn't working too well.

The backside of the heater is attic space.  We are foam insulated at the back side of the roof.  This means the housing for the heater backs up to a HUGE attic space.  It's inside the insulated envelope... but... it's big.   I'm thinking we're losing the heat upwards (obviously).

I'm wondering what sort of insulation is kosher on something like this.  I suspect it gets pretty hot.  Is it within safe building codes to pile a few bats of fiberglass insulation on this? 
« Last Edit: December 20, 2013, 02:17:31 PM by Spork »

Rural

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Re: Electric ceiling heater / building code question
« Reply #1 on: December 20, 2013, 01:54:02 PM »
How tall are your ceilings? Have you put a thermometer up there to check the temperature differential up there and down where you are? I can't help you with the code, unless what you need is the 2006 code, but I think it would be worth looking to see whether what you have is heat in the attic Or heat hovering around the ceiling.

Spork

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Re: Electric ceiling heater / building code question
« Reply #2 on: December 20, 2013, 02:22:11 PM »

I haven't actually measured... but...

The ceilings are 9 ft.  I'm 6'2" and with my gorilla length arms extended I'm easily over 8ft.  It's cold up there too. 

There is a thermostat for the ceiling heater at about 5 ft.  In the winter mornings it is about 62-64 at 5 ft.  We've got a warm snap and it's in the 70s this week, but I can measure the temp at the ceiling with the heater running when it cools down again. 

To be all scientific I should probably also measure a couple feet above the heater.  It's extremely accessible.

Greg

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Re: Electric ceiling heater / building code question
« Reply #3 on: December 20, 2013, 02:46:26 PM »
Check the wiring for the correct connections (red jumper in place) for maximum wattage.

The black metal rough-in box/housing is designed for the temps it should normally see and the unit has a thermal breaker in case of overheating. There are no warnings about insulation contact with the housing so I think it should be fine to insulate over it.  I would use fiberglass blow-in or unfaced batts , but would not use a rigid foam over it, even though it should be fine.

The instructions do say the optimum distance to the floor is 8', so you might be losing a little performance that way.

dragoncar

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Re: Electric ceiling heater / building code question
« Reply #4 on: December 20, 2013, 08:40:55 PM »
I'm confused... where does the fan draw air from?  Maybe it would be better to install a duct in the attic (plus a fan) that moves air from the ceiling next to your stove to the bathroom?  I have no idea if that's feasible but it would use electricity.

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Re: Electric ceiling heater / building code question
« Reply #5 on: December 21, 2013, 04:41:56 AM »
I'm confused... where does the fan draw air from?  Maybe it would be better to install a duct in the attic (plus a fan) that moves air from the ceiling next to your stove to the bathroom?  I have no idea if that's feasible but it would use electricity.

It draws air from the room, pulls it across a heat sink and blows it back out.

I actually have installed a return duct near the wood stove to redistribute air.  It helps some... but not nearly as much as I'd hpped.  Also the bath heater was intended as a "10 minutes a day first thing in the morning".  In the mornings it takes a little to get the stove running.
« Last Edit: December 21, 2013, 04:46:16 AM by Spork »

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Re: Electric ceiling heater / building code question
« Reply #6 on: December 21, 2013, 09:02:38 AM »
Check the wiring for the correct connections (red jumper in place) for maximum wattage.

The black metal rough-in box/housing is designed for the temps it should normally see and the unit has a thermal breaker in case of overheating. There are no warnings about insulation contact with the housing so I think it should be fine to insulate over it.  I would use fiberglass blow-in or unfaced batts , but would not use a rigid foam over it, even though it should be fine.

The instructions do say the optimum distance to the floor is 8', so you might be losing a little performance that way.

I'm pretty sure it's wired correctly.  It was very straight forward.  And the jumper was pre-installed (you had to cut it to convert to 120v).  I don't have a clamp on ammeter, but I guess that would confirm the proper watt draw if I did.

Your opinion on the insulation was what I was hoping to hear... and what I had sort of guessed.  (I mean: I would imagine the majority of homes still have insulation at the ceiling.)  ... and that is also a super simple/cheap fix to attempt.  I think I might even have a few partial rolls of fiberglass I could pile on there.

Greg

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Re: Electric ceiling heater / building code question
« Reply #7 on: December 21, 2013, 09:09:46 AM »
This may be one of those situations where another type of heater, like those heat-lamp ones that were all the rage in the '70's might work better.

The reason I mentioned checking the wires is that I had an experience with a replacement wall unit that used different connections to create different wattages, and someone had either tried it before me and returned it or it was wired differently than it should have been from the factory.  A minute of head scratching solved the issue.

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Re: Electric ceiling heater / building code question
« Reply #8 on: December 21, 2013, 09:25:53 AM »
This may be one of those situations where another type of heater, like those heat-lamp ones that were all the rage in the '70's might work better.


That occurred to me, too.  And heating from the ceiling down is always hard.  We really scratched out heads looking for a place to put a wall-mount heater...   There just wasn't wall space available.

I might also mention: we have polished concrete floors.  There is a huge thermal mass of cold to overcome at the floor level.

Greg

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Re: Electric ceiling heater / building code question
« Reply #9 on: December 21, 2013, 10:13:56 AM »
I have finished concrete floors as well, so I can sympathize a little, but only a little since my floors are my heat source. 

Is your floor insulated?  Might be able to go over it with tile with electric radiant in between.  A really big fluffy bath mat might help too.

Spork

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Re: Electric ceiling heater / building code question
« Reply #10 on: December 21, 2013, 07:17:04 PM »
I have finished concrete floors as well, so I can sympathize a little, but only a little since my floors are my heat source. 

Is your floor insulated?  Might be able to go over it with tile with electric radiant in between.  A really big fluffy bath mat might help too.

Nope, no insulation under the slab.  I don't think that's common around here... maybe it should be.  And since it's a northeast corner, there are 2 sides of the slab (and 2 sides of brick siding) that really absorb the cold. 

We could do radiant... but I'm not sure I'm ready to take that expense.  "It's a tad chilly when I step out of my shower" is really a first world problem.  I'm also still finishing the upstairs, so it is doubtful any serious changes will happen downstairs until that is finished.

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Re: Electric ceiling heater / building code question
« Reply #11 on: December 21, 2013, 09:20:50 PM »
If it's wired correctly I think insulation is the only logical step to take. With resistive loads (such as electric heaters), half the voltage will give you 1/4 of the wattage, so it'll be a way worse heater. My hope is that it's that, because otherwise I don't know how much better it'll get. And, as you say, it's never easy to heat from the ceiling.

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Re: Electric ceiling heater / building code question
« Reply #12 on: December 22, 2013, 03:52:38 AM »
I have used this manufacturer's wall unit, in bathrooms, when nothing else fits. Honestly, it is a really undesirable option. I had one fail quickly, and IMHO the noise to heat ratio isn't acceptable. Performance is much, much better when a fan coil unit is located low on the wall however. Couple of points here. A self contained fan coil unit like this is compromised right out of the box ,since it's ceiling mounted. It's recirculating heated air at the ceiling level, and chances are, you are experiencing significant stratification of air until the entire space is heated up. If you have a digital cooking thermometer, it would be interesting to see the temp. differential from knee level to the ceiling, after this thing has been running for a few minutes.
Since the installation manual specifically ignores the question of insulation encapsulation, it's safe to assume that it's allowable. You are correct in guessing that you have some heat loss into the attic. Some of it is radiated through the metal back box, and much of it is lost through the multitude of small holes in the box. I wouldn't hesitate to take a jumbo sized can of great stuff and build a beehive style cocoon around the entire back box. If this doesn't greatly improve performance, I would think about removing the unit and installing a surface mounted radiant panel over the box box opening. They are thin and fairly discrete, and will perform a lot better with the concrete floor.

Spork

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Re: Electric ceiling heater / building code question
« Reply #13 on: December 22, 2013, 06:54:13 AM »
Some of it is radiated through the metal back box, and much of it is lost through the multitude of small holes in the box. I wouldn't hesitate to take a jumbo sized can of great stuff and build a beehive style cocoon around the entire back box. If this doesn't greatly improve performance, I would think about removing the unit and installing a surface mounted radiant panel over the box box opening. They are thin and fairly discrete, and will perform a lot better with the concrete floor.

I was at least smart enough to seal all the multitude of holes with foil tape.  But while that takes out air movement, I don't know how much actual heat transfer that stops.


paddedhat

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Re: Electric ceiling heater / building code question
« Reply #14 on: December 22, 2013, 07:40:16 AM »
LOL, congratulations, And yes I AM dead serious.  After three decades of homebuilding and being a licensed electrician, I have seen very few (except me, LOL) who ever gave those holes a second thought. One day, a few years back, my local building inspector announces that he wants to see a fully foamed layer surrounding any electrical box that penetrates the outside wall, since testing indicates that all those holes are a major source of leakage.  I said great, welcome to the 80s. He looked at me funny, and I told him that a few of us, with half a brain, have been doing that for the last few decades.

The foil tape is important, I would still either cover the whole box in foam, or use foam to seal the back of the sheetrock, against the sides of the box, if you didn't caulk this already.  That said, If it was my place, I would order a nice 2' x 4' low profile electric radiant panel and use it to cover the whole mess. It will warm that slab up nicely.

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Re: Electric ceiling heater / building code question
« Reply #15 on: December 22, 2013, 07:57:25 AM »
Here comes the science...

I took temperature readings at about 1ft, 4ft, 8.5ft and 1 foot above the heater (in the attic).

beforeafter 10min
1ft6566
4ft6568
8ft6590
attic6367

so... pretty much everyone has been saying (back to the first reply) that the heat isn't making it to the floor.  Holy shit.  I had no idea how bad it was.  If I had sat at the ceiling even longer, I think it would have gone over 90.

The other take here is that there does seem to be significant leakage into the attic.  This area of the attic is a freaking huge area in cubic feet.  (Really high 10/12 roof... it's probably > 20 ft high in there.)

As to other recommendations:
* wiring: I am pretty confident in my wiring....  That's not to say there isn't a wiring fault in the unit itself that (effectively) gives me 120v instead of 240... but I think it's right.
* radiant from above/below:  yeah this is probably the right answer.  I just don't know how much money I want to throw at it in the short term.  It isn't unusable as is.  And a ceramic 120v heater at floor level heats the area up really nicely.  The cost effective solution is to just use the portable ceramic heater I already have.
* I am definitely going to pile on some insulation in the attic -- both over the rough in box and probably some bats laid on the drywall itself.  (Remember: there is NOTHING there.... we're foam and insulated at the roof line.)    I have quite a lot of insulation in my workshop I can steal.  (I used to live in the workshop and it was heated space. It is no longer heated space and a good chunk of the build out will be torn down do make a better workshop space.

paddedhat

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Re: Electric ceiling heater / building code question
« Reply #16 on: December 22, 2013, 09:28:10 AM »
Wow, interesting science experiment you have going there. LOL.  I suspected some significant stratification, but not to that extreme. Looks like you are doing a bang up job heating the attic space as well.

Just as a comparison, I put a 1000 watt, wall thermostat controlled, recessed, wall mount, fan-coil unit in a small (roughly 45 sq. ft.) bath in a new home. The occupant reported that he rarely used it, and when he did, it would make the room uncomfortable hot, quickly.

Rural

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Re: Electric ceiling heater / building code question
« Reply #17 on: December 22, 2013, 09:47:28 AM »
Is the space big enough for a ceiling fan? We have virtually the same situation (concrete slab, Fthough ours is insulated, heaters up high for the whole house, 10" ceilings). Installing a ceiling fan in my office, set on reverse for winter, has made our temperature differential 4-5 degrees on a cloudy day rather than >10 degrees. The only room that won't eventually have a ceiling fan is the bathroom, but if I had a ceiling heater I'd put in a small one (we just use a cheap space heater on the floor for the time it takes to shower).

I take it this bathroom is in a one-story section of the house?

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Re: Electric ceiling heater / building code question
« Reply #18 on: December 22, 2013, 12:09:08 PM »
Is the space big enough for a ceiling fan? We have virtually the same situation (concrete slab, Fthough ours is insulated, heaters up high for the whole house, 10" ceilings). Installing a ceiling fan in my office, set on reverse for winter, has made our temperature differential 4-5 degrees on a cloudy day rather than >10 degrees. The only room that won't eventually have a ceiling fan is the bathroom, but if I had a ceiling heater I'd put in a small one (we just use a cheap space heater on the floor for the time it takes to shower).

I take it this bathroom is in a one-story section of the house?

Yes, this is in an area with no second floor directly above. 

so... we were looking at the ceiling fan option this morning. 

A normal ceiling fan... no. 

Some sort of wall mounted fan like this...  yes, probably.  (pic for reference only...  not necessarily exactly this style)
« Last Edit: December 22, 2013, 12:11:05 PM by Spork »

Rural

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Re: Electric ceiling heater / building code question
« Reply #19 on: December 22, 2013, 12:53:53 PM »
That's actually pretty cool and steampunk-looking. :-)

It wouldn't work quite as well as a flush mounted tradition fan, but should surely be better than the differential you have now.


Editing to add: have you considered getting a ceiling heater with a more powerful fan itself? How would that compare, cost wise, to the auxiliary fan ( purchase and operation)?
« Last Edit: December 22, 2013, 12:55:51 PM by Rural »

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Re: Electric ceiling heater / building code question
« Reply #20 on: December 22, 2013, 01:44:35 PM »
That's actually pretty cool and steampunk-looking. :-)

It wouldn't work quite as well as a flush mounted tradition fan, but should surely be better than the differential you have now.


Editing to add: have you considered getting a ceiling heater with a more powerful fan itself? How would that compare, cost wise, to the auxiliary fan ( purchase and operation)?

That should probably be tossed in there for consideration, too... something like the ceiling radiant mentioned above.  I haven't looked closely at prices ... but the wall mounted fans seem to be relatively pricey (or they look like a plastic desk fan someone has screwed to the wall).

We're going to experiment with a small portable fan for a few days and see if just moving air around will make a difference.


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Re: Electric ceiling heater / building code question
« Reply #21 on: December 22, 2013, 07:10:51 PM »
Where I'm at, you can find working vintage metal fans on craigslist for relatively cheap (compared to the price of fixtures like in your pic). I bought two recently, and at some future date when projects finish up I'm planning to make them into a custom ceiling fan similar to the one in your picture. Just a consideration.