Central heating pump stops with boiler - *update*

[cheekylemon]

Hi all, some good answers on here, I'm hoping you will be able to help me with a small problem.

Basically, when I switch the heating on the boiler fires up, and the pump (which is upstairs with the hot water tank) starts to run. This is fine, but when the boiler stops running, so does the pump.

This seems a little odd, as I would assume the pump would continue to get the rooms to the temperature I have specified on the roomstat. But it doesn't, and the room stat doesn't get a chance to kick in. (Because the heating does not get hot enough).

Also, the radiators downstairs are a little chilly towards the bottom, but hot at the top.

To add evenmore confusion the previous owner changed the control box for the boiler, which I had to remove from the wall to get the tiles off. Two of the cables fell out, which I put back in, as I spotted where they came from. There is also a wire that was only connected to earth, which I assumed was an old wire for the old pump. The other cables for it were not connected, just the earth. I have since disconnected the earth.

I'm confused, and would appreciate any help you can give.

Some details:

Boiler - Potterton (not sure what model, but was installed in 1991)
Pump - Grundfos Scelectric (Fairly new I believe)

 

[cross thread]

disconnected the earth thats always a good idea!!!!!!!!

 

[cheekylemon]

I only disconnected the cable that had been cut. The Live and Neutral wires were not connected, and assumed the person who installed the new control box just cut them, but did not bother with the earth.

As I had to replace the metal box behind the controller, I removed the earth for the dead cable. (Left all the other earths of course).

 

[cross thread]

on most systems the boiler and pump are wired to operate at the same time.the boiler going on and off on its own stat . so if yours is wired correctly with the clock on and stat calling you should have a live to boiler and pump .so even if your boiler stat is off the pump should run,if it isnt the prob my lie with the wiring or some boilers have the pump controlled by a internal stat/timer

 

[cheekylemon]

Thanks Gordongas, I shall check the wiring out tonight incase I have inadvertantly crossed a wire or something.

I appreciate your help

 

[cheekylemon]

I think I may have solved this now. I connected the live of the pump to another terminal (estimated guess if I am honest, after looking at my DIY book, the Internet, and the wiring at the back of the timer).

Now as long as the heating is set to ON, the pump will run, even if the boiler has stopped heating as it has reached its optimum temp. If the room with the stat reached the correct temp, the boiler will stop, but the pump will keep running.

I also checked that the pump does not run when just the hot wated is selected, and it doesn't! Woo-hoo.

Now all the radiators are toasty.

Does this sound like the correct setup now?

Cheers guys.