We now need to do something about our boiler - a notorious Potterton
Suprima 80. Lots of red
lockouts over the past year or so getting progressively worse - a
common pattern from what I have read (and that's an understatement if
ever there was one!). I/we've (I from now on) read lots about the bad
PCBs and have tried to check that aspect out (see below).
The problem now is:
A. On power on at the fuse, the red LED either blinks 2 per sec or does
so after a reset
B. A relay clicks, the green LED is on (steady) but after about 30
secs, it goes out and the red
LED flashes again, usually with green LED going off. No fan no
If, after about 1 hr off at the fused switch (adjacent to the
programmer - this powers the pump and Honeywell 3 way valve too I
believe), the Suprima does start, it then just cuts out again within
about 5 minutes with the same red LED flashing. Other times it has run
for a few hours and then just stopped, with some intermittent bursts
for a few mins, cut outs, and so on. I suspected a) a bad component or
b) bad solder pads.
1. The fan works (when the boiler does start as above, I've seen it
2. The pump works (after fixing a bad solder pad - see below)
3. The motor on the Honeywell V4073A 3-way mid position valve works
(althoug see below).
4. The room thermostat works.
I replaced a duff motor in the actuartor head on the Honeywell 3
position valve, but the valve itself is still a bit stiff. This side
seems to work (although the manual level only goes back to mid position
on the actuator, not all the way over to AUTO as it does on my
ready-to-be- substituted new V4073A 3-Way valve should I l earn how to
"drain down" - can anyone can advise here?. I realise it *could*
microswitches on the actuator head that are part of the problem, but
don't want to risk the new actuator on the old valve.
It was all temporarily fixed after a pump-power solder pad re-soldering
job done on the J8 connector on the notorious Suprima PCB recently,
and/or after the synchronous motor swap last week. We had hot water and
central heating back for several days. We thought the problem was
solved. Alas no.
5. The PCB has been checked for solder pad cracks and dry joints,
several times now. It's has been re-soldered and put back. First big
problem must have been one of the pins on J8 as some new solder on a
clearly bad joint (vaporised solder?) got the pump running again after
was literally boiling (kettling) because of no water flow. If one looks
the wiring diagram on p. 32 of
the "Potternon Suprima Installation and Service Manual" J5, J6, J7, J8,
J9 and J10 have all been
checked and resoldered, I even had a go at what might be the pads for
the three big relays K1 - K3 although I can't be sure where they are.
Whilst solder pad problems on J8 could lead to problems on the pump,
soldering problems on J6 can affect a) the gas valve b) the fan and c)
the overheat stat as this feeds all of these! I've tested the
connection between the upright pins (for all the leads connectors) and
the solder pads and the connections seem 1) sound and 2) make a
connection using a meter. As far as I can tell, the connections are
OK. There *may*
be dodgy components, can't tell. If anyone has any
suggestions as to what to look for on each component, and how to test
it, please say as it would be nice to know which, if any component is
aqctually faulty. It would be nice to be able to exclude the PCB
5. The temperature sensor *may*
be faulty - not checked it - need a
spare to do so.
6. The air pressure switch may or may not be faulty - again, not
tested, no spare for comparison.
7. The Overheat Thermostat has been replaced - so it's unlikely to be
One anomaly is that the mains wiring INTO the boiler doesn't look 100%
right to me. Note, this has not been touched so it was like this when
we moved in. I have always had a feeling that there is something wrong
with how the CH/DHW is wired up though, been something odd since we
moved in. Can't put my finger on it, and with the problems we have had
over the last year, it's all too muddled now to say exactly what.
Repeat, the wiring has always been like this - odd?
Looking at the same Potterton Suprima 80 Functional Wiring Diagram on
page 32, it shows what should be the correct wiring. Looking at the
Live, Neutral and Earth connections for the P U M P and M A I N S
coming in (two three core shite wires), the diagram on page 32
corresponds with our wiring on the B O I L E R PCB WIRING side, but NOT
on the P U M P M A I N S side.
On the 7 way terminal connector shown below, we have a yellow/green
(earth) attached at position 1, which is clearly labelled L on the
terminal block and on page 32 of the manual!
B O I L E R PCB WIRING
y b g/y r b br g/y
o o o o o o
L N E SwL N L E
1 2 3 4 5 6 7
P U M P M A I N S
| | | |
| | | |
| | | |
| | | |
| a | | b |
a+b TWO WHITE 3 CORE MAINS WIRES
No idea why that has been wird that way of what, if any, the
consequences might be. It doesn't look like a sensible thing to do, but
If anyone any bright ideas apart from (call Potterton, British Gas,
and/or a plumber), or replace the PCB altogether, all of which seems
like the last sensible option if nothing else - please let me know.
1. How to "drain down" so I can replace the Honeywell 3 position valve
2. How to test the air switch, temperature sensor(s), PCB components
3. Advice on the wiring anomaly.
4. Other suggestions.