Halstead Ace High Fluctuating HW Temp

[Lozzer1967]

Hi

I am currently having problems with my Halstead Ace High Combi boiler after 5 yrs of faultless service. It started with intermittent DHW, which was cured by the replacement of the DHW diaphragm. Now the DHW kicks in but after a short while the burner light goes off and the water temperature drops for a short time. Then the burner re-ignites and the temperature rises. This is continued throughout the draw.

As stated, I have replaced the DHW Flow Switch diaphragm, the plungers rise when the tap is opened and the switches actuate every time. The Boiler always fires and the the fluctuating temperature problem.

After reading other threads on this site I have removed, checked and cleaned the DHW Heat exchanger and the Water Flow Regulator, but to no avail.

Can anyone suggest what could be at fault or what I could try next ?

Thanks.

 

[twgas]

How did you clean the dhw h/ex? they are not terribly easy to do properly!

 

[gasfitter]

what is the temp diff of the plate to plate and temp of dhw outlet

 

[Lozzer1967]

1 - Flushed it through. TBH it didn't look dirty at all. Flushed virtually nothing out but a few black bits and water seems to flow through easily ?

2 - Haven't got a clue about the temp difference I'm afraid and haven't the means to test it.

Cheers

 

[Lozzer1967]

Anybody ?

 

[twgas]

The black flakes are magnetite, there'll be some stuck inside the plate h/ex, and are what stops the heat transfer and thus causing the temp fluctuations. I would suggest buying a new one, but you will probably need your system cleaning and inhibitor adding to help prevent the same thing happening again.

 

[Lozzer1967]

As an update, I borrowed a multimeter and tested the values as per the troubleshooter section of the manual and everything checked out. swapped the thermistors anyway - no change.

However, I set the hot water temperature control knob to approx two thirds and, hey presto, constant water temp ! Seems to run as hot as before but without the cutting out and coming back on cycle. Now I have obviously got round the problem for now but something must be amiss somewhere. Anybody any ideas ? Could this point to a PCB problem ? Interestingly, if the tests as per the manual check out, the manual states 'replace the pcb'. Now at around £150 a throw, that's not something I would want to change for fun.

Any thoughts ?

 

[lonner]

As an update, I borrowed a multimeter and tested the values as per the troubleshooter section of the manual and everything checked out. swapped the thermistors anyway - no change.

However, I set the hot water temperature control knob to approx two thirds and, hey presto, constant water temp ! Seems to run as hot as before but without the cutting out and coming back on cycle. Now I have obviously got round the problem for now but something must be amiss somewhere. Anybody any ideas ? Could this point to a PCB problem ? Interestingly, if the tests as per the manual check out, the manual states 'replace the pcb'. Now at around £150 a throw, that's not something I would want to change for fun.

Any thoughts ?

had this same problem.
changed both thermistors and no joy

spoke at length with halstead too but they could not diagnose it.

i think its the actual control petitioner as it works on some setting and not on others.

its a tiny micro potentiometer in the pcb which could be replaced if you can get one and re-solder it in place.

hope someone knows a way of getting these parts as a new board for a £2 item is daft.
i say £2 as ive seen similar items but there not the same