I have my hot water set to come on twice a day for 20 mins. After about 15 mins there is a gurgling and hissing sound coming from around the pump/Y-valve area of the pipework in the loft. It is a vented system with the oil boiler in the garage. Also not sure this is connected but one of the radiators upstairs requires bleeding once a week. Any ideas?
Could be boiling the hot tank and overflowing into the expansion tank in the loft ... do you have a tank thermostat wired in, or just the water temperature thermostat in the boiler?
Or the primary pipework could be furred up and you're just getting local boiling in it.
After it's gurgled and hissed, how hot is the water from the taps, don't scald yourself finding out!
It could just be over pumping - the pump is running to fast and pushing water into the expansion tank. This tends to introduce a lot of air into the system. Inspect your expansion tank while the system is running - there should be no constant flow of water into the tank.
If you want answers from uk.d-i-y then why not subscribe to the newsgroup rather than use the awful pile of nonsense that is Homewreckers?
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.