I want to fix a shower mixer tap yo my bath. I thought this would be simple enough, but i asked a plumber if it was a straight forward job. He told me that if my cold water was mains fed i would need a reducing valve.(my cold water is mains fed).Then i asked another plumber for his opinion, and he said i did not need a reducing valve. Will i cause myself problems if i fit the taps without the reducing valve? Someone please help me with this problem.

Dave
It all depends on what your hot water system is.

If you have either a combi boiler or an unvented hot water cylinder
(mains pressure hot water) then you will not require a pressure
reducing valve. Also if you are in an area with low mains water
pressure then you may get away without a reducing valve.

The problem occurs if you have 2 unbalanced pressures entering into the
simple mixer tap configuration. What can happen is that the cold water
overpowers the hot water with the result that you can't adjust the
output temperature very easily.

Any more questions on this please just ask.

Calum Sabey
(Newark Traditional Kitchens 01556 690544)

On Sat, 28 Oct 2006 22:35:54 +0100, davemo
wrote:


I want to fix a shower mixer tap yo my bath. I thought this would be
simple enough, but i asked a plumber if it was a straight forward job.
He told me that if my cold water was mains fed i would need a reducing
valve.(my cold water is mains fed).Then i asked another plumber for his
opinion, and he said i did not need a reducing valve. Will i cause
myself problems if i fit the taps without the reducing valve? Someone
please help me with this problem.

Calum has given a perfect answer.

I ran mixers on an open system for some months waiting for my boiler
to be connected.

Any rash use of the tap caused the overflow to blast water out over
the garden as I was forcing mains cold up the hot pipe into the roof
tank.

davemo wrote:
I want to fix a shower mixer tap yo my bath. I thought this would be
simple enough, but i asked a plumber if it was a straight forward job.
He told me that if my cold water was mains fed i would need a reducing
valve.(my cold water is mains fed).Then i asked another plumber for his
opinion, and he said i did not need a reducing valve. Will i cause
myself problems if i fit the taps without the reducing valve? Someone
please help me with this problem.




If you have different pressure hot and cold water, it will never be
satisfactory whatever you do.


I HAVE done it, but it was a bodge at best. Buy turning the cold right
down you could sometimes get enough suitably warm water to rinse your
hair with.

You may do better if the tank is more than 5 feet higher than the bath,
which mine wasn't ;-)

davemo wrote:
I want to fix a shower mixer tap yo my bath. I thought this would be
simple enough, but i asked a plumber if it was a straight forward job.
He told me that if my cold water was mains fed i would need a reducing
valve.(my cold water is mains fed).Then i asked another plumber for
his opinion, and he said i did not need a reducing valve. Will i cause
myself problems if i fit the taps without the reducing valve? Someone
please help me with this problem.

Most shower mixers are designed to work on 'tank' fed hot & cold. There is
a specific type/make that is designed to work on 'mains cold, tank hot' and
they use the mains cold pressure to suck in the hot water. Can't recall any
brand names, but the best bet is to go to a 'real' plumbers merchant - as
opposed to a 'shed' and ask.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

The Medway Handyman wrote:
davemo wrote:
I want to fix a shower mixer tap yo my bath. I thought this would be
simple enough, but i asked a plumber if it was a straight forward job.
He told me that if my cold water was mains fed i would need a reducing
valve.(my cold water is mains fed).Then i asked another plumber for
his opinion, and he said i did not need a reducing valve. Will i cause
myself problems if i fit the taps without the reducing valve? Someone
please help me with this problem.

Most shower mixers are designed to work on 'tank' fed hot & cold. There is
a specific type/make that is designed to work on 'mains cold, tank hot' and
they use the mains cold pressure to suck in the hot water. Can't recall any
brand names, but the best bet is to go to a 'real' plumbers merchant - as
opposed to a 'shed' and ask.


--

Venturi showers. Trevi boost is the easiest to get hold of (plumb
center do them for ~£200).

A

wrote:


Venturi showers. Trevi boost is the easiest to get hold of (plumb
center do them for ~£200).

Trevi ! That's the one! Thanks for that.


--
Dave
The Medway Handyman
www.medwayhandyman.co.uk
01634 717930
07850 597257

Ta for advice people. I will put the mixer taps on, but i will keep the old ones just in case

Well, whilst everyone is correct in their information so far, it seems
that the original post was looking for a mixer/shower tap as opposed to
a mixer shower- which is seperate to the tap. I stand by my original
posting at the begining, if this is the case. Also just because a
system doesnt owrk with 5ft of head in one location, it doesn't mean
that it will not work on another. It is to do with the differential
betweem the cold pressure (mains) and hot water (gravity). My
experience is that it will be unlikely, but not impossible for this
setup to work satisfactorily.

A professional would fit a PRV as standard, but this is a DIY group
where you can add components on a trial and error basis and save some
money if you dont need the "full" setup. A proffessionals time would
cost more than the component in question, but in this instance (given
this group) this is not the case.

No harm will be done in this instance by trying before buying a PRV.

Calum Sabey
(Newark Traditional Kitchens 01556 690544)

i have a combie boiler. Can i just run off hot water till it stops, change taps,put water back
on causing no harm to the boiler

Dave

If you have a Combi boiler then there is no problem withy your proposed
setup no matter what you use. To fit taps just turn off the mains cold,
then put both cold and hot taps on in your bathroom, and leave them on.
Then do the same with the lowest taps in the house to allow the water
out of the pipes in your bathroom.

You are now ready to remove the existing and put on the replacements.

Calum Sabey
(Newark Traditional Kitchens 01556 690544)

Thanks for your advice mate, you have been very helpful