Confirmation of Boiler wiring please on Baxi PFL 60

10 Mar 2004
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United Kingdom
I have had a Baxi PFL 60 boiler fitted for the past year (controlled off the original Potterton EP2001 programmer) and have had no end of problems with the boiler going into overheat mode. This new boiler (in the kitchen) replaced an Ideal boiler that never overheated. Various heating engineers (including installer) have been out and changed various components around the heating system as they could not find a fault on the boiler, but to no avail and much cost.

Last two visits were from Baxi (Heateam) and the last engineer stated the pump should be connected directly to the boiler and not run from the programmer, and that that was the fault. So I checked the installation book and found the following (please bear with me):-

1. Boiler should have a permanent live power supply
2. Boiler should have a switched live
3. Pump should be connected to the boiler

After checking the wiring I have found:-

1. The pump is connected to the Honeywell control box in the airing cupboard that also serves the Potterton EP2001 programmer
2. The switched live supply terminal on the boiler is linked from the permanent live supply
3. The 'permanent' live supply is only live when the programmer is live (i.e. within programmed times) so when the programmer timer expires power is lost to the boiler (and the pump stops as this runs via the programmer/Honeywell panel).

Thanks for sticking with me so far. What I am really after is:-

* Confirmation from the above that my boiler has been electrically installed incorrectly, or if the above is a legitimate method of connection (?)
* Can anyone explain what should be connected to which terminal and from where in the programmer/Honeywell box and how this should correlate to the programmer wiring in general (e.g. if the permanent live is just that, where does the single switched live terminal receive its supply from).

Although electrically competent I do not wish to rewire my boiler electrics myself, but would like to know how it should look so I can check the engineer's work after previous visits have proved a waste of time, money and effort.

Can anyone help? Is more information needed?

Many thanks in advance

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Mark sorry to say thats gota be rewired or you hav'nt gota chance
bab said:
Mark sorry to say thats gota be rewired or you hav'nt gota chance
Dont know where u r mate bu i live in baxi land & u can get problems with these over heating after a few years when wired right so this needs sorting out quick.wheres the pump in relation to the boiler.
The boiler is downstairs with the programmer on an adjacent wall, and the pump is upstairs in the airing cupboard with the Honeywell board and three way valve. I believe it will be easier to have the pump moved next to the boiler which is in its own small cupboard, to minimise on disruption in running a cable from the boiler to the pump.

I live in Reading and I cannot believe that not one engineer has noticed that the wiring from installation onwards has been FUBAR. At least I now know what the problem is and since I can tell an engineer what I want him to do I might stand a chance.

Thanks for the replies bab. Can you tell me where the wire to the switched live on boiler should come from? Is it the programmer or the Honeywell box upstairs?

I am hoping the engineer, when I find one, can take the permanent live for the boiler from the controller live feed to minimise disruption to the rest of the house.
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Yes the permanent live can come from the programmer.Yes it would be a good move to fit the pump close to the boiler but the switch live has 2 come from the wiring centre depending on demand from the mid position valve.Are u sure switch live is comming from programmer not up stairs at the moment.
The permanent power feed to the boiler, which is also looped to the switched live connection on the boiler is joined (within a box adjacent to the programmer) to a cable from the programmer. This cable is only live when heat is being called for and the programmer timer is on. This cable has live, neutral and earth to the boiler permanent live terminals, with a loop from the live to the switched live (therefore the whole boiler is switched live).

The programmer is also on all of the time as expected so both permanent live and switched live are available at the programmer. I have not removed the cover from the programmer as it doesn't seem to want to budge and I have not located any latches or screw covers yet.

I assume this wiring is a cannabalisation from the old boiler install which did not require a permanent live feed. I will recheck the cable wiring within the box tonight, and also the wiring centre.

Thanks again for your help with this.
:idea: Had one of these keep doing just that and turned out to be the thermistor was not seated correctly on the flow pipe, it sits on with a spring clip that can be easy to dislodge also it sits behind the overheat stat so it is difficult to see and easy to miss (done that my self)

Even so the pump over run should be wired up correct
mark aint gota chance without a permanent live. no over run at all
Markf, unfortunately you are short of at least one, maybe two cores, between the Honeywell connection box and the boiler. Only you will know how disruptive it could be to run an extra twin & earth cable to provide these, but that's what has to be done.

I'm gobsmacked that it has taken so long for your fitters to have realised this, the lesson is to choose tradesmen wisely. (20-20 hindsight, etc.)

Briefly you should run permanent LNE to the boiler L, N, & E connections from the Honeywell box (fed by 3A BS1362 fuse). The orange wire of the control valve feeds the boiler SL (switched live), and the PUMP L from the boiler feeds (not surprisingly) the pump.

Moving the pump may not be straightforward as you may need to move the vent and cold fill pipes too, cables are more forgiving in that case.
OK, so I took a look at the wiring centre last night. The switched live does come from the wiring centre as you suspected bab and not the programmer. Also a label in the wiring centre states:-

If boiler requires pump overrun Cut link L6 also.

There is then a diagram of the Boiler Connections thus:-

Live - Permanent Live
S/L - Switch Live
N - Neutral
E - Earth
P/L - Pump Live

Bold items are my current connections and I now know they should all be used for the Baxi boiler.

Taking what meldrew's_mate and bab has said I understand what needs to be done, but to cut down on the amount of house upheaval (recently laid carpets upstairs I don't reallt want to lift) could the following work-around be done:-

1. Tap into the permanent live feed going into the programmer to also feed the boiler as the permanent live (so the boiler is effectively permanent fed from the programmer block in the wiring centre).
2. Leave the switched live connected in the wiring centre as it is as this currently connects to the boiler switched live.
3. Diconnect what would now be unused neutral wire from the neutral terminal of the boiler connections in the wiring centre and connect this to the pump live terminal (sheathing with red tape to show it is live not neutral).
4. The other end of the neutral wire in step 3 above would now connect to the live pump terminal on the boiler (nothing connected to the neutral pump terminal on the boiler).
5. Cut Link L6 in the wiring centre for pump overrun.

If 1 to 5 above is acceptable and would work then no carpets or boards need to be lifted as the live feed to the programmer can be cut into from beneath the bath. The wiring centre is currently protected with a 2amp fuse.

I realise that the correct way to do this would be to run a new cable as suggested by meldrew's_mate, but would like to know if the above is OK in case this is what an engineer who comes around will do - bearing in mind the previous visits from engineers, cost, problems, etc.

Any advice on the above from bab, meldrew's_mate, or anyone in the know would be appreciated.

btw, the fitters/installers never found the problem, it was Baxi who noticed the pump not connected to the boiler, and me who noticed the boiler is not on a permanent feed.

It doesn't matter a toss where you physically run your cables or make your connections as far as the boiler operation is concerned, as long as they are in the correct logical places, but you of course have to comply with building, electrical and gas regulations :eek:

The boiler isolation fuse by the way should be 5 Amp - rtfm!
You shouldn't need to know where the wires go, that is up to the installer if he has not wired the boiler correctly he has not upheld his part of the deal, give him money and he installs you a boiler as per manufactures instructions.
Where is the boiler getin a N from at the moment The programmer or wiring centre. Hey Chris did i go asleep & miss the upgrade for htg systems from 3amp too 5amp protection on gas.
Hi bab,

The boiler currently takes all of its power (L N E) from the wiring centre boiler terminals. The boiler terminals used in the wiring centre are S/L N and E.

At the boiler end the cable from the wiring centre goes into L N E, with the L being looped into the S/L terminal on the boiler too. Hence the whole boiler is fed by the S/L and not a permanent live.

gstens baxi, I appreciate where you are coming from, and I do not particularly wish to do this work myself - I am competent with electrics but not IEEE qualified and not in posession of all of the wiring schematics. What I do want to do is check that the work is done correctly this time by the installer with minimal disruption to my house, but with no corners cut - and to do that I really do appreciate the information already provided here.

The boiler has been in for nearly a year now and has always randomly gone into overheat - sometimes nothing for a week or two (once even 4 weeks but that was in summer and the boier hardly used), sometimes like yesterday 3 times a say.I have had four different engineers look at the system including the installer and 2 from Baxi (Heateam). It was only the second Heateam eng that noticed the boiler was not supplying the pump - even he did not notice the boiler was running off a switched live (the previous boiler did not use a pump overrun so the old wiring has been connected to the new boiler). :cry:

I understand what you are saying , but the worst case scenario is that the pump fails to run when the boiler is being called for and the boiler cannot get rid of its heat at all and the heat exchanger splits and floods your house. As i said before it is the responsibility of the installer to install the appliance as per installation instructions , your installer has not done this so has not lived up to his obligation to you.

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