Wiring Problems on Hot Water Circulation Pump

[smashy]

Hi All,

I have a megaflow in the loft together with a hot water circulating pump that is not working.

It used to work but was a bit noisy and I didn't really need it so I turned it off (it has a fused switch). Now, having recently become a father, and thinking it would be quite useful, so at the weekend I turned it on again. And it worked OK.

Now a few months ago, I also had some problems with my boiler not switching off, that I traced back to, amongst other things, the froststat (thanks to those who helped with that), and I disconnected it intending to replace it before the winter.

Well being on paternity leave, I've been in the loft trying to replace the froststat. And now the pump doesn't work anymore.

I've traced the wiring through, and it seems the circulation pump receives its power from two sources. One being the froststat itself - and presumably this wont activate until it gets too cold.

The other source is from a connection in the airing cupboard I think, although I can't actually see it, thats just a guess based upon where the wire disappears out of the loft. This wire is a Red/Black/Earth type but not particularly thick, closer to domestic lighting weight. In the airing cupboard there is two immersion heater switches, the time hw/ch timer unit, and a blanking plate that covers lots of wiring connections that I haven't traced through.

I can't figure out what the power source is connected. Am I missing something here? Is it only powered when something else is turned on? If so, I can't figure out what. Is it possible the previous owner has been up in the loft and screwed it up? Is it possible a fuse has blown hence another reason why the froststat has blown?

If anyone has any insight into this, I'd be grateful.

Thanks

Smashy

 

[TheGasMan26]

Most likely the pump you are referring to is your 2ndary hw pump m8, this is used in larger houses so that A.you dont wait an age for the hw to reach the furthest taps & B.the hw does not stagnate in the pipes causing a chance of legionarres disease.

The other supply will be to your HW on terminal in the system wiring centre, and the frost stat is usually wired in series with the hw zone valve so this could well be your problem.

Firstly check that the pump is not receiving power as it very well could have burnt out & that the fuse is ok.

But from what you explain its sounds like the pump is wired in circuit to the frost stat, easiest thing to do is replace your frost stat(cheap & easy) then see where you stand.

Because the other option is that the noise was the 2ndary pump failing, this is bad as they arent that cheap as you have to use a special type suitable for potable(drinking/bathing) water.

 

[smashy]

Thanks TGM26, this was very helpful. The trick was realising the froststat was in series.

I've not yet replaced the froststat, but the pump is working now.

Cheers...