PRV's plumbing 'nightmare'

[waterrat]

hello everyone....
ive just completed a monster project and run up against something i just can't fathom. Ive replastered my living room, which was back breaking, but came out well... i'd never done that before... the i installed a new bathroom. This included laying a new floating floor, installing a towel warmer (draining flushing and refilling the C/H) re-siting the loo and putting in a bath, false wall for a new shower, the full works really, on a 1937 house. I've really enjoyed it, and it aint a bad job, the tiling isnt perfect, but its only me that notices.
when i first turned the water on to the new shower (a mira go thermostatic power shower) it creaked a bit, then pretty much exploded off the wall, it was hilarious and scary at the same time, you couldnt make it up.
so i reassembled it, and tried again, same result pretty much, although the explosion took a little longer to occur. now, after 24hrs of head scratching i figured out that the cold water pressure is too high (about 3 bars i think) so i went out and got a PRV, reduced the water pressure to spec (about 1 bar) and it all worked fine for a while, but then after about three weeks, pop, it did it again, and this time when i reassembled it, the rubber pipe that connects the mixer to the pump was bulging when the water is turned on.

i'm just exhausted with it now, i've single handedly renovated my bathroom and now i think that the problem isnt the DYNAMIC water pressure, its the STATIC water pressure. So at last to my question... can any of you knowledgeable people point me in the direction of a PRV, preferebly 15mm compression fit that will control the static water pressure in me pipes. Or suggest a better fix of course? i am in you debt,

waterrat

 

[Al-Glasgow]

Have you fitted a pumped shower directly to mains cold supply ?

Al

 

[DaleRCL]

What do you mean by power shower? What is the set up?

 

[waterrat]

Hi to you both and thanks
Basically, the bathroom used to be downstairs (in 1937) when it was moved upstairs I think the cold supply was routed up to tbe bedroom above in a 15mm pipe. The hot water is gravity fed but the h/w storage rank is on the same level as the bathroom. The end result is sh*te hot water pressure and too much cold pressure.
The shower has a pump in it, but it does not heat the water, it needs a hot and cold supply . There are no other pumps in the system, I can't think of anything else....

 

[CBF]

you shouldn't have a pump or pumped shower connected to the cold mains thats your problem

 

[gas112]

Your cold supply to shower should come from the tank and connection lower than the one that feeds the cylinder.

But the pipe should not be pushing out anyway is the pipe chrome by any chance

 

[waterrat]

hi again,
the pipe i'm talking about is a rubber connecting hose inside the shower. it bulges if i turn the C/W on.
i realise the cold water shouldn't come straight from the mains, in fact until you said that, i hadnt really given alot of thought to where it came from as i was replacing an existing bathroom. my only consideration for the new shower was the low pressure H/W system,

D'oh.

what to do then? we have a cold water tank, should i be thinking about running a new pipe from that in to the bathroom, because that is gonna be a real headache now!! i think i assumed that the C/W wasn't mains because it was connected to the downstairs bathroom originally. i guess all in all that would have made the water pressures 'nominally equal' down there.

the other thing ive considered, is installing a remote pump for the hot water, and then just using a mixer on the wall in the bathroom. i dunno. any thoughts? thanks for your input ladies and gents

 

[DaleRCL]

You have 2 main options really. Either run a new dedicated cold supply from the tank in your loft to the shower so you have equal incoming pressures both suitable for the integral pump.
Or, if that's too disruptive, change your current shower for a Venturi shower. The main one I know of is Trevi Boost. This is designed for mains water and gravity hot. It is set up in such a way that the force from the mains cold boosts the low pressure hot to give a decent flow rate.
Trying to pump just the hot to bring it in line with the cold mains is not the best idea and you will still have to change your shower valve as you can't pump into another pump. And you certainly can't leave mains connected to a pump.

 

[waterrat]

Dale, thanks for this.
funny how i had complicated things in my head. For some reason i had imagined putting in a new cold supply to the bathroom when in fact its only the shower that needs it. And that is only an hour or so's work, just to run a pipe from the tank, across the loft space and then down behind my false wall. i left that open at the bottom (under the tap end of the bath) for maintainance/air circulation anyway.

i had no idea venturi showers even existed. bloody b and q, i explained our set up and the difference in pressures grrr. If i hadn't already bought a 250 quid shower i would probably go with a venturi one, as it is, i'll run the pipe.

my only concern, is that i don't really know what the C/W pressure will be from the new pipe. The tank is a 180ltr, and the difference in height between the shower C/W inlet and the C/W tank is about 1.5 meters... i was gonna use 15mm pipe.

thanks for your advice and for taking the time to help me everyone
i shall post when resolved and tested, the snow prevents me from completing my mission at present.

waterrat

 

[waterrat]

well, it looks like that's that, new C/W feed installed from loft and the shower sounds much happier! no leaky no more and gets hotter perfect

i discovered on my travels that the tank in the loft (the big one) only feeds the hot water tank below it. there is a smaller header tank for the C/H also..... which must mean that all the cold water taps/appliances in my hoose are directly on the mains... whats that all about. thanks again for your help everyone,

Waterrat

 

[CBF]

sometimes it's easier to run the pipework like that plus you get drinking water at every outlet

 

[waterrat]

i see, thanks. As long as it's not unusual.... there don't appear to be any problems due to pressure anywhere else in the house. its all good