New Shower mixer airlock help

[terryplumb]

OK got that ,but does this work EVERY time ? I.e use bath hot to activate pump ?. Is the supply pipe to pump 22 mm diameter ,and to tap 22 mm and 15 mm to shower ? Is there an isolator on the branch to the shower ,AFTER the pump and bath tap ? If so ,is it a full bore isolator ,lever operated ,or of the type that you use a screwdriver on to close / open ?

 

[Wictod]

Yes, that method of starting shower works but after a week it won't work. Basically this has been the way they have been activating shower previously before the refit but it was constant without any issues. Since the refit the method works for about a week then no hot water. I have come round undone the connection to the hot side on the shower block, got some water coming out, then the pump starts and I tighten back up then after that works for about a week then stops.

The hot supply to the pump is 22mm but in the photo it looks smaller.. It's an optical illusion and is defo 22mm.

I think the pipe after the pump and the cold feed is 15mm, hopefully you can tell by the photo.

The are only two isolators I can see which are under the bath and are the type with the screwdriver slot, not a red or blue lever type. There are no isolators I can see upstream of the pump or upstream of the isolators under the
bath.

Thanks...

 

[terryplumb]

I assume the pump has not been changed ,and any filters contained within it have been cleaned / checked. Its clear from all the info you have given that the installation is far from ideal ,it is what it is. Its clear that there is not enough flow thru the shower / pump/pipework to activate the pump ,but there is through the tap ( which would be expected as its lower and less restrictive by design). The strange thing is why it works for a week and then doesn't ,but it used to every time. Does the bath get filled once a week ? I am clutching at straws here for a plausible theory ,but here goes...bath fills ,loft tank is not replenishing fast enough ,pump sucks in air and it collects in the vertical pipe to shower after the T...maybe ?
Flow switch in pump a bit iffy ?
If cold is from mains ,its holding the hot non return valve closed .

 

[Wictod]

terryplumb, thanks for all your input, really appreciate it.. I know they done nothing to the pump with respect to cleaning any internal filters out.. they made that clear when we challenged them on the problems.. they said they just connected their pipe work to the push fittings and that was that.. We haven't got the specs of the shower mixer as they supplied and fitted and took all the boxes with them but we do know it is an aqua essentials sphere mixer unit and that apparently needs a minimum of 2 bar to operate correctly from what I read on the internet. I suspect your correct in your explanation .. combination of probably filters not clean in the pump / flow switch / air getting in which tips it over the edge so to speak.. I guess the only thing I can do is swap out the mixer for another with a lower pressure operating range, clean the filters in the pump if they're serviceable and if that don't work get a good plumber in to fit a new pump and correct the pipework.. I don't think they're running the bath when the shower is working so only after the shower fails.. thanks again..

 

[terryplumb]

Your welcome mate. I doubt that changing the shower valve will make any difference. Your problem is there is insufficient flow to start the pump. The pressure you refer to is the working pressure ,which is no doubt fine once the pump runs.