Central Heating not Automatically Switching on

[sotal]

Hi,

Just moved to a new house which has a back boiler system in it, with a honeywell Y Plan system.

The Electronic timer works perfectly for Hot Water, but the heating doesn't. The heating just ignores the timer altogether. I have found out I can get the heating to work by switching off the HW, and then moving the switch on the Y Valve to MAN OPEN. But obviously this isn't ideal.

I've just checked the components and everything seems to be functioning, the correct wires become live when I expect etc, so the only thing I could think it could be was the Synchron Motor, So I replaced that but that hasn't fixed anything . I suppose it could be the PCB part of the Y Valve??

I have just checked over the complete wiring for the rest of the system, using the honeywell site for referrence:

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

Everything is perfect execpt and as shown except for the boiler connection. We have a Bax Bermuda 45/3M Backboiler which has four wires rather than 3. There is the Earth and the Neutral which are easy enough but then there is a red and a yellow, but the diagram only shows a Live. Currently the Yellow one is connected as per the diagram, and the red one is connected to a permanent live connection.

The wiring all seems logical as I would guess that one wire is a permanent live and one is a switched live, but are they the right way round?? and secondly I've been trying to find a Baxi Bermuda Wiring DIagram but with no luck but I did find this pdf:

http://www.chaffoteaux.co.uk/uploads/img42c94f1ca05da1.pdf

That PDF has a wiring diagram for a 2 x 2port System, and where it shows the Baxi Back Boiler it says to connect the permanent live to connection number 9 which doesn't seem to be connected to anything else. Could it be that it shouldn't be connected at all??

Do you think the Boiler Connections could be related to the Heating not automatically switching on.

Any Advice would be greatly received although I don't just want to be told to get an expert in as I could have done that alreasy myself!!!

Cheers

 

[Rob]

the correct wires become live when I expect

hmmm then its a mystery or you dont really know what your looking for.

the best and obvious place to start is with the programmer, are you getting power from there to the room stat? are you getting power from room stat to motorised valve?

your making it a bit difficult for yourself

 

[sotal]

yes power is going to the room stat and to the motorised valve.

The room stat works perfectly as when I've manually moved the switch across I can control the max heat setting via the dial. The cylinder stat also works perfectly. The pump appears to be working fine

When you switch HW on you hear a gush straight away and the boiler kicks in etc. When you switch the heating on nothing at all happens, but the Orange wire on the Y-Valve becomes live.

Have you got any idea about the wires for the boiler?? If someone can tell me how they should be wired then atleast I can rule that out, and concentrate on the timer or the y-valve

Cheers for the help

 

[Rob]

the orange wire from the 3 port is the sw/l which should also link to boiler sw/l and pump L.

You should also be looking for 240v at the white wire.

 

[sotal]

Sorry I was wrong there, just been checking over which wires go live again,

and the orange one doesn't go live, but the white wire does go live with 230V




The Orange Wire does however go live when I move the switch on the Y-Valve to "MAN OPEN"

The Orange Wire is connected to the following:

Pump Live
Boiler Yellow (not sure if it should be Red)
Cylinder Stat Connection 1

 

[Rob]

did you replace with a brand new synchron motor. Does sound as though this is at fault.

 

[sotal]

Yes I put a brand new sychron motor on, so that is ruled out

 

[sotal]

Yes I put a brand new sychron motor on, so that is ruled out

Any idea about the wires for the boiler? Is red usually perm live?? and yellow switched?

Is there any way to test the synchron motor? or the assembly? I can remove the whole head easily enough and I can remove the synchron motor any tips on testing them??

cheers

 

[sotal]

Just done some proper testing - writing down my results:

I was testing the grey, white and orange wires whilst changing the settings on the programmer.

Everything off = Grey 230V White 0V Orange 0V

Heating Only = Grey 230V White 230V Orange 0V

Hot Water Only = Grey 0V White 0V Orange 230V

Water and Heating = Grey 0V White 230V Orange 230V


If found a pdf for the Y-Valve:

http://content.honeywell.com/UK/homes/FAQ/v4073aop.pdf

According to that the voltages are correct for the white and grey wires but I presume Orange should be 230V on Heating Only!


I had a quick look at the Y valve, and removed the Synchron Motor. The synchron motor does not move even when removed, nothing at all happens no matter what I press on the programmer.

With Heating On There is 70V going to the Motor
With Hot Water Only There is 4V going to the Motor
With Hot Water and Heating There is 71V going to the motor

The motor still hasn't moved though whilst not being connected. Is 70V the correct ammount to be going to the motor or has the PCB broken?

 

[sotal]

Anyone???


Questions Really are..

1. What Voltage Should go to the Synchron Motor From the PCB?

2. Anyone know about the boiler connections (red and yellow wires)

3. What would happen if you connected a synchron motor straight up to the mains connection? Would it move or is it based on some pulsed signal type thing?

Thanks in Advance

 

[baxpoti]

The boiler wiring should be Live (for the fire front and boiler) Neutral Earth and SWLive ( for the boiler on)

 

[sotal]

thanks baxpoti,

any idea which colour is which? I presume it's right.

Currently red is connected straight to live, but just as a test I disconnected the red altogether and the heating carried on to work as it was before, and the boiler still kicks in.

I guess it could be the fire front though. I never tested that!

The only thing I can think now is that it's the y-valve head but not the motor, which is about £40 to try. I'll have to try one of them unless anyone can think of any other possibilities??

cheers

 

[sotal]

Well just to let everyone know - it was the circuit board in the Y-Valve.

So the whole head had to be replaced - luckily it has a removable head so the job was easy. On the bad side though the cheapest replacement head I could find was £55, I ended up buying a complete v4073a Y-Valve for £35 inc postage! Then I just swapped the head!