Halstead Boiler Problem

chadvandonkey · 11 Sep 2009

Hi,

I've got a problem with my central heating that I just can't fix.

I'll try and keep this simple but basically the fuse keeps blowing in the fused wall switch that supplies the bolier / controller. The boiler works fine when ONLY the hot water loop is running - it runs day after day with no problems at all. The same is true when ONLY the central heating is running - it works fine day in day out. The fuse blows everytime the central heating is or has been on AND THEN THE HOT WATER COMES ON. As soon as the relay clicks in the controller the fuse pops and everything goes dead. Both loops and the boiler system work fine individually so I don't understand which bit of the boiler / system is at fault. It only happens when the hot tank thermostat tries to flip the 3 way valve over to heat the hot tank AND the heating is/has been on.

My boilder is a Halstead Best 30 and the hot water system a conventional hot tank and 3 way valve to switch between water/heating or water and heating.

So far I have replaced the hot tank thermostat, the 3 way valve, the heating controller, the room thermostat and the Aquastat PCB inside the boiler all to no avail.

I'm at a loss now as the system functions fine with either loop running seperately but not together.

Any ideas will be greatly appreciated.... please help...

Thanks.

plummerman · 11 Sep 2009

It sounds like you've got a short circuit somewhere, as you say it's when the valve turns over id be looking for signs of water leakage round the valve which is dripping onto the motor and tripping it out or faillin that getting the multimeter out and checking the resitance of your neutral and live terminals in the wiring centre

Agile · 11 Sep 2009

It would have been cheaper to have called a professional rather than changing all those parts!

Were any parts changed BEFORE the problem started?

Tony

chadvandonkey · 11 Sep 2009

There are no leaks anywhere I've checked.

All of the parts were replaced after the problem started.

It looked like an electrical problem from the start hence the parts I've replaced. The problem started several months ago but I've not got it fixed as the heating hasn't been needed for months.

I'm confused as to why the loops works fine individually.

If the HW is on and the boilder is running you can turn on the CH and the 3 way moves to the centre and all works fine. If you have the CH on and turn on the HW the fuses pops.

And yes you are right - I guess it's the whole Engineer's pride thing taking over. I'm not an Electrical Engineer so wouldn't know where to check resistances although I do have a meter.

Thanks.

Agile · 11 Sep 2009

I agree that its an odd fault and I would normally expect it to be as a result of wrong wiring on the three way valve.

The leak can always be dried up when one mode is running first too.

However, it would seem to be something else that as yet I cannot deduce?

Can you take photos and post there here of each item and the inside of the wiring center and we may be able to see some more clues?

Tony

chadvandonkey · 11 Sep 2009

It just doesn't make sense. All of the parts I've replaced have been replaced with exactly the same brand new items. All of the wiring was done on a change one wire at a time basis so I know the wiring is exactly as it was originally.

The fault actually came on slowly over several months gradually blowing the fuse more frequently until now it's nearly everytime the HW comes on after the CH.

I had ruled out the water pump / ignition & overheat circuits in the boiler etc.

Just need a clue as to what to try next. I wonder if the wiring behind the wall has somehow become damaged?????

I will post pic's but it won't be until mid weekend.

picasso · 11 Sep 2009

have you changed the programmer ? is that what you called the "heating controller" if you have it may be both circuits are to much for the pump, bit of a long shot but cant think of anything else that would fit the symptoms.

bengasman · 11 Sep 2009

Have you replace all items with exactly the same part code numbers and all?

Agile · 11 Sep 2009

chadvandonkey said:
I had ruled out the water pump / ignition & overheat circuits in the boiler etc.

Exactly how have you ruled out the pump ?

Tony

chadvandonkey · 12 Sep 2009

Agile said:
chadvandonkey said:

I had ruled out the water pump / ignition & overheat circuits in the boiler etc.

Click to expand...

Exactly how have you ruled out the pump ?

Tony

Because the pump runs whilst the HW is on so presumably it must work??

Is that not correct?

Any ideas on something I can test would be great.

I'm on the verge of having a whole new boiler but I don't want to find it's just the pump or something simple to replace. Thankfully the pump / valve / stat etc. are all easily accesible so it's not a major to replace the pump.

Yes - all items were replaced with identical brand new items and I do mean the programmer yes.

I guess the only things left are the boiler, the wiring behind the walls and the pump.........

Thanks for the help so far...

chadvandonkey · 12 Sep 2009

picasso said:
have you changed the programmer ? is that what you called the "heating controller" if you have it may be both circuits are to much for the pump, bit of a long shot but cant think of anything else that would fit the symptoms.

Yes mate I have replaced this - and then tried the original again with no joy......

bengasman · 12 Sep 2009

You may find that getting a pro in who can find the fault is cheaper than replacing part after part, or even the hole boiler.

chadvandonkey · 12 Sep 2009

Well tbh I think I'm pretty much at that point now. I've replaced the obvious things.

Problem is getting a guy with the know how to sort it.

Can anyone recommend anyone in the Mansfield area?

bengasman · 12 Sep 2009

chadvandonkey said:
Problem is getting a guy with the know how to sort it.

That, sadly enough, is the biggest problem these days.

A lot of legwork does tend to do the job though. Ask friends, neighbours, colleagues and anybody else you know locally until you find somebody who has had the same chap around for years to service and repair the boiler.
The crucial elements are :
same chap (companies can have good ones and bad ones)
Long time, servicing a working boiler is not rocket science, nor is installing one so that it works. The difference between a good and a bad installer is that the good installer will build a system that is likely to work without problems. Any fool can fling a boiler on the wall and hook it up.[/b]

Agile · 13 Sep 2009

This is a very unusual situation where, so far, I dont have any obvious suspects.

I previously sugested that you post photos of the components, particularly the motor valve and the wireing center.

Can you do that?

Tony

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Halstead Boiler Problem

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