# Ceiling radiant heat



## BT Electric (Feb 7, 2014)

I have a customer that wants a ceiling fan installed Ina living room with ceiling radiant heat. I have never seen a configuration like this, it appears to be similar to in floor heat but is installed in the ceiling with the Sheetrock. 
There is no access to this as there is a bedroom directly above the room and he does not want to cut the ceiling up and have to refinish it. 
I am not going to blindly cut a hole in this ceiling and risk damaging the heating elements. 
Any advice would be appreciated. At this point I have told him no I won't do it but would ask some questions of the forums to see if anyone has a way of accomplishing this without damaging the Sheetrock or the radiant heat. 


BT Electric


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## RIVETER (Sep 26, 2009)

Turn the heat on and use a FLIR to map the ceiling.


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## Somewhere_401 (Apr 7, 2014)

I have seen this before. 

If you have a FLIR camera, after about 30 seconds, you should be able to find the cables.

There is NO Patching this, so the customer needs to be made aware of this risk.

The cables are about 4 inches apart, the cable is normally quite small.

The plaster should be quite hard, and very messy. 

I have told people if they want to use the heating system NEVER put a hole in the ceiling. 

Good Luck


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## BT Electric (Feb 7, 2014)

Somewhere_401 said:


> I have seen this before.
> 
> If you have a FLIR camera, after about 30 seconds, you should be able to find the cables.
> 
> ...



After further research this is the same conclusion I came up with. I said it was Sheetrock earlier and meant to edit to say plaster. It's been a long day! 
I am sure he nor I am willing to take the risk of damage to the heating elements, much less the textured plaster ceiling. 

Thanks or the help!


BT Electric


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## backstay (Feb 3, 2011)

Toner would work too.


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## MDShunk (Jan 7, 2007)

Radiant heat in the ceiling was very popular in my area. The clue is line voltage thermostats on the wall, but no baseboard heaters. The typical install is 3/8" drywall, heat wires applied with a special T-50 staple variant, then 1/4-3/8" of plaster applied over top. The heat wires are normally 4-5" apart. 

The old-school way was to mist the ceiling in the proposed area of the fan box with plain water from a spray bottle. Turn on the ceiling heat stat, and you can see "lines" develop as the water evaporates over top of the actual heat wire first. If you have even the cheapest FLIR camera, you'll see the same thing.

After the wires are located by whatever method, I'd recommend that you outline your box in pencil, then scrape along the line carefully getting through the plaster layer with a thin straight screwdriver until you get down to the drywall paper. Do this carefully. This proves that you don't have a heat wire in there, and if done carefully and you do discover one, you won't nick it. THERE'S NO FIXING THIS STUFF IF YOU CUT IT.


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## Somewhere_401 (Apr 7, 2014)

BT Electric said:


> After further research this is the same conclusion I came up with. I said it was Sheetrock earlier and meant to edit to say plaster. It's been a long day!
> I am sure he nor I am willing to take the risk of damage to the heating elements, much less the textured plaster ceiling.
> 
> Thanks or the help!
> ...


--
The only ceilings I have seen have been with a special sheet rock (plaster board) and temperature plaster coating. 

You can almost always tell when people don't understand the system, they will crank the thermostat to high and then the ceiling cracks. 

If you ever take the ceiling down, the plaster is quite thick, almost and inch and a half thick.

I have seen one ceiling where there was a point of impact in the center, due to to careless workmen. Needless to say, baseboard heat was the only solution.

I have found that people seem to be only happy with this type of heat in the bedrooms, not in living areas.

I would also wonder if a ceiling fan would increase the likelihood of the ceiling developing cracks, especially it is a textured ceiling.


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## BT Electric (Feb 7, 2014)

Somewhere_401 said:


> --
> The only ceilings I have seen have been with a special sheet rock (plaster board) and temperature plaster coating.
> 
> You can almost always tell when people don't understand the system, they will crank the thermostat to high and then the ceiling cracks.
> ...



It is not a good situation for the installation at all. There are some existing cracks and the ceiling is 45 years old, not to mention the 2nd floor joists go perpendicular to the way I would need to install the circuit. 
All around not a good situation, I think I will pass.


BT Electric


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## MDShunk (Jan 7, 2007)

Somewhere_401 said:


> I would also wonder if a ceiling fan would increase the likelihood of the ceiling developing cracks, especially it is a textured ceiling.


The answer to that is NO. I'm not sure how many of these I've done, but the number is definitely in the hundreds.


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## chicken steve (Mar 22, 2011)

My area can stay below 0F for weeks

The only '_ceiling heat'_ home here i know of is of moderate size,_(owned by an EE)_ with a 600A service. :laughing:

The rest of us are apparently stuck with wood stove technology :whistling2:

~CS~


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## 99cents (Aug 20, 2012)

....


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## MDShunk (Jan 7, 2007)

When electric ceiling heat was most popular ('65 -early 80's), it was sized as one watt per cubic foot of heated space for insulation values of the time. That never necessitated anything over a 200a service for the typical 3 bedroom home.


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## chicken steve (Mar 22, 2011)

Methinks you'll find the heat take off Vt vs. Pennslytucky a tad different MD

~CS~


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## MTW (Aug 28, 2013)

Thankfully it's very rare here in southern New England. I've only seen it three times in my long, illustrious career. :laughing: Electricity has long been the most expensive way to heat a home by a wide margin in these parts, so gas and oil heat rule the day.


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## MDShunk (Jan 7, 2007)

When you consider insulation values of each region during the time, it's not so different.


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## MTW (Aug 28, 2013)

MDShunk said:


> The clue is line voltage thermostats on the wall, but no baseboard heaters.


No kidding, Sherlock. :laughing:


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## MDShunk (Jan 7, 2007)

MTW said:


> No kidding, Sherlock. :laughing:


There's almost no limit to my powers of deduction.


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## Somewhere_401 (Apr 7, 2014)

MDShunk said:


> The answer to that is NO. I'm not sure how many of these I've done, but the number is definitely in the hundreds.


--

How often have you drilled a hole into one where the users have heated the plaster to the point of cracking in different spots? I have found that once this started to happen, the old plaster starts to show signs of weakness. Add in the vibration of a fan, one that gets out of balance and you start to have issues. 

I have done the retro fit of a adding a fanbox into a ceiling that was 35' of no break of a textured ceiling, (lower level of a house that had this heat in the bedrooms) and it was fine, as long as it is supported. But once it starts to crack.... Then it is no fun.

with today's tools, it is a whole lot easier to attempt to retrofit these ceilings, but I still won't do it unless the heat is being disabled.

I have found that local Home Inspectors are starting to write these up as "obsolete" and budget for replacement. 

More work for the future.... :thumbup:


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## swimmer (Mar 19, 2011)

BT Electric said:


> There is no access to this as there is a bedroom directly above the room and he does not want to cut the ceiling up and have to refinish it.
> BT Electric


Is there a light fixture in place already? If no, I really need to know how you run cable from the ceiling outlet to the switch box on the wall.


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## BT Electric (Feb 7, 2014)

swimmer said:


> Is there a light fixture in place already? If no, I really need to know how you run cable from the ceiling outlet to the switch box on the wall.



No fixture of any kind, just a blank ceiling. It would be very difficult, almost impossible, to get to the switch without damaging the ceiling. 


Sent from my iPhone using Tapatalk


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## swimmer (Mar 19, 2011)

Maybe try some kind of conduit Wiremold. I've seen a few situations where EMT didn't look bad but these were very non-typical rooms.


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## GrayHair (Jan 14, 2013)

Somewhere_401 said:


> --
> ... I have found that people seem to be only happy with this type of heat in the bedrooms, not in living areas. ...


Having owned and lived in a house with radiant heat, the customer has my sympathy; our feet were always cold. Heat rises and in the middle of winter we could sense the temperature difference just rising from a chair, even with upgraded insulation.

Ceiling fans were not recommended, so in larger rooms we tried a small fan blowing toward the ceiling. That helped a little, but when the radiant failed in out daughters room, we put in a heat pump and had the radiant disconnected.


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## jw0445 (Oct 9, 2009)

I've done this many times. Mark where the fan is suppose to go. If it hits a joist that is better yet, something to screw to. Chip away SLOWLY at the plaster with a screwdriver and hammer. Chances are you will find a wire. When the hole is complete dig out the wire from on top so it will stretch some to the side to mount the box. Only use metal box and metal romex connector. If you can't move the wire to the side you can splice it out with wire crimps, the type you use for well pump wiring.You will have to have some repair work when you get to the wall switch.


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