Gas Works

Unvented Cylinder hot water causing pilot light to go out

Anonymous user 09/03/2024 - 3.05 PM

Hi There. I have a 4 year old Worcester Bosch conventional boiler. Up until recently the hot water and central heating have been working correctly. However having changed to an unvented cylinder seems to have caused a problem which has stumped my heating technician. The CH system is not pressurized, this has a header tank still in the loft. The system is wired in a Y configuration, 3PV and a 2PV near the HW cylinder. When the 3 port valve is in mixed mode or in Central heating mode all is fine. the water will heat up (slowly) and the rads heat up nicely. No failures. However when i operate hot water only, or switch from M to W the there is come water movement, and churning from the pump and then the boiler stops firing, after about 20/30s. When in W mode the pump is "churny" and does get hot. (This is even when the boiler is not running, after having stopped firing) The wiring has been checked several times by the central heating electrician. Both the 2 port and the 3 port valves have been changed. Could anyone recommend anything further to check, or investigate replacing etc. Apologies if I've been unclear in any of my description, so please do as and I will clarify if possible. Thanks