Adjusting a Caleffi pressure reduction valve

[dutts]

Hi,

When we moved into the house the mains water pressure was so high it would splash out of the sinks when opening a tap fully and pop the hoselock fitting off my hose pipe so we got a plumber out and they fitted a Caleffi 553 pressure reducing valve.

This is all good, water pressure in the house is a bit more normal but we’ve since had a Gledhill unvented hot water cylinder installed to give us mains pressure hot water and so our mains pressure usage has increased (like when running a mixer tap with both hot and cold to fill a bath for example).

My question is how do I go about adjusting the pressure reducing valve to give us a bit more pressure?

The dial has a red needle which can be moved and is currently turned to 4 bar and that is approximately what the black needle is at when there are no taps running in the house. Got the dishwasher on at the moment when I took the pic.

There’s a screw adjustment on the end but not sure how much I should turn this and in which direction? does the + and - correspond to the effect of the valve in reducing the pressure of the pressure itself?

The tech sheets and instructions for the valve I’ve found online have confused me a little and so I want to make sure I’m doing the right thing before I touch it.

Thanks in advance

Rich

 

[Harry Bloomfield]

Clockwise + to increase pressure or you sure you need to do that?

 

[dutts]

Clockwise + to increase pressure or you sure you need to do that?

Wasn’t too clear in my original post so sorry, the problem is if for example I’m filling the bath with both taps on full, and then turn on the hot tap in the bathroom, that’s just a trickle. Assumed giving the whole system a bit more would help or maybe I’m barking up the wrong tree?

 

[Johntheo5]

Turn the screw clockwise to increase the pressure.

What does the pressure gauge show with all those taps opened??.

There is always a fall off in pressure through a PRV with increasing flow even if the upstream pressure is fairly constant.

The 533H only appears to be a micro pressure reducing valve (3/8"?) for example a flow of only ~ 10LPM gives a pressure drop of 0.8bar.

You require something like a 22mm 5336 which flows 20LPM with a 0.8bar pressure drop.

 

[Harry Bloomfield]

Wasn’t too clear in my original post so sorry, the problem is if for example I’m filling the bath with both taps on full, and then turn on the hot tap in the bathroom, that’s just a trickle. Assumed giving the whole system a bit more would help or maybe I’m barking up the wrong tree?

Static pressure and flow rate are two separate things, see the post above for a potential solution. You can have good static pressure, then due to restrictions or too narrow pipework, the pressure can disappear when a tap is turned on.

 

[Madrab]

You shouldn't just 'turn up' the pressure without understanding what impact that may have. You need to check the pressure when say 3 or 4 outlets are running at the same time, that and check the flow - how much water you get out of an outlet, into a bucket timed over a minute - then report that back here

If the static pressure - no taps running - is 4 bar and it doesn't drop much lower than 3 bar when multiple outlets are being used then you don't need to increase the pressure. 4 bar static pressure is the higher side of mains pressure and the higher the pressure the more strain it puts on fittings and outlets and increases wear and tear.

 

[dutts]

Thanks for all of your replies. I’ve got some more info that you asked for.

Turning on an upstairs tap drops the pressure on the gauge to a little over 1 bar (from just over 3), then turning on a further tap drops that to below 1.

I didn’t have a big enough bucket but at my tap in the garage I could fill about 9.5 litres into a bucket in 30 seconds.

 

[Johntheo5]

Looks like the wrong type of PRV, see post #4.

Can you measure that upstairs tap flow with the bucket or whatever that drops the pressure by 2 bar.

Then close in the tap to give a pressure drop of 0.5/0.8bar and measure this.

 

[Madrab]

There seems to be 2 different series 553H valves from Caleffi the 553H micro series 3/8" (DN8) for specialist applications and the standard 553...H series for mains water which the OP seems to have. The dots after the 533... seems to denote the extension and the model (6) is designated by the size of the connections so if the OP's is 15>22mm then it would be the 553(6)..H, nothing like being confusing

https://www.caleffi.com/sites/default/files/file/01252_en.pdf

https://www.caleffi.com/sites/default/files/file/01332_en.pdf

@dodgie , is the supply pipe coming in from below 15mm and the flow pipe after the valve 22mm?

 

[Johntheo5]

The 5336 flows 20LPM at 0.8bar drop in pressure so maybe this one installed? If so then either defective PRV, blocked strainer, or simply very poor mains pressure.

 

[Madrab]

One of three possible problems, if you have a dynamic mains pressure of below 1 bar.

1) Faulty PRV
2) Poor dynamic mains pressure
3) Restricted mains supply

Unfortunately you need more investigation into your mains before even considering an unvented.

Is that a 15mm pipe on your incoming mains, if so then that's a choke point too, especially if you have 4 bathrooms and are planning an unvented too