I too saw the other posts and it may be a problem with the diverter, but I want to check out the PV as the first main contender. I didn't get any air in when I "bled" the PV (due to my ignorance), since I stopped when I got a little water out the valve. All the air got in when I depressurised the system and then filled up the PV with air. I expect an experienced engineer would have been able to tell at that point if the PV was gone, but I was hoping for the best (ie it was just low on pressure). When I had to take loads of air out of various rads, I was suspicious and I have to say that I think the PV is very likely gone. May be other problems as well mind!
One comment and update. I mentioned that the rads all warmed up much quicker after recharging the PV and I could not think why. I now think that since the PV membrane was almost certainly ruptured, that lots of air came through it and into the system. I expect that this did a backflush on the heat exchanger and pushed out crud from it. Hence, now it works much better and the water flow through it is also much better, giving the faster warm-up.
Since the noise went away immediately after I recharged the PV, I think that a defective PV is involved. As time has gone on, the air that was in it has been absorbed into the water in the system and so we are getting ever nearer to the initial state.
Interestingly, when we moved in, one particular rad was completely full of air! I thought this was strange, but after recharging the PV, it was this rad that was again full of air. Hence, I think that I might now know where it came from in the first place....
Thanks for the comments and good luck with your problem(s) as well.
One comment and update. I mentioned that the rads all warmed up much quicker after recharging the PV and I could not think why. I now think that since the PV membrane was almost certainly ruptured, that lots of air came through it and into the system. I expect that this did a backflush on the heat exchanger and pushed out crud from it. Hence, now it works much better and the water flow through it is also much better, giving the faster warm-up.
Since the noise went away immediately after I recharged the PV, I think that a defective PV is involved. As time has gone on, the air that was in it has been absorbed into the water in the system and so we are getting ever nearer to the initial state.
Interestingly, when we moved in, one particular rad was completely full of air! I thought this was strange, but after recharging the PV, it was this rad that was again full of air. Hence, I think that I might now know where it came from in the first place....
Thanks for the comments and good luck with your problem(s) as well.
