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orbis June 10th 05 09:28 PM

Mixer shower problem
 
Hi folks,

I wonder if someone can offer any advice.

I've just retiled my bathroom, and needed to remove my mixer shower
unit in the process. Having refitted it a few days later, it's behaving
totally differently - beforehand there was a nice gradual change in
temperature as you changed between hot and cold, with no noticeable
change in pressure.

Now it seems to be only doing either hot or cold, with no happy medium.


The pressure also changes - it's difficult to describe but here goes...
Starting from cold, you turn the temperature lever a long way and
suddenly there is a dramatic increase in pressure and the shower goes
(very) hot. If you turn the lever a long way back the other way, the
water suddenly goes ice cold and the pressure drops again. Wherever the
lever is between these two extremes could produce either hot (high
pressure) or cold (low pressure) water from the shower, depending on
which 'extreme' you last visited. Clear as mud, I know. It's b*ggered,
basically.

Our hot water system's unvented, which I sort of assumed meant that
both hot and cold supplies would be working at the same (mains?)
pressure. Anyway, the hot/cold shower feed is just teed off the feed to
the bath taps, which, er, work fine.

Is it possible there is air trapped in the unit - or dirt/scale build
up, in which case should I attempt to completely open the mixer unit up
and give it a good clean? Or is something likely to have gone kaput -
in which case am I likley to be looking at new parts or a new shower?
The only identifiable mark on it is the word "Hydramax".

Cheers.


BigWallop June 10th 05 10:55 PM


"orbis" wrote in message
oups.com...
Hi folks,

I wonder if someone can offer any advice.

I've just retiled my bathroom, and needed to remove my mixer shower
unit in the process. Having refitted it a few days later, it's behaving
totally differently - beforehand there was a nice gradual change in
temperature as you changed between hot and cold, with no noticeable
change in pressure.

Now it seems to be only doing either hot or cold, with no happy medium.


The pressure also changes - it's difficult to describe but here goes...
Starting from cold, you turn the temperature lever a long way and
suddenly there is a dramatic increase in pressure and the shower goes
(very) hot. If you turn the lever a long way back the other way, the
water suddenly goes ice cold and the pressure drops again. Wherever the
lever is between these two extremes could produce either hot (high
pressure) or cold (low pressure) water from the shower, depending on
which 'extreme' you last visited. Clear as mud, I know. It's b*ggered,
basically.

Our hot water system's unvented, which I sort of assumed meant that
both hot and cold supplies would be working at the same (mains?)
pressure. Anyway, the hot/cold shower feed is just teed off the feed to
the bath taps, which, er, work fine.

Is it possible there is air trapped in the unit - or dirt/scale build
up, in which case should I attempt to completely open the mixer unit up
and give it a good clean? Or is something likely to have gone kaput -
in which case am I likley to be looking at new parts or a new shower?
The only identifiable mark on it is the word "Hydramax".

Cheers.


You had to turn the water off at isolator valves, before you worked on the
shower. The problem is probably in the cold water isolator valve, not the
shower mixer. Make sure both isolator valves are fully open.



orbis June 10th 05 11:13 PM

If only! Annoyingly there are no isolator valves on the supply to the
bath taps (and therefore the shower mixer). I think this may be against
the regs, but that's a problem for another day...

I had to completely turn off the water to work on the shower.


BigWallop June 11th 05 01:40 AM


"orbis" wrote in message
oups.com...
If only! Annoyingly there are no isolator valves on the supply to the
bath taps (and therefore the shower mixer). I think this may be against
the regs, but that's a problem for another day...

I had to completely turn off the water to work on the shower.


If the water was off and drained, then has something jammed in the cold
water outlet from the water tank? Did you wrap PTFE tape or joint compound
around any fitting when re-installing the mixer valve? Is the hot water
supplied from a different source than the cold, or are they both supplied
from a storage tanks?

The only other thing I can think of, is that you have turned the hot water
supply on, more than it was before. Like hot water from a combi-boiler
supplied from the mains, and the cold supply from a tank in the loft. The
hot water will be reaching the mixer at a higher pressure than the cold
water unless a regulator (gate) valve is in the line somewhere. This
regulator valve may need resetting.



orbis June 11th 05 11:50 AM

No cold water tank, sealed hot water cylinder - unvented system. On
every other outlet both the hot and cold seem to be working at
mains-type pressure. Since there's no pressure difference between
hot/cold anywhere else I guess it could be some debris in the mixer
itself. Will turn the water off again and investigate.

The only reason I'm wary is that the entrance to the inner sanctum of
the mixer unit is via for of those 'star' screws. Which has always said
to me 'you don't want to be doing this unless you know what you're
doing'. Ah well!

Thanks for your help, BigW.


Tim Mitchell June 14th 05 12:33 PM

In article . com, orbis
writes
No cold water tank, sealed hot water cylinder - unvented system. On
every other outlet both the hot and cold seem to be working at
mains-type pressure. Since there's no pressure difference between
hot/cold anywhere else I guess it could be some debris in the mixer
itself. Will turn the water off again and investigate.

The only reason I'm wary is that the entrance to the inner sanctum of
the mixer unit is via for of those 'star' screws. Which has always said
to me 'you don't want to be doing this unless you know what you're
doing'. Ah well!

I took my shower mixer to bits, it had torx screws, but inside it was
actually very simple, so I wouldn't be too scared. Mine has some mesh
filters actually inside the mixer, so it could be you've got something
similar with some crud in it.

It certainly sounds like a hot/cold pressure imbalance for whatever
reason.
--
Tim Mitchell


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