Help explain my system

mcbobbyb

Hi. I've a basic motorised valve on the hot water pipe from the boiler which has a t section before the immersion. It's controlled by a thermostat downstairs. How does this work. The direction on the motorised valve points down towards the ground.

John.G

Can you post a picture please?. Is there only one motorized valve? and can you get the make/model number of it. Also have you got a cylinder thermostat?. it is normally strapped onto the cylinder ~ 1/3 the way up?

mcbobbyb

Sorry I can't post a picture. The pipe that enters the top of the cylinder heating coil has the motorised valve on it. No other thermostat or valve. When I set the stat low ie 15 degrees no power goes to valve. When it's set high the valve has power. I have has it set low and high and seems to make no difference, as in it heats the rads and not just the water

K.Flyer

It could be getting power, but not turning, it may be seized in the open position.

John.G

mcbobbyb wrote: »

Sorry I can't post a picture. The pipe that enters the top of the cylinder heating coil has the motorised valve on it. No other thermostat or valve. When I set the stat low ie 15 degrees no power goes to valve. When it's set high the valve has power. I have has it set low and high and seems to make no difference, as in it heats the rads and not just the water

It may be something like this.... can you get a few details off the motorized valve

https://www.plumberparts.co.uk/advice/heating-systems/y-plan-heating-system

Calahonda52

why can't u post a picture, you have enough posts?

eg: DANFOSS HP22 2 PORT MOTORISED VALVE
https://www.ie.screwfix.com/danfoss-hp22-2-port-motorised-valve.html

on the black part there is a lever that can be moved to the other side and keep the valve open mechanically, if it doesn't move then valve is stuck

It might be easier to take off the white plastic piece and see if the motor works when the power is applied via the stat.

when putting it back it needs to align with the slot in the motor and don't over tighten it
if the valve is stuck, it might move by GENTLE persuasion with a vice grip or pliers, it rotates either way, all the way around

mcbobbyb

I just can't seem to be able to post pictures, at least not from my phone. Will try laptop. In theory how should it work. I was thinking when the stat is not calling for heat the valve diverts water from rads.

whizbang

If its a 3-Port valve; Yes it can divert water from Rads - then only heats the cylinder heating coil. But this depends on the controls; Read the description in the first link above.

If its a 2-Port valve; No; the water is shared between Rads and cylinder heating coil. (You can turn off individual rads manually)

Most likely its a 2-Port as shown in 2nd link above.

Sounds like motor/valve is stuck as above.

John.G

mcbobbyb wrote: »

I just can't seem to be able to post pictures, at least not from my phone. Will try laptop. In theory how should it work. I was thinking when the stat is not calling for heat the valve diverts water from rads.

Which one of these does it look like??

mcbobbyb

It's a 2 port valve similar to a Honeywell. The model is a tzv22. The motor is gone in it and it was stuck open. I've removed the onside part and can open/ close the vale by hand now.
It was located on the section after the cylinder where the pipe heads back downstairs presumably to the rads.