Can you handle the pressure?

[Wetbehindtheear]

Need a little help from someone a bit smarter than me.

I need to increase the water pressure to an irrigation system I've just installed. I have a plan to do this but dont know if it will work. Currently the system is fed from a 15mm copper pipe and outdoor tap fixing kit. (Actually I thought I'd start by getting rid of that silly self tapping connector thingie and put a propper 15mm tee in with a gate valve to isolate and remove the 'pinch point' from the system if you understand me)

OK back to my super plan. This is to take a feed direct from the 22mm supply pipe just after it leaves the stopcock. I was thiking about taking two feeds creating a big 'U bend', if you will, and from the U bend draw off a fresh 15mm supply pipe to my hose via a 15mm reducing tee.

My thought is this. When the system is closed the pressure in the main 22mm pipe and the U bend will be exactly the same. But when the hose is oppened the pressure at the 15mm reducer will now be approximately 1.5 times the pressure in the mains pipe because water is now escaping via the two 22mm pipes I've drawn from the mains pipe.

Am I right?

Don't laugh too loud if I'm wrong. I also thought I may need to add a 22mm non-return valve to each of the supply arms on the U-bend to ensure all the pressure for the mains pipe is 'pushed' towards the hose coupling.

OK....fire away I'm thick skinned. And many many thanks if you can help.

Cheers, Wet behid the ears!!!

 

[Blake]

Remove the DIY outside tap fitting first as this only creates a small hole when it is screwed into the pipe. You should notice a difference straight away.

As for the rest of your plan, it's been a long day and I don't have the mental ability to work out what you are proposing to do

 

[Wetbehindtheear]

Fab we both agree about the silly hose fitting!!

The short version of the rest......if I take a second feed from the main 22mm pipe and join the two pipes together will I get more pressure still?

Mains
-
-
---------non return--------
- -
- ---------------Hose (higher than mains pressure now)
- -
---------non return--------
-
-

Thanks for your reply!!!!

 

[Wetbehindtheear]

Bugger it changed my super picture when I posted it! The 'hose' should be at the end of the two feeds from the non-return valves. I'm trying to be too smart now.

 

[WaterTight]

Do you need more pressure or more flow?

 

[Wetbehindtheear]

I really need both to be honest. I'm stuck with 15mm pipe once I exit the home so I'm hoping the increase in pressure will create a greater flow rate too

 

[WaterTight]

I think it gets a bit complicated and sciencey at this point but my uneducated guess is..

1) You won't increase your pressure no matter what you do. It is fixed.

2) You will increase flow by increasing pipe sizes, removing bends and self-tapping connections

 

[PlumbBobBob]

i agree, the only way to increase pressure is to pump tanked water, but then the cost is going to shoot up.

 

[philtheflush]

and also i would ghange the gate valve to an isolating as gates are normally used on low presure pipes ie gravity feeds

 

[kay-jay]

pressure is fixed! tinkering will only increase velocity. as teve said only way to increase pressure is a pump. you need to check your current flow rate and estimate how much more you would require. it is illegal to pump mains water in most circumstances. i think the threshold is something like 11 or 12 litres per minute. if this is within your requirements you just need to ask building control who should authorise it providing you give full details of the pump and zone and timing cotrols if you need more than 12 l/s only option is tanked water. may well need a bloody big tank though depending on the size of the irrigation system......