Pump Shower air lock effecting water supply.

karltimber · 25-01-2015 3:52pm #1

More plumbing

Have a power shower downstairs supplied from an immersion tank upstairs.
Hot water supply was getting slower and slower, especially since the summer.
Checked out the pump motor, supply at the shower, all seemed fine.
The cold water was pumping fine but not the hot.

Eventually looked at the immersion tank, which has a priority flow fitting for the shower.
So the shower takes priority over the tap hot supply.
Opened the compression fitting (under pressure) at A (in the attached pic) and let some water out and possibly some air.
Now the shower is good again – well 80% good. So an air lock was causing it.
As you can see from the pic, there is no where for any air to vent off, from this shower supply.

Question – what can I fit along this ¾” pipe to vent air every now and again.
Instead of breaking the seal at point A each time. There is a ball valve there too.
Is it easier to add a ¾” T and another ball valve to vent it ?

Pic shows the basic setup.

K

Sleeper12 · 25-01-2015 5:50pm

I think you are mistaken about your setup. I don't believe that your shower has priority at all. there is a flange fitted to the top of the cylinder. this allows the pump to take hot water a few inches below the top of the cylinder. The reason for this is so your pump doesn't suck any air from the top of the cylinder. I think it's a coincidence that the shower seems to have improved when you opened the fitting.
I would think that the real problem is either the pump itself or possibly the thermostatic cartridge on the shower.

karltimber · 25-01-2015 6:17pm

ok, so could it be that there was an air lock in that pipe, the one that takes water a few inches from below the surface.

IF there was air in that shower pipe, it has no-where to go !
And I released some if it when I broke the seal ??

K

Sleeper12 · 25-01-2015 6:52pm

it's very unlikely air in that pipe. it's designed so it doesn't draw in air as air can damage the pump. never say never but my money would be on the problem being the pump or cartridge.

karltimber · 25-01-2015 7:20pm

Thanks for that

explain what a thermostatic cartridge does please ?
didn't even know I had one.

Thx

K

Sleeper12 · 25-01-2015 7:47pm

the cartridge is part of the shower. it's the brains as such. It mixes the hot and cold water. when they fail it's usually on the hot side rather than the cold side.

Calahonda52 · 25-01-2015 10:46pm

The air, if any, at A, goes left and up the vertical pipe as shown.
A is the top of what is called a surrey flange
This vertical pipe is ur expansion pipe and must always be free to allow cylinder vent if it boils
The pressure u describe is only the static pressure in the vert pipe caused by the cold water feed tank being X feet above.

karltimber · 31-01-2015 9:42am

Sleeper12 wrote: »

the cartridge is part of the shower. it's the brains as such. It mixes the hot and cold water. when they fail it's usually on the hot side rather than the cold side.

has a look at the t-cartridge yesterday - a fully contained plastic unit.
Is it a replacement for this type. can't seem to open it at all.
The 3 washers are the only things replaceable.
At stg100 for this part, how can I be sure that's the issue ( which it probably is)

thx

Pump Shower air lock effecting water supply.

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