Shower works only when sink tap turned on

[Anna204]

Hi there,

We have a mixer shower in our bathroom. In order to make the shower work we have to turn it onto full (at which no water comes out) and then turn the hot tap in our bathroom sink immediately on and off, at which point water then comes from the shower.

Does anyone have any ideas what this could be? I'm not sure if it's anything to do with our gas boiler and vented hot water cylinder - both are quite old but other than this issue we haven't had any problems.

Any advice would be great.

Thanks,

Anna

 

[rpm]

Instead of opening the tap try lowering the shower head to the floor, sounds like a pump issue.

 

[Anna204]

Thanks for your reply.

The shower head is fixed to the wall and there's no way to lower it without removing the tiles.

Is the pump issue something that a plumber can easily sort? I just wanted to get an idea of whether it's a relatively straightforward job or if it's going to be very costly?

 

[rpm]

Couple of Q
New shower & pump or old just started playing up?
Is there a pump for the shower even?

Can`t advise on £`s without eyes on.

 

[SimonG]

Could need a negative head pump or a pump repair. Needs answers to RPM's questions.

 

[stevetheplumber]

i would be looking at the mixer assuming it worked previously the we must assume it has the correct type of pump the pump works when the basin tap is used so it would appear the pump is functioning which only leaves the mixer not passing enough water to kick the pump in check for filters blocked or catridge not functioningmy guess would be its on a normal pump and borderline on head and now theres a restriction its not kicking in even a scaled up head could be the fault try removing the head

 

[DIYBS4]

I have exactly the same issue. We have a boiler and vented cylinder and thermostatic shower mixer, gravity fed so no pump. Mains pressure cold to the mixer.

Any suggestions please?

 

[Harvest Fields]

Have you checked the inlet filters in the mixer?

 

[DIYBS4]

Have you checked the inlet filters in the mixer?

I have replaced the cartridge as it was scaled, but still the same issues.

 

[Harvest Fields]

I have replaced the cartridge as it was scaled, but still the same issues.

The cartridge isn’t the filters though mate. Have you got a picture of the shower and the pump please?

 

[DIYBS4]

There is no pump, the hot is gravity feed from the vented cylinder, the cold is from the mains.

The shower is a concealed mixer type with one knob for on-off and one knob for temp which has this inside it (this is the one I replaced like for like for the old one to see if it solved the problem):

Thermostatic Shower Valve Cartridges. Type 6 SP151 with Grub Screw fitting | Steam Shower Spares

I am thinking the issue may be with unbalanced pressures between hot a cold. Is there a solution with NRVs or PRVs that anyone could recommend?

Thank you

 

[Riley]

So has it ever worked

 

[stevetheplumber]

sounds like mains cold and gravity hot opening the basin tap drops the mains pressure and then the hot comes through

pressure reducing valve on the shower feed should work