Baxi Heat Only wiring - another dilema :(

[Robert Tyrrell]

Good morning guys and gals
Yesterday, I went to replace an old Sime heat only boiler with a new BAXI, and didn't notice that the wiring was something that I hadn't come across before so I'm looking for a little advice on what to do.
This is being done for a relative so I'm not charging the going rate and need to get done as fast as I can so that they have heating.

The problem is, as you will see from the photo, that I don't just have LNE connections. I also have what looks to be a live to the pump, and a 'heat demand' connection.
I understand what each does but what I don't understand is how?

I am presuming that the brown live wire is a switched live from the programmer via the junction box (Which is a complete mess and looks like spaghetti junction) , but what do I do about the live to the pump, and heat demand?


My thinking is this:
The programmer sends power on the live (protected by the F2A fuse in the photo) of the boiler so that it fires, but it also sends power via the 'Heat demand' to the pump live.

The whole thing is protected by a double pole fused spur with a 3 amp fuse but it's upstairs in the airing cupboard next to the 'Spaghetti box'.

AHA

 

[Last Plumber]

Live neutral and earth are normally brown blue and green
Heat demand is your switched live that brings boiler on and the pump is obvious.
The brown should be your permanent live which is used for pump over run and fan ( if it's got one).
Is that what you wanted to know

 

[Gasmk1]

get a timeguard wiring centre and follow wiring very easy to do and large enough to make the wiring nea thttps://www.tlc-direct.co.uk/Images/Products/size_3/SMTRT049A.JPG

 

[Robert Tyrrell]

Gasmk1
Thanks for the reply, and I'll look into that for the future.
The problem with this is that I can't spend any cash on the job as they don't have it so I'm just trying to sort it with the minimum of alteration and expenditure

 

[Last Plumber]

Just make sure that when you connect that switched live to the new Baxi, that the terminal is for 240V ( I've not fitted Baxi for ages so not seen current wiring, Vaillant have a few options inside for voltage and control ). That's presuming the Switched live is 240V of course.

 

[Robert Tyrrell]

Live neutral and earth are normally brown blue and green
Heat demand is your switched live that brings boiler on and the pump is obvious.
The brown should be your permanent live which is used for pump over run and fan ( if it's got one).
Is that what you wanted to know

The Baxi Heat only boilers don't have a pump over run and they state that the live to the boiler should be connected to the switched live from the programmer.

LNE - Brown blue and green? Yes I did know this already but thanks anyway

If you look you can see that it's a 5 core cable with two blacks and I wondered how the pump got it's live from there as it looked just like a connector block to me, with no obvious links.
The pump is upstairs in the airing cupboard and the boiler downstairs in the utility room.

Anyway - If I link the pump to the heat demand, in the junction box, connect the heat demand to the boiler live, and connect up the N & E, it should all work shouldn't it?

 

[Robert Tyrrell]

get a timeguard wiring centre and follow wiring very easy to do and large enough to make the wiring nea thttps://www.tlc-direct.co.uk/Images/Products/size_3/SMTRT049A.JPG

Just looked at that and it certainly looks complicated to me. I usually just stick to the old Honeywell 10 way junction box and use their wiring plans as they seem pretty straight forward and easy for my simple thought processes

 

[Last Plumber]

The Baxi Heat only boilers don't have a pump over run and they state that the live to the boiler should be connected to the switched live from the programmer.

LNE - Brown blue and green? Yes I did know this already but thanks anyway

If you look you can see that it's a 5 core cable with two blacks and I wondered how the pump got it's live from there as it looked just like a connector block to me, with no obvious links.
The pump is upstairs in the airing cupboard and the boiler downstairs in the utility room.

Anyway - If I link the pump to the heat demand, in the junction box, connect the heat demand to the boiler live, and connect up the N & E, it should all work shouldn't it?

Yes Robert, just looked at Eco blu wiring ( don't know if that's your boiler ) and it does look like it is wired the same way as people did it many many moons ago, very strange !

You're quite correct Sir, if you connect the two blacks and link those to the SL in the boiler, connect N and E and put permanent live somewhere safe, you've cracked it.

( obviously I don't know which boiler you are using and haven't seen the job and I do apologise for the LNE brown blue green issue thing)

 

[Gasmk1]

Just looked at that and it certainly looks complicated to me. I usually just stick to the old Honeywell 10 way junction box and use their wiring plans as they seem pretty straight forward and easy for my simple thought processes

its simple as the instructions are with the box no trying to cram 3 or 4 neutrals into 1 connection same for the earths

 

[ShaunCorbs]

You sorted it now robert ?