Potterton Profile 100e lockout

[cookie72]

Hello

Hope somebody can help with this. Our boiler locks out every morning.

We have had a number of plumbers come by to all claim to fix the problem but none return when it stumps them. This problem has come and gone. We had the system powerflushed on the recommendation that it was a circulation problem and now the boiler cuts out in the morning.

We have had the pump overrun stat replaced, the central themostat and replaced the pump. The boiler will work fine all day but in the morning it cuts out. We leave the boiler on all the time and have a programmable thermostat that drops the temperature to 17c at night. We have not replaced the PCB board because we will be replacing the boiler. But since x-mas is here and the guy who was suppose to replace the boiler went MIA as our early x-mas present any suggestions. Given the snow and below 0c conditions we can't fit a new boiler since we need to have a new flue installed which would involve cutting a hole in the roof. Just trying to get us through the next month and not have to wake up at 4am when the house is freezing. Our system is sealer and pressure is at 1.5bar. We have forced open the CH valve thinking that this might allow the overheat problem to move away from the boiler but to no avail.

We have a hot water tank and the system charges the tank at 630am and 5pm. I have tried to fire the hot water channel thinking that this might be the problem and that works fine.

It seems when the system gets cold it doesn't want to work.

Any suggestions?

Many thanks

 

[twgas]

I assume you have to reset the overheat - the button underneath.
Is there a by-pass fitted? what number is the boiler 'stat on?
What type of valves do you have, in the airing cupboard?
Is the pump wired to the boiler pump live or switched live?

 

[cookie72]

I assume you have to reset the overheat - the button underneath.

Yes

Is there a by-pass fitted?

By pass is fitted and have the fully closed to force water through the system as the CH valve has been locked on open

what number is the boiler 'stat on?

Have had it on 5 during day. Tried lowering to 4 at night to no avail.

What type of valves do you have, in the airing cupboard?

Honeywell.

Is the pump wired to the boiler pump live or switched live?

Pump is wired to the boiler I think.

Thanks for your help.

 

[twgas]

how have you locked the CH valve open?
By central stat do you mean the "boiler control stat" or "overheat 'stat"?
When the room 'stat reduces to the lower setting does the pump continue to run?

 

[cookie72]

Hi Mick

how have you locked the CH valve open?

Our plumber locked the valve in the open position and put a match behind it.

By central stat do you mean the "boiler control stat" or "overheat 'stat"?

Boiler control stat

When the room 'stat reduces to the lower setting does the pump continue to run

When the room stat lowers at night the house is usually at the right temperature and when the boiler shuts off the pump will run for a few minutes and then shut off. We only seem to have the problem when the system starts up in the morning. We are going to replace the system as soon as we can as I have already chucked more good money after bad but just want to get us through the next couple of weeks. Perhaps I'll just leave the bloody thing on all night!

Thanks

 

[twgas]

You need to know what the temperature of the boiler flow is, when the cut-out occurs.can you measure it from the time the room stat reduces until it cuts out.
The overheat wont be cutting out when the system is cold - it is by definition an overheat 'stat.

 

[cookie72]

Aside from standing at the boiler in the wee hours of the morning I don't know when it goes off. I have gone around again and bleed all the rads and did find some air pockets that have moved around the system since being power flushed. I have a laser therm. so I will try to find out return temp and revert. When I say system is cold - I mean the system hasn't fired for a while. Would leave the system off and fire it up in the morning but don't want my pipes to freeze.

 

[Tipper]

Could be the pump failing and if it doesn't pump consistently, ie sometimes does, sometimes doesn't, especially after a rest overnight, then the overheat thermostat will trip.

 

[cookie72]

We replaced the pump last year.

Fingers crossed I think I have found the problem. I opened up the motorised valve on the heating circut and found that the manual override was a bit bent causing the gear to jam. Moreover putting the override in "open" actually didn't do anything. The gears were very gunky. I have cleaned it out with a toothbrush and sprayed some lithium grease to make it operate more smoothly. So I am thinking the valve would get stuck in the morning that would cause the boiler to overheat. I'm also thinking if the boiler was working all day that the valve would stay open and the pump would run given how cold it is. Fingers crossed we won't wake up to a cold house in the morning. Does that make sense? I'm not a heating engineer but it seems logical to me.

Plumber coming by tomorrow and hopefully we get the boiler running until the weather lets up so we can replace the bloody piece of crap. Guy Fawkes day will come early next year.

 

[twgas]

I would suspect the O/H will be activating only a short time after the room stat shuts down.
If the valve fails to open it is unlikely to cause the trip as it would not be turning the boiler on, unless the microswitch in the valve is sticking, in which case the boiler may overheat, especially as you have the by-pass closed at the moment.
I'd hrdly call a profile a cr4p boiler

 

[JohnD]

surely one of the points of a bypass is to prevent overheating? the profile has a big iron exchanger which will hold a lot of heat when it stops firing, and this will be a prob if circulation stops at the same time.