I have a central heating system that works when it feels like it. when i turn on the boiler it heats up quickly and then thermostat cuts out (boiler one as no room stat fitted). the pump has been changed and is pumping, the boiler stat has been changed. and the three way valve appears to change position when controlled by timer unit. when the boiler does work at mid temperature (no.2) it is fine until it is turned up or down and then water flow appears to stop as pump gets warm but there is no heat in the pipes either side of it, although the motor and shaft are turning. Yesterday I also had hot water in the header tank and it overflowed. The highest radiatior in the house is cold when rest are hot and bleeding is not changing this.CAN ANYONE HELP PLEASE - is this air or a blockage? I cannot work it out because at temp 2 the system works fine except for highest rad.
Super challenging problem with heating
- Thread starter daderj
- Start date
I have a central heating system that works when it feels like it. when i turn on the boiler it heats up quickly and then thermostat cuts out (boiler one as no room stat fitted). the pump has been changed and is pumping, the boiler stat has been changed. and the three way valve appears to change position when controlled by timer unit. when the boiler does work at mid temperature (no.2) it is fine until it is turned up or down and then water flow appears to stop as pump gets warm but there is no heat in the pipes either side of it, although the motor and shaft are turning. Yesterday I also had hot water in the header tank and it overflowed. The highest radiatior in the house is cold when rest are hot and bleeding is not changing this.CAN ANYONE HELP PLEASE - is this air or a blockage? I cannot work it out because at temp 2 the system works fine except for highest rad.Sponsored Links
Sounds like a blocked cold feed pipe to me, easiest way to check is to open the system drain cock and see if the header tank drains.
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did i miss something?
I think what Chrisr is referring to is that powerflushing will not clear a blocked cold feed, that will have to be done manually. powerflushing will clean the rest of your system if it's done right.
Try putting a decent magnet on the pipework where the cold feed tees in, if it sticks to the pipe it's got sludge in. To clear it you would have to drain or bung the f&e tank and cut the pipework so you could get something in and poke it all out. Be careful though as there will be water ready to come out so have lots of old towels ready. Also if you do have a blocked cold feed it's because your system is badly sludged, and it will need a good clean as well.
Most blocked feeds are VERY solid!
I once applied about 10 Bar and that did not shift it. Later a hammer and screwdriver used as a chisel but that was not much good either.
Only a masonary drill is likely to have much effect on a bad blockage.
Normally cut out the pipe and replace.
Tony
I once applied about 10 Bar and that did not shift it. Later a hammer and screwdriver used as a chisel but that was not much good either.
Only a masonary drill is likely to have much effect on a bad blockage.
Normally cut out the pipe and replace.
Tony
If its not too bad you might be lucky and get away with sticking a hose pipe on the vent and blasting it with mains pressure.
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