Honeywell V4073A Diagnostics

[Chetz01]

First time poster long time lurker

So recently I have noticed that when we have our programmer switched to do Hot Water only the radiators also get warm despite Central heating set to off and thermostat set to lowest. If we want central heating only or both HW/CH that also works ok.

After some research on here I have reason to believe its the 3 port valve located in our airing cupboard, this is a Honeywell V4073A1039 (with a little bump on the case). I am reasonable competent DIYer but haven't done something like before so I followed a guide to power down the electrics to the system and test the Auto/Manual lever which when the power is off is very loose like its not actually moving anything.

My house is reasonable new built in the last 15 years and everything seems easy to access, I have been looking online but I can't tell whether I should buy a new Synchron motor or the replacement valve head? (I would only buy original gear)

Aside from the above my only other worry is whether I should drain the system out or not? I think changing the valve head is a reasonable easy task as long as I take care to see where each wire goes?

If I am completely missing anything else I would appreciate any advice!

 

[75pete]

The bump= no need to drain.
Quick and easy diy job, just ensure you isolate the power supply.

 

[Chetz01]

Thank you Pete, going to order up a new one now, it seems to come with the metal valve so I'll just keep that in my spares box!

 

[75pete]

Have a look at ( Google )Port valve diagnosis and repair. Nice, clear video that explains the valve and it possible problems/fixes.

 

[Chetz01]

Just to let you know I got this sorted in the end thanks to the advice on the forum. I changed it out myself within about 40 minutes, it took a while as it was in a awkward place! Thank you so much