Heating and hot water only work independently...

[Noob2013]

Hi there,

Just after a bit of advice for a family members central hesting system.

They have an old style Centroller 3000 controller which controls the central heating and hot water.

The system is a back boiler (not a combi) with a hot water tank, pump and a honeywell 3 port valve.

Central heating works fine when it's selected on the controller, but when you select to have the hot water on aswell, it stops the central heating and allows hot water.

So the both work fine independently but not at the same time which they used to. They say you can hear the controller click off when the other option is selected. I'm having a look today so after a bit of heads up advice.

The pump is only a few years old and is running, though it feels pretty hot.

Does it sound like the 3 port valve is faulty ( I know you can slide it to manual to get over it) or does it sound like the controller is playing up?

If it's the controller, is there any new style direct replacements for the Smiths Industries Centroller 3000?

I'm guessing it doesn't sound like an air lock issue either.

Any help would be appreciated.

Thanks

 

[Richard Burns]

I would say one of the micro switches on the three port valve has failed so the three port valve cannot hold at the mid position i.e. it is either fully closed (HW only) or fully open (CH only).
changing the head would resolve this (if it is the newer style ones). But confirm before just swapping it.
The controller seems to be working as it is only switching the supplies on and off and this seems to be happening.

 

[Leesparkykent]

When the hot water is satisfied by the cylinder thermostat does the valve wind back over to heating only?

 

[Noob2013]

Thanks for the info

I would say one of the micro switches on the three port valve has failed so the three port valve cannot hold at the mid position i.e. it is either fully closed (HW only) or fully open (CH only).
changing the head would resolve this (if it is the newer style ones). But confirm before just swapping it.
The controller seems to be working as it is only switching the supplies on and off and this seems to be happening.

 

[Noob2013]

When the hot water is satisfied by the cylinder thermostat does the valve wind back over to heating only?

I'm not too sure but I will find out today when I have look.

 

[tony mc]

I'm not too sure but I will find out today when I have look.

Are you sure its a Y plan and not W plan

DHW priority: W-Plan
A variation on Y-Plan uses a 3-port Diverter (rather than Mid-Position) valve which switches all flow to either DHW or CH, never to both simultaneously. This is suitable for use with fast recovery DHW systems and is known as W-plan

Schematic

 

[Noob2013]

Just an update.

I motorised the valve back and forth several times and it has now been working OK for a week.

Must of been a bit stuck as heating hasn't been on for 6 months plus.

Thanks for all the input.