Hi All please help
my son has a sime combi boiler and the heating is good BUT when you turn the hot water tap on the water comes hot then cold then warm and so on
Can any one tell us what is going wrong
Some one has said it could be the diverter valve but this person is not a heating engineer
Jacko
scale or air in the heat exchanger are the most common causes.
When my diverter valve packed in the radiators started to get hot when I ran the tap, also got warm water from the cold tap
most likely to be scaled up domestic hot water plate heat exchanger...........best bet if you cant do it your self phone british gas and a fixed fee of about £180 they will sort it
quote:
Originally posted by deanwelch
most likely to be scaled up domestic hot water plate heat exchanger...........best bet if you cant do it your self phone british gas and a fixed fee of about £180 they will sort it
get the p/n off the one in it and buy a replacement. much better than mucking around with so called wonder cleaning potions that cost £15-20 a go.
plate heat exchanger will be held in by 2 screws or allen keys remove them (turn water off and isolate flow and return, drain boiler first) put exchanger into solution of 50/50 boiling water and ds40(from plumbcentre around £25) for about a hour then flush out with cold water...........replace the 4 seals or silicone GREASE them reasseble and test or british gas on 08005244854
new heat exchanger likely to be more than £180 retail or call british gas 08005244854
Something as simple as the outside temp of the water? I've noticed in mine the max temp of the hot water will be x degrees, but that's x degrees higher than the feed, so if you're feeding water in thats 1 degree, it's not going to be scorching coming out.
i had a similar fault with a Baxi a few years ago. It was the hot water diverter valve. Cant remember exactly how they work but i recall there was a
rubber diaphragm behind the valve that had perished. New diaphragm fixed it but it was a bugger to trace the fault.
The operation of the valve was something along the lines of in normal operation the boiler heats water for the heating system. When you turn the tap
on the heating water is stopped and the hot tap water is 'diverted' through the boiler. As it works on pressure a split in the diaphragm
stops the valve working correctly. You will get warm water and then cold soon after as there will be residual water in the boiler that is getting
warmed up over time, when you turn the tap on it is this amount of warm water you get out followed by cold.
i have done hundreds over the last 25 years any other heating engineer will tell you the same from the symptoms you gave.............if heating flow pipe gets hot when you run hot tap then divetor is faulty.........if not plate is blocked.....if you can give more symptoms or boiler model even better gc number **.***.** in this format and i will find out how much parts are but very likely to be bloody expensive........ps i dont work for british gas i just like to tuck them up when i know how exoensive the parts are or other option take out breakdown insurance but you cant claim for 28 days............