Odd voltage readings on 3-way valve & heating always on with hot-water

[westhesmallholder]

Since moving into a new (old) house we've been chasing issues with the heating and hot-water. It's a standard system with boiler, hot water cylinder and 2 feed tanks in the roof.

The issue we face is that the heating always comes on with the hot-water.

Initially when we looked at the 3-way valve is was very stiff, so we replaced both the mechanical and electrical part. We think it worked ok for a while, and then again we got stuck with both coming on and the hot water not really getting hot. So, we then changed the electrical motor. \

WIth the new motor in we are now testing the system and it would appear like its working as expected when the heating is on alone, but when the hotwater is on alone our rads are hot again.

I just tested the voltage across the wires feeding the 3 way valve. I get some odd low-voltage readings on the heating wires. Please see readings below. I also noticed when switching off the power to check the motor that there is a slight buzzing in the fuse box that disappears when i turn off the switch that powers the heating. Could either issue be related to the problems we are having with the system?

Heating On Only: White: 240v, Grey 240v, Blue 0v, Pink/Orange 240v
Hot Water On Only: White: 6v, Grey 6v, Blue 0v, Pink/Orange 240v
Both Heating & Hot Water: WHite 240v, Grey 8v, Blue 0v, Pink/Orange 240v

All advice welcome. Thank you!

 

[CBW]

Voltages seem ok. Can you post a photo of the 3 port valve and all other external controls?

 

[terryplumb]

Did you replace the brass body and the actuator head ( in other words the entire thing) ?

 

[CBW]

Did you replace the brass body and the actuator head ( in other words the entire thing) ?

Initially when we looked at the 3-way valve is was very stiff, so we replaced both the mechanical and electrical part.

I would say so Terry

 

[ianmcd]

As @CBW some pics would help we need to see your wiring

 

[terryplumb]

Also said the electric motor was changed, which would be odd if the entire valve and actuator was new .

 

[Johntheo5]

Switch off the power to the programmer, get someone to watch the valve for movement when power restored, if no movement, switch on the HW only and ensure the cylinder stat is calling, turn up the stat if required, valve should not move.

Also ensure Port B is connected to the HW and Port A to the CH.

 

[westhesmallholder]

Thanks for the replies.

Yes, we replaced the whole brass T and the electrical unit, then just replaced the motor as well.

The metal arm on the switch has a resting position of halfway….part of me has been wondering if the valve is getting the full movement, but when I read that the ‘MAN’ (manual) override is in a fact to the middle position (HW and heating) it makes a bit more sense.

Thanks for any advice in advance.

 

[westhesmallholder]

Switch off the power to the programmer, get someone to watch the valve for movement when power restored, if no movement, switch on the HW only and ensure the cylinder stat is calling, turn up the stat if required, valve should not move.

Also ensure Port B is connected to the HW and Port A to the CH.

Yes, followed this procedure. Valve is moving. I wonder if it’s just not moving enough….

 

[Johntheo5]

Yes, followed this procedure. Valve is moving. I wonder if it’s just not moving enough….

The valve should not move when HW only requested.

 

[CBW]

I’m confused slightly, is there another valve behind that 3 port? I can see x2 black cables, and doesn’t look looped.

 

[terryplumb]

What's connected to the terminal block to the right of the pump ? Doesn't appear to be from the mid position valve ??

 

[ianmcd]

On the body of the pump there is an arrow showing direction of flow, it should be pointing towards the inlet to the mid position valve, that pump looks to be fitted the wrong way round

 

[Johntheo5]

I can't see that arrow but assuming the pump head hasn't been turned through 180 deg then it looks as if it could be pumping in the correct direction.
Does the label on the 3 port valve state mid position valve?.

 

[ianmcd]

I can't see that arrow but assuming the pump head hasn't been turned through 180 deg then it looks as if it could be pumping in the correct direction.
Does the label on the 3 port valve state mid position valve?.

The arrow is on the side of the body, even if you turn the head through 180 deg it still pumps in the same direction , you only rotate the head to ease electrical connections, only the pump body decides the direction