Central heating probs

[109er]

Today I switched on the central heating to test it was OK.

Its a combi boiler unit.

Master control switch on - OK

Thermostat - OK

Switched off the master control switch - OK

Next thing I know is the hot water system is working overtime
and all the radiators are too hot to touch, and the room temp is
up to 27C. Turn the hot water off at master control switch, all
stops. Turn hot water on again and --- hot rad's again

Any ideas why or what to do while waiting for the engineer/fitter
arriving tomorrow afternoon.

[KTF]

So you demand hot water but instead you get warm rads?

[marshalla]

Stuck zone valve ?

(I'm guessing this is the first time you've had the heating on since earlier in the year).

[alex290568]

Likely to be the diverter valve that's stuck. It may be saved by removing and cleaning or it may be knackered

[109er]

KTF said:

So you demand hot water but instead you get warm rads?

I get both

[109er]

marshalla said:

Stuck zone valve ?

(I'm guessing this is the first time you've had the heating on since earlier in the year).

Your right, as I said - just checked to see if its working.

Obviously its not working properly. Switched the whole system
off at the power source for 10 minutes - seems to have done the
trick but, I still thinks it needs checking over.

Good job its a rented property and they arrange for all work/jobs
to be done, and they pay

[109er]

Should be interesting when the engineer comes this afternoon.

The system has packed up completely now