combi problems

[salmon]

My combi boiler gives plenty hot water when my heating is switched of but when i switch the heating on it runs cold (flow switch?) all help welcome

 

[kevplumb]

 

[Agile]

This will be interesting as its quite an unusual situation.

I hope the poster has really described it correctly.

Tonyt

 

[dotto]

This will be interesting as its quite an unusual situation.

I hope the poster has really described it correctly.

Tonyt

Maybe priority HW signal not working???

 

[ChrisR]

Is it a white combi?

 

[Slugbabydotcom]

My combi boiler gives plenty hot water when my heating is switched of but when i switch the heating on it runs cold (flow switch?) all help welcome

Given the following formula:-






Amount of help is directly proportional to the amount of information given by the OP






I can safely deduce that your boiler is knackered and needs fixing

 

[baxpoti]

Switch the heating off when you need hot water

 

[Paul Barker]

The primary flow switch on some boilers when the diaphragm is getting stretched will make for heating but not hot water as the extra resistance to flow in the dhw circuit makes the difference. The way to trick these boilers is to call for heating then turn on a tap, the DV swicthes over without losing the instruction to the burner provided by the primary flow already activated by heating demand.

My diagnosis is new primary diaphragm, possible pump is tired, possible dhw heat exchanger is sludged up, but diaphragm will likely fix it for now.

 

[gavinda]

thats a great crystal ball paul

 

[Agile]

Paul, the strength of push by the primary flow switch varies greatly between boiler models and the heating circuit restrictions.

Some models push harder in CH and others in DHW. Thats not helped by those customers who turn off individual radiators.

I expect the flow switch is involved in this case but as the OP has disappeared then we will probably never know.

Tony