air in shower pump

[scotsquine]

I had a Mira88 shower and a Mira PPT3 pump fitted several years ago and this has worked very well until last week when I had a new hot cylinder fitted , very similar to the previous one as far as I can tell. Now every morning I have to let air out of the shower by taking the head off , pointing the unit into the bath, turning the control to its hottest and waiting for the pressure to increase. Then the water runs hot.
Any suggestions how I can convince my plumber that the problem lies somehow with the installation of the new HW tank and that I don't need a new shower system installed ?

 

[Softus]

Easy - get a different plumber.

Your shower can't possibly be the cause of air accumulating in the pipework. Since you say that the cylinder was changed, my best guess from afar is that the outlet from the cylinder isn't correctly plumber such that air can escape up the vent pipe.

Can you take a picture of the pipework at and around the top of the cylinder, and post it here for us to see?

 

[scotsquine]

Thankyou for replying
My plumber is coming back tonight I hope, but if I've still got the problem I'll take the photo

 

[scotsquine]

the plumber hasn't been yet , but on the phone he reckons that the shower pump(which is in the loft where it's always been) needs to be moved but I don't agree. I haven't managed to send the photograph,sorry[/img]

 

[Softus]

Hi scotsquine

I've received your images.

I can't see the supply to the shower, or the pump, but the second image appears to clearly show that the pipework rises from the soldered tee on the horizontal pipe coming from the top of the cylinder, before turning on a compression elbow and disappearing into the wall.

If the supply to your shower is on the other side of that wall, then it should be obvious to any heating engineer that air will collect in your shower supply before passing toward the vent.

If my assumptions about the bits I can't see are correct, then the pipework is fundamentally wrong. It wouldn't be very hard to put it right though, as follows:

1. Remove the soldered tee.
2. Turn the existing compresion tee into a coupling.
3. Place that tee higher up the vertical pipe, turning the branch 90° to the right and pipe from the branch into the elbow that's going through the wall.
4. Add a new tee, higher than the one fitted in step 3, and make the cylinder outlet into the branch of that.

This is the kind of problem that results from someone just blithely fitting a new cylinder but taking no care to check all the venting arrangements.

Just curious - is your new cylinder taller than the old one? Or was it the same size but raised on a new or higher platform?

 

[scotsquine]

Hi softus,
yes, the new cylinder is slightly bigger in all dimensions and is on a new hardwood base. I had to raise the level of a slatted shelf above by a couple of inches which restricted the photo angles.
thanks very much for your help

 

[Softus]

Aha! There's yer problem then.

Your plumber didn't change the surrounding pipework (enough) to accomodate the taller cylinder.

Did my suggested changes make sense to you? You could tackle this yourself if you wished, since there's virtually no draining down required on the cylinder outlet - just shut off the inlet to the cylinder and run the kitchen hot tap. Also turn off the heating so that it doesn't keep pushing water out of the top. A good job for a novice to cut his teeth on!

 

[scotsquine]

Hmmmm....you're right about the novice, but wrong about his teeth.(scotsquine means scottish lass !) Although I was able to tackle the shelf-raising project - using glue very successfully(it will have to be wrecked to allow more work done!) I won't be having a go at the pipework

 

[Softus]

Oops. No offence meant scotsquine.

All the best - I hope you find a good heating engineer to make the changes.