Turning the Heating off stops the CH Pump

[chaffordred]

Does the pump stop running or is the problem you have no (poor) circulation?
When you have HW only selected.

The pump stops running. The circulation is fine. As I say if I wire the pump live to a permanent live everything runs as it should except I don't want to leave it like that as I don't think it would be wise to have the pump running all the time.

Something just cuts the pump out when I turn the HTG OFF at the programmer but leave the HW on.

 

[chaffordred]

Can you post some pictures of the inside of the wiring centre?

This is an unusual fault because generally the pump is electrically connected to the same voltage that fires up the boiler. (Either directly in parallel in the wiring box, or via the boiler PCB)

As this started after replacing the 3 port valve there's almost certainly a wiring error.

Thanks. I'll get some wiring pictures up.

From what I can see the pump live goes in to two wires which go downstairs. These two wires are Red and Blue (with a small red sheath).

The red wire I take to be the Pump Live.

The blue (with red sheath) goes to the HTG NO on the programmer. (I am 90% sure of this as it is the same colour and comes from the same wiring loom).

Does this sound correct? Thanks.

 

[jackthom]

If you can identify the pump flex, the green and the blue should go to a common earth and Neutral respectively, while the pump live should be connected to the same point as the live that triggers the boiler to fire up.

 

[Dean744PiN5]

sounds like the pump isnt wired into the s/live on the motorised valve (orange wire). which also as the call (1) from cylinder stat wired into which would explain why boiler comes on but not the pump when htg off hw on selected at timeclock.

 

[twgas]

From what I can see the pump live goes in to two wires which go downstairs. These two wires are Red and Blue (with a small red

I think the valve orange should also connect here.

 

[Dean744PiN5]

The blue wire is live and when I disconnect the red wire I get no heating, but the boiler still fires up and I get Hot water.
Thanks.

Think this is the clue to where the wiring has gone, sounds like pump live is connected to common on the roomstat, so when htg on hw on is selected pump and boiler run, but when htg off hw on selected no live to pump but cylinder stat sending s/live to boiler to fire it up.

 

[matt1e]

It sounds to me like it is still wired in part as per a gravity hotwater pumped central heating system ie
The boiler is controlled via the hotwater on terminal and the pump is controlled by the ch on terminal via the room stat
it's definitely a wiring issue

Matt

 

[chaffordred]

[/img]

OK Finally managed to upload a Pic. Apologies for the quality of picture, but it was a bit tight in the airing cupboard

The flex's on the bottom from left to right are:

CYL STAT FLEX (LEFT) - 3 Way Motorised valve flex (middle) - Pump Flex (RIGHT)

As you can see the pump live (Brown Wire) connects to two wires. These 2 wires are 1 X RED and 1 X BLUE with red sheath. These wires go downstairs.

The orange wire from the 3 way Motorised valve (Black flex) connects to the CYL STAT 1 (blue wire) and these go into a red wire which goes downstairs.

Fingers crossed this sheds some more light on the wiring problem. Cheers.

 

[matt1e]

Move the brown wire from the pump flex from where it is and reconnect it into the terminal to the right (the one that also contains the valve orange)

Matt

 

[jackthom]

Yep as Matt says. The red lead in that connector will be to fire up the boiler.

 

[Dean744PiN5]

as per my earlier post

 

[matt1e]

as per my earlier post

You were correct too,looking at the pic that's exactly where it is connected at the mo (ch on/roomstat com)

Matt

 

[Dean744PiN5]

brownie points to us both

 

[Dean744PiN5]

only problem is i done myself out of a job on my own patch

 

[chaffordred]

Guess what?


For the first time in I don't know how many years I can have the heating on without HW ON and more importantly the boiler not sounding like it is about to explode!

A Massive thank you to everyone that contributed towards sorting this out.

Cheers guys!