halstead ace he 30 dhw problem?

Hi All,

I wonder if there is someone out there who can help with a very strange fault on a Halstead Ace HE 30 ?

The boiler is about 5 years old but being in a holiday home has only had limited use, probably equivalent to less than a year of a normal full time boiler.

Symptoms are:-

Central heating is fine.

Hot water is the issue, if I run a HW tap near the boiler (within six feet) the boiler fires up, the water runs hottish, more than warm but not really hot, i.e. you can still hold your hand under the flow. The flow is fine, very similar to the cold.

Now, and this is the interesting bit, if I open a second nearby HW tap, just a bit then the flow from the first tap goes up in temperature to that you would expect, i.e too hot to keep a hand in it.

Turn off the second tap and the first tap goes back to hottish (but not hot enough to give a good hot shower).

My first thought was the flow switch but I have measured the contact closure and it closes as soon there is any flow and stays on solid.

The only clue I have is that you can hear the boiler going from one burner noise level with the one tap flowing to a louder noise when the second tap is opened, I guess this is the burner being modulated.

Somehow the boiler is seeing a marginal increase in flow and deciding to go into a higher heat mode.

The second tap doesn’t produce any hot water but I wouldn’t expect it too, the boiler has only ever been able to keep one tap flow hot, yells from the shower when the kitchen tap is run…but I guess that’s normal.

As the flow switch is on, and it’s a simple on/off control, what is causing the boiler to go into ‘hotter’ mode when two taps are open but not when just one tap even when the flow is strong?

Incidentally things used to be fine so it is definitely some sort of fault.

I am reluctant to start buying thermistors, hydroblocks etc. until I can work out just where the fault is.

Any ideas would be more than welcome.

Many thanks

John

John B
September 2012