Dead leg?

[David937]

Hello,

I have noticed something which I suspect is a dead leg, when I turn the cold water tap on and then off the boiler detects a demand for hot water and starts the ignition sequence and then stops.

Boiler: Vaillant ecoTEC+ 937.

How could this problem be resolved?

Thanks you.

 

[bengasman]

Cut off the dead leg?

 

[corgiman]

and stop worrying about it today

Its Xmas

 

[swbjackson]

Check valve and shock arrestor possibly.

 

[David937]

Were would that be?

Also I forgot to add that we fitted Bosch cold fill washing machine recently and the hot water pipe for the existing CDA (crap domestic appliances) washing machine was just capped off.

 

[David937]

Were would that be?

Also I forgot to add that we fitted Bosch cold fill washing machine recently and the hot water pipe for the existing CDA (carp domestic appliances) washing machine was just capped off.

 

[Agile]

Run some water fast out of your capped off hot water pipe in case you trapped some air inside.

In any case after a few weeks/months it will probably dissolve anyway.

Or fit a non return valve AFTER the boiler on the hot water outlet.

Tony

 

[David937]

I forgot to mention that we didn't cap it off; we just closed the valve.

And the machine was installed in July so I would have thought any air would have dissolved by now.

 

[Agile]

Run some water fast out of your capped off hot water pipe in case you trapped some air inside.

Or fit a non return valve AFTER the boiler on the hot water outlet.

Tony

Or just run some water from the "closed valve" then. The effect is the same!

Tony

 

[Deleted member 105431]

set d88 to 1.

 

[David937]

set d88 to 1.

I don't see d88 in the manual but I will try it out, what does d88 do? I am inclined to find out.

Talking about Vaillant boilers, do you think that the commissioning display system is very helpful e.g the boiler can be easily range rated etc?

 

[David937]

Thank you

I set d88 to 1 and the problem is nowhere near what it used to be and will only occur if you close the tap very fast.

d88 was not in the manual on the Vaillant website but was in the manual that came with my boiler.

 

[Deleted member 105431]

d88 sets the minimum flow of water before the demand for hw is acted upon, the higher the number the more water must flow before the demand is recognised. might be worth fitting a non return valve on the hw outlet too.

 

[David937]

d88 sets the minimum flow of water before the demand for hw is acted upon, the higher the number the more water must flow before the demand is recognised. might be worth fitting a non return valve on the hw outlet too.

Thanks.

How much is a non-return valve?

 

[Deleted member 105431]

d88 sets the minimum flow of water before the demand for hw is acted upon, the higher the number the more water must flow before the demand is recognised. might be worth fitting a non return valve on the hw outlet too.

Thanks.

How much is a non-return valve?

about £2.