Ravenheat RSF 820/20 Boiler

[MKM]

Hi can any one help I have a proplum with the hot water if i have the c/h on the hot water is very hot but if the c/h is off the water is just warm i have adjusted the flow to just five litres per minute but this has had little afect. when you have a bath or a shower the radiators become very hot. could this be a divertor valve problum or ?

 

[gasmick2]

Hi if you switch the switch to water only does the boiler fire up????
if not then you have a problem with the 3 way valve this boiler is factory set at 52,000 btus and only uses the 80,000 on the water only so to get the correct temp for the hot water you will have to replace the whole valve a genuine one will be about £130 or so plus the cost of fitting

mick

 

[MKM]

hi thank you for your information. yes the boiler does fire up when only on DHW and runs like you would exspect but the temp of the water is still cool compared to when the centrel heating is on. after about five minute all the radeators our very hot. the boiler does not drop down too low flame not unless you turn the thermostate down two about 25%? as to say that the hot water is not reaching temp.

 

[gasmick2]

hi dont forget the water temp going in this weather must only be about 5 deg and the boiler is rated to heat the water up with a flow rate of 9 lts at a 35 deg rise above the incoming temp so you need to measure
the cold in and the hot out and the flow rate and work out what it is doing perhaps you need to slow the flow rate down to compensate for the temp diff just another thing while on water only feel if the heating pipes are getting hot at all if they are then the 3 way valve is letting by meaning some of the power is getting pushed around the rads and not heating just the water as it should be

mick

 

[MKM]

Thank you Mick.
I have tested the incoming water and the out coming temp and this has worked out to be a rise in temp of 21.50c at a flow rate of 5 Liters per minute
I have had this problem for 4 month and have put the central heating on when i need hot water as this brings the temp up to a satisfactory level. to answer you question dose the centrel heating pipe get hot when on hot water only? the pipes are not the only thing that get hot you can not put your hand on the radiator. so it sounds to me the this 3 way valve could be the problum do you think?