Potterton Profile tripping out occasionally - why?
A number Potterton Profile owners suffer from this irritating problem. The boiler works perfectly for days or weeks then out of the blue it stops dead and sits silently, refusing to respond. The fix is to press the reset button back in, located on the underside of the boiler. Phew!
But the trouble is although this gets the heat back on, it doesn’t fix the reason for the button occasionally popping out in the first place and you just KNOW it will do it again. The real cause is the boiler overheated. The button underneath is an overheat protection thermostat and it pops out when the heat exchanger in the boiler gets dangerously close to boiling. Paradoxically the last thing you want your boiler to do is to actually boil, so the overheat thermostat monitors it 24/7/365 and pops out if it gets too hot.
So the real question that needs answering is why does your Profile get too hot and pop its thermostat once in a while? There are two possibilities. Firstly, the main control thermostat might be failing. This is the temperature control knob on the front of the boiler, bottom right, calibrated 1 to 5. This actually sets the temperature of the water coming from the boiler for circulating around the radiators. It tends to fail by losing its calibration, in such a way as to make the boiler deliver ever hotter water for a given setting. Most people set it on 3 or 4 and if their overheat button starts popping out occasionally, discover they can stop it happening by turning the control down to 2, or perhaps 1. Eventually this stops working and the overheat button still pops out with the temp control set to minimum, and this indicates a new primary control thermostat is needed. I buy them in batches of 10 or 20 so that gives you an idea of how common a fault this is.
A second, more subtle cause can be the pump over-run thermostat. When the boiler is turned off by the room thermostat or programmer, if the gas burner happens to be running then there will be an amount of residual heat in the metal of the cast iron heat exchanger which continues to heat the water for a minute or two after the gas burner shuts off. To prevent the water in the heat exchanger stopping flowing and actually boiling due to this effect, the circulating pump needs to continue to run for a few minutes after the boiler turns OFF. To achieve this, the pump is powered by a “pump over-run thermostat’ inside the Profile boiler. This keeps the pump running until the heat exchanger cools to a set temperature. I don’t know what it is exactly but probably 80c. As you can probably imagine, for the boiler to run the pump there needs to be a mains power supply into the boiler, even when it is set to OFF. This is called the “permanent mains supply”.
Now a problem arises if a plumber, electrician or whoever doesn’t understand this and decides to leave out (or worse, disconnect) the permanent mains supply. It really isn’t obvious why it is present in the first place just by looking at the boiler, so this happens from time to time. The net result is when the boiler is turned OFF by the room thermostat or programmer while the main burner happens to be running, AND the boiler is approaching set temperature too, the pump over-run will not operate and the boiler will momentarily boil, tripping the overheat thermostat. If the extra permanent live cable connection is missing from the boiler terminal connection block, then this is quite likely to be the cause of the overheat button popping out occasionally. Or more subtly, I’ve seen the permanent live wiring present and connected but not actually still live when the boiler is OFF. This too will cause the overheat button to pop out. The fix is, naturally, to install the permanent live supply permanently as the manufacturer intended…
I’ve written more about the Potterton Netaheat Profile on my Netaheat Repairs website, here:
https://netaheat-repairs.co.uk/potterton-netaheat-profile-boiler.html
If you’d like your Profile fixed, text or call me on 07866 766364
Neta heat profile keeps tripping out having to push reset button to enable to have a bath etc. Will not stay on certainly wont be able to have heating on later in season. Has been amazingly reliable up to now. Living in Fareham Hampshire my son read your reviews said to contact as he has a lot of faith in her still before i result to having a new boiler as have been advised. Hope to hear from you soon. Sounds like you are very busy fingers crossed.
Hello Janis,
This is a common fault on your boiler and usually failure of the control thermostat – easily fixed! I’ve just seen your text too so I’ve replied to that with costs to fix it. Let me know if you’d like to book a visit. Kind regards, Mike
Hi Mike
My Potterton Profile 80e boiler has failed to fire up after the electricity got cut 3-4 times due to high winds. This had happened a few months ago but fired up after switching off and oning the thermostat. Now, it fails to fire up on doing the same. The engineer changed the heating pump, not sure why? and when switched on my house electric socket switchs were tripping every time when attempting to turn on the heating pump. The engineer says he is not sure why the home sockets are tripping and suggested changing the PCB(£300). Please can you advice.
Many thanks
Surren
Hi Mike, I have a problem with my Potterton Profile boiler. We had been away for a few days (boiler working fine before we left) and when we switched the hot water on when we got back the boiler did not come on at all. Timer/pump and diverter valve working but boiler not firing/no fan etc. I had a look at the control board and noticed the fuse looked black so changed it and the boiler fired straight up – great I thought. However, after and hour no pipes were getting hot and the air from the flue was not hot like it usually is. Any idea what else is wrong? It only looks like a low flame through the little window so I guess it’s something to do with that but don’t know how to rectify this. Thanks in advance for any advice/help. Regards, Simon.
Hi Simon, the fuse usually blows when the flue fan fails, although in this case the fan seems to be working again after replacement of the fuse. This suggests to me the main burner solenoid coil on thw gas valve has failed. Check it by measuring the resistance. It should be approx 4kOhms but if it is open circuit or a short circuit, this will be the problem and a new solenoid coil will fix it. Hope that helps, Mike
Brilliant help. Thanks so much. Wife nailed through a pipe. Got it fixed but boiler wasn’t firing up. Found the reset button thanks to you and its all good.
Hi Simon, I am trying to find out where to connect the Brown Wire from the Overheat Thermostat reset button as it came off from its location.
I have see the wiring diagram where one side is connected to the Electronic Control but I cannot find what the Electronic control looks like.
Hi Derek,
The electronic control means the PCB, I reckon.
The brown wire FROM the pcb connects onto the overheat ‘stat….
Hi Mike
My Potterton Profile 80e boiler has failed to fire up after the electricity got cut 3-4 times due to high winds. This had happened a few months ago but fired up after switching off and oning the thermostat. Now, it fails to fire up on doing the same. The engineer changed the heating pump, not sure why? and when switched on my house electric socket switchs were tripping every time when attempting to turn on the heating pump. The engineer says he is not sure why the home sockets are tripping and suggested changing the PCB(£300). Please can you advice.
Many thanks
Surren