H/W and H/W with C/H together but NO C/H ON IT'S OWN - HELP!

[Wildeman]

I am not sure if that would cause the issue but it has been piped like that since the house was built.

 

[doitall]

If that drawing is correct, I'm surprised it don't blow the fuse.

You show T7 connected to the N, whereas it should be Programmer 1 and the grey wire, meaning you don't have a neutral to the pump and boiler in the htg only mode.

Actually it may just be not very clear.

 

[D_Hailsham]

I am not sure if that would cause the issue but it has been piped like that since the house was built.

But you do mention a lot of air in the system.

You show T7 connected to the N, whereas it should be Programmer 1 and the grey wire, meaning you don't have a neutral to the pump and boiler in the htg only mode.

If you improve the contrast on the pic you will see it it OK

Hint to OP please don't do the drawing with a 7H pencil next time

 

[Wildeman]

7 is connected to Grey from the valve, the cylinder stat as well as HW Off on the Programmer, it is not connected to Neutral

Sorry for the light drawing, it must be the scanner!!!

I mentioned a lot of air in the system but I am thinking that from the noises it makes, not getting any air out of the upstairs rads

 

[doitall]

I think you're down to changing the valve.

Can you do a pipe drawing.

 

[Wildeman]

I have already replaced the valve body and actuator three weeks ago.

A pipe diagram will be hard as I stated in previous posts the floor boards are the large ones and I do not fancy cutting them up with a circular saw seeing as the pipes and wires are tight to the underside of them (know this from a bad experience with a pipe and wire!!)

 

[doitall]

Just the cupboard, and pipes above would do for starters.

 

[Wildeman]

I have the pics below but would be prefer a drawing?

View media item 15439 View media item 15492 View media item 15442 View media item 15443

 

[D_Hailsham]

I have already replaced the valve body and actuator three weeks ago.

So it's unlikely to be the valve. Which leaves us with a fault in the rest of the system.

You could try some tests with the valve removed from the circuit (electrically, not physically )

Turn off power
Turn HW and CH OFF at programmer, turn both CH and HW stats down to min.
Disconnect the Grey from terminal 7 and Orange from terminal 8.
Disconnect the Room thermostat from terminal 5 and connect it to terminal 8.

The boiler is now controlled directly by the two thermostats.

Remove the valve actuator and turn the valve by hand so only the CH port is open.

Turn on power and CH ON at programmer
Turn Room stat up.
Boiler will run.

If the problem occurs, it is nothing to do with the valve. It must be a problem in the pipework.

If the problem goes away, it must be due to the valve.

 

[Wildeman]

I will try that and see what happens.

If the problem still persists what is the best way to try to find a partial blockage - don't want to rip out all the pipework and rads

 

[Wildeman]

Would a magnet on the pipes in the airing cupboard be a start as presumably it will stick to the iron build up in the copper pipe??

 

[doitall]

I don't think thats the problem.

Can you get someone to switch the boiler on and change the modes whilst you hold a glass of water under the vent pipe to see if it sucks it dry.

 

[Wildeman]

Yes I can but it will have to be tomorrow now as they are all in bed!!

 

[doitall]

We'll still be around.

 

[Wildeman]

Please find below a Pipe Diagram drawing

View media item 15752
I had a quick look in the F&E tank this morning to check it had water in it which it did but there was "gunk", looked like slime all over the top of the water!!

I will try the glass of water later when I can get another pair of hands