I think I have a faulty safety thermo on combi bolier

I am having a problem with my combi boiler intermittently shutting down and showing a red light (flame failure)

It seems to happen when there is a demand for hot water, but I am not

100% sure about this, but not far off.

I think the safety thermostat may be faulty. If I was to remove the safety thermostat temporarily and connect the two cables together to see if that removes the dreaded red light syndrome, would the boiler work ok whilst like this?

It would only be an experiment for a few days to see if it removes the red light problem.

Is it safe to do this?

Steve

Reply to
steve
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NO

If you do this and the problem is not the safety thermostat then whenever the problem recurs the system is not protected. An explosion takes milliseconds.

Reply to
John

Is there anyway (as a novice) I can test the safety thermostat for a fault?

Or is it a matter of buying a replacement and perhaps wasting my money?

Any advice gratefully received.

Steve..

Reply to
steve

Err yes. Sorry to sound smug but yes, you can test them but finding out on such a critical item is not an option. If you had some electrical knowlage you would'nt be asking here. If it has been a non safety matter elsewhere I would be more helpfull. I would suggest calling a good plumber.

Reply to
James Salisbury

I don't see any problem in testing them, as long as you know that if you screw up it can be lethal. (though perhaps not particularly likely to be so (but you could get lucky))

Turn off power. Remove stat. Either drain system, or plug hole.

Immerse sensing end in hot water of various heats, and measure response. If you need to test at temperatures of over boiling, add lots of salt to the water.

Do not attempt to modify it, or bypass.

Reply to
Ian Stirling

True but for what it costs just buy a new one and eliminate it from th chain, get one with new leeds attached where possible, more than onc I've been tricked by the leeds tracking a small current to boile chassis.

With regard to shorting them out, that depends on how they work, i can't be assumed that they are all simple interuptors anymore wit modern electronic sensing methods. A neighbour asked me to help him as his boiler wouldn't light the othe day. The boiler was ancient Can't recall the make but it was basically multipoint style of heat exchanger with the cooling veins of 15mm pip running through. A previous fitter had shorted out the oh stat (mos likely because parts were unobtainium) and told them to leave the tem control where it is (though the user had forgotten exactly where tha "where it is" was. He had taped the whole thing together with closur plate tape.

Man I could have earned money from Gas Installer sending in pictures but this is a neighbour.

I had to refuse to fix it of course, and said I'd look out for a bette boiler for them.

A few days later they said they were going to ask their original ga fitter to find them another boiler because they had always stuck wit him.

I suppose if he jumped off a cliff they'd follow.

Probably if I see who it is I should give local corgi inspector a rin anonymously. Lives are put at risk by these guys

-- Paul Barker

Reply to
Paul Barker

Remove stat. Either drain system, or plug hole.

Reply to
steve

This type do not usually require that you drain the boiler down. If you have some heat conducting grease when you install the new one that is so much the better (to make good contact with its location). I doubt very much if a replacement unit will exceed £10.

The red light is a lockout indicator which might be due to overheating or due to flame failure.

There is also the possibility that the boiler is actually over heating!

Reply to
Ed Sirett

It seems to happen when a hot water tap is turned on. It will happen before the water gets hot.

If the tap is turned on and off several times in a very short space of time, this will increase the chance of it happening.

If it is down to overheating, what are the likely reasons for this happening?

Steve......

Reply to
steve

A bit more info.....

You can actually see the gas igniting, then a switching sound several times followed by the flame extinguishing and the red light.

It will always fire up normally when pressing the reset button.

Steve..

Reply to
steve

For a description of what happens when one of these overheats, see "The Self-Uninstalling Gas Water Heater"

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was a 1970's model and didn't have the overheat stat. The 2000 one which replaced it did (and it's a bog standard electrical component, so easily replacable if needs be).

Reply to
Andrew Gabriel

I strongly suspect (in no particular order) :

a) Some control system failure which means the pump is not running when doing HW. b) the secondary heat exchanger is blocked on the primary side thus not permitting the water to flow. c) the temperature sensor for HW has become insensitive. d) the flow sensor for HW gets stuck in the on position which means the boiler continues on after the tap is closed. e) Some problem with the diverter valve

Reply to
Ed Sirett

That could just the way the OH stat switches off, especially if it is dodgy.

Reply to
Ed Sirett

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