Hot water not hot, just warm

[JonathanTaylor]

Hi chaps, my hot water is running warm at best. My radiators are very hot, so the boiler must be heating the water OK, but the water from the tap is tepid. Any tips about what I should look at first to investigate? Jonathan

 

[Newboy]

What's the supply arrangement for your hot water?

Combi/unvented/vented?

 

[JonathanTaylor]

What's the supply arrangement for your hot water?

Combi/unvented/vented?

It's unvented mate

 

[Agile]

When was it last serviced?

Tony

 

[TCCHeating]

//www.diynot.com/diy/threads/megaflo-problems.450311/

See this thread. You may have a similar problem.

 

[JonathanTaylor]

When was it last serviced?

Tony

Middle of last year, it's not due again for months.

//www.diynot.com/diy/threads/megaflo-problems.450311/

See this thread. You may have a similar problem.

I don't think it's the same - that one seemed to be a new installation, where-as mine has worked for 6+ years without issue.

I have a clearer idea of the symptoms now - if the controller lights for both hot water and heating are on, then the boiler fires for less than a minute before switching off - it then repeats this cycle every few minutes. Neither hot water nor radiators get up to temperature. If only the hot water light is turned on (on the controller), then the boiler does not fire (I checked and the stat on the front of the boiler was 'on', but the boiler did not fire up). If only the heating light is turned on (on the controller) then the boiler fires, and the hot water pump circulates hot water around the heating system.

 

[JonathanTaylor]

Do you think it is a faulty controller, or maybe the mid position valve?

Here's a video of the 3 way valve - it only appears to be moving to two positions.