Pump always on....

[mike_j]

I have an old Worcester Heatslave Highflow boiler (model 41-311-39) - with a few issues,which after using various plumbers with no success - I have taken it upon myself to learn how it works.

I have had problems with having both central heating and hot water on at the same time, I have now remedied this by changing the 3 port diverter which was faulty, only to find the thermastate on the hw to be faulty - this has now been changed as well. So I now have both working properly.
But the pump is running continously - is this correct on this model or should it cut out once the ch thermastate cools once the timer turns the system off.

Also what is the optmium / correct presure for this system and does anyone know whare I can find technical documentation for this model.
Learning all the time !!!

oh and I forgot there is a humming sound from the system when cooled - is this to do with the pump ?

 

[COG]

You will get a copy of the instructions from worcester if you phone their literature line and tell them the model ie 3.5 or 4.5 BF/RSF/OF they dont go by the gas council number (seem silly but ).The pump should run for 5 mins after the end of the last demand, this is controlled by the small pump overrun board, easy to change it just unplugs. the book advises a min of 1 bar system pressure.