I've seen it suggested that the Suprima gas valve has two coils but I can't find any detail on how it works.

I wondered if one is for start and one for run?

Our boiler is lighting, but then immediately dropping out - as if it's not detecting a flame. However once it's running it's fine until it reaches temp. If there was an intermittant flame detection issue I'd expect the drop-outs to be much more random.

Any thoughts welcome.

wrote:

I've seen it suggested that the Suprima gas valve has two coils but I
can't find any detail on how it works.

I wondered if one is for start and one for run?

Our boiler is lighting, but then immediately dropping out - as if it's not
detecting a flame. However once it's running it's fine until it reaches
temp. If there was an intermittant flame detection issue I'd expect the
drop-outs to be much more random.

Any thoughts welcome.

You have replaced the thermocouple? I'd replace it again with a good
quality one before looking for another fault.

--

Roger Hayter

On Sunday, November 6, 2016 at 1:42:56 PM UTC, Roger Hayter wrote:

You have replaced the thermocouple? I'd replace it again with a good
quality one before looking for another fault.

Suprima doesn't have one.

wrote:

On Sunday, November 6, 2016 at 1:42:56 PM UTC, Roger Hayter wrote:

You have replaced the thermocouple? I'd replace it again with a good
quality one before looking for another fault.

Suprima doesn't have one.

Just showing my ignorance then! But it must have some sort of flame
detector?

--

Roger Hayter

On Monday, November 7, 2016 at 11:37:17 AM UTC, Roger Hayter wrote:

But it must have some sort of flame
detector?

Yes - it does it via the ignition lead. The old red ones are a known weak point but mine has been replaced by the later white one.

However if that was faulty I'd expect the drop outs to happen randomly. In practice, once the boiler gets going, it runs fine until the it reaches the boiler 'stat limit. Then it mostly won't restart, going through three ignition cycles then locking out.

It may well be the PCB (again) but I'm wondering if the gas valve has separate ingnite and run coils and the run coil is failing when hot.

En el artículo ,
escribió:

It may well be the PCB (again) but I'm wondering if the gas valve has separate
ingnite and run coils and the run coil is failing when hot.

Counting the number of wires to the gas valve may be your answer. If
it's only two, there can only be one coil.

I'd still whip out the pcb and check it carefully fro dry joints,
especially where wires plug into the board. As someone else said, the
headers (sets of pins mounted on the pcb) are often poorly soldered and
develop dry joints.

--
(\_/)
(='.'=) systemd: the Linux version of Windows 10
(")_(")

wrote:
I've seen it suggested that the Suprima gas valve has two coils but I can't find any detail on how it works.

I wondered if one is for start and one for run?

Our boiler is lighting, but then immediately dropping out - as if it's not detecting a flame. However once it's running it's fine until it reaches temp. If there was an intermittant flame detection issue I'd expect the drop-outs to be much more random.

Any thoughts welcome.

Assuming this is a fairly modern modulating boiler, one coil is
notionally Start and the other is for modulation of the gas flow to turn
the wick up and down.

On Sunday, November 6, 2016 at 8:41:24 PM UTC, Bob Minchin wrote:
Assuming this is a fairly modern modulating boiler, one coil is
notionally Start and the other is for modulation of the gas flow to turn
the wick up and down.

Suprima isn't a modulating boiler.

wrote:
On Sunday, November 6, 2016 at 8:41:24 PM UTC, Bob Minchin wrote:
Assuming this is a fairly modern modulating boiler, one coil is
notionally Start and the other is for modulation of the gas flow to turn
the wick up and down.

Suprima isn't a modulating boiler.

OK. Digging further, it does seem that the Suprima name with various
suffixes covers a wide range of boilers and newer ones modulate, old
ones don't.

I cannot explain why a non modulating boiler has two coils.

Hopefully some one can???

Bob

En el artículo ,
escribió:

Any thoughts welcome.

You do know the Suprima is notorious for PCB failures?

BBC Watchdog did an item on it a few years ago and Poxy Batterton had to
pay up. They reimbursed me for the cost of a replacement PCB.

--
(\_/)
(='.'=) systemd: the Linux version of Windows 10
(")_(")

In message , Mike Tomlinson
writes
En el artículo ,
escribió:

Any thoughts welcome.

You do know the Suprima is notorious for PCB failures?

BBC Watchdog did an item on it a few years ago and Poxy Batterton had to
pay up. They reimbursed me for the cost of a replacement PCB.

+1 Dry soldered joints where the mains connector pins are too heavy
to be properly wetted by the solder bath. Fault follows a service visit
as the engineer *wriggles* the connector to disconnect the supply.
(Ancient Profile model).


--
Tim Lamb

In article ,
Tim Lamb writes:
In message , Mike Tomlinson
writes
En el artículo ,
escribió:

Any thoughts welcome.

You do know the Suprima is notorious for PCB failures?

BBC Watchdog did an item on it a few years ago and Poxy Batterton had to
pay up. They reimbursed me for the cost of a replacement PCB.

+1 Dry soldered joints where the mains connector pins are too heavy
to be properly wetted by the solder bath. Fault follows a service visit
as the engineer *wriggles* the connector to disconnect the supply.
(Ancient Profile model).

My parents' suprima had too little solder on much of the board, although
what did for it eventially was a LV supply capacitor going high ESR,
presumably causing the microcontroller to crash with too much ripple on
its power supply. Did a swap for a refurbished one from Geoff (CET Ltd).

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Just to close this - had a discussion with Geoff at CET. On the gas valve, he explained it does have two coils but they're in series (hence it only has two wires going to it). So it either works or it doesn't.

It seems the default position is to change the PCB first. So he sent me a refurb one and sure enough all is well now.

The board does seem to have an issue connected with flame detection - the green LED would continue to flash after the gas lit, then close the gas valve. If it was going to keep going OK then the green LED went solid immediately the gas lit.

Very random issue - today it had worked fine from 6Am to 2PM, when I swapped the PCBs. Yesterday it was a nightmare, constantly going into lock-out.

I did a bit of reading up on the gas valve and it seems it's actually two valves in one, each having a different class of shut-off.