DIY Doctor UK DIY Forums

Help needed ! My dad has a Baxi WM 40/3 OF . The rads come on when we need hot water only. We only have a complicated installation manual. The dials on the rads don't turn. Don't think they ever did.
Under the water tank there is a yellow plastic clip on tag that says heat on / heat off. Around a copper pipe. The valve turns easy when I unclipped the tag, turned to heat off & got hot water only. Result!
Until a electrician friend said you must Never Touch a Yellow Tag. It's there to stop you turning the valve.
I have googled for a couple of hours and cannot find any image or note about this valve or yellow plastic tags.
I've never had central heating. My late mum knew the instructions.

Yellow is normally associated with gas, but doesn't appear to be in this case.

Theres normally a motorised valve, and I suspect this or the 2 or 3 port valve will be at fault.

The manual valve you have adjusted would have been set at mid point to give heating and hot water.

Look for a brass valve with an electric motor in top, near to the pump location

thanks for your reply. I have tried to upload an image but it doesnt seem to work.
I have looked for what you described but there isnt anything. I had just hot water on this morning & tested the pipe. The pipe above the valve was hot but below was cold. So I am right in thinking its water in the pipe, not gas ?
Is it safe to leave it turned to heat off ? Will it harm the central heating ?
Sorry I cant add a photo..

I think your friend may have assumed it was gas, when you mentioned a yellow tag.

If the heating is working then yes, leave it as it is until you get sorted. There's that many safety devices on boilers now, if it didn't like what was happening, the boiler would lock out on fault.

Thank you for your help.