Sorry for the long post, but it's better to include as much detail as poss.
Standard fully pumped Y plan with 9 rads, boiler and HW tank upstairs, system is 25 years old, Glow worm fuel saver Mk2 60kBTU. 8 rads with TRV's.
Over the years it's had 2 replacement pumps, the original Grundfos (@10 years) Wilo (another 10 years) another Wilo that needed a new capacitor @ 4 years, 2 thermocouples and 2 synchro motors. Fernox MB1 used initially and latterly F1.
System has been regularly maintained and largely very efficient and trouble free. Chemically and mechanically descaled as required.
Last April the system was drained and flushed through and the pump impeller was descaled as there had been some kettling, airlocks developing in the first rad on the system with some intermittent hot overrun to the F&E tank (but no overflow)
Last autumn before starting the heating up, it was partially drained and the air trap was replaced, descaled the impeller again and as there was still some noise, treated it with X400 sludge remover in early Dec.
Left the x400 in for 4 weeks and the noise gradually disappeared to nothing.
Mid Jan drained it completely (a lot of grey water) then refilled and emptied 3 times, running the heating and HW separately between each fill, each rad closed and opened each time.
Then re-filled and added F1. During the following week it got noisier and noisier, sometimes just banging and cutting out. Checked the pump again found the speed switch was a bit flakey and not always starting (pump has always run at speed 3).
Replaced pump with a new Wilo.
Now it all works perfectly, BUT the motorboat noise - and to a lesser extent the kettling - is still there. I've adjusted the bypass which reduces the noise but also the efficiency of the heating. There's still some intermittent return to F&E tank and air in 1st rad.
I've ordered some Fernox silencer, but does any one have any other ideas?
The fact that it was perfectly quiet with the X400 in it suggests there's not much wrong, but I don't know If it's advisable to leave that in permanently with the F1.
TIA
Standard fully pumped Y plan with 9 rads, boiler and HW tank upstairs, system is 25 years old, Glow worm fuel saver Mk2 60kBTU. 8 rads with TRV's.
Over the years it's had 2 replacement pumps, the original Grundfos (@10 years) Wilo (another 10 years) another Wilo that needed a new capacitor @ 4 years, 2 thermocouples and 2 synchro motors. Fernox MB1 used initially and latterly F1.
System has been regularly maintained and largely very efficient and trouble free. Chemically and mechanically descaled as required.
Last April the system was drained and flushed through and the pump impeller was descaled as there had been some kettling, airlocks developing in the first rad on the system with some intermittent hot overrun to the F&E tank (but no overflow)
Last autumn before starting the heating up, it was partially drained and the air trap was replaced, descaled the impeller again and as there was still some noise, treated it with X400 sludge remover in early Dec.
Left the x400 in for 4 weeks and the noise gradually disappeared to nothing.
Mid Jan drained it completely (a lot of grey water) then refilled and emptied 3 times, running the heating and HW separately between each fill, each rad closed and opened each time.
Then re-filled and added F1. During the following week it got noisier and noisier, sometimes just banging and cutting out. Checked the pump again found the speed switch was a bit flakey and not always starting (pump has always run at speed 3).
Replaced pump with a new Wilo.
Now it all works perfectly, BUT the motorboat noise - and to a lesser extent the kettling - is still there. I've adjusted the bypass which reduces the noise but also the efficiency of the heating. There's still some intermittent return to F&E tank and air in 1st rad.
I've ordered some Fernox silencer, but does any one have any other ideas?
The fact that it was perfectly quiet with the X400 in it suggests there's not much wrong, but I don't know If it's advisable to leave that in permanently with the F1.
TIA
