Unvented pressurised system - some say you can’t add a shower pump - technically why (forgetting any legal restrictions if there any)

[Elkato531]

Clearly none of the problems being touted are real

Well you clearly know best. Obviously the water regs are there to restrict your freedom to do what the hell you like and not to help ensure adequate supply and water quality for everyone.
If you are looking for validation for breaking the rules, you're in the wrong place.

 

[Mikerightsecondtime]

Well you clearly know best. Obviously the water regs are there to restrict your freedom to do what the hell you like and not to help ensure adequate supply and water quality for everyone.
If you are looking for validation for breaking the rules, you're in the wrong place.

So you are saying it is impossible to boost pressure at a 2nd floor shower, if the shower runs on an unvented system. Is that right? One way would be to put a pump on the shower feed, but you think that’ll be like Chernobyl, so what do you suggest - or is it just ‘computer says no’ and we can’t look beyond the obvious or what the rules say

 

[Elkato531]

As already mentioned, if you have 3 bar incoming pressure you should still have 2.3 bar at a height of 7m. There will be a little extra pressure loss due to resistance of pipes and fittings but there will still be more than enough pressure for a good shower. If you have poor flow, the problem will lie with the flow rate and not with the pressure. Flow rate is mainly affected by restrictive pipes (usually the pipe from the external stopcock into the house) and this is where you can make the biggest improvement. Many properties have 1/2" copper pipe and older properties may still have steel or lead pipe. Internal corrosion, particularly of steel pipe) can reduce the internal diameter significantly. Upgrading to 25mm MDPE can make a large improvement.
Your installer should have tested both pressure AND flow rate before advising on an unvented system. Unfortunately, many installers fail to do this.
Attempting to boost the pressure to deliver more flow would be a bodge tackling the symptoms and not the causes. And, as you already know even if you fail to understand the reasons, it would be against regulations.

 

[Mikerightsecondtime]

Ok, for the benefit of others who may read this thread with a similar issue. I managed to improve the performance of the shower by about 30%. That took it from a slightly weaker shower, to fairly good, but not as good as you’d get with a 2 bar shower pump on it - but easily good enough for a spare room shower. How? (1) attached a WRAS approved flowflex inline shower booster (approx £130) to the hot pipe inlet to the shower. This is safe for unvented systems and is safe and compliant to use in this location on the pipe run (as specifically set out in the supplier website under the unvented systems section). This improved the shower by 15%, and complies with regulations. (2) attached a wide bore shower hose between the mixer and the shower head (£10). This improved the shower by a further 10%. 3) bought a mira beat 4-spray 110m shower head (£40) and this improved the shower by a further 10%. So total cost about £160, and shower experience now moves from slightly underwhelming to good and ok. The in-line booster was easy to fit, took about 30 mins.Hope this helps people looking into this and helps you cut through the wailing you sometimes get in here of people offering problems and not solutions.

 

[dilalio]

Hope this helps people looking into this and helps you cut through the wailing you sometimes get in here of people offering problems and not solutions.

There's always been an inline booster.
Powershowerbooster - inventor was/is on here.

As for your parting comment, I wonder if you'd object if a layman commented on how he could do the job you do or did, with no rules to abide by?

 

[Mikerightsecondtime]

the solution I have applied complies with all the rules. If a layman said what they planned to do in my job that was against the rules, but gets the result they want, I’d say, you shouldn’t do that because of X,Y,Z, but what you CAN do is A,B,C - and if you do that, it should give you a good result. I’d be looking for that A,B,C to be the most pragmatic, cost effective solution. E.g. if a new shower head would fix it, I’d recommend that rather than a new shower. In my case it’s gone from can’t do with no solutions, to maybe dig up the incoming main, etc. all the while there was a solution that works, is compliant in every way and safe, and cost less than £200. Unfortunately ‘hHere’s always been an in-line booster’ doesn’t help when that is only mentioned after I bring it up! Anyway, hopefully someone reading this can get to the end of the story a bit quicker now and cut through to a decent low cost solution that works. All the best.

 

[dilalio]

the solution I have applied complies with all the rules. If a layman said what they planned to do in my job that was against the rules, but gets the result they want, I’d say, you shouldn’t do that because of X,Y,Z, but what you CAN do is A,B,C - and if you do that, it should give you a good result. I’d be looking for that A,B,C to be the most pragmatic, cost effective solution. E.g. if a new shower head would fix it, I’d recommend that rather than a new shower. In my case it’s gone from can’t do with no solutions, to maybe dig up the incoming main, etc. all the while there was a solution that works, is compliant in every way and safe, and cost less than £200. Unfortunately ‘hHere’s always been an in-line booster’ doesn’t help when that is only mentioned after I bring it up! Anyway, hopefully someone reading this can get to the end of the story a bit quicker now and cut through to a decent low cost solution that works. All the best.

You didn't ask for other solutions.
Your post seemed hell bent on sticking in a standard shower pump.

Ambiguity in posts aside, I read your posts as I'm doing it and you can all be damned!

As did a few other tradesmen, it would seem.

Perhaps the issue is how you came across in the written word - as is often the case on forums.

Good luck and perhaps be a bit more open and grateful for professional opinion, in future. It'll get you much further