Central heating wont turn off with hot water on

relief123 · 17 Apr 2006

Hi.
I have a problem basically when my hot water comes on so does my central heating radiators, and they wont turn off... its running on a sealed system with 2 port valves.
Would it be one of the valves stuck or damaged??
how can i check??

Softus · 18 Apr 2006

1. Turn off DHW and CH.
2. Turn on CH whilst observing the relevant MZV.
3. Feel the pipe existing the CH MZV - should get hot.
4. Turn on DHW, then turn off CH whilst observing the valve again.
5. Feel the pipe again.

Also, if the valve is actuating, then you'll be able to tell by moving the manual lever what the position of the valve is.

The fault could be a wiring fault, programmer fault, faulty valve, or stuck/blocked valve. Most commonly it's a stuck valve or failed synchron motor. You can replace the motor (isolate first as it's usually a mains voltage), and some valve actuators can be changed without draining the system. If it's a stuck valve then just replace it, but this requires a drain down.

There are plenty of threads on this stuff if you want to read up on it. Come back here if you need more help.

Beans-on-Toast · 18 Apr 2006

It's such a pleasure to read such an informative reply, Thank You....Softus
This type of reply is so helpful in educating the general public in regard to a common understanding of h/w & c/h systems. We all understand that we are not qualified to commission a boiler although we should be able to check pressures, set timers efficiently, bleed radiators and towel rails and be able to evaluate the level of service required by that household over a period of calculated years

from the current boiler.

I think I may be giving the general public the benefit of the doubt, What Do You think....?

Softus · 18 Apr 2006

Perhaps you'll think me suspicious, but I think there's more to your post than meets the eye.

Are you a new member, Beans-on-Toast?

croydoncorgi · 18 Apr 2006

My favourite quote from 2005:

I'm a corporate lawyer - I can manage setting a f****ing heating programmer.

No she couldn't - the reason the system was all over the place was that the actual time-of-day was set wrong!!

Never underestimate the General Public!

geoff@cetltd · 18 Apr 2006

I can better that

(CORGI fitter) - ... andf how do I test the air pressure switch

or ... is the spark meant to stop when the boiler lights

or .. how do you test resistance

or ... this pcb doesn't work, it's doing exactly the same as the other one

now, colour me cynical, but these people are meant to have a clue

oilman · 18 Apr 2006

I wonder if BOB DOLE had Beans-on-Toast for breakfast.

Softus · 18 Apr 2006

oilman said:
I wonder if BOB DOLE had Beans-on-Toast for breakfast.

relief123 · 18 Apr 2006

Softus Thanks for the very informative reply mate and to all others that had a go, I will try all that later and let you know the outcome, I am a training plumber so will probably be back more than not to pick your brains if thats ok with you lot..
Many thanks

relief123 · 18 Apr 2006

Oh a quick one would it be ok to freeze the pipe rather than drain down or may this cause problems with the new valve

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Central heating wont turn off with hot water on

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