Potterton Profile 60e Air Pressure Switch Faulty

[Razoo]

My Potterton Profile 60e has stopped working. There is no pilot light or ignition cycle.

I have established that the air pressure switch is not operating, although the fan is running normally. If I simulate the operation of the air pressure switch, the boiler ignites correctly.

I have checked the flexible tubes to the air pressure switch and they appear OK with no obvious splits or leaks. The in-line restrictor (pneumatic inductor) is not blocked. The mechanical operation of the air pressure switch itself does seem to be a bit hesitant and 'sticky'.

I intend to replace the air pressure switch and also the two flexible pipes. The existing air pressure switch (which itself might already be a replacement) doesn't look exactly like the pictures of the alleged correct pressure switch on the Internet. The microswitch is orientated differently - mine has the terminals at 12 O'clock when the pressure switch is mounted (mounting screws at 9 O'clock, pneumatic connections at 3 O'clock). More significantly, the existing (faulty) air pressure switch is rated 0.7mbar, whilst the replacement air pressure switch I've been offered is rated 0.35mbar.

Can anyone tell me the correct pressure rating and part number for a Potterton Profile 60e air pressure switch?

Is there anything else I should check on the boiler?

Thanks,

Razoo

[Roger Chapman]

My parts list which dates from about 1990 has:

Pressure switch - Honeywell C6065A1192 P.I.L. Part No 642220 G.C. Part No 378036

No idea what the rating is. I bought one last year for my boiler but memory being is I can't remember what I did with the old one which was apparently not faulty. I think I trimmed the ends of the pipe to get a good seal.

FWIW I got my bits from keeptheheaton.com and would use them again if more parts are needed.

Not that I can think of atm but with a memory like mine that is not to say there isn't. We had a thread going last year (or possibly a bit earlier) when I was trying to sort out my boiler. There might be something useful in that if you can find it with such a vague direction.

[Roger Chapman]

snip

The problem solving chart suggests you are on the right lines unless there are sparks occurring elsewhere. Only only other check is is there

240 volts between T2 and T4 on the electronic control. If the answer is yes you need to replace the electronic control.

[geoff]

In message , Razoo writes

There are different makes and models of APSs. Phone up a central heating merchant and ask, they should know.

The pressure rating is set for a particular boiler, you can't just put a different one in You should not adjust the pressure rating of the APS unless you really do know what you are doing. From the questions you are asking and the way you are approaching the problem I don't think that you do

Just in case you are unclear as to what I am saying, don't put an incorrect APS in and try to adjust the pressure. That you ask says to me that you have moved outside your competence zone into potentially dangerous territory

You don't say what you have done to check the APS, so here we go, from the start to check out your APS

First easy check is to (gently) suck or blow (depending on which tube) down one of the tubes to the APS and see if that causes the boiler to fire up. If it does, then the fan is not causing the APS to transfer (which may or may not be a fan problem - could be a blockage or something somewhere

Now to check the APS itself. Power down the boiler and take the molex connector off the pcb (always measure from the pcb , then you are testing the loom as well) Zero the probes of your multimeter by touching them together and registering the resistance. Check the Normally closed to common resistance of the APS at the molex connector, it should not be more than a couple of ohms (the connections are stamped on the microswitch)

Now, suck or blow on one of the tubes to operate the APS and kink the tube so that the air cannot escape - this a - checks for a rupture in the diaphragm and b - makes it easier to check the normally open to common resistance which should also be a couple of ohms or less

[Tommy]

have you checked to see if the overheat stat has tripped?.... its on the underside of the boiler covered by an obvious plastic flap!

[geoff]

If it had, the fan would not be running, would it ?

[Tommy]

second thoughts

Sounds like the dps venturi may be restricted or a flue problem, check the flue terminal could be overgrown plants if not get the boiler serviced.

[geoff]

Shall we try and solve this in a logical manner ...

or like a headless chicken

Please leave this to me, I'm fairly good at this

[Tommy]

Its all yours chicken

[geoff]

Good - f*ck off then

[Roger Chapman]

Not on my Profile. The only thing under an obvious plastic flap is the securing screw for the removable base. Vision of the OP opening a flap and having endless trouble trying to press up a solid steel screw. :-)

[Razoo]

Yes, they should.... unless you get spotty yoof on work experience.

Agreed, and that's exactly my point! I had searched for a replacement APS on the Web and noticed that the ones offered as correct for my Potterton Profile 60e were rated 0.35mbar. The one I had removed was rated 0.7mbar. Obviously one had to be the wrong rating - but which one? The Potterton documentation is very basic with no real technical content, so that's why I asked the question on this ng.

A visit to Interpart yesterday established that the correct APS rating is

0.35mbar, which means the wrong APS had been fitted previously (not by me, because all work up until now had been carried out under a maintenance contract).

I do have the facilities at work to calibrate these pressure switches, but I see no need to at the moment.

Well thanks for the vote of confidence!

Obviously not, hence my question to establish what the correct APS rating should be.

Not so! I was trying to avoid *exactly* that error by establishing first what the correct APS rating should be.

Yes, I did all those checks and the APS was operating correctly, although as I said in my op, the mechanical operation of the air pressure switch itself did seem to be a bit hesitant and 'sticky'.

However, all this is irrelevant as I have now established that the existing APS (0.7mbar) is the wrong rating for the boiler. I have therefore purchased a new APS of the correct rating (0.35mbar, Part No. 642223).

Rather annoyingly, Interpart could not supply new flexible tubes, so I've now got a new APS, mounting bracket, screws and anti-kink springs - and no new tubes!

I fitted the new APS yesterday evening, but still have a problem - see my latest post. in this thread.

Thanks for your detailed input.

[Razoo]

I have replaced the incorrect 0.7mbar APS with a new 0.35mbar APS.

Although the fan runs, the APS is still not switching over.

The APS sensing tubes and the flue are completely clear, and gently sucking on the LP tube causes the APS to change state.

I cannot find any air leaks in the APS sensing tubes (although I am going to test for leaks again tonight, just to be sure).

The boiler cover seals are in good condition.

I'm now wondering if the fan, although running, might not be running at its normal rate. It seems to be running OK, but I have no benchmark to compare it with.

Is the performance of these fans prone to dropping off?

Is there anything else that may affect operation of the APS?

Thanks,

[Razoo]

Thanks Roger - the APS I have just bought is Part No. 642223 (0.35mbar)

[Razoo]

The reset was checked early on and it isn't tripped.

[Roger Chapman]

Says 642220 above, not 642223. Are you sure you have the right pressure switch?

[Razoo]

I'm as sure as I can be in the absence of any useful technical information from Potterton.

Interparts checked on their database and in a manual and confirmed Part No.

642223 as correct.

I researched the APS from two online suppliers and they were both offering the 642223, 0.35mbar APS as the correct unit for Potterton Profile 60e.

Finally, an eBay seller is also offering this same APS for the 60e.

If it's not right, a lot of people have got it wrong!

[Heliotrope Smith]

Part no 642220 is for Profile Prima 60e Gc no 41 605 73

You do have a Profile 60e Gc no 41 605 42?

[Razoo]

Yes, Profile 60e (not Prima), GC No. 41-605-42

[Roger Chapman]

In which case I may have inadvertently tried to mislead you, sorry for that. I have a Profile Prima but I have always understood, perhaps incorrectly, that they were essentially the same boiler, the difference being the presence or absence of separate connections for the domestic hot water circuit.

The sales leaflet I obtained prior to purchase was for "The Profile Range". I had temporarily at least forgotten that when I went out to buy my boiler back in 1991 I was persuaded that I didn't need separate connections for the DHW as I was planning on a fully pumped system unlike the then existing system with gravity DHW.

Incidentally I have now found the possibly defunct pressure switch I replaced last year. The label says P = 0.4mbar Max. 6mbar.