My Potterton Profile 80e often doesn't start up

[NZH]

My Potterton Provile 80e gas central heating and hot water boiler often won't fire up on its own .

We tend to have the Honeywell timer control set to Continuous in winter, and run the hall thermostat at 20degress, and turn it down when we go to bed to about 16 degrees; until a couple of weeks ago, the boiler would turn itself off and on, as it should, but recently it stopped firing up during the night, with the reseult that the house was cold when we got up at around 7 a.m. The hot water timer is set to come on at 0630, and this also isn't working.

The boiler starts when I press the reset/manual startup (?) button underneath it, and generally works and gets the heating up to temperature, but once it's got there (and it doesn't get there every time), it often won't start up again on its own, when the temperature drops below the 20 degrees (or 16 at night). Hot water is fine too when I do a manual start up.

Initially I thought it might be an overheat problem, we found some coolspots on some radiators and have flushed and balanced the rads, so that when the boiler is working, the rads are ok. But I don't think it can be an overheating problem as the boiler fails to start at night or during the day when the room temperature drops below the temp set on the hall thermostat, and its clear that the boiler hasn't run for hours overnight - probably since turning the hall stat down from 20 to 16.

The fan at the top of the boiler was replaced in October 2009.

Anyone got any ideas please?

Many thanks in advance - Neil

 

[seco services]

is it having to be reset everytime ?

 

[combispecialist]

That reset button is the over heat stat tripping so its overheating for some reason and can do this for many reasons.is the bypass open??the boiler stat should never b on max cos they had problems wiv o-heating wen on max,is pump over run working?is there still sludge in system?first u need to check bypass and turn stat down to 4-5

 

[NZH]

Some more detail about the symptoms of my Potterton Profile 80e problem:

The temperature in the house has dropped, radiators are cool/cold, hall thermostat is set to 20 degrees where it has been all day.

If I turn the hall thermostat downwards to see at which temperature it clicks - it's at about 18 degrees. Turning it back up to 20 doesn't cause the boiler to fire up.

The Grundfos Selectric pump in the immersion cupboard below the Honeywell V4073 Mid Position Diverter Valve is running, and I can hear/feel water passing through it.

The boiler outer casing is cold, so hasn't been on for some time, there is a little gurgling inside the boiler - sounds like water falling down.

The thermostat on the boiler is set to 4, which is where it normally is.

The Honeywell Timer/control unit next to the boiler has CH = Cont; HW = Auto (due to come on in 10 minutes time at 4:15pm).

The reset/manual button underneath the boiler is "out", so able to be depressed to manually fire up the boiler.

The boiler has started up now that I've pressed the manual button underneath it. I predict a cold waking up in the morning.

The system was power flushed by a plumber two days ago.

Not sure what else I can tell you experts out there..........

 

[seco services]

was it power flushed properly ? don't sound like it. its overheating and tripping.

 

[NZH]

is it having to be reset everytime ?

that's the bizarre thing, it doesn't have to be reset every time, a couple of days last week it seemed to run fine (before the power flushing)

 

[NZH]

was it power flushed properly ? don't sound like it. its overheating and tripping.

I think so, it took all of Friday, and the pump was removed and a unit larger thatn a Henry vacuum cleaner was put in its place, fresh clean mains water was pumped in, old sludgy water pumped out, inhibitor left in system afterwards. Rads balanced.

 

[NZH]

That reset button is the over heat stat tripping so its overheating for some reason and can do this for many reasons.is the bypass open??the boiler stat should never b on max cos they had problems wiv o-heating wen on max,is pump over run working?is there still sludge in system?first u need to check bypass and turn stat down to 4-5

combispecialist,
Not sure where the bypass is to check if it's open.
Boiler stat never on max, always on 4
How do I check if pump overrun is working?
Sludge should have been removed during all day power flush on Friday.

 

[NZH]

It's now 4:25pm, about 10 minutes since I pressed reset button, boiler casing is hot and boiler has gone out. Rads coming warm now.

 

[seco services]

what tripped again ?

 

[NZH]

what tripped again ?

It stopped running, not sure if that was a trip or if the boiler reckoned it had done it's job.
Checked the reset button to see if it was in or out, it was out, and I've pressed it and restarted the boiler. Time now 1632 according to my PC clock.

 

[NZH]

OK 1647hrs, just noticed that boiler has stopped again, boiler casing is hot, manual button is out..

Hall thermostat still set to 20, but when I turn it downwards it clicks at 19 degrees.

 

[seco services]

what does the boiler stat click at ?

 

[NZH]

what does the boiler stat click at ?

Almost at zero; below 1 there is a sort of arrowhead that decreases in size to a point in an anticlockwise direction, and the click is when I'm almost at the pointy bit.

There is no click if I move the boiler stat up to Max.

 

[combispecialist]

wot u need 2 do is get the boiler working by pressing the rest button,stand and waite while its running,is there any gurglying noises??if so it may be air in system causing boiler to overheat??does the flow pipe get red hot after being on for only 20-30 secs???if so this would suggest circulation or pump issue???if the system was really sludged up did the plumber replace ne pipework in airing cupboard i.e air sep or h section????if he didnt then that could be cause as flush wont completly unblock a badly restricted air sep.only other thing is if the flow pipe isnt red hot and the over heat is still tripping then its a faulty o-heat stat.hope this helps u