Ok I have trawled most of the posts on this subject and they all suggest one thing - sludged up system. But I am not convinced as there are some weird things happening to my system
It is an ideal w2000 boiler with 2 position motorised valves for CH and HW.
The pump is a Grundfoss Selectric. Gravity and pumped I guess.
Ok so faced with a expansion tank pumping water into the tank like crazy I identified that the CH motorised switch was seized so replaced the whole thing. All seemd ok but noticed even though the rwb 20 prog controller was off the pump was continuously running and the only way to turn off the boiler was to switch it off at the mains or turn the boiler thermostat down to zero.
I replaced with RWB 29 which is the Siemens direct (and expensive) replacement. No joy. Well, the room thermostat and immersion tank thermostat have both been replaced and the motorised valves whirr when the thermostats kick in but still the boiler and pump runs continuously.
There is a frost controller which I also replaced and even when the connecting wires for this were open circuit the pump and boiler still ran independantly. The overflow feed into the expansion tank is connected to the pumped flow into the hot water tank and the only way to stop the pumping over is to manually switch the motorised valve to allow permanent flow into the tank. Of course the water is now hot enough to melt Titanium... Pump is set at minimum flow, boiler at 4 (max 6)
So last ditch before I call the experts
1. Does the boiler have a second thermostat that keeps the pump running until the water gets to a lower temp then stops the pump/shuts system down independently of the rwb29? In which case if so it's faulty
2. Could it be the pump is not getting enough flow and the boiler is overheating then pumping over due to gravity / syphon effect? In which case is there a sticky non return valve that is allowing syphoning to take place?
I am reasonably competetent with DIY and I have checked all the obvious stuff. But why is it all still running in spite of the RWB29 being permanently in the off position - clearly the pump and boiler are getting a feed from somewhere - I thought it was the frost thermostat but I have replaced it too and it makes no difference whether I switch it in or out.
HELP !! IF YOU ARE IN THE WALTON ON THAMES AREA AND CAN HELP LET ME KNOW!! I will pay you of course. The boiler was last serviced in 2003 and is a cast iron job. Any suggestions welcome!! I am about to kick the cat.... Rich
It is an ideal w2000 boiler with 2 position motorised valves for CH and HW.
The pump is a Grundfoss Selectric. Gravity and pumped I guess.
Ok so faced with a expansion tank pumping water into the tank like crazy I identified that the CH motorised switch was seized so replaced the whole thing. All seemd ok but noticed even though the rwb 20 prog controller was off the pump was continuously running and the only way to turn off the boiler was to switch it off at the mains or turn the boiler thermostat down to zero.
I replaced with RWB 29 which is the Siemens direct (and expensive) replacement. No joy. Well, the room thermostat and immersion tank thermostat have both been replaced and the motorised valves whirr when the thermostats kick in but still the boiler and pump runs continuously.
There is a frost controller which I also replaced and even when the connecting wires for this were open circuit the pump and boiler still ran independantly. The overflow feed into the expansion tank is connected to the pumped flow into the hot water tank and the only way to stop the pumping over is to manually switch the motorised valve to allow permanent flow into the tank. Of course the water is now hot enough to melt Titanium... Pump is set at minimum flow, boiler at 4 (max 6)
So last ditch before I call the experts
1. Does the boiler have a second thermostat that keeps the pump running until the water gets to a lower temp then stops the pump/shuts system down independently of the rwb29? In which case if so it's faulty
2. Could it be the pump is not getting enough flow and the boiler is overheating then pumping over due to gravity / syphon effect? In which case is there a sticky non return valve that is allowing syphoning to take place?
I am reasonably competetent with DIY and I have checked all the obvious stuff. But why is it all still running in spite of the RWB29 being permanently in the off position - clearly the pump and boiler are getting a feed from somewhere - I thought it was the frost thermostat but I have replaced it too and it makes no difference whether I switch it in or out.
HELP !! IF YOU ARE IN THE WALTON ON THAMES AREA AND CAN HELP LET ME KNOW!! I will pay you of course. The boiler was last serviced in 2003 and is a cast iron job. Any suggestions welcome!! I am about to kick the cat.... Rich