[RAINS]

I know this is a completely the wrong forum to ask but some of us have day jobs like central heating......

I have a Halstead Quattro Gold Boiler which when i turn on the hot water does not start the boiler unless i turn it on fully. As you turn down the flow the boiler goes off.I get hot water if the heating is on.

I have read through the documents and replaced the DWH thermistor but this has not made any difference the schematics now say to change the PCB, circuit board... am i clinching at straws by trying it myself to save costs or should i just get someone in !!!

Can anyone help ?

[deanym]

IS it a combi? If so add some water/pressure to the system then try that, if the system is underpressured it will not light for safety reasons.

[RAINS]

Originally Posted by deanym

IS it a combi? If so add some water/pressure to the system then try that, if the system is underpressured it will not light for safety reasons.

Thanks for the quick response the pressure i've topped up so when the heating is on it's just under 2bar when off just over 1.25bar. As the CH works ok i'm thinking it's something else?

[the whistler]

Could I recommend you try the central heating forum on www.diynot.com

There are experts on there who know just about everything about every boiler in existance!

[Kebabhead]

Originally Posted by RAINS

I have a Halstead Quattro Gold Boiler which when i turn on the hot water does not start the boiler unless i turn it on fully. As you turn down the flow the boiler goes off.I get hot water if the heating is on.

Can anyone help ?

This a safety feature of all boilers

What is happening is when you turn the tap, you are restrict the flow of water inside the boiler which becomes superheated and the bolier shuts down as a safety precaution.

You need to keep the water pressure constant hence why you should turn the hot water tap on full

[temsy]

I have the same boiler and this has happened with mine on more than one occasion.
My problem was with the rubber diaphram in the changeover valve(large brass cross shaped junction piece) which had corroded.
The diaphram is lifted by the flow of water when hot tap is opened, if there is a hole it doesn't lift, but more water pressure is able to lift it.

You can replace just the diaphram or the complete valve

Hope this is of help

[Bat-man]

Originally Posted by temsy

I have the same boiler and this has happened with mine on more than one occasion.
My problem was with the rubber diaphram in the changeover valve(large brass cross shaped junction piece) which had corroded.
The diaphram is lifted by the flow of water when hot tap is opened, if there is a hole it doesn't lift, but more water pressure is able to lift it.

You can replace just the diaphram or the complete valve

Hope this is of help

Exact same thing happened with ours a couple of weeks ago.

[RAINS]

Originally Posted by temsy

I have the same boiler and this has happened with mine on more than one occasion.
My problem was with the rubber diaphram in the changeover valve(large brass cross shaped junction piece) which had corroded.
The diaphram is lifted by the flow of water when hot tap is opened, if there is a hole it doesn't lift, but more water pressure is able to lift it.

You can replace just the diaphram or the complete valve

Hope this is of help

Many thanks lads

Do you recommend to change the diaphram or the complete valve and is this something i can do myself without technical knowledge but lots of common sense !!!

[temsy]

Originally Posted by RAINS

Many thanks lads

Do you recommend to change the diaphram or the complete valve and is this something i can do myself without technical knowledge but lots of common sense !!!

I am not a plumber and have similar attributes to yourself and have repaired mine on both occasions.
First time I replaced the whole valve because i was told that was the problem.
Secod time the just the diaphram (obviously cheaper).

Get your parts from your local plumbers merchants and don't forget the fibre washers.

Be carefull with the circuit boards but i they do get wet allow them to dry throughly before attempting to switch on.

[RAINS]

Originally Posted by temsy

I am not a plumber and have similar attributes to yourself and have repaired mine on both occasions.
First time I replaced the whole valve because i was told that was the problem.
Secod time the just the diaphram (obviously cheaper).

Get your parts from your local plumbers merchants and don't forget the fibre washers.

Be carefull with the circuit boards but i they do get wet allow them to dry throughly before attempting to switch on.

I have just ordered the diverter £40 and while i was there i thought i'd get a new microswitch £5 from Ezypart, cheapest i could fined others asking >£100.
Delivery on Monday.

Just read that i need to move the pump first to get at the valve.... going to give it at try, will let you know and thanks for your advice