Central heating systems

[KNIPEX]

HI guys, i will be quite honest im not that good on wiring central heating systems proberly as i have done very little with it.

went to a job today where there was a problem, when you switch the water on the heating comes on aswell, even though there are seperate switches on the controller for this.

by turning the stat down the heating stays on.

any ideas what this could be, its a new house and has always had this problem, however with no wiring diagrams or anything im finding rather hard to find out whats going on.

any help or diagrams would be great.

thanks in advance.

 

[bugsy]

signal cable to the valves sound like they are linked , or the terminals are linked in the programmer .
what type of system is it

 

[GT1]

3 port valve could be u/s too and not operating properly..

have you found the wiring centre..?

 

[bugsy]

Lenny has posted various central heating schematics on sticky links thread, might be worth having a look and downloading them

 

[Guest123]

Need a bit more info mate......S plan, Y plan etc.

2 port/3 port valves etc, cylinder stat, roomstat???

 

[KNIPEX]

Need a bit more info mate......S plan, Y plan etc.

2 port/3 port valves etc, cylinder stat, roomstat???

i dont know mate if its s plan y plan sorry, what does this mean??

has a 2 port valve but ive been informed its been changed, does have a cylinder its not a combi boilor and has a roomstat aswell.

also a couple of pumps attached to the pipes also.

 

[Deleted member 9648]

Mate it really isnt to hard if you understand how it works.
The programmer htg on output supplies the room stat.The switched side of the roomstat will open a motorised valve which will allow water to flow through the heating circuit. The same applies to the hot water output from the programmer,through the cylinder stat to open a valve.
On some systems there are two valves,one for hot water and one for heating,this is an S plan. On others there is only one valve,a 3 port 'diverter' valve which sends the water either down the htg or h/w pipes or both depending on what is calling for heat.This is a Y plan.
Inside the valve(s) is a microswitch connected to a permanant live and when the valve opens this switch closes to start the pump and boiler.
I'ts just a series of switches which will start the pump and boiler and send the heat down the right pipe.
Armed with this info and wiring diagrams fault finding is fairly straight forward.
A non electrical issue which can cause the symptoms you have is a faulty valve body....the wet part of the valve...a duff one can allow water to leak past into the circuit which should be closed off. If all the electrical gear is operating correctly this could be the problem.

 

[Guest123]

i dont know mate if its s plan y plan sorry, what does this mean??

has a 2 port valve but ive been informed its been changed, does have a cylinder its not a combi boilor and has a roomstat aswell.

also a couple of pumps attached to the pipes also.

If the zone valve has just been changed then this has to be the place to start. Generally accepted practice is as follows...

Grey - permanent live

Brown - switched live in from stat

Orange - switched live out to pump/boiler

 

[bugsy]

I think he needs a bit more than that Lenny , Where are your CH posts , might be an idea to send him a link

 

[Guest123]

Here they are.

http://www.electriciansforums.net/e...cal-forum/11718-central-heating-diagrams.html

 

[gaffer]

What type of programmer have you got?.The Towerchron QE2 has an internal link that had me scratching my head for ages,could be CH and HW are reversed.
Also as Lenny says check connections at the valve,if you tell us the type of valve might be able to help a bit more.

 

[bugsy]

Knipex is now playing a game of seek and ye shall find ( I hope )

 

[KNIPEX]

thanks guys im going bk there next week so will report back.

 

[pmac10]

some dual channel Hortsmann controllers also have an internal link which may have to be removed dependant on the heating system to which it is fitted