need help wiring cyl thermostat, pump & motorized valve

[jules1969]

Hi, I tried to replace our faulty danfoss motorized valve today with an identical unit but got into problems with the wiring....

I'm struggling in particular to work out the wiring from the cylinder thermostat. There are two black wires which are wound together at the end and come from the same terminal inside the stat, plus an earth, a blue & brown. The two black wires have become detached from the 'main loom' where the pump & motorized valve etc are all connected. What do I connect these black wires back to? The stat is a danfoss AT model, cant seem to get any clear info from their website.

We now have no CH or HW due to my stupidity!

regards,

Jules

 

[Breesey]

Sounds like a bit of a horses that you should get an electrician to look at. No disrespect but you are clearly not cut out for the job

 

[gas4you]

Go to the Honeywell website and search for 'Y' plan wiring diagram.

 

[jules1969]

You are right, I'm not qualified but I'm desperate! The problem to be honest is the poor wiring carried out in the first place, no proper wiring box was used so it is really hard to see what is what, wires were just crammed into a connector strip.

cheers, jules

 

[ChrisR]

It's hard to find :

http://content.honeywell.com/uk/homes/Catalogue/Sundial%20Plans/3.4%20Y%20Plan.pdf

Much easier to descramble a rats nest if you have a continuity tester (beeper) such as you'd get on a multimeter. Less than a tenner..

 

[MANDATE]

I think it would be easier for you if you understood how the cylinder stat works. It is basically a switch but instead of having two terminals it should have three, all of which are used in conjunction with a motorised valve.
It is the same as a two way switch. ie one wire comes to the switch but there are two wires leaving the switch. The one coming in, comes from the programmer HW ON terminal. This is easy to test, if live when on and dead when off.
One of the wires leaving the stat goes to the boiler to operate it when HW is demanded. When the cylinder is hot enough (satisfied) power is diverted to the third terminal. A wire goes from this terminal to join up the grey wire of the motorised valve. So that accounts for three wires.
The power to the grey is needed to operate the MV and light the boiler when using CH. Now if HW is not on then theres nothing going in or out of the cylinder stat, To cater for this there is a HW OFF terminal on the programmer and a wire is fed from this terminal also to join up with the grey wire. Normally the joint would be in the terminal box, but it could just as easily be connected to the third terminal at the stat.
So that would account for another wire and I would think your two blacks from the stat are the those just mentioned. (one from programmer and one to grey wire on motorised valve) Again easy to test
The brown or the blue will come from the HW ON terminal at programmer and the one remaining would go to the boiler.
Now normally a blue wire would indicate a neutral wire and if it's being used as a 'live' it should have a red sleeve on it.
Have a look at the orange wire from the MV because this connects to the same wire to light boiler. ( it will be the red or blue).
Once you're clear where these wires are coming from and going to, you just have to indentify which terminal is which on the stat.
As suggested study the wiring on the honeywell site.
Hope it helps, obviously when you know how it all functions it is a lot easier to see where wires should go.