Clueless girl -Potterton Puma 80E locks out - HELP Please!

[Ludi]

Hi, we have a Potterton Puma 80E combi boiler and it keeps locking out. When we turn the CH off and then turn the hot water on, at the beginning the boiler does turn itself on, the flame alights, but after a while dies and goes to a lock out mode. Sometime we manage to reset it again, sometime we have to wait for a while. When we don't use the hot water and only turn the CH on, when the boiler is cold the flame usually lights up and it works for some time(30 min, sometime 1h or longer), then it goes to lock out mode. We have to wait for a while again, takes a few attempts to reset it. Just keeps locking out everytime we press the reset button. And when we manage to turn the heating on and then we turn the hot water on, then it locks out again.
Not sure whether i've explained our problem correctly. Sorry, i'm not english, and don't have a clue about the boilers. I've search this forum, but still don't know why it keeps locking out. We have no dripping taps, it's a 2 bed bungalow and the boiler is in the garage.
in last six weeks we had about 5 or 6 visits from the BG engineers/plumbers and they have replaced some iverted?? valve, expansion vessel, pump, thermistor, stats, drained the boiler, div valve, psb/transformer, replaced ignition board, something called NCS PRV and are coming in again tommorrow to replace the gas valve. The boiler is 8 years old and has been serviced every year. Any ideas what could be wrong? I'm just worried they don't really know what's wrong and will have to get a new boiler. Forgot to mention that the BG engineer mentioned that our water flow is low, 8l/minute when cold and about 4l/m when hot. Not sure whether this is related or not. Any help/suggestions would be greatly appreciated.

 

[bengasman]

Don't get a new boiler, bar one or two parts, it already has been renewed.
Sounds like it is overheating somehow.
If it is done under an insurance policy, just keep getting them back and eventually someone will find the problem

 

[Ludi]

Any idea what could cause overheating?
We didn't manage to turn the CH on/restart the boiler all night, the house is really cold (so happy it's not winter). When we tried to switch the boiler on, it does turn itself on, you can hear the fan, but the flame won't light up, it goes to lockout mode after few seconds.

 

[bengasman]

Can you hear something clicking when you turn the boiler on?

 

[Ludi]

no, no clicking.

 

[Agile]

It is a very simple fault but unfortunately many of the BG people are quite inexperienced on these older boilers which are a little different.

I cannot say exactly what is wrong in your case from what you have written but its nothing serious and I dont think the gas valve needs replacing but many engineers dont really know how to adjust them for minimum gas pressure.

A low water flow is a bit of a problem on that model and its absolutely essential that the minimum gas rate is set properly and ideally rather on the low side. If the engineer has a problem you are welcome to let him call me for advice. Phone number in profile.

You may not be English but you write and spell better than some english people we see on here!

Tony

 

[Ludi]

Thank you. Not sure whether they would do it (call), sometime they get a bit 'touchy', kind of ''i know what i'm doing'' if you know what i mean, which obviously they don't. They just keep changing different parts. I'll try to suggest to them to check the gas rate.

 

[Agile]

I cannot say exactly what is wrong in your case from what you have written but its nothing serious and I dont think the gas valve needs replacing but many engineers dont really know how to adjust them for minimum gas pressure.

Tony

 

[Ludi]

Didn't read that properly. Thanks for pointing that out.

 

[Ludi]

The BG engineer just left. changed the gas valve, we've asked him about the minimum gas pressure and he said that it's fine. The boiler worked for about 5 minutes and it's gone again (after he left). Same thing. Locked out again. So now the BGman ordered another part.
My partner mentioned that sometimes it does make a 'clicking' noise when it's trying to turn the flame on, but not all the time, and i've never heard it myself. There was no clicking when i was reseting it.
I know i'm not giving you much (any) technical info, but any other suggestions?

 

[DP]

Ludi, if you want a peace of mind, kick up a stink and demand you get someone who CAN diagnose your boiler problem to fix it instead of trying this and that. What is taking place will drive you nuts (also many nuts and screws do get lost when someone unknowledgeable starts tinkering) as part changing exercise is devoid of any reasoned approach to fix faults

 

[Ludi]

It is driving my nuts. We tried that and once they've send 3! engineers, they came, looked, changed few parts, the very same day it stopped working. Then they send a 'manager', senior guy, who said that he's been working with this boilers for many years, he changed one of the parts and it broke again. Really tired of this. But i'll try again. Thanks.

 

[Gasguru]

What's the cold tap flow like. Poor hot water flow is nearly always down to a blocked flow limiter on the cold water inlet isolating valve.

Have they checked the main modulation circuit board? Often have plenty of iffy joints.

 

[Agile]

This is amazing!

When I go to repair a boiler, I have to make just one visit and diagnose the fault and expect to complete the repair on that visit!

This is only a boiler !

If you take a trip on a 737 for example, you expect it to fly for several hours until it gets to its destination without developing any serious faults. The guys who fix planes are not paid much more than the BG people yet they seem to do a much better and more reliable job!

Tony

 

[Ludi]

The BG guy said that our water flow is low, 8l/m cold, 4/m hot and said that it should be at least 9l/min. So we rang water company and they are coming to check the mains outside today, i think. Otherwise he said that we will need to get a new pipes into the house. We don't really have a problem with the water pressure/flow (apart from when we turn the tap in the kitchen and then at the same time in the bathroom, or we turn the waschine machine on, but i think that's normal with the combination boilers, isn't it? ). Otherwise the water flow seems to be fine to me. As they are coming in again, i'll ask them to check the main modulation circul.board and cold tap flow but i'll assume they'll say that it's been checked and it's ok. I've done some search on the web about this type of boiler and many times people mentioned some HW and CH temp.sensor resistance? and something called HW flow switch?, so we asked them if they can check it as well, and again, they said that it's fine, as it's within the parts which have been changed. I honestly think that they dont' know what they are doing. They are just guessing.
It is amazing, and I would probably use a different word as well. I expected it to be sorted by second visit. Anyway, hopefully they'll sort it out soon. Thanks for your help.