PRV fitting question

[amvs]

I urgently need to replace the prv on my baxi bahama 100 - ideally tonight. The question is do I need to fully drain the ch system? Or will I be o.k. if I let the pressure out of the system (not hard as it drops very quickly due to the leak prv) and switch off the water supply?
the valve itself looks like a simple job to replace just want to make sure I'm not going to flood the kitchen
Any advice would be very gratefully recieved [/b]

 

[HERTS P&D]

Just drain it down, refit new PRV, add inhibitor, fill and bleed.

Andy

 

[Boilerman2]

While you have the boiler drained check the air charge in the expansion vessel - lack of air in the vessel is the probable reason your old PRV failed!!

 

[amvs]

Thanks for the advice guys - got a problem

Changed the prv and checked pressure vessel but when I turned it back on it's making a dreadfull noise and doesn't seem to be able to stay on

Have a got an airlock? How should I bleed them boiler?

Please help! I think i've bust it, got two young kids and it's freezing tonight

 

[fishhead1]

is it venting from the auto air vent(top of boiler)?

 

[amvs]

Thanks for the advice guys - got a problem

Changed the prv and checked pressure vessel but when I turned it back on it's making a dreadfull noise and doesn't seem to be able to stay on

Have a got an airlock? How should I bleed them boiler?

Please help! I think i've bust it, got two young kids and it's freezing tonight

 

[amvs]

is it venting from the auto air vent(top of boiler)?

Seems to be. If I loosen the plastic valve cap a little air comes out, then water (so I put the cap back on)

When it was noisy the pressure valve was oscillating rapidly between 1 and 2 barg. That's stopped now but the boiler is only firing up for short periods ~ 25secs then shutting off. The combi part doesn't seem to be working either as the hot water coming out of the tap 2 feet from the boiler is only lukewarm

Does that provide any clues?

 

[amvs]

Panic over - got it working.

Heat output seems low but then it's pushing 20 rads and is the original boiler from when the house was built in 1999. Hope I can keep it limping along until the weather warms up, then replace it