No hot water except when heating on

[archie456]

Hi,

I'm trying to fix a problem which has developed with my hot water system.

Its a conventional gas boiler system with a hot water cylinder and two motorised values (which I assume one controls the hot water and the other the heating).

Essentially, I get hot water only when the heating is on. As its summer now the heating is off and so I get hot water.

I've fooled the system into giving me hot water by taking both motorised value heads off, manually turning the hot water valve on and the heating one off, then setting the boiler to produce both hot water and heating and setting the room stat up high.

This works ok, but is obviously not a final solution.

I would appriciate any pointers for what to look at - Especially if its a fault with the boiler (as I have insurance to fix this).

The boiler is a Potterton Suprima 80 (The board inside has been replaced a few times due to a lockout fault)

Cheers.

 

[Agile]

It will probably be a problem with the hot water valve head which can be replaced seperately. But it could be other things too which is why a heating engineer may be a good idea.

It might just be a failed motor. They can be replaced on their own on some brands of valve.

Boiler insurance usually covers system controls like motor valves. You need to check your policy wording.

Tony

 

[archie456]

It will probably be a problem with the hot water valve head which can be replaced seperately. But it could be other things too which is why a heating engineer may be a good idea.

Thanks for your reply.

So, whats the best way of checking the value heads?

I guess I could remove both heads, and then turn on the heating / hot water to see if the move?

 

[Agile]

Only certain types can be taken apart.

The easiest thing to do is measure the resistance of the motor winding first. They can go opencircuit or the motor can seize up. Sometimes they can be got to move again by oiling but usually thats only a temporary repair.

Tony

 

[archie456]

I've taken the heads off before - so I'll try that.

I'd rather stay clear of the electricity - but just out of interest, is it mains electricity or a lower voltage? Could I use my multi-meter (which I use on my computer to check the mother board power) to check the voltage being received by the valve heads?

 

[Agile]

Its mains voltage so take care.

Measuring voltages will not help much.

You should measure the motor resistance. Also see if the output cog will turn freely.

Tony

 

[archie456]

Excellent. Thanks - I'll give that a try.

 

[archie456]

Hi there!

I look both motor controlled valves apart and turned on the heating and then the hot water.

Both valve heads moved as they should - so I can only conclude that they are fine.

I know the valve section of the motor controlled valves is also working fine, as when I manually twiddle the values I can turn the hot water and heating on and off.

So its got to be something else.

I've noticed that when there is a demand for heating the boiler fires, the pump starts and the valves move. (The boiler shows a green continuous light).

But when there is a demand for heating the boiler remains off, the pump powers and then turns off - but the values move correctly. (The boiler shows a green flashing light).

The boiler is a Potterton Suprima 60.

So it guess its the think telling the boiler to come on?

How can I check this.

 

[Boilerman2]

It will be a failed Microswitch in the Hot Water Valve Head on hot water only are you getting 230v at the SwL terminal at the boiler? if not then replace the hotwater valve actuator

 

[archie456]

It will be a failed Microswitch in the Hot Water Valve Head on hot water only are you getting 230v at the SwL terminal at the boiler? if not then replace the hotwater valve actuator

Where can I find this? (I'm a bit of a layman at this!).

Is it part of the boiler? I have boiler insurance and so that would be an easy win if it is!

 

[archie456]

It will be a failed Microswitch in the Hot Water Valve Head on hot water only are you getting 230v at the SwL terminal at the boiler? if not then replace the hotwater valve actuator

Ah - I read your post again - You mean the microswitch is in the Motorised valve head I assume?

 

[powell30]

Most heat only boilers are 'dumb'. If your boiler fires on heating but not hot water then 99% of the time it's external.

Just change the port valve.......40 minute job including drain down.

Simples