Although my central heating system is very quiet in operation, when the system switches to heat the hot water cylinder it makes quite a racket. It sounds as if there is air circulating through the pump with all the knocking and groaning noises that is coming from it! The cylinder does get hot though and the cylinder thermostat works OK. There is a pipe with a shut-off valve connected between the entry to the cylinder coil and its outlet (an adjustable bypass?) could this need adjusting and what is its actual purpose?
Thanks for any advice.
KG
Thanks for any advice.
KG