Sime Halstead 30/90 (Trio?) - No DHW unless CH is fired.

[GarethE]

Hi there.

So many people on here with problematic Halstead boilers (and, thankfully, experts too).

I have a Sime Halstead 30/90 combi boiler (I think also known as a "Trio" in some places). Basically, the boiler won't light for DHW. If the boiler is ALREADY alight for central heating and you turn on a hot tap then you get hot water.
The flame doesn't go out or anything - keeps going quite happily.

The problem is that when you want hot water you have to wait for the heating to come on first (not the end of the world - but annoying all the same).

I've just had a heating bloke out who checked it over and said the divertor valve is fine - operates the microswitch OK but doesn't ignite the boiler. He checked over a few other things but couldn't identify the fault (and that cost £100!).

What do you think? Any ideas?

 

[HarrogateGas]

Was he looking at the right valve for operation.....id be dubious.


If what he says he has checked is fine your lookingat something electrical, microswitch, PCB or thermistor.

 

[GarethE]

Was he looking at the right valve for operation.....id be dubious.


If what he says he has checked is fine your lookingat something electrical, microswitch, PCB or thermistor.

Thanks for the swift response.

Not sure - he certainly prodded about around the divertor (a Giannoni one) and seemed happy it was working - how he could tell I'm not sure.

If I pop the microswitch off the top and turn on a hot tap, a pin should push out of the top - is that a valid test for me try?
Basically (forgive my ignorance) if the pin comes out it must be working OK? No situations where the pin comes out, operates the switch but something else in the valve is not working?

He changed the DHW thermistor and that had no effect.

 

[Agile]

I would say that you should not have paid him anything if he did not fix the boiler !!!

The pin in the diverter valve should come out when DHW is drawn and it should operate the microswitch.

Tony Glazier

 

[GarethE]

I would say that you should not have paid him anything if he did not fix the boiler !!!

The pin in the diverter valve should come out when DHW is drawn and it should operate the microswitch.

Tony Glazier

Regarding payment, that's interesting. I enquired with a few heating/plumbing numbers in the area - they all charge around £55 per hour for time - no guarantee of a repair - if they spend the time trying they want paying. (that's why I want to look at it myself now)


Regarding the diverter pin - what the chap said was that when DHW is drawn, the pin comes out, operates the microswitch (suggesting divertor is OK) but something further down the line is amiss preventing the ignition (something I plan to confirm - multimeter at the ready).

If the burner is already alight (for CH) then you can turn on the hot tap and you get hot water. Radiators go cold if DWH is running for a while (which seems normal to me). The burner doesn't go out - keeps going and heating the water as long as you want it.
The issue is when the heating is off - no ignition.

 

[GarethE]

The latest:

Checked the divertor microswitch with multimeter - definitely OK.

On second look, noticed that radiators get quite cold before the boiler fires up - which has made me rethink...

Could be an fault with a delay in ignition (for both DHW & CH) - maybe pressure sensor problem. What do you think?

Is that something a novice (i.e. me) could replace or does it need an expert?

 

[Agile]

Is there a SYSTEM flow switch on your boiler?

If not then it sounds as if the PCB could be faulty.

I would not want to pay anyone by the hour if he could not guaranty that he would correctly diagnose the fault! A no fix-no fee policy would engender confidence in the professionalism of the engineer!

Tony

 

[GarethE]

Is there a SYSTEM flow switch on your boiler?

If not then it sounds as if the PCB could be faulty.

Tony

No, not aware of a system flow switch. The only switch relating to system flow I can see is the one on the divertor - and that is OK.

Hope it's not the PCB - the engineer that came out called Halstead and apparently you can't get them any more.

Do you think the pressure switch could be relevant? One other symptom I noticed - when I opened the boiler (removed outer case and sealed front containing the pressure switch, fan & combustion chamber) it lights more quickly for DHW - instant 50% of the time. Didn't want to leave it that way so replaced the front and now it's slow to light as it was before.

What do you think?

 

[Agile]

Because of the rather vague way that you have tried to explain the problem, I still dont know if the only problem is mostly cured when the combustion chamber is open.

If that were the case then the problem is likely to be with the fan, venturi or APS. All of these however should only be dealt with by by a CORGI engineer. You are not even supposed to open the combustion chamber unless registered.

I expect that if I needed a PCB then I could find one!

Tony Glazier

 

[GarethE]

Tony,
Thanks for your help - much appreciated - and sorry for the vagueness. I'll try to clarify:
1. Turning on the hot tap with the boiler burner unlit - divertor activates, fan starts, but burner but doesn't light (no ignition spark).
2. If the burner is already alight (for CH) - then turning on tap we get hot water.
3. On the CH side, radiators get quite cold before burner lights - then they warm up OK.

So: my conclusions based on this were that the boiler, basically, is just slow to light (ignore the original topic title). I suspect if we followed point 1. above and waited long enough, then the burner would eventually light - but haven't tried...yet.).


Regarding opening the boiler - there's three sections (let me know where I should have stopped):
A. The outer white enamelled case (which I removed) contains the PCBs, pump, divertor, etc. and a sealed box.
B. The sealed box (which I opened) contains the sealed windowed combustion box, fan and the pressure switch.
C. The combustion box (which I have no intention of opening) contains ignition, burners, heat exchanger, etc.
http://www.halsteadboilers.co.uk/pdfs/Trio/TrioCombi.pdf

The picture showed here: http://www.halsteadboilers.co.uk/html/userGuide.asp?cat=-1&prod=63
Looks a bit like it (not exactly the same model though) - this is what ours looks like with A and B removed (and is basically where I got to).

When I had opened A and B, I noticed that the burner would light instantly around 50% of the time when turning on a hot tap. With B replaced, I tried the hot tap a number of times and it wouldn't light - symptom 1 above returned.

Question is: Does that sound like a temperamental pressure switch or something else

I may be in touch regarding that PCB - it's SIME part number is 62306.55 - GC part number is 309 330.

 

[Agile]

The problem is likely to be with the fan, venturi or APS. All of these however should only be dealt with by by a CORGI engineer.

You are not even supposed to open the combustion chamber unless registered. That is the sealed chamber you described.

Tony

 

[GarethE]

Tony,

OK thanks - won't go in there again.

I'll get an engineer out.... let you know what happens...