Hi all.
My first post but hopefuilly someone can help
As the post might suggest I've got a very noisy central heating system..and its definately the pump. Essentially it sounds like the bearings of the pump have had it ..but ..can only be so if I have had 3 duff pumps in a row. It does sound very similar to a system I had before (in a different house) when it was full of air..but I am fairly convinced this isn't yhe problem..see later.
System is mostly new (boiler, H/W tank, pumps controls etc all new with only a few old pipes remaining). Boiler is a Worcester Greenstar 29 HE installed 3 years ago in the porch down stairs miles away from the pumps which are located in the airing cupboard upstairs. The pumps are a 'Grunsfoss pump plan' with a 15/50 to the hot water cylinder and a 15/60 to the heating system. 'It' is mounted vertically with the H/W pump on the top and C/H on the bottom. Pipework is 28mm from the boiler up through the loft and down into airing cupboard with separate 22 MM to H/W and C/H.
It is a sealed system (around 1.5 bar cold and 2 bar hot) with automatic air traps on the 28mm flow & return in the loft and one above the pumps.
Most of the rad's have TRV's apart from the bathroom (to ensure there is a bypass)
Tried so far:
1) Bleeding everything 1001 times > no evidence of air in the system + noting coming out of the automatic vents
2) Emptying system and refilling (only additive is fernox inhibitor)
3) Replacing pump (twice .. so 3 in total)
4) Replacing pump plan housing
5) Increasing system pressure
6) Turning pump down...still noisy..not as much but really need to run it on '3' to get the heat around..its a fairly big old house.
Professional plumber installed the system and he hasnt' been able to resolve (he changed pump housing and pump once).
OH, one last thing, its been noisy since day 1 but its now driving me nuts...
Anyone?
Cheers
Jon