replaced shower, now pump doesn't kick in

[Monnie]

I have replaced a 17yr old Hansgrohe BIV shower (min 0.5bar) with a Mira Atom bar valve(0.1bar) However when I try to use it there is a whirring sound in the valve, a trickle of water from the showerhead and the pump (Stuart Turner Showermate( also 17yrs old) doesn't kick in unless I take the shower head to floor level, (even then it doesn't always work) or turn the temperature control to cold. With the bar disconnected, the water flow through the pipes looks fine, in fact slightly stronger on the hot side.
I have a gravity fed system - cold tank in loft and hot tank next to shower in airing cupboard.
I could call out a Mira engineer but if the problem isn't caused by a defect with the Mira valve, it will cost me £70+ for the callout.
I would be very grateful for any suggestions as to the cause or solution to the problem. Thanks

 

[Dean744PiN5]

how much distance between shower head and base of cold water storage tank? if its less than 1m that is probably not enough to start the valve flowing and activating the shower pump (especially with the built in non return valves)

 

[Monnie]

I haven't looked in the loft but I suspect it is slightly under 1 metre to the top of the showerhead.
The old shower worked perfectly, but maybe it didn't have the resistance of the valves.
Once this one does get flowing (with the pump switched off), there is more flow than with the previous shower, but that whirring sound is still there.
Can you suggest a solution that doesn't involve major alterations, and do you suspect that the shower valve is probably working OK?
Thanks for your help.

 

[Phill Peck]

What shower valve is it.
If it has non return valves built in the pressure might not be enough to open them until the pump is running.

 

[Monnie]

It's a MIra Atom EV thermostatic bar mixer valve. Minimum 0.1bar.

I have a horrible feeling you are right. about the non return valves It's strange how it kicks in when the temperature is set to the lowest setting, as though it doesn't like the hot side.
We have had a look at the valves and they do seem to move OK. I don't suppose they become less resistant with use, do they?
Thanks

 

[Phill Peck]

0.1 bar is approx 1m of head so as said above you'll need 1m from shower head to tank outlet.
Does it kick in if the shower head is lowered?

I have removed non return valves in the past they are not really nessisary on a gravity system. However this would probably invalidate your warranty.

If anything they will to ably get more "sticky" with time.

Although it says min 0.1 bar these showers are generally designed for high pressure systems.

 

[Monnie]

Thanks for the info. The pump doesn't kick in every time the showerhead is lowered. We did consider removing the non return valves but I don't think Mira has make that very easy. Looks like one of those torx keys will be needed. I might have to do that.
You live and learn.

 

[kbdiy]

You have a duplicate post running here. Check your other post for my suggestion - correct commissioning is needed in my view.

 

[Monnie]

We did adjust the temperature control inside, as when it was first installed the control had to set to maximum to obtain a warm shower.
I don't know if that is common, I don't suppose they want to burn their customers with the first shower.

 

[StuartTurnerLtd1]

Hi all, this will not solve your issue but will help to understand the issue. A 17 year old Showermate will have flow switches on both hot and cold to activate the pump.

Chicken and egg. If there is no or very little gravity flow at the point of use the pump will not start as it will require a decent amount of water movement to activate the flow switches.

We as a company are receiving more and more customer with FLOW switch operated pumps complaining that the pumps are not starting due to no or very little flow (trickle)

Over the years this complaint has increased as shower/taps etc end equipment has become more restrictive. High pressure fittings being fitted to low pressure gravity systems.

The upshot is we are specifying more and more negative head pumps (universal) that don't require this flow to activate them.

If equipment is not fitted or there is any doubt if a good gravity flow will exists the answer is use a negative head (universal) pump.

 

[Monnie]

Thank you for that information and advice.
The pump has had a lot of use and so when it becomes unserviceable I will look at the negative head flow pump as a possible replacement, although I understand they are somewhat more expensive.
In the meantime I will just have to get use to a bit of fiddling to get the pump started.
Thanks

 

[Dean744PiN5]

looking at the manual for your valve looks like the non-return inserts can easily be removed, and then put back in ever needed

 

[Monnie]

Thanks Dean. Everyone is so good about sharing what they know..I love this forum