Hot Water Puzzle

[WhoMe?]

Hi,

I have an issue with the hot water supply to our new bathroom which has stumped a couple of plumbers and a builder, short of spending a lot of money for something that might cause more problems. I'll try to explain it clearly and would be grateful for any ideas:

We live in a 200 yr old Victorian house where the upstairs shower (electric) room had hot water supplied to the taps at a very low pressure from a cylinder and cold from the water tank, no bath installed. We recently got a new bathroom fitted (a complete overhaul), we installed a new electric shower, doubled vanity and a bath. All taps are mixers. The builder installed new pipework and connected the cold to the mains, with the plan to put the hot on a pump.

All installed fine with no pump at first, when the mixer taps mix it made an awful noise which is due to the unequal pressure apparently. A negative head 2 bar Stuart Turner single pump was then installed, which when it was turned on nothing seemed to happen. The builder then discovered that this was because the water was just pumping out of the expansion pipe's vent. It seems that the hot water supply to the bathroom is T'd off the expansion pipe just under the water tank (which according to Stuart Turner tech advice is causing the problem and would a be okay if T'd off the expansion pipe much closer to the cylinder). A plumber thinks that the problem is that there's still unequal pressure in the mixer tap.

The solutions that I have heard are the following, I'll try to rank in order of severity:

1. None return valves - although the plumber was doubtful
2. A Warix flange
3. Cold water back onto tank and pump both
4. Run a new pipe to cylinder for hot water and T of expansion pipe lower down
5. Install an unvented cylinder - we live in a old house and not sure if the pipes will stand up to it. In about 10years we also plan to go ASHP so maybe a wasted cost now as I understand they need specific cylinders.
6. Unvented and re-pipe house. Obviously expensive but 'destroying' house now is better than later after we refurb.

Has anyone got any views on what's causing the problem and how to fix?

Thanks

 

[ETAF]

Just a DIYer Not a plumber - But I did setup with the builder a bathroom with shower mixer over the bath in a bungalow with hotwater tank in the loft

Where is the issue - Bath Taps , Sink Taps ? Both - I assume the shower is fine.
The shower I assume is OK, as that is on the water Mains supply ?

we installed a new electric shower, doubled vanity and a bath. All taps are mixers.

I assume the hot works OK on its own and the cold on its own.

With all our cold water on mains supply , we did have an issue on the bath / shower as the cold water was at a much higher pressure and i looked at fitting all sorts of pumps - BUT only had a small hot water tank + pump needs to be reported to our local water authority.

I made sure we had 22mm pipework from the cylinder all the way to the hot tap for the bath , which was not the original case as it dropped to 15mm for a short length.
I also made sure the taps were low pressure types, and NOT needing 1bar to work , and we used full bore isolation valves.

I also got a bigger bore shower hose 11mm from screwfix (I know that is not your issue, on an electric shower , but our shower is off a bath mixer tap) and i also put a pressure reducer fitted onto the cold supply to the bath only
My shower works great , even though the shower head is probably only 24" or less below the bottom of the hot water tank.

maybe a pressure reducer on the cold water supply at the taps , i would make sure not on the cistern as that would slow the fill time.
i think this was the one i purchased from screwfix
https://www.screwfix.com/p/reliance-valves-predator-pressure-reducing-valve-15mm-x-15mm/914hr

But as i say not a plumber

 

[picasso]

Either pump hot and cold or preferably unvented cylinder.

 

[fixitflav]

We live in a 200 yr old Victorian house

Minor point - Victoria took the throne in 1837, 184 years ago

 

[polesapart]

Fair point.

George IV was King of the United Kingdom of Great Britain and Ireland (and also King of Hannover) in 1821.

 

[polesapart]

And we'd just finished kicking the s*** out of the French at Waterloo (not the station).

 

[BoilerBob]

Always good to get the stick out and give the duplicitous frogs a good thrashing. Bob

 

[WhoMe?]

Thanks for the advice from the 1st 2, not that sure how helpful the last few are. Maybe a hidden message . Alright, 150ish years old.

 

[fixitflav]

And we'd just finished kicking the s*** out of the French at Waterloo (not the station).

With a bit of help from the Prussians

 

[fixitflav]

Fair point.

George IV was King of the United Kingdom of Great Britain and Ireland (and also King of Hannover) in 1821.

Then William IV before Vicky

 

[polesapart]

With a bit of help from the Prussians

Yes.

Some say the Prussians were a touch tardy in showing up only when the Old Guard had been turned back by Wellington's troops; others that the arrival of Blucher's fresh army was decisive in turning a French defeat into a rout.

What's your view?

 

[fixitflav]

What's your view?

I don't have one, I'm afraid. I know there were Prussian troops under Blucher taking part, but I haven't studied it enough to know how much each mob contributed. Probably opinion varies depending on the historian anyway.

 

[WhoMe?]

I say Wellington was winning with a struggle and the old timer put the nail in the coffin. A fresh army on the flank would scare most.

Not about my plumbing....