Shower doesn’t start until I open a tap

[Dave4290]

Moved into a house which has weird shower issue.
Shower is mains fed mixer with a pump. When I turn the shower on no water comes out, however if I turn the sink tap on for a few seconds and then turn it off the pump kicks in and the water comes on in the shower.

any ideas whAt causes this and if it can be easily fixed
Thanks

 

[Registered Gas Man]

Number of things could be wrong but we need a bit of detail to help. A mains fed shower combined with a pump is not really a thing, it's usually one or the other...

Can we have some pictures of the hot water tank and the pump?

 

[Madrab]

It may be that the cold is mains and the hot is pumped gravity. Even then though that kind of setup will always be prone to issues. It should really be redone properly and be one or the other. Easy fixed but will need a bit of work by someone that knows what they are doing and familiar with gravity systems.

 

[just pumps]

Could it be the shower hose and head were changed prior to you moving in and the hose is a small bore.

 

[Harry Bloomfield]

My guess would be the pump pressure switch, is not seeing a low enough drop in pressure to switch on. Turning the tap on, drops the pressure just enough more for the switch to activate.

 

[just pumps]

My guess would be the pump pressure switch, is not seeing a low enough drop in pressure to switch on. Turning the tap on, drops the pressure just enough more for the switch to activate.

Which I`ve seen before after the hose & head have been changed.

 

[Dave4290]

Thanks for the replies, and apologies for the slow response (PC issues).

The shower is on the ground floor and the hot water tank is in a cupboard on the floor above. The cold is mains fed and the hot is mains fed but goes through the pump (to increase water pressure I assume) which is on the other side of the wall in the adjacent room.
I actually changed the shower head myself recently as I wanted a wider one, but the issue was present before and after.

 

[terryplumb]

Show us a picture of your hot water cylinder , I doubt your hot water is under mains pressure.

 

[Dave4290]

Show us a picture of your hot water cylinder , I doubt your hot water is under mains pressure.

Sorry I am probably not explaining it very well and may have confused things.

Here is hot water tank

 

[terryplumb]

Your hot water is gravity fed ,and pressure would be poor ,hence a pump has been fitted . There is insufficient water flow through the shower to trigger the pump . This could be the shower head itself ,or the flexible hose are too restrictive to flow. Remove the shower head and let the hose hang down .Then run the shower and see if pump now starts.

 

[Dave4290]

Your hot water is gravity fed ,and pressure would be poor ,hence a pump has been fitted . There is insufficient water flow through the shower to trigger the pump . This could be the shower head itself ,or the flexible hose are too restrictive to flow. Remove the shower head and let the hose hang down .Then run the shower and see if pump now starts.

Ok, I will try this in the morning as my son has just used the shower so it will start fine now without having to run the tap first. It is when it has been left for a while that I notice the issue.
Will report back
Thanks

 

[just pumps]

Your hot water is gravity fed ,and pressure would be poor ,hence a pump has been fitted . There is insufficient water flow through the shower to trigger the pump . This could be the shower head itself ,or the flexible hose are too restrictive to flow. Remove the shower head and let the hose hang down .Then run the shower and see if pump now starts.

Actually, remove the head and hold the hose up high where it would normaly be first before lowering it if it doesnt start the pump.

 

[terryplumb]

Ok, I will try this in the morning as my son has just used the shower so it will start fine now without having to run the tap first. It is when it has been left for a while that I notice the issue.
Will report back
Thanks

Yes ok. The fact that it occurs after it has been left idle would be indicative of the non return valves sticking .

 

[terryplumb]

If I have understood you correctly ,it's not just the pump doesn't kick in ,but no water whatsoever comes out the shower head when shower is turned on, after being idle ( probably overnight) but once it gets working ,you can then use it repeatedly without issue ( for the rest of the day)...is this all correct ??

 

[Dave4290]

If I have understood you correctly ,it's not just the pump doesn't kick in ,but no water whatsoever comes out the shower head when shower is turned on, after being idle ( probably overnight) but once it gets working ,you can then use it repeatedly without issue ( for the rest of the day)...is this all correct ??

Yes that is correct