When HW is on the rads are heating up too

[crockett]

i'm sure your header tank should have some water in it too, as I don't think this particular boiler is a sealed system boiler

 

[petit_pablo]

from the boiler...2

Really! Minimum should be 3, flow / return / gas.

Either way, turn the boiler on, follow the pipe that gets hot 1st and see where it goes. It has to have a pump and vlaves somewhere

 

[mackemdave]

Update...yes its three including the gas pipe......and I have now found the pump and two silver boxes both of which have moveable arms on the side so I presume these are the diverter valves....is the pipe that gets hot first the central heating?

 

[crockett]

The pipe that gets hot first is the flow. you will have to get someone to turn your room stat up while you look at which diverter valve ( silver box ) motor makes a noise. This will tell you which valve controls which circuit, either hot water or heating. I expect the heating valve is faulty, either the motor inside or the valve body itself

 

[mackemdave]

-----valve-------------pump----------
l
l
l
valve
l

The pipework is like this is the one that is inline with pump the heating valve?

Thanks for your help on this its appreciated

 

[D_Hailsham]

You can find the boiler installation manual at Baxi PartsArena

With two Motorized valves (silver boxes) you have an S-Plan. It looks like this:

 

[mackemdave]

My basic diagram didnt come out as expected the pipework is in the form of a T with valves on the left on the horiontal and one on the vertical

 

[crockett]

Still looks like an s plan system. Your diverter valve on the heating side has a problem

 

[D_Hailsham]

My basic diagram didnt come out as expected

You are not the first to learn the hard way that the system automatically removes blank spaces.

the pipework is in the form of a T with valves on the left on the horizontal and one on the vertical

The diagram, unfortunately does not say anything as there is no standard way of doing things.
The easiest way to find which is which is to turn the thermostat right up on the HW cylinder. The valve which works is in the HW circuit; so the other valve must be in the CH circuit. If that does not work, try turning the wall thermostat right up; that should operate the CH valve. The other will then be the HW valve.

If you can't get either valve to work, you will just have to trace the pipes to the HW cylinder or the nearest radiator!

Your diverter valve on the heating side has a problem

The OP has zone valves, not diverter valves. A diverter valve looks like a mid-position valve but you can only select the A port or the B port, there is no mid-position where both A and B ports are open.

 

[crockett]

I stand corrected...... it is a zone valve