Replacing a central heating pump

[RichardAJ]

I have to replace the pump on my ravenheat 820/20 and was wondering how difficult this was going to be?

what are the steps that i have to do to ensure that i don't break something else on the system. do i have to drain the system first etc?

Cheers,

Richard

 

[Bamba71]

Drain the system (unless there are isolation valves either side of the pump) on most pumps you can just rermove the 4 allen key screws to remove just the head of the pump rather than remove the whole pump body (as sometimes the nuts are dificult to remove) then remove the pump head off your new pump & replace, the wiring is just an earth, neutral & live, if you do remove the whole pump make a note of the direction of the arrow on the side of the pump so the new 1 goes in the same way.

 

[45yearsagasman]

Its a combi so I would advise against touching the isolating valves unless you want to replace them as well.If you can get away with it then as suggested change the head only.Still need to depressurise system and protect all the eletrics from water damage.

 

[RichardAJ]

thanks for the information. the pump has now been replaced. On a separate not the water pressure is still quite high and i have bleed radiators etc. Do you have any other ideas where air could be stuck?

 

[ChrisR]

WHat makes you think it's stuck? If the boiler was full of air it wouldn't run. The Auto air vent should be left open to let air out, but it's probably shut cos they leak when they're old.

 

[RichardAJ]

The heating is firing but the pressure is getting close to the 3bar release valve. I had assumed that air was trapped within the boiler itself. Is there any way i can manually open up the air valve?

 

[45yearsagasman]

If your pressure is rising to near 3 bar you need to check the expansion vessel precharge.This should be done with NO pressure in the system.Precharge should be approx 1bar. If it requires pumping up use a car tyre pump with an accurate guage.Once this is done the system can be refilled(cold) to 1 bar.