The Netaheat Profile is different from all the preceding Netaheats. So different that I don't really regard it as a Netaheat at all, but it bears the name so I'll include it here! The Netaheat Profile was short-lived model. Not because there was anything wrong with it, quite the opposite, it is an excellent boiler! It was shortlived because they changed its name to plain 'Potterton Profile'.. The 'Netaheat' part of the name being dropped and the boiler went on to sell in tens of thousands as the Potterton Profile. The Netaheat Profile is a complete redesign of the Netaheat from the chassis up. The case is different, the heat exchanger is different, as are the gas valve, control board and burner assembly. A further important difference was the addition of an overheat protection thermostat which makes this boiler suitable for installation is sealed system format, unlike all previous Netaheats. The Profile was never the runaway success that the Netaheat was however, mainly because by now all Potterton's competitors had learned from the Netaheat and developed similar and equally good boilers and the Netaheat Profile was no longer the only candidate in the marketplace for high efficiency wall mounted gas boilers.
Here are the common problems with the Netaheat Profile:
1) Thermostat failure.
The boiler overheat thermostat trips, requiring the user to press the hard-to-find button back in. (It's deep in a hole in the underside of the boiler in case you need to find yours...) When tripped, the boiler simply appears dead. Nothing happens whatsoever. There can be three reasons for it tripping: Failed primary thermostat leading to the boiler genuinely overheating, failed overheat protection thermostat producing false trippings, boiler heat exchanger overheating locally due to accumulation of corrosion deposits. The easiest way to diagnose this is to replace both thermostats together as a first step. If doesn't fix it, I suggest replacing the boiler. The heat exchanger cannot be effectively cleansed in my experience. Powerflushing has minimal effect so a new heat exchanger would seem a good solution, but the heat exchanger is not, and has never been, available as a spare part.
1) Flue Fan Failure
As with all Netaheats, and all fanned flue boilers of any make in fact, failure of the fan is a common fault. Combustion air is drawn by the fan through the combustion chamber so it is a safety-critical component. If the fan fails to start, the safety device which tests to see if the fan is running before allowing the pilot to light will detect the failure and stop the boiler from lighting. To the user the boiler will stay silent (or possibly hum quietly) instead of bursting into life as normal when a demand for heat is turned on. The fan on the Profile is freely available as a spare part and is fairly straightforward to install.
2) Air Pressure Switch failure
The safety device which tests the fan for correct operation is the air pressure switch. These are know to fail occasionally and the result is the fan runs, the boiler sounds for all the world as though it is about to light, but no ignition ever occurs. Secondly, there is a hard-to-find air restrictor inside one of the hoses that feed the air pressure switch and this tends to block. Sometimes all I have to do to fix a Profile is to remove this restrictor and clean out the blocked hole.
3) Control board failure.
Having so many functions, the control board can fail in a variety of different ways. The burners may randomly light and go out, or simply refuse to light. The Pilot may light but the boiler fails to progress to main burner ignition, sometimes with the pilot ignition spark continuing indefinitely. The boiler may also seem to start it's ignition sequence correctly by running the fan, but then shut down and start over again repeatedly and rarely progress to lighting the pilot.
4) Gas Valve failure
The 'combined function gas valve' turns the gas on and off to the pilot light and to the main burner in response to electrical signals from the other controls, and it regulates the gas pressure to the main burner. When they fail the pilot or the main burner fails to light. There were several different gas valves fitted to the various sizes of Profile and all were pretty reliable. The White-Rogers gas valve fitted to most is no longer available.
6) Pilot light failing to light or being very small.
Easily fixed and associated with lack of proper servicing. A problem common to many boilers. The pilot jet has become blocked or partly obstructed with debris and needs poking out with some fusewire. Part of the manufacturer's service procedure!
The Potterton Netaheat Profile is the first and last of of the Netaheat range to feature an overheat protection thermostat as standard. This is to allow it to be connected to a sealed heating system as well as an open vented system. As usual, there is a corresponding drawback! The overheat 'stat is somewhat prone to nuisance tripping and needs to be re-set occasionally. The boiler will appear totally dead and lifeless when the overheat thermostat trips and it is NOT obvious how to re-set it. Nor is it obvious that it exists at all let alone might have tripped. There is a hole about an inch in diameter in the underside of the boiler, and deeply recessed in this hole is the re-set button. Have a grope around the underside of the boiler and find the hole (next to the fixing screw under a hinged cover), and press the recessed button. If it clicks, just the once when you press it, the overheat 'stat was tripped and the boiler will now work. If it won't click then it wasn't tripped in the first place and the fault lies elsewhere.
Now to the causes of the overheat ‘stat tripping. Most common cause is the main boiler temperature control thermostat failing to work. They lose their calibration with age, turning OFF at an ever higher temperature as the years pass. Try just turning yours down to minimum. If this fixes the tripping, the main control thermostat is failing. Second possibility is the main thermostat sensor has come adrift from the pipe it senses. A new clip will be required to fx it back on. Third possibility is the overheat thermostat itself has lost its calibration and now trips at too low a temperature. Quite rare. The forth possibility is the pump over-run thermostat has failed, and when the room thermostat, cylinder thermostat or the programmer turn the boiler OFF, the pump stops too instead of running on to distribute the residual heat contained within the body of the big, heavy cast iron heat exchanger. This makes the heat exchanger overheat and trip the overheat thermostat too. The fifth possibility is the heat exchanger is heavily contaminated with products of corrosion, which insulate the water from the metal of the heat exchanger. This makes the heat exchanger genuinely overheat even though the water is not boiling. For this, power flushing or otherwise cleansing the het exchanger is necessary but unfortunately this is expensive and rarely successful and a new boiler usually ends up being installed.
The Netaheat Profile is generally an easy boiler to diagnose and repair (apart from the heat exchanger contamination problem). Anyone telling you it needs replacing because it's too old to get spares for is sometimes fibbing, in the hope of selling you a whole new boiler....
If you'd like me to fix your Netaheat Profile, contact me here.
First created 7th May 2011
Last updated Wednesday 14th November 2018