Baxi Bermuda 401 - radiators heating when HW on

[ady611]

Hi there

i am after some help please, i have a Baxi Bermuda 401 back boiler system. the problem is that the radiators upstairs are heating up even when the program timer switch is set to Hot water only.

could this be residual hot water flowing into the radiators if the hot water cylinder is up to temp? or is there a problem with the system.

many thanks ady

 

[dcawkwell]

You haven't said if this has just started.

It is badly piped.

Inserting a zone valve after the pump will prevent the gravity
circulation into the central heating.

 

[ady611]

hi sorry, this has been happening for a while but thought is was time to investigate

im not sure if it is badly piped. all i do know is that the heating system is piped with micro bore pipe

 

[DP]

When you select HW on the programmer, HW ONLy part will be active.

When you select CH, does HW also fire up on the programmer. If yes, the that is the way it works.

 

[ady611]

hi DP

when HW only is selected then the HW is activated but after a while the radiators upstairs start to heat up too, the radiators downstairs still remain cold.

when CH/HW is selected then both work as expected

 

[namsag]

Either a passing motorised valve on a fully pumped system.
Or passing anti gravity valve on an old gravity system

 

[MikeyGas]

As above with regards to the anti-grav valve, but have seen a couple of systems with no valve fitted at all.

If on a gravity system then check that there is an anti grav valve fitted and clean/replace as necessary, if not then fit a double check valve after the pump.

Forgot to add, when you run HW only turn the room thermostat to off and see if this help's, as one programmer that I have come across (Danfoss) requires that when in HW only then the roomstat should be switched off.