Help with Drayton motorised valve heating system

So I've recently moved into a house with gas central heating, before I have only had electric only flats so I'm a bit new to it. During the past cold few days I thought I'd test the central heating to see if there were any issues.

The programmer is a siemens RWB29 and seems to work just fine, I can set the programmes and the two lights light up to indicate they are sending the signal for heating. The problem seems to come from a Drayton motorised Mid-position valve that keeps defaulting to the water only setting for my water tank, even when the programme on the thermostat is set to both heating and water.

There is a button on the side of the wall next to the Drayton valve that when pressed seems to send power to the valve turning it to the correct setting. This worked for a bit, but now when it is pressed it'll change the valve to the right setting and then at some point (maybe 15 minutes) turn itself off and default back to the water only setting.

I have also looked around the house and can't find a room temperature control anywhere, so I don't think this house has one.

I'll include pictures of the valve and the button (which has no writing on it)

Does anyone have any ideas if I am using this wrong? or maybe the valve is not working as intended?

If you set the program for heating only, do you get constant heating?

James said:

If you set the program for heating only, do you get constant heating?

Click to expand...

If I set it to heating only, the valve sticks in the "W" position. So It doesn't send any water to my radiators. I have a feeling that there's something about the connection with the programmer that's not right.

If the heating has ever worked correctly, then the issue could be just a loose connection… or the motorised valve has stuck.

With great care, and the heating system isolated.. you could take the cover off the white “JB1” box and look (but don’t touch) and see if there is any loose cables.

It sounds as though although the programmer is switching the heating on, the valve is not getting the message.



There will be a way to remove the motorised part of the valve from the pipework without getting wet… you can see if the valve on the pipe can be turned to each position manually.



If you don’t know how motorised valves work… there is a regular live and neutral that energises a little motor that turns the valve… when the valve is fully in one of its open states, a little micro switch gets pressed when sends a signal to the boiler to fire up.
If the valve is sticking, it might not open fully enough to reach the micro switch, meaning the boiler doesn’t get its signal to start.

The little black tag on top of the valve showing W, M and H should indicate at what position the valve is at…

The unit in your first pic is a Honeywell Home BDR91 RF receiver, and is designed to receive a signal from a programmer or room stat, or cylinder stat etc.
Are you saying the lights light up on the BDR91 when you operate the programmer, if so there might be a transmitter unit connected to the programmer?

The button on the BDR91 is for pairing the unit, and will prompt the switch to turn on, but without the transmitter unit signal, I believe the dropping back to 'off' is what the unit would normally do. It's not designed to be just an on/off switch!

I didn't think your Siemens programmer is in itself an RF device. So the question is - what is/was operating the BDR91?
It might be a cylinder stat, in which case worth checking the batteries in the transmitter unit.

Honeywell do nice portable room stats that the previous owners might have taken with them, mistakenly or on purpose?!

PS in your first pic neither indicator lights on the BDR91 are on - is that the permanent state of it? If so it's not doing what it should!

Avo Mk8 said:

The unit in your first pic is a Honeywell Home BDR91 RF receiver, and is designed to receive a signal from a programmer or room stat, or cylinder stat etc.
Are you saying the lights light up on the BDR91 when you operate the programmer, if so there might be a transmitter unit connected to the programmer?

The button on the BDR91 is for pairing the unit, and will prompt the switch to turn on, but without the transmitter unit signal, I believe the dropping back to 'off' is what the unit would normally do. It's not designed to be just an on/off switch!

I didn't think your Siemens programmer is in itself an RF device. So the question is - what is/was operating the BDR91?
It might be a cylinder stat, in which case worth checking the batteries in the transmitter unit.

Honeywell do nice portable room stats that the previous owners might have taken with them, mistakenly or on purpose?!

PS in your first pic neither indicator lights on the BDR91 are on - is that the permanent state of it? If so it's not doing what it should!

https://homecomfort-techlit.resideo.com/emeadocuments/pim%20-%20renamed/bdr91-m-pl01.pdf

Click to expand...

Thanks for the help this fixed it. I saw this Honeywell room stat in a drawer when moving in and thought it must be an obsolete programmer since it has mounting holes and places for cables to go on the back of it.

Took it out and stuck some new batteries in it and everything seems to work perfectly, the light comes on on the BDR91 and the valve switches correctly when I set the temperature on the Honeywell room stat.

Thanks again for the help! I genuinely thought I was gonna have to get someone in for a repair.

glad it was such a simple fix.....

And good job the previous owners didnt take it with them