Ball a stop isolation valve - easy to swap?

[Madrab]

Nope, it's the same but it does mean you have a slightly more complicated, not difficult, system. More things needed to be balanced rather than just put a box on the wall and pipe to it or remote pump both hot and cold therefore balancing isn't an issue, which was the understanding. He's suggesting just pumping hot and using a PRV to balance the cold which could work but more things that could go wrong over time IMO. A good universal pump won't be cheap either.

 

[dishman]

Just a small update:

I was contemplating getting a pump as you know.

But, before i made the decision, I decided to see how a shower would perform without one.

First, I swapped the high pressure tap for a proper (rubber compression washer) low presure tap.

Flow went from 5.5-6L/min to 10L/min.

I then swapped the restricted bore isolation valve for a full bore valve.

Flow went from 10L/min to 14.5L/m

A pretty decent increase in flow!

I then installed a mixertap/shower to see if a shower was even do-able at 0.2 bar.

The result is pretty good! It seems a lot better than the electric shower and that was testing with hot water only. A bit of cold in the mixer and it should have a pretty good flow.

As it is a manual mixer (two taps) it should not be hard to balance.

I do not think I need a pump after all.


To further preserve the flow as much as possible, I am hunting for the widest bore shower hose (pretty hard once you look for one) and the shortest required length. They seem to max out at around 11mm bore. However, a lot of manufacturers do not seem to be consistant in how they measure it.

 

[ianmcd]

Don't fall into the trap of comparing a shower with an open tap flow rate.

Typically a shower needs about 0.5 bar pressure remaining on the pipework to give a good exit speed.

To get that you need at least 5 m head of water to the top of the loft tank. Even ignoring pipework flow resistance.

Tony

Really Tony ? and how many posts have you ranted on about people not knowing the difference between pressure and flow rate ? so you measure the distance to the top of the loft tank ? what if the loft tank is only half full ?

 

[dishman]

Update:

11/12mm bore shower hose is the maximum bore I could find. Using the minimum length required (1.25m) the flow out of the shower head is pretty good. With hot water alone it is OK/pretty decent. Maybe towards the minimum of an acceptable shower. But, better then the electric shower.

What is more interesting is that when the cold water is added (mains pressure), even though only a small amount is required, this has the effect of assisting the hot water (boosting it's pressure). So the shower becomes pretty good. It must be some form of venturi effect (even though it is not a venturi shower).

While looking into pipe runs and flow rates etc I found this really useful page.

http://www.johnhearfield.com/Water/Water_in_pipes2.htm

According to this 1m of 15mm pipe is equivalent in resistance to a length of 7m of 22mm pipe.

I have noticed I have a short 50cm run of 15mm pipe (plus elbows) before the hot bath tap. If this equates to being the equivalent of 4m worth of 22mm pipe, I may swap it out....I guess every little helps.

 

[dishman]

Update:

Due to an inability to stop fiddling. I decided to replace the small section of 15mm pipe plus two 90 degree elbows. It was around 50cm of pipe in all before the hot bath tap. I replaced it with 22mm pipe and two 45 degree elbows and got rid of any isolation valve.

The tap has now been replaced with a victorian style mixertap and shower with full turn taps (traditional washers).

Measuring the flow, I now get in excess of 16 litres per minuite (it overflowed the bucket for the first time).

The flow is now good enough for the shower to be fed from the mixer tap (and therfore the hotwater tank), removing the need for the electric shower. The pressure is just about good enough being gravity fed. I personally would have no issue with the shower. It does not have the force of pressurised shower but it is certainly no dribble.

So from switching out the high pressure taps:

5.5l/min to 10l/min

Swapping out the restricted bore isolation valve 10l/min to 14l/min

15mm pipe to 22mm and a victorian mixertap 14l/m to over 16l/m.

Not bad at all I'd say......

 

[AGAS]

really ?

 

[dishman]

Really...is the shower good enough? Or really.... did I get those increses in l/m?

To be clear, the l/m were those measured from the taps, not the shower.

1) The shower is equivalent if not better (especially in winter) than the electric shower I had before. However, as it is now using hot water from the tank it is much more cost effective. The hot water is also far more consistant as it is coming from a tank.

2) Yes, those increases in flow from the taps are accurate. They were carefully measured each time I changed somthing.