Could someone help please.
After remedying a problem with the feeder tank going a dry, the back boiler is now firing smoothly again. Result is hot radiators, but tepid DHW.
Investigated the airing cupboard: DHW pipe (going to the coil) is hot after leaving a manual-3way-valve, six inches of horizontal pipe then a 90degree bend to go up to the HW tank opening. Pipe goes lukewarm after the 90degree bend.
Could this be a blockage ? And would a shop bought sludge clearer solve it ?
Also, manual-3way-valve is a white plastic 'simplicity make, and has been seized in the mid way both open position for over 10 years.
Would like to be able to switch between CH & HW. Also this valve is the noisiest part of the whole system.
Can anyone recommend a cheap replacement?