CH Danfoss timer wiring

[newbuild100]

Long story. Im about to do a bit of work on my hot water system at home. The system whilst old, works fine but im about to replace a gate valve (to the rads) with a electrically operated valve. (If I want hot water to the rads, I simply open the gate valve which allows hot water to the CH system) There is a danfoss 715 timer installed to fire up the pump/boiler. Gloworm boiler and fully pumped sysytem by the way

Im confident of doing the pipework but ill be unsure about the wiring in the timer, when I come to wire up the new valve.
Ive made drawings of the present wiring in the timer, and have pictures.
Theres three lots of wires at present by the way, (boiler wire) (wire from a wall socket to fire the timer itself,) (and a wire to the pump)

Can anyone help re which wire (on the new valve) should go where in the timer please ??????

Much obliged

 

[stem]

If you are using a standard motorised valve, the brown wire, that when live, will open the valve. That will need a live supply from the timer.

The Danfoss 715 comes in single and dual channel versions which have different connections. If I had to guess I would imagine you have a dual channel as I assume you are wanting to have separate time control of the central heating. If you do have the dual channel version, the terminal that supplies the motorised valve is terminal 4 marked 'heating on'

You will also need a neutral and possibly (depending upon the manufacturer) an earth connection to the valve.

The grey and orange wires from the motorised valve are there for switching / isolation purposes when used in conjunction with an 'S Plan' installation, with motorised valves for both the heating and hot water. But they are not necessary for what you want to do.

It would be a good idea to incorporate a room thermostat in the wiring to the valve at the same time that way you can have increased comfort and save energy.

I am a bit confused when you say

Im about to do a bit of work on my hot water system at home.

and then describe modifying the valve to the heating, with no mention of the hot water side of the installation, so I hope I have understood correctly what you want to do.

Ive made drawings of the present wiring in the timer, and have pictures.

It might have been useful if you had included them in your post so we can see them.

 

[newbuild100]

Sorry about that confusion. When I said hot water system, I meant the whole system generally. As per my original post, the whole system works well enough BUT went I want hot water to the radiators, I have to turn the gate valve on, allowing hot water to the rads. Obviously, this is mainly in the colder months.
In spring time, I will generally close the valve. If I then put the boiler on, I will only get hot water to the hot taps.

The danfoss timer is (I'm sure) dual version. ie I will be able to have just hot water (to taps)............. OR hot water to taps AND the radiators. All timed of course.
Thus, my original post. I want to wire up (when installed) the motorised valve to open/close when I want hot radiators.
Your answer had given me ideas and tomorrow I will look at the sketches/ photos of the present timer wiring and go from there.

I'm sure once I've done it, it will appear very straight forward.!!!!

Meanwhile, any other input would be great.
Thank you so far

MS

 

[stem]

Thanks, I thought that may be what you meant, but it's best to be clear.

 

[newbuild100]

Here goes then. Included are some pictures of what ive got and a small wiring diagram of the timer from the danfoss brochure. Whilst the timer works for the system as it is, once I wire up the new valve, I think it may need altering slightly (??????!!) If I can explain more about the wiringat present. Theres the cable coming into the timer to actually power the timer itself. (brown to live/blue to neutral/yellow to earth)
The cable to the boiler . . . .(yellow to earth/blue to neutral/brown to terminal 4). The cable to the pump. . . .(red to terminal 4/green to earth/black to neutral)

When the timer and new valve are wired up corrctly, should the brown and red (boiler wire and pump wires to terminal 4) be switched to terminal 3 ? (ie to fire up "On DHW"), and then use terminal 4 to fire up the valve im putting, ie, to open said valve. (Even if im right, and theres four wires on the new valve, my loose theory doesnt tell me where any of those 4 wires go in the timer ???????!

I hope that helps a bit folks

 

[stem]

You are on the right lines. Here is a diagram of what you are trying to achieve. (The earths are omitted for clarity) With it wired like this, the pump and boiler will run when the hot water is switched 'on' The motorised valve will only open when central heating is switched 'on' I have shown a room thermostat in the circuit, because it would be so easy to add and worthwhile. Just leave it out if you don't want it, the wiring is the same.

You don't need to use the orange and grey wires at the motorised valve, they are for an S Plan system.

You may find it difficult to get 4 wires in one terminal at the programmer, so you may have to join two or more of them together in a separate screw connector along with a single wire to go to the programmer terminal.

The downside of this arrangement is that you cannot have the heating on alone, you must also have the hot water on too, otherwise the boiler & pump will not operate. If you set the programmer to 'gravity' the hot water is automatically selected 'on' for you when the heating is set to be 'on'.

If you were to add a second motorised valve to your hot water system and a cylinder thermostat, you would have what is known as an S Plan this would allow you to have independent control of both hot water and heating. The wiring would be considerably more complicated though.

 

[newbuild100]

Excellent, Thats pretty much perfect and just what im after. What though, do I do with the two wires that wont be used ? Do i use some kind of "end stop" and tuck them away somewhere ?? (the red and the grey)

 

[stem]

The orange and grey wires only go to a potential free microswitch inside the valve so they won't have any power on them. But it's good practice to put them in some terminals rather than leave them floating around loose in case they touch something they shouldn't.

Unless the motorised valve is right next to the programmer then you will need to have a junction box to connect the the motorised valve's flylead anyway, so get one with a few spare terminals in.

 

[newbuild100]

HAHA, I just PM'd you Stem !

 

[newbuild100]

Well folks, all the work i wanted to do has now been done. Old gate valve changed for electrically operated one. I drained the full system completely, BUT theres another problem. The bolier will only stays lit for a few minutes before cutting out. Many moons ago, after draining the system down to change a rad, the same thing happened and i took a while to suss out that the ballcock was stuck in the tank (in the loft), thus starving the boiler of water. A quick tap solved that and the whole system has been fine since. Not this time though. The tank has adequate water.
Clues are as follows . . . .
I have bled all rads.
I have taked the little bleed screw out of the middle of the pump, the pump spins ok.
Its a Glow worm (Space saver) boiler and at its lowest point, there is "bleed screw". If i connect a hosepipe to the screw and undo it (and put the other end of the hose in water) there seems to be air in it. A lot of air ! I left the screw undone for 30 mins or so, and whilst i can hear/see water being replaced in the tank, still air is coming out ! I get the impression air would continue to be expelled if i left it !

Any clues anyone ????

 

[stem]

Most likely an airlock has been introduced somewhere in the system that is preventing the water circulating around the system. If so finding it can be difficult, but, if air is still coming out, and water still going in then the system is still not completely filled.

Have you checked that the motorised valve is opening? When the valve's lever is moved manually, there will be some resistance felt when the valve is closed, and then loose and floppy when it's open.

The valve should have been latched in the manually open position when the system is refilled, as this helps prevent airlocks forming during the filing process.

 

[newbuild100]

Thanks stem. Once again patience has won. I left the valve open until eventually after much gurgling and burping, I have heat to my rads. I need to tidy up some loose ends, then swap a few wires in the timer and hey presto, things will be perfect..... After 20 odd years !!

Thanks very much again
I appreciate your assistance
MS