Shower pump hunting

[Mattox]

Hello all,

I'm at my wits end...

I have fairly recently taken the plunge and re fitted my entire bathroom. I should probably add at this point that I am not a plumber and before I undertook this mammoth task I had no plumbing experience whatsoever. I hope that this has not now let me down at the final hurdle...

Before starting this job we had no shower and were desperate for one so I took the opportunity of a blank canvas (and it was really blank as I had to rip out every single pipe from the bathroom, most from the loft and all from the hot water cylinder as they were 70 year old galvanised steel pipes) to fit one.

The problem is that after working fine for the first month or so, the pump has started hunting for a few seconds every 5-10 minutes and I can't stop it.

My system is as follows:

2 story house, water tank in loft, shower upstairs, hot water cylinder downstairs in a cupboard in the living room. All pretty much vertically in a line. Cylinder is vented and the pump is a negative head Stuart Turner 1.8 bar twin impeller shower mate. I've fitted it in the bathroom behind the bath panel to avoid noise in the living room. Cold water feed is 22mm direct from tank in loft (separate to taps) converted to 15mm before pump connection. Hot water feed is 22mm via Surrey flange from cylinder and a 600mm gravity loop up to bathroom floor, converted to 15mm before pump connection.

Can anyone tell me what might be wrong or where to look as I'm all out of ideas. There doesn't appear to be a leak anywhere and it's a brand new pump.

HELP!

 

[Newboy]

Is the pump feeding all the appliances in the bathroom?

 

[Madrab]

Sounds like you might have a slight weep on one of the feeds, valves or outlets that the pump is feeding, the pressure drops and the pump picks that up, it fires up and when the pressure is replaced it stops.

 

[Mattox]

Hi. Thanks for your reply. The pump is just for the shower so it has a bespoke feed from the hot tank downstairs and the cold water tank in the loft

 

[Madrab]

The only reason the pump would hunt is if the switch inside is telling it to run, that pressure is controlled by the expansion vessel on the pump. When the switch registers a pressure drop in the feed pipes it activates the switch turning the pump on. When that pressure rises again it switches off.

If it's a brand new pump I wouldn't suspect the EV has an issue, therefore the next place to look would be for a pressure drop downstream of the pump somewhere.

 

[Mattox]

The only reason the pump would hunt is if the switch inside is telling it to run, that pressure is controlled by the expansion vessel on the pump. When the switch registers a pressure drop in the feed pipes it activates the switch turning the pump on. When that pressure rises again it switches off.

If it's a brand new pump I wouldn't suspect the EV has an issue, therefore the next place to look would be for a pressure drop downstream of the pump somewhere.

So by downstream do you mean the cold or hot in to the pump from the two tanks?

 

[Madrab]

nope, downstream is after the pump (in plumbing terms downstream is after something, upstream is before) ..... it's the drop in pressure in either the hot or cold feed to the shower that is triggering the switch. So I'd check first for a very small weep somewhere.

 

[Mattox]

nope, downstream is after the pump (in plumbing terms downstream is after something, upstream is before) ..... it's the drop in pressure in either the hot or cold feed to the shower that is triggering the switch. So I'd check first for a very small weep somewhere.

That's one thing I haven't checked. And hopefully that is where the problem lies as nearly all the new pipe work is against the wall on the other side of the bath and impossible to get to. I had to build a stud wall which the feed for the shower mixer valve is hidden behind.

I take it anything after the mixer valve (Riser pipe and two shower heads) should be fine as when the shower is off the valve should be fully closed and not allowing a weep of any kind?

 

[Madrab]

Yes, the new shower shouldn't be passing, as long as when the shower drips when turned off it then stop after it has drained?

What kind of fittings/couplers are in the wall you can't get into? Was it tested before sealing up?

 

[Mattox]

Yes, the new shower shouldn't be passing, as long as when the shower drips when turned off it then stop after it has drained?

What kind of fittings/couplers are in the wall you can't get into? Was it tested before sealing up?

Yes, the shower stops dripping after it's turned off. Sometimes though, after about half an hour or so of the shower being off the shower head releases water for about 20 seconds and then stops. To eliminate the valve (mixer), I removed it and fitted two compression valves directly to the supply pipes and switched the pump back on. Same result unfortunately. Pump hunted for a couple of seconds every 10 minutes or so.

Pipework downstream of the pump is push fit (sorry) for a short stretch until it links up with valve supply pipework (copper with solder ring fittings) along and up the wall to the mixer valve.

I'm pretty much all out of ideas now. Still no signs of any leaks anywhere and the shower works perfectly fine. I just have this annoying noise all the time which means I'm constantly turning the pump on and off when not in use to stop it.