Fault with electrical skirting boards / air con system

[silentboarder69]

Hi,
I went to carry out a fault find on some heated electrical skirting boards today. It's a new build block. There's a room stat on the wall, and in the ceiling there is a fan system, linked to the buildings vents/air con system. With the fans running, the voltage going to the heated skirting boards is 0v. When I adjust the roomstat up to 30, the fans turn off and the voltage to the skirting board changes to 15v.
Any ideas?

Thanks

 

[SirKit Breaker]

Your post is a bit vague. What is the voltage of the system meant to be etc. My interpretation of what you have written is as follows, but i am guessing.

If the fans are ON then the heating doesn't need to be, hence no volts.
If you turn up the stat, the heating is switched on and you get 15 volts at the skirting board and they warm up, the fans switch OFF cos if they stayed on the would pull out all the heat, and so the house would not warm up.

As i see it the system is working properly, assuming the correct voltage is 15V.

Cheers..........Howard

 

[silentboarder69]

Hi Howard,
thanks for the reply, it's a domestic installation, 240v.
What you've said is correct, ie fans on heating off and vice versa. There is another heated skirting board in the hallway, and that runs direct from a 240v supply. It appears to be the same elements, so I assume that all the skirting boards run at 240v. The problem boards are in the lounge, in the bedroom the setup is the same, but I didn't check the running voltage.
I think the roomstat is functioning OK, but when the system switches between fans and heating, something isn't functioning correctly.

Rick

 

[truckster]

I'm only guessing but presumably there is a contactor for the skirting rads if they are running on the stat? Faulty contactor, loose connection maybe?

 

[silentboarder69]

I'm just reading the voltage of the cable supplying the skirting boards. I'm not sure how these work, is there a solenoid or something somewhere which switches the supply between the fans and the skirting boards?

 

[truckster]

As I say I'm only guessing, haven't come across this system before but the load of a bunch of skirting heaters would be over the rating of most roomstats I would think, therefore perhaps it does have a contactor in it, again only a guess but is there a contactor near the CU?

 

[silentboarder69]

There is a contactor, controlled by a timer. This is on. It controls both the lounge and the bedroom. The bedroom works fine, so I'm thinking the contactor is OK.
Each room has, as far as I can see, has a roomstat, fan and the heated skirting. Both rooms are controlled by one contactor. The bedroom is fine, and the fan in the lounge works. Does the roomstat switch the fan and skirting, or does it send a signal to a control device?

 

[truckster]

Off the top of my head I would say the r/stat may control the fan directly and the heating via the contactor. Open the contactor and you will probably have two feeds and two loads, one of the load wires may be loose.

 

[silentboarder69]

The contactor is there to allow a timer to control the whole heating system. I'm just trying to find out how the roomstat, fans and heated skirting boards are controlled! How is the power switched from the fans to the heaters?

 

[truckster]

I'm not there so I am working blind. If the r/stat turns on the heating and kills the fans it's either the fans are working off the n/c in the stat or via a n/c on the contactor, when the contactor is enenergised it opens the fan cct. and closes the heater cct. The r/stat is either energised by the contactor or by the timer(more likely)

 

[silentboarder69]

Hi Truckster,
thanks for all your replies, but there not right for this setup. The timer controls the contactor on the CU. Neither of these devices are linked to the problem. I'm trying to find out if anyone has set experience with this and knows how the fans, roomstat and skirting boards are wired together.