Posted by Clive Oldfield on August 03, 2000 at 02:14:31:
Hi, I have a VCW-sine 18 Vaillant boiler about 12 years old.
Recently the hot water is geting to about 70 degC, which is
too hot IMHO. It appears the gas burner isn't being regulated
when the hot water gets to 60 degC. It does get modulated
for central heating OK (proving the NTC resistor is OK?) and will
read max 60degC on 'summer' on the dial. I've had the PCB out,
tweaked the domestic hot water pot and no change - still high 60's
maybe 70degC. The flow switch goes up/down OK and appears to
move the microswitches OK.
Where else should I check for this fault?
Any help much appreciated,
Clive.