Improving water pressue outside for sprinklers

Wasn't sure if this thread should've been posted in the 'Garden' forum but because it's about water pressure, thought this forum was more appropriate.

I have bought two garden sprinklers from Screwfix. When one is connected, it works fine but when both are, they don't work properly. This must be because of not enough pressure is being created.

I thought my water pressure was fine. It's certainly fine indoors. Apparently, Screwfix say you need 2.0 bar to operate the sprinkler but don't know for two.

What I'm wondering, are there certain things I can replace to increase the pressure?
For example, would it help if I replaced the hose connectors that have the built in water stop valves with ones that don't? Increasing the hose size? Replacing the garden tap with a special one? Using a more rigid pipe between the sprinklers?

Thanks very much.

suppose you could try installing a valve of some description on the sprinkler closest to the outside tap and gradually close it till both sprinklers are getting the same amount of water, obviously wont be as good a spray as just one being on but if the end up with both at a reduced rate is adequate then its a cheap fix

Just let the rain do its work!

You need to establish the mains dynamic flow and pressure first to see what you've got (and mm per wk )

Could the issue be hosepipe size rather than pressure.

I never understand the diff between flow and pressure.........

Notch7 said:

I never understand the diff between flow and pressure

Click to expand...

Flow is the amount of water that runs out a pipe in Litres per minute, Pressure is the force behind it that pushes it through the pipework and out that outlet in Bar.

When mains pressure is low, when you open more than one outlet, the mains water (dynamic) pressure isn't strong enough to maintain the same amount of water traveling through the pipe & exiting both outlets per min. Dynamic pressure is the amount of pressure that can be maintained by the mains when there are multiple open outlets at the same time.

Add to that a restrictive accessory that needs a certain pressure to say operate a mechanism - a sprinkler - then if you don't have good dynamic pressure/flow that can't be maintained by the mains, then it aint going to work properly .....

Water stop ends used on our mains supply definitely slow things down and we have good mains flow rate and pressure.

Notch7 said:

flow and pressure.........

Click to expand...

Amps and Volts.

Madrab said:

You need to establish the mains dynamic flow and pressure first to see what you've got (and mm per wk )

Click to expand...

Thanks for all your help, I really appreciate it.

How would I actually establish the flow and pressure to know if it will work or not?
Is it worth getting this?

I'm even toying with the idea of getting this which could fit under the kitchen sink since the garden tap is on the other side but not sure if it's made for an issue like this.
Ironically I've got a shower pump that I've had for years and never been used but has hot & cold inlets/outlets!

For now, I could replace the hose & fittings that have the stop valves inside if you think it might make a difference? The hose that I'm actually using to connect the first sprinkler to is one of these expanding ones that have the fittings built-in.

Finally and just so you know, the two sprinklers are connected together in a daisy-chain fashion. Would it make a difference if they had their own hoses connected directly to the tap using a splitter? Currently, the hose from the tap to the first sprinkler is about 10 metres, then about 6.5 metres from sprinkler to sprinkler.

Thanks again.

Sprogginz said:

Thanks for all your help, I really appreciate it.

How would I actually establish the flow and pressure to know if it will work or not?
Is it worth getting this?

I'm even toying with the idea of getting this which could fit under the kitchen sink since the garden tap is on the other side but not sure if it's made for an issue like this.
Ironically I've got a shower pump that I've had for years and never been used but has hot & cold inlets/outlets!

For now, I could replace the hose & fittings that have the stop valves inside if you think it might make a difference? The hose that I'm actually using to connect the first sprinkler to is one of these expanding ones that have the fittings built-in.

Finally and just so you know, the two sprinklers are connected together in a daisy-chain fashion. Would it make a difference if they had their own hoses connected directly to the tap using a splitter? Currently, the hose from the tap to the first sprinkler is about 10 metres, then about 6.5 metres from sprinkler to sprinkler.

Thanks again.

Click to expand...

If one hose works satisfactorily, then you know you have enough pressure.

Problems using two, suggest you don't have adequate flow to support two. Flow can be measured with a calibrated container, a litre jug, at the kitchen sink as litres per minute using a clock or watch. Every bend, every bit of pipe, every valve and tap in the system will resist the flow coming out at the far end.

The pump might work, it will help pull water in from the mains, but I will leave it to others to let them comment on that.

EFLImpudence said:

Amps and Volts.

Click to expand...

I struggle to get my head around the fact the voltage and current can be out of phase

Sprogginz said:

Is it worth getting this?

Click to expand...

If you want to work through this yourself then no reason not to get the pressure gauge.

Flow can be measured at the outside tap, see how much water you can get into a bucket in a min.

Dynamic pressure - connect the gauge to an appliance outlet and then run 1 then 2 taps and see what the drop is from 0 to 1 to 2

Don't fit that pump, it's for gravity fed supplies and shouldn't be used on the cold mains supply.

Change the hose to a non compressed good quality one - Hoselock is one, there are others.

Adding another hose and/or supply won't make a difference if the dynamic mains pressure (not flow) isn't up to it. A 15mm water pipe will happily supply enough water volume for 2 sprinklers, only if the mains pressure can maintain it.

How are you plumbing the sprinklers? If you take the supply from the tap to one sprinkler, then to the other you'll struggle to overcome the fact that it's simply easier for the water to exit the first sprinlker than carry on to the second. You'll get too much pressure drop at the first sprinkler. As a starting point you need to run independent supplies from the tap.

But I think you'll be unlikely to have the flow you need anyway. As a rough guide, I have flow at 20l/min and can only run one at a time.

It's not legal to pump from the domestic system, though I'm not convinced it would cause any problems.

If you want to run more than one sprinkler at once I presume that's because you want a system you can turn on and leave for a period and turn off having the whole garden done. Rather than being at home in the day to move the pipe around? If so, either your options are to pump from an IBC to get the flow you need, and use a ball-cock to refill. Or you need electronically controlled valves so you can have only one sprinkler going at once. You could scavenge some valves from a washing machines/dishwashers, particularly the type where the inlet valve is at the tap rather than the appliance. There are relatively easy solutions for programming the valves using Raspberry Pi or Arduino.

For two sprinklers, I'd go for programmed valves, in a box near the tap and run the sprinklers from there. For more sprinklers and a larger garden running a circuit of pipe around the outside, then having valves at the outlets might be easier as it avoids the need to run a large length of pipe for every sprinkler. But you do need a power circuit too. You can fairly easily program a circuit system to do soaker hoses, baskets, individual plants as well as the sprinklers.

For pumped storage you would want to use a level switch to turn the pump off when the IBC is empty as generally you'll struggle to store enough water to do the lawn in one blast. With a bit of maths you can work out how many IBCs worth you need and use another level switch to turn it back on when the IBC is full. Aim for one soaking a week rather than running everyday, it's better for the grass roots to think they need to go deeper to find water. If you like a challenge you could add a water gauge and level sensor to measure the amount that's landed and reference that.

Sprogginz said:

Would it make a difference if they had their own hoses connected directly to the tap using a splitter?

Click to expand...

It's worth trying, won't cost much.

I have a client who is suffering from low pressure on his garden sprinklers. Would it be acceptable for him to use two garden taps (with non return valves) to run the water through his hoselock pipes. IE one tap at either end of the system?

Edit- Yes the suppy in the house drops when the current exterior tap is being used. The client is considering paying for a new MDPE supply to replace what I assume is the old lead pipe.

Is it possible to ask for two MDPE feeds or am I showing my ignorance with regards to flow/pressure?