Vaillant hot water too hot

[ibrahaj04]

I have a Vaillant VCW 242EH and for a while now i have been putting up with the problem of the domestic hot water supply being just too hot, it is unbearably so. I have set the temperature selecter valve to the lowest setting (still boiling hot). I did increase it to the three setting to check that the water section is tripping the servo control valve and therefore the microswithches and it does, it also goes back after the water has been turned off.
I do have a slight leak on the water section and on the domestic heat exchanger which does look a mess rust etc.
Could there be a problem with the D.H.W thermostat or could it be due to the heat exchanger?
Any help would be welcome as it has been a good boiler.

 

[B.O.B DOLE]

I have a Vaillant VCW 242EH and for a while now i have been putting up with the problem of the domestic hot water supply being just too hot, it is unbearably so. I have set the temperature selecter valve to the lowest setting (still boiling hot). I did increase it to the three setting to check that the water section is tripping the servo control valve and therefore the microswithches and it does, it also goes back after the water has been turned off.
I do have a slight leak on the water section and on the domestic heat exchanger which does look a mess rust etc.
Could there be a problem with the D.H.W thermostat or could it be due to the heat exchanger?
Any help would be welcome as it has been a good boiler.

it could be the thermister

 

[geoff@cetltd]

Or the temp control on the motherboard fallen apart

else, it is the thermostatic control board (the middle one)

 

[ibrahaj04]

Thanks for the advise, had a look at the board and nothing jumps out at me but it does make sense.

 

[Agile]

At the extremes there are only TWO causes of the water getting too hot !

Too little flow rate OR too much heat input ( caused by gas settings ).

You can check the flow rate by measuring the time for one litre of water and calculating the litres per minute, should be around 9 li/min.

You can also check the gas setting by looking at the gas meter and measuring the time in seconds to use one cubic foot as measured on the small round test dial ( if it has one ! Other ways if not ) Should be around 30 seconds for 1 cu. ft.

Tony

 

[ibrahaj04]

As far as the water supply goes that is fine. British Gas checked the flow rate whilst they were trying to flog me a new boiler for £2500 fitted and an easy one "straight swap"(his words) to boot.

If the thermistor has gone would this not account for the too much gas bit as it wouldn't know when to stop heating the water.

My queston would be is it the NTC-resistor that has gone or the D.H.W thermostat?

 

[Agile]

Amazing how you try to point someone towards the possible cause and they totally ignore what you tell them and want to look at some other aspect.

Better go back to watching the climate change warnings on TV.

Tony

 

[CorgiIOW]

Amazing how you try to point someone towards the possible cause and they totally ignore what you tell them and want to look at some other aspect.



Tony

Strikes me, that this chap just wants a quick fix solution, is it, or isn't it!

Agree with ya, do the basic checks first.

 

[ibrahaj04]

Ok sorry should have checked these first.
The Water flow rate was set at 9L/min.
0.027m3 gas flow.

 

[Agile]

Why do I have this idea that you are just quoting figures you have looked up in the manual or someone else has mentioned?

You have quoted a volume of gas, 0.027 Cu Metres. What does this volume represent?

Tony

 

[ibrahaj04]

Right thanks for the advise, checked gas flow against one in manual too much gas, gas consumption in manual states 2.82 m3/h. Never thought to check if things had been twiddled

 

[Agile]

Am I clairvoyant or something?

 

[kevplumb]

I have a Vaillant VCW 242EH and for a while now i have been putting up with the problem of the domestic hot water supply being just too hot, it is unbearably so. I have set the temperature selecter valve to the lowest setting (still boiling hot). I did increase it to the three setting to check that the water section is tripping the servo control valve and therefore the microswithches and it does, it also goes back after the water has been turned off.
I do have a slight leak on the water section and on the domestic heat exchanger which does look a mess rust etc.
Could there be a problem with the D.H.W thermostat or could it be due to the heat exchanger?
Any help would be welcome as it has been a good boiler.

it could be the thermister

shurrup muppet 242 dont have thermistors