Vaillant TurboMax 242E combi - no CH and CH demand indicator stopped lighting up

[abbot2]

Hi all,

I've got a Vaillant TurboMax 242E combi boiler, it was working fine so far, but this morning when I tried to turn on the CH (using external thermostat), CH did not start, CH demand indicator does not turn on, and there is no hot water in CH (but tap hot water works fine). I checked PCB connections, and tried linking PCB terminals 3 and 4 together (which connect to external thermostat) as troubleshooting guide suggests, but CH demand still does not light up. Troubleshooting guide now says "replace PCB" at this point. Is this really the only solution? Boiler was running fine and CH did work yesterday.

Thanks for your advise!

 

[SimonJohns]

Try the third option

Pay someone qualified and experienced in this to fix it

It's a gas appliance.

 

[jtsplumbing]

Did it come up with a fault code ? don't mess around inside boiler you could cause more problems, fault may not be with boiler! get some one in who knows what they are looking at, you could finish up replacing parts that are not needed.

 

[abbot2]

Did it come up with a fault code ?

It is a really old boiler, it does not have any kind of display, just 7 LEDs: power, hot water demand, central heating demand, fan operation, ignition, flame, burner lockout. Power LED is on. Hot water demand turns on when I open the hot water taps. Central heating demand did turn on when I switched on the heating with thermostat, but does not turn on now. All others (except burner lockout) did burn during normal burner operation, and still do turn on if I open the hot water taps.

I tested the thermostat - it still does short-circut corresponding wires when it is on, so thermostat is not a problem. Also there is 240V voltage present between terminals 4 and 5 when the thermostat is on as required by boiler manual.

 

[jtsplumbing]

Sorry but we DO NOT give out to much information on repairing gas appliances other than some basic tips on what to look for like low water pressure ! did you check this ?

 

[abbot2]

Water pressure is fine (~ 1.5 bar), and if I understand correctly hot water from taps would not work if it was low water pressure, right?

 

[Barry98]

This plumbing forum will not provide advice to anybody with regards to boiler repairs or any other form of gas plumbing without you first providing us with your Gas Safe Registration number in a thread - for very obvious reasons. If you're not qualified to touch gas, you should stay well clear of trying to!