Tell me about electric heated ceilings

[xantia_v6]

Later thi year, we will be making renovations to an apartment in the UK. I have renovated a few houses, but there is one aspect of this one which is a mystery to me.

The apartment was built as part of a large development in about 1990. It has underfloor slab heating, but the electric panel also has timers and breakers marked as 'ceiling heating'. The ceilings look like normal artex ceilings of the period, with no visible clue as to the location or construction of any heating system.

I will need to take down parts of the ceiling to refurbish the bathroom ventilation, and there will certainly be some electrical work to be done.

Is anyone familiar with ceiling heaters of that era? Are they resistive film stuck to the plasterboard and then skimmed over with artex? Will I need to remove a whole ceiling at a time? How do I find the connection points to disconnect them?

Thanks for any advice.

[thorter]

Never seen one, but I recall they were thin flexible resistive sheets just laid on the top surface of the plasterboard, then covered with as much insulation as possible. The ceiling then heats to the high 20s C, and it works because of the large area radiating. They were claimed to give a very comfortable environment.

[myglaren]

There is a bit here that might help. The others that I saw were American unfortunately.



Waffle waffle

[xantia_v6]

I got to investigate this recently. The heating system system was made by Devi (later merged into Danfoss).

The ceiling heating is controlled by an electronic thermostat on the wall. Turning the knob on the thermostat brought on an LED and a relay could be heard to click, but an infrared thermometer did not detect any warming.

A quick check found that the relay is faulty and not actually passing any current. A resistance check and quick calculation showed that power dissipation of the elements would be about 250W, which is much less than I expected (1000W - 1500W).

Yesterday I got around to dropping the ceiling. My first look at the heating elements was:

And when the whole ceiling was down, there were 3 of those strips, giving a total power of 750W.

Note the neat line of the slice where someone has previously replaced a sheet of plasterboard. Perhaps after repairing the heating...

So the system has been running for at least 13 years on just one strip, and not at all since the relay failed.

I will be stripping it all out.

[mickthemaverick]

Mike, if those elements are intact and surplus to your needs I'm thinking they might make useful garage warmers for working on the car in the depths of winter manually controlled ws and when needed. What do you think?

[CitroJim]

Mike, if those elements are intact and surplus to your needs I'm thinking they might make useful garage warmers for working on the car in the depths of winter manually controlled ws and when needed. What do you think?

Yes, good plan!

[xantia_v6]

You are welcome to them. I don't see an easy way to repair the 2 that have been sliced, but you may think of something.

[MattBLancs]

Really intriguing, never heard of those! Basically radiant panel.
Are the strips aluminium? Would think solder or even mechanically joined back together (e.g pop rivets) would allow them to live to warm another day??