My SMC pump,after 25 years service became very noisy (like the bearings were shot - squealing noise) so I thought I would fit a new one. Because the Union connectors were very tight - 24" stilsons would not budge it and I didn't want to disturb any joints in and around the HW Cylinder- I had to partially drain the system and fit the new pump, gate valves either side of pump were fine, surprisingly.
On filling the system I had the inevitable airlock problems and I have lost count how many times and methods - top down and bottom up - I have filled the system up and re-bled it.
When firing up the boiler it goes for about 4-5 mins then reaches temperature and cuts out. The pump is in the airing cupboard and next in the flow is the 3 port motorised valve. After about a further 4-5 mins with the pump still running the 22mm flow pipe into the HW cylinder gets nice and hot as you would expect. However, the return at the bottom of the coil coming out of the HW cylinder remains stone cold, as does the return into the top of the boiler. Classic signs of an airlock i would guess? I have done all the things like gently pumping mains water pressure in via the boiler drain valve, etc.
Today, my daugher's boyfriend and his dad who are both in the heating installation business both came to look and were equally baffled by this. His dad suggested that the new pump may be faulty or the heat exchanger in the boiler could be blocked. So we are going to try a different pump tomorrow to eliminate that. But if that is not the problem I'm not sure how to confirm if the fault is with the heat exchanger in the boiler and what can be done about it?
The boiler is a wall hung Thorn EMI Olympic 38/50B and although is 25 years old, I'm told is a good boiler, better than most modern ones, so I would be relutant to change it and besides it worked fine before I changed the pump.
The new pump I bought to replace the noisy one is a Wilo Gold RS60
I would very much welcome any feedback into this problem and how it might be sorted out.
Thanks in advance
On filling the system I had the inevitable airlock problems and I have lost count how many times and methods - top down and bottom up - I have filled the system up and re-bled it.
When firing up the boiler it goes for about 4-5 mins then reaches temperature and cuts out. The pump is in the airing cupboard and next in the flow is the 3 port motorised valve. After about a further 4-5 mins with the pump still running the 22mm flow pipe into the HW cylinder gets nice and hot as you would expect. However, the return at the bottom of the coil coming out of the HW cylinder remains stone cold, as does the return into the top of the boiler. Classic signs of an airlock i would guess? I have done all the things like gently pumping mains water pressure in via the boiler drain valve, etc.
Today, my daugher's boyfriend and his dad who are both in the heating installation business both came to look and were equally baffled by this. His dad suggested that the new pump may be faulty or the heat exchanger in the boiler could be blocked. So we are going to try a different pump tomorrow to eliminate that. But if that is not the problem I'm not sure how to confirm if the fault is with the heat exchanger in the boiler and what can be done about it?
The boiler is a wall hung Thorn EMI Olympic 38/50B and although is 25 years old, I'm told is a good boiler, better than most modern ones, so I would be relutant to change it and besides it worked fine before I changed the pump.
The new pump I bought to replace the noisy one is a Wilo Gold RS60
I would very much welcome any feedback into this problem and how it might be sorted out.
Thanks in advance
