OT: Pressure Relief Valve

Hi all,

A bit OT but hopefully a few of you will have come across what I'm after.

I have a ridiculously over-engineered watering system to water my balcony gardens, and when I'm only watering one section the pump is way too over-sized and the pressure cutout setting means that the pump is starting and stopping more often than I'd like.

Rather than go down the route of a VSD pump to lower the pressure, I thought of using an adjustable pressure relief valve to circulate excess water back into the tank. Something like this one. Only thing is, this one is about $A500-$600, and if I was going to spend that sort of money I'd just put a VSD in and do it properly.

Does anyone know of a more entry-level/domestic market pressure relief valve? It'll need inlet/outlet ports somewhere in the range of 3/4" to 1", and adjustable pressure somewhere in the range of 50kPa to 300kPa.

ASF said:

Hi all,

A bit OT but hopefully a few of you will have come across what I'm after.

I have a ridiculously over-engineered watering system to water my balcony gardens, and when I'm only watering one section the pump is way too over-sized and the pressure cutout setting means that the pump is starting and stopping more often than I'd like.

Rather than go down the route of a VSD pump to lower the pressure, I thought of using an adjustable pressure relief valve to circulate excess water back into the tank. Something like this one. Only thing is, this one is about $A500-$600, and if I was going to spend that sort of money I'd just put a VSD in and do it properly.

Does anyone know of a more entry-level/domestic market pressure relief valve? It'll need inlet/outlet ports somewhere in the range of 3/4" to 1", and adjustable pressure somewhere in the range of 50kPa to 300kPa.

Click to expand...

Can't you just water more than one section, and do the rotation slower ? EDIT : i meant less frequently....

The one section in question is the section that's undercover. When it rains, everything else gets rained on, and I'm left with just needing to water this one little section on it's own.

I can water another section with it, and the problem goes away (that's what I'm currently doing) but in the interests of saving water, I'd like to be able to water just that one section

ASF said:

The one section in question is the section that's undercover. When it rains, everything else gets rained on, and I'm left with just needing to water this one little section on it's own.

I can water another section with it, and the problem goes away (that's what I'm currently doing) but in the interests of saving water, I'd like to be able to water just that one section

Click to expand...

Is saving water a budgetary issue that they are charging you for use?

Won't a pressure relief valve prevent the pump from building up to cut out pressure?
Might be better just to put a pressure tank on the system to prevent short cycling

Create a new section, called "return to tank" that is automatically added to your discharge when only the covered section is watered.

One new valve must be cheaper than a PRV

padees said:

Is saving water a budgetary issue that they are charging you for use?

Click to expand...

No, it's an issue of tank size.

This whole setup is on a high-rise balcony, and space is extremely limited. I don't have mains water available out there (and the cost to get it there is enormous due to the layout of the apartment), so I have a small tank which I refill manually using buckets whenever I get an email to say that it's empty.

Based on my current usage, I can get about a week's worth of watering out of the tank before it's empty, but if I wasn't watering things that had already been rained on, I could stretch that time out a bit longer, which is especially helpful if I'm going away for more than a week in the rainy season.

chelton said:

Won't a pressure relief valve prevent the pump from building up to cut out pressure?
Might be better just to put a pressure tank on the system to prevent short cycling

Click to expand...

I don't want the pressure to build up to cut-out pressure, that's the point. I want it to build up to around 150kPa and then stay there for as long as I have it set to water the plants. If I have two sections open, the flow rate is such that the pump never (or only very rarely) reaches the cutout pressure, which is what I'm after. But when I only have a small section, the flow rate is low enough that the pressure builds up way too fast.

daba said:

Create a new section, called "return to tank" that is automatically added to your discharge when only the covered section is watered.

One new valve must be cheaper than a PRV

Click to expand...

True, and I initially tried that, but it wasn't as effective as I'd hoped. I have to put it right at the end of the watering lines or else the sections beyond that don't get the right pressure, and then to avoid having too much back pressure and cutting out anyway, I had to use a full size return line. That's physically difficult due to the highly, um, "custom" nature of my system, and the fact that it needs to be somewhat aesthetically pleasing because it's outside my loungeroom window. Getting a line that size back into the tank is also a pain, because it's an extremely snug fit and gets pulled in and out of position to be refilled. A relief valve, if I can get one, will sit neatly between the suction and discharge lines of my pump out of sight and doesn't require any extra wiring. The lines to and from my pump are long enough that it shouldn't cause too much of a "short circuit" by doing that (I hope).

How about these
https://www.irrigationwarehouse.com.au/category111_1.htm

Bingo! That's what I'm after. Thanks chelton!

Or you can try pool components for cheap and nasty

https://www.ebay.com.au/sch/i.html?...+pool.TRS0&_nkw=pressure+relief+pool&_sacat=0

I love cheap and nasty! I found those sort of things early on in my search, but unfortunately most of them are designed to just vent to atmosphere to relieve the pressure. Not quite the result I'm after and I'm not sure my downstairs neighbours would appreciate it