This story illustrates just how awkward and stressful some jobs can be.
Called out to a customer who I have worked for before. Pott. Puma 80e
combi with symptom no heating upstairs. So I obtain a diverter valve
actuator as these are invariably the root of many of the problems with
this model. Arrive: house warm downstairs, cold up stairs and in loft
Fill kettle as there wont be any water when when the boiler is in bits.
Pressure is 1 bar (a bit low but not desperate). Low pressure warning
light is off. Boiler is working and does HW mode fine (for a half scaled
up 24kW job). So turn off, add drain hose, drain point undoes but does
not produce, which is normal. Customer very impressed when I put tray
underneath drain point, don rubber gloves, wiggle jumper in drain point,
catch jumper, put thumb over gushing hot hole, replace jumper and secure
in place before the tray is 1/2 full. The rubber gloves give you a few
seconds to work with the hot water.
Water stops coming out of hose, but pressure still at 1 bar, uh? OK gauge
is faulty? tap gauge, tap gauge harder (with pin hammer!) , gauge moves
to zero in half a dozen jumps. Gauge buggered so refilling will be a
matter of guess work. Dismantle, remove actuator housing, actuator seems
built in on this unit. I'm 100% certain that the actuator was easily
removed, like it just falls out, when I have done battle with these
bastards before. Anyway after spending about 15 minutes trying to see if
I can open the housing, and failing, I try the alternative approach maybe
the actuator is OK.
I would not have had any difficulty if I'd gone and got the £80+VAT
entire diverter valve and simply canabalised it for the actuator housing
Clean up the unit and drop new and old ones into my tea mug, add hot
water from kettle, both grow, although the old one is not so good. The
gubbins of the diverter valve all seem reasonably free so I put it all
I am now the proud owner of a new actuator widget (£25) which will mean
that I'll never have to fix another Puma, ever. Unless like on this unit
the actuator is unreplaceable.
Water back on, close drain point, check auto air bleed unit is OK
(amazingly it is), begin refilling and tapping the gauge (with the
hammer) till I have 1 bar +/- 0.3 bar (which is what the gauge jumps up
or down each time it's hit).
At this point I notice that the boiler is leaking from at least
1) Flow isolator - i deliberately did not touch it.
2) Return isolator - as above.
3) Flow NTC sensor.
4) Return NTC sensor.
5) The joint holding the PRV.
Light bulb moment. The real fault was not a lack of primary flow but
lack of primary water. Also the gauge is F****d and low pressure switch
has failed in the OK state. That's TWO faults simultaneously - that
defies Clarke's dictum which says there is only one fault unless you add
another one whilst fixing the first one. So _all_ I've got to do is fix
the leaks, refill, bleed and collect the rent.
OK. none of the above leaks are really serious so leak sealer is called
for. get tub from van. Also the NTCs are really easy to fix as they are
screwed connections with a flange, so any of tape, string, gunge, liquid
PTFE, a fibre washer or a small O-ring would work. So I fixed them.
The isolators were inaccessible as far as replacement was concerned.
You can't syphon neat leak sealer it's too viscous.
Find that the customer has a nice empty 2 litre plastic milk bottle to
hand. Wash out dregs. add leak sealer and dilute, syphon into a radiator
(which I switched off at both ends? - a good move as it turned out).
OK. Refill. to about 1 bar give or take. It's now quieter than earlier
all the kids have gone to a neighbours house which is warmer, I can hear
hissing. OK it sounds like it might be coming for the PRV, check outside
the water's pissing out. Search van for replacement - I have one! generic
3 bar PRV with two 1/2" female iron connections. The Potty unit is 1/2"
on the outlet but the inlet (after some abortive tries to remove it) is
in fact held by a pair of grub screws (and presumably an O-ring). get
right hex key from van, it's a good fit on the grub screw but only if I
use one of the imperial sizes (?!), bend key 30 degrees, it's going to
break if I try anymore, try tightening it a little first, no joy.
Anyway even if I got it out the inlet connection might have been all of a
piece with the valve so I'd be shafted.
Think how am I going to explain that there is no way I can fit a new
boiler before Christmas.
Light bulb moment II. Add my generic PRV downstream of the broken one.
Now of course the existing discharge pipe must be abandoned. Remember
that was one of the things that one of the "house of horrors" cowboys was
done for - leaving the discharge pipe disconnected when installed a new
But there again, needs must, at 4pm. Decide that the customer would
rather have a tiny chance of scolding water over their kitchen worktop
than the certainty of Xmas dinner wearing their overcoats.
Comfort myself that a real cowboy would simply have plugged the PRV
outlet with a 1/2" plug allowing a tiny chance of an exploding boiler
during the Queen's speech.
Refill ( tapping gauge as I go) water coming out of the various leaks I
couldn't fix. OK time for some heat then open the rad containing the
sealer and then fill all the rads with water instead of air. Can't do my
usual trick of putting things up to 2 bar and then bleeding as this will
just make the leaks into a flood and stop the sealer working.
OK Electric ON, pump starts, much air is moving around but things settle
down. Switch on heating. Nothing, fan starts, but no ignition, no gas.
The fan and APS relays can be seen strutting their stuff but no spark &
Extreme frustration is too mild a term.
You remember "Das Boot" they fix the whole bloody U-boat and escape from
the sea bed against improbable odds only to return to their home port and
be gunned down.
Try reseating every connector, no joy. Check all controls and switches.
Am expecting to be killed by customer (6'3"), he'd have every right, I go
into a house that has HW and ground floor heating and leave them with
Recall that a couple of years ago I did battle with a Puma and had this
problem, it simply started up after about 10 minutes of agonising, no
reason why it stopped and none why it started again. So decide the best
course of action is to clean up and tidy up. After about 10 minutes it
started without explanation. Heat. 10 minutes later the house is warming
up. The leaks have stopped the pressure has been left at 2 bar.
New boiler (not a Potterton) scheduled for mid Jan.
I feel years older than I did at the start. I am coming to the conclusion
that the key skill for 'plumbing' is not, "the knowledge", strength of
grip or a van full of "bits" but FORTITUDE.
- posted 12 years ago