Why has my combi boiler suddenly stopped delivering domestic hot water?
Question:my worcester bosch greenstar 25si gas combi delivers central heating fine but all hot water taps run cold. when tap is turned on the boiler appears to start up but then goes off again before any hot water is delivered. gas, electricity and water supplies to the boiler have recently been isolated and then restored. fault indicator does not light up. i,m bamboozled, can anyone give me a solution to this problem before i reluctantly call in an engineer.
Answers:
When that same problem happened to me it was the change over switch that needed changing.
does it make it louder noise than usual when it fires up to run the hot water?..maybe air getting into the system. you may need to read the manual and check about the pressure level dropping.
you have an airblock in the system that needs to be bleed out though 1 of the rads.
attach a hosepipe to rad nearest a outside door adn turn off stop ****, open valve on red and let it flow into drain/garden when all gone fill system back up.
if u r getting htg then i would b looking at
hot water flow switch/thermister/diverter
if its a greenstar its probably 13 months old as they only come with a 12 month guarantee, but it dose sound like the h/w thermistor.
it's one of two thinks. one been the water flow turbine switch that detects the flow of your cold water entering the boiler or it could be the diverter valve that sends the water round the heating or just round the boiler for the hot water
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