Help needed please!
My uncle's house has 11 rads fed via microbore, a brand new Grundfos 15-16-130 pump and a 15-20 year old Potterton Netaheat boiler (serviced every year and heats water ok). Few weeks ago he asked me to look at a non-working rad in the bathroom. I noticed the lockshield valve was fully open so I closed it off, opened it a 1/4 turn and hey presto one very hot rad. However, one of the three very large rads in the lounge (all 6ft high!) didn't work, even though hot water was getting to the TRV it just wasn't filling the rad. I bled it and released some dirty water but it wasn't dirty enough to suspect a blockage. Due to time constraints it was left as is.
Yesterday he called to tell me the bathroom rad was no longer working, the 6ft one in the lounge still didn't work and now a rad in the hallway had just stopped working overnight. I've bled the faulty rads, checked the balancing on all rads, checked the pump for air and released some of the water via the drain port near the hallway rad to see if it was blocked with sludge, again no problems. So now I am baffled.
However, one thing I did notice was, bearing in mind the heating was on full, when bleeding the rads the pressure was very low, not really a dribble, but certainly wasn't coming out with the force I expected. Also, despite the thermostat being set to high, the boiler kept switching off. I have also been told the CH is noticeably cooler when the Hot Water comes on.
Anyone have any tips on what the likely problem is? Is it the motorised valve? Could the Grundfos be faulty (all three speeds seem to work ok)? It just seems there is not enough pressure in the system to force hot water to all the rads. I had also thought maybe the microbore is blocked somewhere under the flooring but clean water seems to be getting to the cold rads so I don't think that's the problem?
Any thoughts anyone? Cheers.
My uncle's house has 11 rads fed via microbore, a brand new Grundfos 15-16-130 pump and a 15-20 year old Potterton Netaheat boiler (serviced every year and heats water ok). Few weeks ago he asked me to look at a non-working rad in the bathroom. I noticed the lockshield valve was fully open so I closed it off, opened it a 1/4 turn and hey presto one very hot rad. However, one of the three very large rads in the lounge (all 6ft high!) didn't work, even though hot water was getting to the TRV it just wasn't filling the rad. I bled it and released some dirty water but it wasn't dirty enough to suspect a blockage. Due to time constraints it was left as is.
Yesterday he called to tell me the bathroom rad was no longer working, the 6ft one in the lounge still didn't work and now a rad in the hallway had just stopped working overnight. I've bled the faulty rads, checked the balancing on all rads, checked the pump for air and released some of the water via the drain port near the hallway rad to see if it was blocked with sludge, again no problems. So now I am baffled.
However, one thing I did notice was, bearing in mind the heating was on full, when bleeding the rads the pressure was very low, not really a dribble, but certainly wasn't coming out with the force I expected. Also, despite the thermostat being set to high, the boiler kept switching off. I have also been told the CH is noticeably cooler when the Hot Water comes on.
Anyone have any tips on what the likely problem is? Is it the motorised valve? Could the Grundfos be faulty (all three speeds seem to work ok)? It just seems there is not enough pressure in the system to force hot water to all the rads. I had also thought maybe the microbore is blocked somewhere under the flooring but clean water seems to be getting to the cold rads so I don't think that's the problem?
Any thoughts anyone? Cheers.