Dynamic pressure equals static pressure

Joined
18 Aug 2010
Messages
1,012
Reaction score
27
Location
London
Country
United Kingdom
Hi

I've read the professionals on here often talk about how important the dynamic pressure reading is as compared to a static reading.

So having bought a gauge from Amazon today :LOL: I took some readings.

My static pressure at the garden tap is 2.8bar. When I open the kitchen tap full blast the pressure at the garden tap is still 2.8 bar. The flow happens to be 19l/min.

So, what does it mean if the static pressure is exactly the same as the dynamic pressure?

Thanks
 
Sponsored Links
My static pressure at the garden tap is 2.8bar. When I open the kitchen tap full blast the pressure at the garden tap is still 2.8 bar. The flow happens to be 19l/min.
One possibility is that the capacity of the system upstream of your garden tap is way more than 19 liters/min.
Was it 2.8 bar or 2.80 or 2.800?
 
Sponsored Links
Pressure reducing valve, if present and set to 2.8, and there is more pressure available will allow more in to maintain the pressure.

If the garden tap has a check valve then with a gauge on the outlet and negative pressure in the system, the pressure gauge will hold steady.

Put the pressure gauge on a washing machine valve and do the test again.
 
pressure reducing valve on the incoming main?

Pressure reducing valve set at 2.8 bar. Mains/street pressure is 5 bar, say. Turn on kitchen tap, pressure would typically fall to say 1.8 bar, except PRv opens up to keep the downstream pressure at 2.8 bar.

Do you have a Megaflo?
 
Hi Onetap/Dan

I don't have a Mega Flo, I have a thermal store.

I've had a look and I do seem to have a PRV but it seems to be after the garden supply is tapped off the mains. In the pic below you can see the mains coming up from the floor, the unlagged pipe you see tapped off is what I presume to be the garden outlet. The PRV is then fitted after that.




 
Hi Dan

Will measuring the pressure from the grey cap tell me the true potential pressure in the system?

Thanks
 
Thanks.

So should I switch the stop cock off, remove grey cap, attach gauge and then re open stop cock?
 
I am not sure what you are going to do or why you are suddenly so interested.

But you can buy a pressure gauge, usually 0-6 bar and screw it into the port currently closed by the knurled grey plug.

Tony
 
Hi Dan

Will measuring the pressure from the grey cap tell me the true potential pressure in the system?

Thanks

That port shows the pressure downstream of the PRV which will/should be about 3 bar, or 2.8 bar with your meter.

It would only fall below 2.8 bar with a draw-off if excessive restrictions in the pipes prevented enough water passing to maintain 2.8 bar (what you're checking for), or if the upstream mains pressure was too low.
 
Thanks Onetap.

Tony, at present I have a TS which is buggered and needs replacing. I want to decide whatsort of system to replace it with. Whenever that question is asked on this forum you professionals all ask what the flow, pressure and dynamic pressure is. That is why I wanted to measure it.

What I have noticed is that if I have a shower running and then open a tap there is a significant negative change in the amount of water coming out of the shower. Whether this is a flow of pressure issue I have no idea.

One of the things I want to resolve with the new system is this issue, ie two outlets should run at the same time with no discernable drop in water delivery.

Thanks
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Sponsored Links
Back
Top