Hello. We have a Ravenheat csi 85 - csi 85t boiler. there is no hot water unless radiators are on. on a earlier post on here a reply said it is a hot water stat on left of boiler that would be at fault. Is this the D.H.W sensor or the overheat cut off thermostat ? Can i replace it myself or is it a job for a skilled man. Thanks , Martin

Martin Sharpe, March 2011

thanks for that very helpfull

martin sharpe, March 2011

If your model is similar to the older versions it will have a rubber diaphragm in the water section, these frequently tear and stop the hot water working unless heating is on at the same time. The diaphragm needs replacing, simple job if you can get the mains water turned off and get the water diaphragm section out, its usually only 6 screws and the section comes apart, mind how you prise it open though, there are springs in there and if it all pops out you won't know how to re-assemble! Careful.

Taliskerman, March 2011