Combi - no hot water

The MIL looked at it and froze the pipes?

When the wife revealed to all the absence of cold water the MIl gave me a look that froze my nadgers.

Arthur

Oh dear.

If the boiler is apparently "starting" - i.e. fan runs; then it could well suggest an issue with the gas valve or the electronics driving it.

Might condensation be a cause?

Arthur

Possibly if it were to get onto the electronics, but that would be obvious from looking. You could try the other obvious thing of making sure that all connectors are pushed firmly home.

Although as I said the boiler 'fires up' when the hot tap is run. So it seems that searching for an electrical fault caused by condensation seems a long shot.

Arthur

What do you mean by "fires up"? Fan runs and burner lights?

Does it run at full power or low power? Presumably if it is firing up as in the burner lighting, after a short while the burner goes off because heat is not being transferred to the hot water?

When a hot tap is turned on the boiler fires up as in makes the usual noises..then remains like this until the tap is turned off, as though its running fine except the water remains stone cold. I don't know anything about low or high power.

Should it be easy to see if the burner lights up?

Arthur

I took the front cover off and there is a tiny port hole window. If there is supposed to be a pilot flame/ignition spark visible thriough this, I can't see anything happen. And the noises I am hearing may be just the fan.

Arthur

So the heat has to be going somewhere. What happens if you turn down the room thermostat and then run the HW? My guess would be that the radiators will get warm.

If so, it suggests the diverter valve inside the boiler that directs the primary (heating) circuit water to the heat exchanger instead of the radiators. A common fault is that they stick.

Many boilers have variable output power. On high output the boiler is usually making more noise because of the fan running faster.

If there isn't a sight glass then check the meter.

Just checked the manual and it points out the cut-off button. There seems nothing to lose by trying it but it seems to be stuck unless we're supposed to apply a heavy action to it.

Arthur

I have the check valves closed to the rads since discovering the leak mentioned a fews ago on here. And the c/h is now switched off. The hot water was working earlier today but then just quit. As said, the fan/pump turns on when using the hot taps. There is a viewing hole but nothing happening there. Re; this viewing hole, should something be happening when just the hot water is on?

Arthur

So the burner can't be lighting at all or running for any length of time. The water would boil and the burner would turn off.

Can you normally see the blue flames through there when it's running the CH?

If you can normally see flames then yes it should be the same.

If other gas appliances are working, then this fault is probably the gas valve, a sensor or the control electronics in the boiler.

Theres definitely nothing happening behind the viewing hole. This hole is normally hidden behind the fascia panel so I don't know whats visible during normal operation.

Looks like I'm calling a corgi guy in the morning. Do they charge heavy on boxing day; assuming they have the time.?

In the meantime I will switch the thing off and hope something magic happens.

Thanks for your help.

Arthur.

If you were a CORGI guy receiving a call on Boxing Day for a distress purchase, what would you do?

Hopefully it's nothing too major. There are many sensors for measuring and safety and these can easily prevent operation.

He could take a fancy to the MIL.

Arthur.

If it cuts a long story any shorter at this time on Boxing day ...

I had a similar problem last Friday.

She was not wrong, there was however central heating as normal.

Boiler is a Worcester Bosch Siemens Greenstar, 4 Years old. Initially suspecting a stuck diverter valve, I looked on the W.B.S. website but what I saw intimated the boiler was not made of standard UK plumbing bits - it was very "Geeairman", as were the electrics.

Preferring to avoid a similar rude awakening anytime soon (or ever in fact) I called W.B.S. in, it turned out to be it was the diverter valve (siezed solid). This was replaced, the annual service done and an old water leak *from the flue* traced and remedied in 40 minutes.

The point is the particular details of what you observe will depend on how the whole set-up is interlocked. The boiler electronics may wait for feedback from the diverter valve that it has successfully opened for hot water before it fires the boiler. OTOH it might not ...

HTH.

DG

I left the combi switched off last night then tried it again first thing this morning. It was just the same..no hot. Then 5 minutes ago..the MIL must have given it a 'look' and it the hot water came back.

Is this a woman thing..beyond our understanding?

Arthur

PROBABLY a stick valve, and with low voltage yesterday with all those turkeys frying, not enough power to move it..

Get it seen to ASAP - it will happen again.