Existing Faulty Underfloor Heating System

[thelifeoreilly]

Hi there,

Recently bought a 19th Century terraced house with a two storey rear extension (kitchen at ground floor level, bathroom at 1st floor level). The heating system for the house is a combi boiler and there doesn't appear to be a thermostat in the house just a timer on the boiler. There is no radiator in the kitchen but a towel rail in the bathroom.

That said, there is a timer/controller outside the bathroom (photo attached) and a switched spur/fused spur in the cupboard in the bathroom (photo attached) I can only assume this is for underfloor heating. The house was rewired in 2007 and the DB chart references a shower pump which after an hour searching I can't locate, so again i presume this has been allocated to the underfloor heating.

The timer/controller won't turn on, there is a 5amp fuse in the switched spur and nothing in the fused spur. There is no logo identifiable on the controller so I'm hoping a clever member of this forum can advise!

Many thanks in advance

Controller

• thelifeoreilly
• 31 Oct 2012
• 1

Won't turn on, no logo or info abovious

Switched Spur/Fused Spur

• thelifeoreilly
• 31 Oct 2012
• 1

 

[stem]

I would agree with your deductions. To me it seems likely that the original switched FCU was for a shower pump and the second FCU was fitted for the underfloor heating. (The shower pump would have been removed when the combi boiler was installed)

However it is impossible to say with any certainty what is actually the case. For all we know, as we can't see it in the photos, there might actually be no wiring at all to any of the items shown in your photos. The only way to be sure is for someone competent to remove the various wiring accessories and test any wiring that is there to see where it goes.

Perhaps the UFH is faulty and so someone has removed the fuse to stop it being used. On the other hand someone may have borrowed the fuse to use it somewhere else, perhaps in the summer and never replaced it.

If you want a new controller, it's a Timeguard TPT88 and you can get one by clicking here and the instructions can be found by clicking here.

 

[thelifeoreilly]

Thanks Stem,

The instructions look like the correct controller so it is really making me think there is UFH.

I have removed the controller face plate and there is definitely wiring to the controller, there was also no fuse in unswitched FCU. I inserted a 13AMP fuse but still no life in the controller. Is there anyway to determine which fuse I should be using?

 

[stem]

The controller regulates the floor temperature heated by an underfloor electric element which is usually woven into a mat that is placed into the adhesive when the floor is tiled. The current drawn by the heating element will determine the fuse rating. This varies, but I would expect it to be somewhere between 100 & 200 watts per square metre. Generally a 3A fuse is used for loads upto 700w, 5A for loads upto 1000w and 13A for loads upto 3000w.

I think that you will need someone who is able to test the circuits with some appropriate test equipment to determine where the fault lies. The circuit diagram is shown in the instructions I sent you the link to.

I'm assuming here that you have tried pressing the "mode" key which selects between 'on' 'off' & 'auto'

 

[thelifeoreilly]

Stem,

This wasn't top priority but with weather so cold I'm persisting!

I used a multi-meter and there's power to the controller so thinking faulty controller and will try replacing.

Fingers crossed it resolves the problem!