£2k for water main upgrade, other options?
- Thread starter Iknowcraig
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Dan, I'd be interested to hear why you believe this would not work? I don't want this to descend into an argument over who knows better, as many threads do, but rather genuinely intrigued to the answer.
For my part, all of the reading I've done on the subject says that reducing the pipework resistance anywhere in the run will result in increased flow.
From a practical perspective, here are some observations which seem to back this up (but happy to be corrected):
1. Boilers usually have 22mm primary flow and return tappings, yet increasing the primary flow and return pipes to 28mm or above reduces pressure loss. Not to mention some heat exchangers which have extremely small bore pipework internally.
2. Water softeners typically have 22mm inlets and outlets, but increasing internal pipework to 28mm results in an increase in flow rate.
3. My Megaflo cylinder has 22mm tappings. After increasing the pipework to and from it to 28mm, I saw a significant increase in flow rate.
Look at the innards of a 22mm stopcock, which are well below 22mm. Look inside a 22mm zone valve the bores drops to about 15mm inside.
If there is 4 bar static pressure and say 30 litres per min at the boundary from a 20mm pipe (approx 15mm), taking it using 20mm/15mm into and around the house will mean a substantial flow and dynamic pressure drop around the house. Using 35mm to the house, 22mm inside the house for much of the pipework (like a dedicated 22mm pipe to a combi or unvented cylinder) and full bore stoptaps, will not reduce that 4 bar and flow rate too much.
If the OP has spare 35mm pipe parallel it up from the boundary to the house. Blue plastic pipe is cheap. I advised a friend to parallel up 25mm blue pipe from the boundary to the house as he had enough left over (25mm was coming in from the road) and go with 22mm on some legs in the house like a dedicated pipe to the combi - a big renovation job. It was 45 foot from the water entry point in the house to the boundary. It worked very well. When in the shower (ATAG combi), if other cold taps are opened the effect on the shower is so little it is hardly noticeable. The larger bore pipes also give more water storage which helps when a cold tap is initially opened reducing the effect on a shower. In the OPs case larger bore pipes store more water which is being pushed along his internal pipes by the 4 bar from the street.
I did advise him to put isolator/flow regulators on the H&C outlets to balance the system, which greatly helps, even a poorly installed system. The toilet does not need to refill in 30 seconds, so a 6 litres per min cartridge was put on the toilets.
https://www.bes.co.uk/flow-regulator-ball-valve-cp961-15mm-17527
If there is 4 bar static pressure and say 30 litres per min at the boundary from a 20mm pipe (approx 15mm), taking it using 20mm/15mm into and around the house will mean a substantial flow and dynamic pressure drop around the house. Using 35mm to the house, 22mm inside the house for much of the pipework (like a dedicated 22mm pipe to a combi or unvented cylinder) and full bore stoptaps, will not reduce that 4 bar and flow rate too much.
If the OP has spare 35mm pipe parallel it up from the boundary to the house. Blue plastic pipe is cheap. I advised a friend to parallel up 25mm blue pipe from the boundary to the house as he had enough left over (25mm was coming in from the road) and go with 22mm on some legs in the house like a dedicated pipe to the combi - a big renovation job. It was 45 foot from the water entry point in the house to the boundary. It worked very well. When in the shower (ATAG combi), if other cold taps are opened the effect on the shower is so little it is hardly noticeable. The larger bore pipes also give more water storage which helps when a cold tap is initially opened reducing the effect on a shower. In the OPs case larger bore pipes store more water which is being pushed along his internal pipes by the 4 bar from the street.
I did advise him to put isolator/flow regulators on the H&C outlets to balance the system, which greatly helps, even a poorly installed system. The toilet does not need to refill in 30 seconds, so a 6 litres per min cartridge was put on the toilets.
https://www.bes.co.uk/flow-regulator-ball-valve-cp961-15mm-17527
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You don't increase the flow, you limit the reduction. If you read what I originally wrote you will see I mentioned upstream and downstream.
If you have a significant restriction at the start of the run, once the flow is gone its gone. Upsizing something after the fact does not magically get the flow rate back up. It just maintains what is left.
Restrictions through orifices like softeners and cylinders can be calculated but there you have the Bernoulli principle. In boiler heat exchangers they can be restrictive (Vaillant 4 series being a great example as well as Intergas). But there you have charts to calculate what is needed to overcome that restriction and size the pump accordingly. It is also about heat transfer down the pipe with that as a different DT will place different requirements on the pipe sizes, where you have design velocity to consider as well. You can get more energy through a 22mm diverter valve than you might think.
So, upgrading the pipe work downstream of a significant restriction will do nothing to improve the raw performance of a main. It will just limit any further drop in performance. If the OP has 10m of 20mm main coming in and that is restricting his flow down to say 25l/min, putting 32mm MDPE in afterthat will only service to maintain that 25l/min. Whereas fitting an accumulator at 4 bar, or upping the first 10m could well see him hitting 60l/min.
Most regular Unvented cylinder safety groups regulating down to 3 bar will probably give out around 40 l/min on that kind of pipe work, but that is not much more than a guess. The size of the tapping off the street supply will also be a factor and the water companies charge more for a larger connection.
One other advantage of an accumulator is that you have a store of water should there be a break in the service from the street - something that can happen rarely or a lot depending on where you live.
If you have a significant restriction at the start of the run, once the flow is gone its gone. Upsizing something after the fact does not magically get the flow rate back up. It just maintains what is left.
Restrictions through orifices like softeners and cylinders can be calculated but there you have the Bernoulli principle. In boiler heat exchangers they can be restrictive (Vaillant 4 series being a great example as well as Intergas). But there you have charts to calculate what is needed to overcome that restriction and size the pump accordingly. It is also about heat transfer down the pipe with that as a different DT will place different requirements on the pipe sizes, where you have design velocity to consider as well. You can get more energy through a 22mm diverter valve than you might think.
So, upgrading the pipe work downstream of a significant restriction will do nothing to improve the raw performance of a main. It will just limit any further drop in performance. If the OP has 10m of 20mm main coming in and that is restricting his flow down to say 25l/min, putting 32mm MDPE in afterthat will only service to maintain that 25l/min. Whereas fitting an accumulator at 4 bar, or upping the first 10m could well see him hitting 60l/min.
Most regular Unvented cylinder safety groups regulating down to 3 bar will probably give out around 40 l/min on that kind of pipe work, but that is not much more than a guess. The size of the tapping off the street supply will also be a factor and the water companies charge more for a larger connection.
One other advantage of an accumulator is that you have a store of water should there be a break in the service from the street - something that can happen rarely or a lot depending on where you live.
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My post overlapped with Hard-On's but he (rather suprisingly) speaks sense there.
It can come in handy when you have a full house though.
Fit full bore stoptaps and better again.
A 9 litre toilet cistern will fill in 1.5 minutes with a 6 litre/min flow regulator. Dual flushes for pees use even less than 9 litres. There will be no problems regulating a toilet fill to 6 litres/min in a normal house.
Dannyboy, you never wrote "numpty", how disappointing.
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So I think what you're saying agrees with what myself and JohnD said.
In my previous post, I used the phrase "increase flow" quoted here:
Let me clarify that - I should have said increased flow at the outlet - ultimately, we are talking about increasing flow at a basin or more typically a shower. It doesnt matter to OP if he has more flow at the boundary, if that flow is then lost by the time it gets to his shower.
So the question is - if you have 20m of 20mm bore pipework to the boundary (call this pipe A) delivering 30 litres/min. You then have 20m of 20mm pipework from your boundary to your shower (call this pipe B), resulting in reduction of flow to 20 litres/min.
1. Would increasing B (after boundary) to 32mm limit the reduction in flow (i.e. increase flow at the outlet)? For arguments sake, we now get 25 litres/min at the shower. From what you've said, I think you agree it would.
2. Now let's upgrade A (before boundary) to 32mm, but leave B (after boundary) at 20mm. This means A now has more flow (eg. 35 litres/min), but B (after boundary) still reduces this flow to 25 litres/min.
It's the same difference in terms of resultant flow at the shower outlet. The figures are made up, obviously, but the principle applies - increasing the pipe diameter before or after the boundary gives the same benefit when looked at in terms of flow rate at the outlet.
Yep Dannyboy. The 35mm pipe will not make it better for sure. That is why I asked what the flow rate is at the boundary. If it is say 30 litre/min, large bore pipes from the boundary, under the ground and throughout the house will pretty well maintain that 4 bar and 30 litres/min.
In mains pressure systems, unvented cylinders and combis, it is advisable to have a dedicated large bore pipe from the main stopcock to the combi or unvented cylinder. Also, a manifold after the combi or unvented, as they do in many new builds in France. 10mm plastic pipe is taken to the hot outlets from the manifold with 15mm to the shower or 22mm to the bath/shower. A flow regulator is fitted for each leg on the manifold. This greatly assists in balancing the H&C system. They also have a manifold for the cold supplies - again with flow regulators on each leg.
What you meant was it increases flow over putting in small bore pipes. It will not increase flow from the boundary. What to get from the boundary is what you get, which in most cases is fine. It will maintain the flow.
Dannyboy had to do a U turn for sure, but he got it in the end which is nice.
No u turn from me.
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So this was all covered by the first few posts which were friendly and helpful.
It's clear to see that not much has changed on this forum. Sometimes posters are right or wrong, that's ok, that's what adult discussion is for.
I've no idea why people would come on this forum and give the impression they are primary school kids. Maybe some issues there?
It's clear to see that not much has changed on this forum. Sometimes posters are right or wrong, that's ok, that's what adult discussion is for.
I've no idea why people would come on this forum and give the impression they are primary school kids. Maybe some issues there?
H
Hot&Cold
Considering temporary traffic management is required the quote is not to excessive but you can ask for quotes from other water self lay companies
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