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I have a vented CH system using a Potterton Neta-Heater. It has a std three way valve and pump upstairs next to the HW cylinder.
System has been running perfectly OK until a few weeks ago when I noticed that the downstairs rads were not particularly warm whilst the upstairs ones were pipping hot.
Checked if there was any air in the rads but all OK and I have checked the operation of the three way valve, CH, HW or CH + HW, which seems fine.
The pump was replaced 4 to 5 years ago and the motor is running and changes speed when selected, though clearly I cannot confirm the the impeller is actually connected or spinning.
The feed to the rads were very hot, but the rads were very often luke warm and the outlet from the rads fairly tepid. Though now at times even the feed pipes are luke warm and some of the rads now do not even seem to get any hot water?
The main feed pipe from the boiler is piping hot but the return pipe not particularly hot.
The boiler will only run for short periods, obviously the boiler temp/thermistor is heating up fairly quickly and you get a sort of 'sooty' over hot smell.
Would appreciate comments and suggestions. Is it likely to be the pump or a blockage in the downstairs pipework?
System has been running perfectly OK until a few weeks ago when I noticed that the downstairs rads were not particularly warm whilst the upstairs ones were pipping hot.
Checked if there was any air in the rads but all OK and I have checked the operation of the three way valve, CH, HW or CH + HW, which seems fine.
The pump was replaced 4 to 5 years ago and the motor is running and changes speed when selected, though clearly I cannot confirm the the impeller is actually connected or spinning.
The feed to the rads were very hot, but the rads were very often luke warm and the outlet from the rads fairly tepid. Though now at times even the feed pipes are luke warm and some of the rads now do not even seem to get any hot water?
The main feed pipe from the boiler is piping hot but the return pipe not particularly hot.
The boiler will only run for short periods, obviously the boiler temp/thermistor is heating up fairly quickly and you get a sort of 'sooty' over hot smell.
Would appreciate comments and suggestions. Is it likely to be the pump or a blockage in the downstairs pipework?
