Back boilers

[daiplayer]

Hi all

I been called to a property where somebody had broken the central heating programmer.
The customer has bought one ( horstmann 2 channel) and asked me to wire it.

The point that was there before has long gone and only has the wires remaining. L ,N , + two others.

The property has a back boiler.

Im not too clued up with these ( hence the training course coming up in feb.
Now L+N ....easy.

buy what of the other two ? i thought since it being a two channel prog.. one out would be SWL for the CH on . plus SWL for HW on ?

is this correct for a back boiler ? as i tried this but to no avail. however when the live is linked with both outgoing SWL's the boiler fires up ?
correct programmer ?

any help is always apprieciated :_D

 

[keniff]

Is there a junction box you can trace back to then see what core does what valve?

 

[daiplayer]

No , tbh i havent really got a clue.
i just assumed they were changing like for like.
:-( im confused

Is it right that a back boiler will be a two channel then ?

 

[daiplayer]

View attachment 16991this is the programmer connections. i connected live , n....
One swl to number 1
one switch live to number 4 .
when it didnt work , i switched the SWL's over .

It was working before the programmer broke so i cant see any other problems happening with it :_(((((

thought :- see the dotted lines in this diagram ? do i have to place a link in this myself ?

 

[TAZ]

Do you know if it is gravity hot water pumped central heating or fully pumped?

 

[keniff]

I can't see your attachments but sometimes you have to put a link in the programmer especially if its volt free, last one I did had 2 valves just like a normal boiler setup

 

[daiplayer]

Do you know if it is gravity hot water pumped central heating or fully pumped?

I have no idea ..... how do i find out/ check this ?

 

[daiplayer]

basically it shows a dotted line between the live terminal , and the ( on a 2 way switch ) , would be the common for the HW on.
same as the CH on . i assumed this connection was internal but now im thinking it has to be done myself.

I have no access to the switch live conductors when the prog is fitted :-/

 

[daiplayer]

im gunna try and link it i think. see what happens , hope i dont blow up a £55 programmer though , lol :-D

 

[TAZ]

Are there any motorised valves cyl stat etc in the airing cupboard. Quite often if it is gravity hot water, the pump was usually near to the boiler & was switched on by using the ch switch on the timer to switch the pump on, the HW had to be on as this provided the switchline to fire the boiler up. The only control on gravity was either an old mechanical cyltrol valve on the return pipe or a tapstat on the flow to the cylinder

 

[daiplayer]

Are there any motorised valves cyl stat etc in the airing cupboard. Quite often if it is gravity hot water, the pump was usually near to the boiler & was switched on by using the ch switch on the timer to switch the pump on, the HW had to be on as this provided the switchline to fire the boiler up. The only control on gravity was either an old mechanical cyltrol valve on the return pipe or a tapstat on the flow to the cylinder

sorry if im talking like a plank but i havent a clue....lol

 

[daiplayer]

cant wait for my central heating course as this area is perplexing me at the mo.
any good sites / books i can look through ? :-/

 

[TAZ]

Having been corgi registered in the past & plumbing for 25 years plus electrical i often get called in to sort out central heating problems i guess if you know how a system works it makes fault finding so much easier. I am sure Honeywell used to do training courses for this i believe.

 

[daiplayer]

Yeah im due to attend this course 12 feb

 

[Guest111]

yes you do have to put a link in,one live will feed the boiler and the other the pump.You will probably find its pumped heating and gravity hot water so when the boiler fires on water only it energises the boiler,on water and heating it also energises the pump,there is usually a way to interlock the water and heating switches so that when you select heating it turns the water on as well,we had this system many years ago,hope this helps you.