Pumped shower problem

hi all,

I hope someone could help me with this as it's got me stumped and the only thing left is to try random things to try and sort it, which I don't want to to...customers getting annoyed too.

House has had new bathroom fitted by us, old bathroom had gravity shower via a (aqualisa, I think)..mixer valve. Cold tank is quite high in loft, about a meter at a guess, bathroom on 1st floor.

Pipe from cws went along loft, then down to shower, hot teed off hot feed in airing cupboard on first floor, up to the loft and along, down to shower, all 15mm, all well below cws.

We put a 2 bar pump next to hot tank in airing cupboard, redirected pipes down to pump and then back up into loft, connected to existing pipes along loft. Fitted new Victorian style concealed mixer shower.

Now what happens is when you turn the shower on you sometimes just get a drip drip from shower head and pump doesn't kick in. 'Sometimes' if you wait, or turn the hot and cold lever backwards and forwards, the drip drip will increase and the pump will start, everything's fine, doesn't sound like air coming out.

If you switch off the pump while the shower is going, the shower will continue to run, at a reduced rate. If you turn the shower off and back on without the pump on, it will continue to run on gravity only.

Trouble is, if you go back later, it goes back to drip,drip?

We've replaced ball cock on cws tank as old was scaled up, as it wasn't filling up quick enough and thought was running dry and air locking, nope.

We've replaced pipes across loft as old went up and down, nope.

Now do I need auto air vents on the supply pipes, or nrv,s?

Help.

Sounds like the pipes are either running into a neutral or negative head position given they are up and through the attic or there is air in the system. Were you able to bleed through the pump to the shower head before running the pump? Does it have a flanged feed from the hot cylinder?
Given you are only getting a drip through (little or no flow), then you may need to fit a universal pump or a manual switch for the pump that bypasses the flow switches.

Madrab said:

Sounds like the pipes are either running into a neutral or negative head position given they are up and through the attic or there is air in the system. Were you able to bleed through the pump to the shower head before running the pump? Does it have a flanged feed from the hot cylinder?
Given you are only getting a drip through (little or no flow), then you may need to fit a universal pump or a manual switch for the pump that bypasses the flow switches.

Click to expand...

Thanks for reply.

Pipes are running along loft floor, so deffo all well below tank.

There could be air, but when it runs, it's runs fine.

There is a secondary feed off the hot tank, which I used, I have heard some rumours that this isn't a good idea, I can't work out why tho.

The pump does start if you wiggle the pipes in the airing cupboard.

They may be well below the tank but the corrected length of the pipes (fittings/valves/pump/actual pipe distances) may be overwhelming the available head, say around 0.1bar. That's why your only getting a trickle. If the pump is turned off at the mains then turn on the shower and turn the pump back on, does it start up and continue running? If so, it's probably a head issue.
Most pumps need at least 1-2 L/min to activate unless it's a universal, then it uses a pressure drop to activate. If the installation is only dripping then flow isn't enough, that's either down to not enough head or air is restricting flow. You never said if you were able to bleed the pump prior to 1st start?

Madrab said:

They may be well below the tank but the corrected length of the pipes (fittings/valves/pump/actual pipe distances) may be overwhelming the available head, say around 0.1bar. That's why your only getting a trickle. If the pump is turned off at the mains then turn on the shower and turn the pump back on, does it start up and continue running? If so, it's probably a head issue.
Most pumps need at least 1-2 L/min to activate unless it's a universal, then it uses a pressure drop to activate. If the installation is only dripping then flow isn't enough, that's either down to not enough head or air is restricting flow. You never said if you were able to bleed the pump prior to 1st start?

Click to expand...

I don't think I've tried that one, if you start the shower without the pump, you get a drip, I'm sure nothing happens if you switch the pump on.

I did flush through the feed pipes after install into a bucket and thinking about it the flow was very good?!

Latest development is if you wobble pipes in airing cupboard to pump, it starts.

Have you removed the non return valves in the inlets on the shower valve if fitted

Have you fitted a negative head or positive head pump

This is the pump I would have fitted, would have saved you all the problems you've had.


http://www.showerdoc.com/stuart-turner-monsoon-universal-2-0-bar-twin-shower-pump

Is it a low pressure shower? May not have the head to provide flow through the shower. Wiggling the pipes will probably fool the switches into thinking there's flow.

steve32 said:

Have you removed the non return valves in the inlets on the shower valve if fitted

Have you fitted a negative head or positive head pump

This is the pump I would have fitted, would have saved you all the problems you've had.


http://www.showerdoc.com/stuart-turner-monsoon-universal-2-0-bar-twin-shower-pump

Click to expand...

As Steve says
Remove the check valves from the shower inlet and all will be good.
Check valves are not required on tank fed supplies and are too restrictive to initiate flow.

Have you Installed air vents at the highest points?

steve32 said:

Have you removed the non return valves in the inlets on the shower valve if fitted

Have you fitted a negative head or positive head pump

This is the pump I would have fitted, would have saved you all the problems you've had.


http://www.showerdoc.com/stuart-turner-monsoon-universal-2-0-bar-twin-shower-pump

Click to expand...

No didn't open up shower before I fitted it, not sure how easy that will be as its concealed.

Standard pump so negtive I think, I didn't buy it.

Madrab said:

Is it a low pressure shower? May not have the head to provide flow through the shower. Wiggling the pipes will probably fool the switches into thinking there's flow.

Click to expand...

Don't know on the shower, I didn't buy it.

I'm sure there's enough head, as flow was very good from feeds into bucket, that's why I'm confused.

picasso said:

Have you Installed air vents at the highest points?

Click to expand...

No, that was my next port of call, but it shouldn't need them, should it?

A standard pump is positive head. If you can't remove the valve to remove the check valves swap the pump for a negative head one.
Either of these will work.
Let us know how it goes.

Standard pump is positive
A negative head pump will have a mini expansion vessel attached to it and will cost 2-3 times a positive one.
It works by charging the vessel to 2 bar which creates flow when the shower is opened and the pump will kick in.

If u didn't supply the pump tell them they've provided the wrong pump and a negative head or "universal" pump is required. The one in the link above will solve the problem

Reading your OP again, the behaivour of - When it runs fine, turn off pump and it continues to flow fine under gravity but then leave it for a while and then it's back to a trickle suggests air is being introduced into the feeds over time. Are the feeds dedicated to the pump? Is the hot flanged? That coupled with pipework going into negative head areas will all exacerbate that effect. If it isn't a LP shower too then the flow through the check valves and cartridges slows it beyond activation, that's clear by the trickle out of the shower head. Does flow increase at all if you drop the shower head?

Realistically the fixes are, remove the check valves and see if it flows enough, could try air vents but ideally you would want to fix the feeds if air is an issue IMO, could fit a manual activation switch and finally most expensive is to change the pump to universal.