Underfloor heating thermostat caught fire

[europa16]

Hope I can get some advice we're not sure where to turn...

 

A year ago, we bought an ProWarm electric underfloor heating system with a digital thermostat, for the kitchen.

It was fitted shortly afterwards by our electrician (who's registered), and the system has worked great so far.

 

This weekend, we went away overnight (20yr old son stayed home to look after the house), and on way home got a frantic phone call from our son, telling us the thermostat was on fire, it was now on the floor burning away, and melting the corner of the fridge.

He'd rang the fire brigade (who arrived before we got back home) after the fire alarms in the house went off. 

 

There is a separate fuse on the consumer board for the underfloor heating system, and a separate fuse in the wall before the thermostat, so if it was a power surge, both these should have tripped before anything worse could happen. 

So we strongly believe the thermostat was faulty.

 

I don't want to go through insurance unless necessary (premium raise and loss of excess) but we need to replace the thermostat, wiring for the underfloor heating, and a new fridge.

 

We're still in the process of redecorating the kitchen so cosmetically, it won't cost much (piece of plasterboard).

How to we proceed - do we go after the owners of ProWarm or someone else?

I'll post photos if I can (phone won't let me at the moment)

[europa16]

[king12345]

OMG!

This must be reported to the manufacturer immediately as they might recall the thermostat. 

However,  the fault might lie in your wiring or consumer unit.

It is possible (very unlikely but possible) that the fuse mcb serving the thermostat is faulty and didn't trip, or it did but too late and thermostat was already on fire.

The thermostat should still be under warranty, so contact the manufacturer but before giving them the thermostat take lots of pictures and videos of it.

Also, IN WRITING,  let them know that you don't want the thermostat to be disposed of or "misplaced", it's your property and as such should be treated.

They'll probably try to send you z replacement thermostat and that's it, refuse and tell them they've got to pay for the damage.

All of this assuming the electric is ok.

Or if you want a quick (but costly) solution,  call your insurance. 

 

[europa16]

Thank you for your reply.

First thing we said was, if they want us to send it to them, absolutely not a chance! 

We’re happy to pay for an independent report,  as we are almost certain it is the thermostat that is at fault.

 

But no idea who to ask - are there specialists that can look at this mound of charcoal and wiring and make a determination, which are accessible by the public? I know the fire brigade have their own forensic investigators for this sort of stuff.

 

found the unused remote control for it in the drawer this afternoon - somehow don’t think it’s much use now!

 

Don’t know how much use Trading Standards are with these sort of things?

Worth getting in touch with them? 

[ericsbrother]

now if the mains wiring into the thermostat was done wrong or even the terminals for the cbale not tightened properly you will get overheating and possibly a fire so dont jump  to conclusions.

 

Do you have  the circuit diagram that shows the mains connections?

Are there any details of links that need to be made on the mains input for different systems (common on boiler controls).

 

If there are and these are done incorrectly it will still apparently function but not cut out when too hot so you then keep feeding current into  bits that should be off at that stage.

 

A good electronics person may yet be able to tell you where things started to go wrong by looking at the wiring, board and diagrams and the end result.

 

The manufacturer will also be able to examine and test what is left so dont be afraid of sending them the remnants, you have photographs and a fire brigade report so they arent going to deny its existence but you should let them know that you expect to be able to get someoe else to examine it as well if you arent happy they have done ther nvestigations dispassionately

[europa16]

Thank you for your reply.

The thermostat is only linked to mats in one room, and the load is well below the maximum the thermostat could handle.

All the wiring is still together, albeit charcoal - it was all fitted and tested by a qualified spark but we are getting another spark to look over all the wiring and the unit. 

 

Our neighbour is an electrical engineer and he seems to think the fire originated with the thermostat not the installation. 

 

The manufacturer want loads of paperwork, including minor works cert but we are in the middle of ongoing works (which building control are aware of and have ongoing checks).

 

This supposed to be for the lifetime warranty but we never bothered with the extended warranty and this happened within the statutory 1 yr warranty they supposedly give.

 

We aren't handing the unit to them.

Been told that by a fire investigator today.

[ericsbrother]

sorry but you are missing the point about how the connections are made and their likely influence. It dioesnt matter it here are a hundred mats connected if the mains link going into the board is done incorrectly.

also your use of wording such as "the installation" doesnt give much help, yes the fire started in the thermostat but WHERE ?  the board has a number of parts that get warm but the most likey culprit is hwere the mains is switched on and off and that is the bit that is doen by the installer.  generally you will have a neutral tht stays "on" all of the time and mains that goes into a switch that is connected to the sensors that then  switch the power on and off whilst stioll using the live unswitched connection to provide the current for the low voltage parts of the system. It is qwuite easy to misred the installation of this as the same board may be used for several differnt systems and thus the links need to be made in a different configuration for each system. Confuse type 1 with type 2 and you may well be passing a current permanenty though the system causing it to heat up to a point of no return.

that si why you need to get a decent copy of the circiut diagram (not the installation diagram) from the makers so you can pass that on to your tame electronics bod to see what they make of the remnants

[europa16]

The thermostat was supplied specifically for use with the mats we purchased, as a full kit. The thermostat is designed solely for use with underfloor heating. As previously said, the system worked perfectly fine for 10 months, no issues with tripping, no weird smells or overheating.

We’ve had another electrician come along and look at all the parts and the wiring, and he tested the mats, which were within 1% of the resistance ohms listed by the manufacturer.

We also found out that the full ufh system is at the very top end of what the manufacturer deems as acceptable (3600w). The thermostat is designed to handle this amount, allegedly, though but could this high wattage have played a part?

[ericsbrother]

as said, you need an electronics person to inspect it, not an electrician. You will need to see the theoretical circuit for the same reason.

I am not suggesting the fire started anywhere else other than this thermostat but an trying to suggest ways you can determine why it caught fire and that may not be an inherent fault within the control circuitry.

A loose screw  on the mains input can create a lot of resistance and heat, as can a dry joint on one of the components on the board (difficult to find that now it has melted all of the solder).

You do need to trust the manufacturer if you cant find an independent authority though becasue they have an interest in making sure they dont burn other people's houses down