Combi boiler - radiators on when hot water running

[adinic]

I have a Baxi Combi 80e & have recently noticed a problem. 3 of the upstairs radiators are getting hot when the boiler is serving only hot water.

With the central heating turned off & all the radiators cold I turn on one of the hot water taps. Within 5 minutes 3 of the 4 radiators upstairs are hot. Non of the other radiators, in the house, are affected.

Any ideas? Is there a directional value within the boiler that routes the water it heats?

 

[DP]

One word comes to mind. SERVICE

 

[landyandy]

Is there a directional value within the boiler that routes the water it heats?

Yes , it's a diverter valve.
No guarantee that the diverter valve is the problem.

Andy.

 

[bengasman]

Baxi 80 often suffers from failing diverters when the system is not clean.
Check if the boiler is dirty inside; if it is, 90% sure diverter died.