knocking pump 
Dear all
My pump is making grumbling / knocking noises when hot, but not cold.
It's a "WSP Gold" and part of a traditional CH / HW tank system installed in a new house in 1999.
When the water comes on at 5am its nearly silent, but as it gets hot the pump starts to get louder and after about 20 mins when it's at about 60 degrees C it is making noises that sound like a pipe knocking against it's fittings. About 6 knocks per second. It builds up gradually abd starts by just getting louder, grumbling till it seems its not balanced inside and knocking. The pipework is secure and not knocking. I've listened to the pump by putting a screwdriver to my ear and touching the pump with the other end, and it seems to be coming from there.
I've bled the radiators and only water came out - no air, also bled the pump and got the same results (everything switched off for the bleeding).
The HW cycle ends after 30 mins and about 30 mins later the CH comes on. Same symptoms again exactly.
Everything else works as it should except for these noises. The rads get hot all the way up, the water gets hot in reasonable time, etc. The boiler is happy I think.
There's a living room stat for the CH at 20 degrees C, a tank stat for the HW half way up set at 55 degrees C.
The boiler has a volume knob type control for the gas set at 4 out of 10. I've moved this down to 3 and the pump still feels too hot to hold (60 C?) but seems a bit quieter after 30 minutes of demand.
It was set at 3 but I increased it to 4 in December to get the rads hotter so could it be that ?
Or is my pump on its way out ?
If it's the pump, do I need to match same manufacturer / model or can I chose an equivalent ?
What are important things in the specification which I need to be aware of ?
Also, do all pumps fit in a standard physical size or do I need to measure the gap it fits in the pipework ?
Wife is complaining of being woken by banging at 5am (boom boom)!
thanks in advance
Dear all
My pump is making grumbling / knocking noises when hot, but not cold.
It's a "WSP Gold" and part of a traditional CH / HW tank system installed in a new house in 1999.
When the water comes on at 5am its nearly silent, but as it gets hot the pump starts to get louder and after about 20 mins when it's at about 60 degrees C it is making noises that sound like a pipe knocking against it's fittings. About 6 knocks per second. It builds up gradually abd starts by just getting louder, grumbling till it seems its not balanced inside and knocking. The pipework is secure and not knocking. I've listened to the pump by putting a screwdriver to my ear and touching the pump with the other end, and it seems to be coming from there.
I've bled the radiators and only water came out - no air, also bled the pump and got the same results (everything switched off for the bleeding).
The HW cycle ends after 30 mins and about 30 mins later the CH comes on. Same symptoms again exactly.
Everything else works as it should except for these noises. The rads get hot all the way up, the water gets hot in reasonable time, etc. The boiler is happy I think.
There's a living room stat for the CH at 20 degrees C, a tank stat for the HW half way up set at 55 degrees C.
The boiler has a volume knob type control for the gas set at 4 out of 10. I've moved this down to 3 and the pump still feels too hot to hold (60 C?) but seems a bit quieter after 30 minutes of demand.
It was set at 3 but I increased it to 4 in December to get the rads hotter so could it be that ?
Or is my pump on its way out ?
If it's the pump, do I need to match same manufacturer / model or can I chose an equivalent ?
What are important things in the specification which I need to be aware of ?
Also, do all pumps fit in a standard physical size or do I need to measure the gap it fits in the pipework ?
Wife is complaining of being woken by banging at 5am (boom boom)!
thanks in advance
