Help me fix my SHITE shower pressure in somewhat complex setup with limited access!

jforte1

Hi all,

Looking for some advice to help get a nice steady pressure (& not scalding) shower in our main bathroom.

I would’ve liked to pump the shower only but unfortunately, the hot & cold feeds that lead to this shower are all underground in walls & I have no access. The feeds come from the attic to a cupboard, go underground, & then split off to all the other sinks & toilets in the house. I only have access to the hot & cold feeds BEFORE they split off to different rooms underground.  

System Summary

Location: Ireland

Setup: Hot water cylinder and cold water storage are both in the loft

Tanks:

• 1 × small tank (for the heating/rads system)
• 2 × large black plastic tanks about 2.5 m apart — not balanced or linked together
• Tank A feeds the hot water cylinder (hot feed)
• Tank B feeds the cold water supply for the house
• Tank B sits roughly 1 m lower than Tank A 

Showers:

• Bristan Zing 2 thermostatic mixer (TMV) – main shower
• Triton T90sr electric shower – gravity-fed, *low-pressure only* – ensuite in master bedroom 

Boiler: 

• Oil-fired

What I’ve Tried So Far

I’ve fitted a single-impeller positive head Stuart Turner Showermate 2.0 bar pump on the hot feed only for the whole house. This helped some, but mostly the main (Bristan) shower is still unusable because of scalding water or very poor pressure at the right temperature.  What happens is the pump cycles & pressure fluctuates badly I can’t get a steady pressure without being scalded. If I mix the water with cold the pump cycles on & off. 

Note: I checked the flow ratios for hot to cold & it’s 11:1 (max is 5:1 for a good TMV shower valve). This has led me to consider pumping both HOT & COLD Feeds.

I put a thermostat on the water cylinder & tried setting up a zone heating system (to control the cylinder temp independently & increase overall heating efficiency) only to realized I had failed to isolate the water cylinder from the downstairs heating loop. Long story short - I can’t control the cylinder temp that way.

I also tried messing with the thermostat on the boiler to try & manage scalding temps but it seems impossible to get a consistent hot shower temperature as our radiators use the coils in the cylinder as a heat leak & the cylinder heats up if the central heating has been on for a while…

Recent Developement

While tracing the pipework in the attic, I found a “T” branch off Tank B (main cold feed) that I’m 90% sure supplies Triton T90sr electric shower separately. That would be great news as this T90sr shower only accepts gravity-fed pressure water.

Plan

1. Install an isolation valve on the cold-water spur from Tank B that I believe feeds the Triton shower and confirm it won’t be receiving pumped water.
2. Upgrade to a Stuart Turner 2 bar twin-impeller pump to boost both the hot and cold feeds from Tank A and Tank B to the whole house, including the Bristan shower (but not the Triton).
   

However, I do know most twin pumps require both feeds to come from the same storage tank, whereas my hot comes from Tank A and cold from Tank B (& they are at slightly different heights).

Questions

1. Can I safely pump both feeds as-is, or would linking the two large tanks (A & B) be required?
2. Would pumping Tank B’s cold line interfere with the Triton T90sr if both showers were used simultaneously? (The pump would be placed after the T branch)
3. Do I need to fit an S-flange or Essex flange on the water cylinder outlet to prevent air ingress?
4. Will the toilets and sinks be able to handle the new 2-bar pressure, since they were gravity-fed previously?

Any advice or confirmation would be hugely appreciated before I buy the twin pump or modify the tanks!

TL;DR: Hot comes from Tank A, cold from Tank B (different heights, not linked). Bristan TMV shower has pressure/temp issues — currently only the hot is pumped. Planning to install a twin pump downstairs to boost both feeds but not sure if I need to link the tanks, vent the cylinder with s-flange. Also unsure if toilets will handle 2 bar.

Thanks so much for your help,

-J

ImTiredOfItAll

The showermate pump is designed for showers only. They are not a system pump. They are designed for both hot and cold running at the same time. I'd be stunned if this pump doesn't burn out in the very near future

Lenar3556

https://www.boards.ie/discussion/2058427457/help-me-fix-my-shite-shower-pressure-in-somewhat-complex-setup-with-limited-access

The experience with the shower was likely due to very different inlet pressures between hot and cold. Most thermostatic cartridges cannot handle this.

Q1 - This is something to check with the manufacturer of any pump you decide to use. But a 1 meter difference in tank height equates to 0.1 bar pressure difference, I wouldn’t have thought it would make any material difference.

Q2. Potentially yes. The T90 should be piped directly into the tank.

Q3. Unless you have a high pressure (unvented) cylinder you cannot pump the tank feed to it. You could pump the outlet, and twin impeller pumps are often located in hot presses for this purpose.

Q4. Unlikely to be an issue.