Power Shower Pump Not Cutting In

[PhilD2]

Hello
I've had my power shower pump for about 5 years. Right from the word go I was often having to lower the shower head in to the bath to get the pump to cut in but now sometimes it just wont cut in at all. It seems to be ok if hot water hasn't been used for a while but as soon as I use some of the water i.e. by someone having a shower then it won't cut in again for at least a couple of hours.
I presume the hot water tank not being full is lowering the water pressure and therefore the pump does not have enough pressure on it to force it to cut in.
Any guidance or advice on what I can do would be much appreciated.
Forgive my extreme ignorance on the subject but as well as a tank in the loft I also have an immersion heater, for which I do not turn the power switch on. Will turning this on make any difference - due to the erratic nature of when the pump kicks in I am struggling to diagnose it by trial and error.

Thanks
Phil

 

[PhilD2]

Sorry, forgot to mention above that the Pump in question is a Showermate 1.2 bar single.

 

[hi-spec plumbing heating]

Sorry, forgot to mention above that the Pump in question is a Showermate 1.2 bar single.

and how it plumbed in.

 

[PhilD2]

Hi, some more information again.
The pump is in a positive head position. It is sat under the bath, with the immersion heater in the airing cupboard and the cold water tank in the loft.
Would putting in a larger cold water tank increase the water pressure?
Thanks.

 

[hi-spec plumbing heating]

Hi, some more information again.
The pump is in a positive head position. It is sat under the bath, with the immersion heater in the airing cupboard and the cold water tank in the loft.
Would putting in a larger cold water tank increase the water pressure?
Thanks.

no it's not a larger tank that gives pressure it is hight.
hows the hot plumbed in ?
surrey flange, tee of the hot feed, in 22mm or 15mm ?
does it come from the cylinder through bathroom wall to under bath or up into loft then down ?

most probs with pumps are air or flow switch related.

 

[hi-spec plumbing heating]

just noticed it's a single pump your using is this between the mixer and shower head ?

 

[PhilD2]

Hi, the pump is between the hot water outlet from the immersion heater and the mixer.
All the pipework is 22mm but to be honest I don't know how to identify a surrey flange.
Sorry my answers aren't much help in diagnosing it, I'm considerably out of my depth here.
It seems to work fine until a certain amount of water is used up and then won't work again for a while.
When I take the shower head off completely it is more likely to work but often even without the shower head on it still doesn't cut in. I have replaced the shower head and it is more likely to work with the new one but still works better with no shower head.

 

[hi-spec plumbing heating]

where is the cold to the mixer from ?

 

[PhilD2]

The cold is on a direct feed, there is no pump on the cold supply. When I turn the shower on and the pump doesn't kick in the cold water is still coming through.

 

[PhilD2]

Oh and also I forgot to mention that the flow generally to the hot taps in the bathroom (in particular the sink) is fairly low. These are not connected via the pump though.

 

[hi-spec plumbing heating]

i can now see why you have had problems from day 1.

you have a pump on the hot side feeding mixer but the cold supply is direct. your pressure either side must be equal. yours isn't.

showermate 1.2 single is designed to go between the mixer valve and showerhead.

not how you have it supply feeding mixer.

read the instructions they will tell you.

http://www.stuartturner.co.uk/default.aspx?page=283

 

[PhilD2]

Thanks a lot for your help, I hadn't picked up on that from the installation manual.
It would be a lot of disruption (removing tiles etc) to relocate the pump so it seems that one option then for me is to buy a twin pump to replace the current pump - connecting the hot in the same position but also connecting the cold feed through the other side of the pump, so that both are connected prior to the mixer valve. Judging by the link you sent me that is the correct installation for twin pumps.
Would you anticipate that this would work - i.e. do you think it is likely that the reason I've been having problems is just down to the fact I have fitted it incorrectly?
Alternatively are there pumps that do work by just taking a hot feed? I have been doing some internet research and it doesn't seem that there are any that work that way.

Thanks again for your help.

 

[hi-spec plumbing heating]

when you say direct cold feed, you mean from the mains.

 

[PhilD2]

No sorry my terminology isn't great. It's not direct from the mains I just meant it was direct from the tank rather than via a pump.

 

[hi-spec plumbing heating]

you have unbalanced pressures need to be both from a pump.