Question about Vaillant combi flow rate

[fastbike]

I've got a problem with my VCW GB 242 EH being reluctant to fire up (not quite operating the microswitch when DHW is drawn; subject of recent post)

I need to confirm whether the fault really is in the water valve section (diaphram etc) or conceivably the secondary heat exchanger being scaled up, leading to insufficient differential pressure to operate the valve.

I've just measured the DHW flow rate at 10 litres/min whereas the manual states "nominal capacity of domestic water" as 8.7 l/m.

This suggest to me that the heat exchanger is not the problem - Can anyone kindly confirm that my line of thinking is correct ?

 

[Agile]

You are missing the point!

The manual is talking about the ability to heat water and not the maximum flow rate.

Your diverter valve is presumably failing.

toNY

 

[fastbike]

You are missing the point!

The manual is talking about the ability to heat water and not the maximum flow rate.

Your diverter valve is presumably failing.

toNY

erm.. not sure whether I missed the point or not...
If vaillant mention 8.7l/m then I'm presuming that it must operate OK at that rate, so the higher rate I am getting ought to be sufficient to definitely operate the flow sensor.

Incidentally, I believe that the diverter valve itself is OK - because when the servo does manage to operate, the diverter mechanism works perfectly. The root cause is probably the diaphram in the water section, not the diverter.

Thanks for the reply though!
- Steve

 

[Agile]

Again you HAVE missed the point!

The flow rate that they quote, as I said before, is in relation to heating water!

The flow rate to turn the boiler on should be less than 3 li/min.

Tony

 

[libby lou lou]

never mind