how can i fix my baxi wm531rs?

Hi,

If your radiators reach a good temp then the boiler is fine. Lack of hot water is going to be down to several things:
Assuming a full ypumper system; is the tank thermostat set to the correct temp? It is stuck to the side of the hot water cylinder 1/3rd up from the bottom of that cylinger. Try turning up the temp. Does it click when you turn it up and down? If not then replace it.
Is the a 3 port motorised valve? If so watch the lever on the back or side of it as you first turn off the tank thermostat and then turn up the room stat then reverse the operation and the lever on the valve should swing from side to side. If you then turn up both stats the lever will go to the middle. If not it needs replacing or the stats need replacing.

Manualy open the 3 port valve by swinging the lever right over to the tap side (see maring on the valve, or sdee which pipe goes to the cylinger) that should give you full heat hot watwer.

Good l;uck

Nick
August 2007