Hot water on combi going hot and cold Help and information on all topics relating to your central heating, air conditioning and ventilation issues.

[fordey]

Hi, I have a glow worm combi.
The central heating is fine, but we have a problem with the hot water, when I use the shower the boiler cuts out and fires up again which obviously makes the water go hot and cold. When filling the bath, we have to run the hot tap very slowly.
The boiler is 2 years old and has been working ok, this has started in the past 2 weeks. All the plumbing and radiators were also replaced when the new boiler was put in. Any ideas?

Many thanks for any help/advice.

[bazza]

[quote="fordey"]Hi, I have a glow worm combi.
The central heating is fine, but we have a problem with the hot water, when I use the shower the boiler cuts out and fires up again which obviously makes the water go hot and cold. When filling the bath, we have to run the hot tap very slowly.
The boiler is 2 years old and has been working ok, this has started in the past 2 weeks. All the plumbing and radiators were also replaced when the new boiler was put in. Any ideas?

Many thanks for any help/advice.[/quote]hi difficult to say without being able to look at boiler as it cud be a number of faults but sounds most likely that it cud be scaling within the heat exchanger which means the primary water will not take enough heat from the exchanger which in turn wud activate the boiler thermostat which wud explain the boiler shutting down and restarting and wud also cause reduction in the hot water flow if you find this is the problem all u need to do is drain the system flush it out and add an inibitor to protect the system hope this helps

[danster]

I have the exact same problem as fordey...(although I have a `sabre` type combi boiler. )However I live in Glasgow, an area which doesn`t suffer from scaling etc.... any clues?

[bazza]

[quote="danster"]I have the exact same problem as fordey...(although I have a `sabre` type combi boiler. )However I live in Glasgow, an area which doesn`t suffer from scaling etc.... any clues?[/quote]hi danster problem cud be at diverter valve try switching boiler on and off and watch to see if spindle moves in and out and and the micro-switch is made (u will hear a clicking sound ) if the spindle moves ok but there is no clicking sound then it is likely the micro switch is faulty and will need replacing hope this helps gud luck bazza