Slow starting shower pump solution !

[Jules]

Came across this problem last week, thought I would share it in case it saves someone an hour of piddling about!

Fitted a new Mira bar mixer shower in place of old Triton. Runs off an existing Salamander pump fitted in loft. Dubious whether enough head but been working fine for 4 years, so what the hell.

All worked perfectly for a week, then got a call back to say pump not coming on.

Did the usual stuff, purged/bled pump, checked filters, etc. Pump would not kick in for about 30 seconds! Took hose off bar valve, no improvement. Purged pump again, checked all filters, tried full cold, full hot, etc. Finally took Mira off, refitted Triton, shower pump kicked in right away! Was starting to think it might be something to do with Mira being a 1/4 turn ceramic disc? Put Mira back on, pump not kicking in again. Maybe not enough head on the CWS for the pump/Mira combination, but then why did it work OK on the Triton?

Just as I was losing the will to live I had a look in the valve outlet and realised there was a flow restrictor in there. Hooked it out, problem solved!
Its worked fine for a week now, kicks in immediately every time.

The only thing I don't understand is why did it work for a few days initially, and then suddenly stop? Any ideas?

 

[Jules]

So this week I have been back AGAIN, 2 months later, to the shower pump I posted about above!
According to the lady, the pump is taking between 30 seconds and 2 minutes to kick in. I asked her to show me what she does.
She pulls the pull cord which switches on the fused spur to the shower. She then gets in the shower and opens the valve (ceramic) and waits for the water. She says that sometimes it dribbles, then pump comes on, and sometimes it dribbles but pump doesn't come on for up to 2 mins.
I have not witnessed this because it comes on straight away every time I go to test it (sods law).
I repeated all the things I did in February and left her with it. I asked her to try opening the valve first, wait for the dribble, then pull the cord. My reasoning being it would test whether problem is due to lack of water or not.
It is a positive head pump in the loft, but only has 400mm head between it and the base of the CWS. The shower head is about 500mm directly below the pump. (HWC in airing cupboard next to shower room).
I am thinking the Mira shower might be more flow-restrictive than the Triton, which is why it worked fine for 4 years and now it doesn't?
What if I fitted non-return valves on the pump outlets? Would this keep enough water in the pump to kick start it?
Or is the whole thing just a coincidence and she needs a new (neg head) pump?
I am out of ideas and would really appreciate any experienced thoughts / advice....