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Electric Radiant In Ceiling - Hot Spots


dtontarski
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I inspected a home today with electric radiant heat in the ceilings. The heat was fairly even across the ceilings (about 80-85 degrees) after the thermostats had been cranked all the way up for about 20 mins. However, in one room (the longest room in the home) there were a few 95-100 degrees hot spots. Any thoughts on this condition and how I should address it in my report?

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Presumably there was no visible reason in the attic/or space above for the hot spots? Or no access?

I only see elec radiant ceilings about once every 2 years, so I start by telling my clients that they are "rare" and I doin't get the kind of day in day out experience with them as I do with other systems.

It's too late now, of course, but I would have left the system cranked for a while and retested (LAser thermometer?)

Based on what you said, I don't know of any reason to be concerned.

Maybe someone will have more knowledge about them.

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Mike -

I guess I should have called this a "hotter" spot. I don't see much of this, and when I observed that most of the ceiling had relatively even lower temperatures, I thought I'd take advantage of this resource to ask if I should be concerned. Sounds like I shouldn't be. As always, I'm just trying to be thorough and use all of the tools and resources afforded to me.

Thanks - this is a great resource.

Dave Tontarski

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I agree that it's not a problem however, a call to the manufacture, or the local rep, doesn't hurt either. Gives you a chance to pick their brain about their products, talk about inspecting their product and to get technical/application information mailed to you. Manufactures don't want their product installed/applied incorrectly however, you may find remodels try to fit a square peg in a round hole.

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Does not seem very hot to me. I inspected one of these over the past summer, then on the first cold day we had in the fall the home owner called complaining his family was freezing and what was I going to do about it. The first thing I asked was if he had checked the breakers - he assured me he had and they were all on. I agreed to drive the 30 minutes out to the house and check it out, but it would not be for 3 days. So the family froze for 3 days and when I arrived at the house he was pissed and ready for a confrontation. On the inside I was thinking “oh-shit did I screw up, am I going to have to buy this guy a heating system?â€

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Originally posted by dtontarski

I inspected a home today with electric radiant heat in the ceilings. The heat was fairly even across the ceilings (about 80-85 degrees) after the thermostats had been cranked all the way up for about 20 mins. However, in one room (the longest room in the home) there were a few 95-100 degrees hot spots. Any thoughts on this condition and how I should address it in my report?

I inspect a dozen or so every year. What you describe is normal.

- Jim Katen, Oregon

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Hi Randy,

I think that just reading surface temp isn't going to tell you that much about a ceiling radiant system because it's not the surface temperature that keeps people warm, it's the radiant heat emanating from the ceiling. It travels equally in all directions, irrespective of other conditions. One room might be drawing more surface temperature off the ceiling for whatever reason, while another will not, but the folks in the room below will be perfectly comfortable.

I know this is hard for folks to understand, because they have this misconception that heat rises, when that' s not the case. Heated air rises, not radiant heat. Heated air is displaced by heavier colder air and the heated air is pushed upward near the ceiling, giving people the mistaken impression that heat rises. Well, radiant heat will even pass through a vacuum. That's how this planet is heated. So, ceiling temp is only telling you that the heating element is getting warm. It's impossible, as an inspector, to know how much ceiling temp is being drawn away by types and thicknesses of materials. The determining factor in whether a radiant ceiling system works is whether the folks in the home are comfortable and we don't have the luxury of seeing the home re-furnished and decorated and knowing how folks will live under those systems, so predicting performance is quite literally impossible during a home inspection, regardless of whether they system is perfect.

Here's an extreme example of radiant heat. When I was running the MP station at Ft. Carson, Colorado, my MP's used to freeze their petoonkies off outside the gate shack, while standing out on the main gate checking cars and waving people by during the winter months. The heaters in the gate shack didn't help because the doors were opened so often and the shacks were so exposed to the wind. The poor guys would come down with colds and the flue and it got so bad that we had to change them out every two hours. It was a huge hassle and a scheduling nightmare.

I finally got fed up with it and talked the command into purchasing some quartz radiant heaters to stand outside the doors of those shacks, directed at the spots where those MPs had to stand. Once we did that, our guys could literally stand out there in the worst type of weather for hours without getting chilled. The air around the heater and between the heater and the MP was still cold, but the MP was being heated by radiation and wasn't dependent upon the air temperature around him or her for warmth. That's what's going on with these ceiling radiant heat systems and why all the surface temp tells you is that the element is on.

Hope that's clear as muck.

ONE TEAM - ONE FIGHT!!!

Mike

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Originally posted by randynavarro

Did a condo last week where I actually may have found an apparent defect.

One of the room was 82-90 deg. (and yes, I found a few spots around 100 deg. or so). The other half was 64-68 deg.

Gonna be tricky to deal with if they want it fixed as the roof is flat!

If it was 64-68 degrees across the whole room's ceiling, the coil in that room probably wasn't working at all. It's either a thermostat problem or a broken wire in the ceiling. Either one's easy to fix. Tell them to call an electrician who's worked on these systems before. He'll know what to do.

- Jim Katen, Oregon

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Did a condo last week where I actually may have found an apparent defect.

One of the room was 82-90 deg. (and yes, I found a few spots around 100 deg. or so). The other half was 64-68 deg.

Not to leave any stone unturned, I undrstand that these systems can also be zoned? Could this be the case[?]

Thanks for the opportunity.

Craig

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With radiant ceiling panels, not all of the ceiling will be heated. There should only be enough panels installed to heat the room properly. In my home (I have this type of heat) Much of the ceiling is not hot, as those portions of the ceiling are just normal sheetrock. If you inspect a home with this type of heat and you have attic access, you can find the heated panels quite easily by lifting the insulation. You will immediately see the difference in the backs of the panels. In this area (Southern NM), when I look at a 12x20 room, there may only be 2 or 3 heated panels, with the remainder being normal sheetrock. Oh, by the way, my heating bills are on a par with the dino fuel heated homes around.

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Originally posted by sbrooten

With radiant ceiling panels, not all of the ceiling will be heated. There should only be enough panels installed to heat the room properly. In my home (I have this type of heat) Much of the ceiling is not hot, as those portions of the ceiling are just normal sheetrock. If you inspect a home with this type of heat and you have attic access, you can find the heated panels quite easily by lifting the insulation. You will immediately see the difference in the backs of the panels. In this area (Southern NM), when I look at a 12x20 room, there may only be 2 or 3 heated panels, with the remainder being normal sheetrock. Oh, by the way, my heating bills are on a par with the dino fuel heated homes around.

I thought Randy was saying that an entire room wasn't heating. Now that I re-read his post, it seems like only a portion of a room's ceiling wasn't heating. I'm not sure exactly what he meant.

There are two different types of radiant ceiling systems. The one you're describing uses pre-manufactured drywall panels with heating cables embedded in them. The other kind uses cables that are stapled up on ordinary drywall and plastered over. In either case, as you described, the entire ceiling might not be heated.

- Jim Katen, Oregon

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Originally posted by randynavarro

I thought Randy was saying that an entire room wasn't heating

I did not clarify that well. One entire half of one room was not heating. The other half was.

There was consistent heat in all areas of the ceilings in the other rooms in the unit, so its probably a pretty safe bet that this was a defect in this one room.

Not necessarily. In my experience, each room's ceiling has only a single circuit or "coil" of heating cable. Either it works or it doesn't.

That room's coil might have been installed on only part of the ceiling as Steve Brooten described in an earlier post.

- Jim Katen, Oregon

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Originally posted by randynavarro

Well, then perhaps it reinforces the idea that we, during a normal home inspection, can't really say a whole lot about radiant heat as Mike O suggested earlier.

Its on or it ain't.

That's exactly it.

And even that conclusion may be in question at times.

There really shouldn't be any doubt. If you've got an IR thermometer or a volt stick, it's pretty easy to show that the coil is working or not working.

- Jim Katen, Oregon

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You may want to tell your clients that it's an inefficient system...

What authoritative source might that be from? (Didn't you worn me that everything on the web might not all be true?)

A study, from the mid 90s I think, found electric radiant to be significantly more efficient than all other electric heating systems, including heat pumps. Using individually zoned rooms wisely can also offer major savings over many central "dino fueled" systems that also exhaust lotsa un-captured heat.

I've heard that bald HIs don't have any problem evaluating radiant heat in the ceilings. I can't confirm this - yet.

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Hi Bill,

According to a manufacturer of ceiling mounted radiant electric panels, they're to up 20 % more effective (if installed perfectly with an effective radiant barrier above the heat source)than conventional electric basenboard heat. There are still conductive losses to consider as well.

The fact is that both convective and radiant panel systems are are 100% efficient at converting electricity into heat...they even use the wiring in the house as a radiant heat source. I shouldn't have said the system was inefficient.

One gallon of fuel oil has 134,000 btu's x .90 for losses =120,600. At $1.90 per gallon that's .00001575456 dollars per btu.

At 3400 btus per kwh and a modest 12 cents per kWh, the cost per btu for elctric is .00003529411 dollars per btu. Look at the 5th and 6th digit to the right of the decimal.

Radiant heat heats people and things, fuel burners heat air which then heats people and things. I had radiant heat in my shop and it was no fun when you went under a car.

Nearly fifty years after first appearing on the scene, radiant ceilings still take a back burner to other systems which ignite stuff on site and burn it in a box. Radiant systems are cheaper, easier to install and take up no floor space. These are very desireable features. Cost of operation is their only draw back.

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