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pressure reducing valve

A pressure regulator is a valve that controls the pressure of a fluid or gas to a desired value, using negative feedback from the controlled pressure. Regulators are used for gases and liquids, and can be an integral device with a pressure setting, a restrictor and a sensor all in the one body, or consist of a separate pressure sensor, controller and flow valve.
Two types are found: The pressure reduction regulator and the back-pressure regulator.

A pressure reducing regulator is a control valve that reduces the input pressure of a fluid or gas to a desired value at its output. It is a normally-open valve and is installed upstream of pressure sensitive equipment.
A back-pressure regulator, back-pressure valve, pressure sustaining valve or pressure sustaining regulator is a control valve that maintains the set pressure at its inlet side by opening to allow flow when the inlet pressure exceeds the set value. It differs from an over-pressure relief valve in that the over-pressure valve is only intended to open when the contained pressure is excessive, and it is not required to keep upstream pressure constant. They differ from pressure reducing regulators in that the pressure reducing regulator controls downstream pressure and is insensitive to upstream pressure. It is a normally-closed valve which may be installed in parallel with sensitive equipment or after the sensitive equipment to provide an obstruction to flow and thereby maintain upstream pressure.Both types of regulator use feedback of the regulated pressure as input to the control mechanism, and are commonly actuated by a spring loaded diaphragm or piston reacting to changes in the feedback pressure to control the valve opening, and in both cases the valve should be opened only enough to maintain the set regulated pressure. The actual mechanism may be very similar in all respects except the placing of the feedback pressure tap. As in other feedback control mechanisms, the level of damping is important to achieve a balance between fast response to a change in the measured pressure, and stability of output. Insufficient damping may lead to hunting oscillation of the controlled pressure, while excessive friction of moving parts may cause hysteresis.

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  1. M

    Pressure reducing valve - can I remove?

    As part of full house renovation, I've switched from a conventional boiler/gravity fed tank to a combi boiler. Under the old system I note that a pressure reducing valve has been fitted to the pipework feeding the shower mixer (assuming as mains cold overpowering the supply pressure from the...
  2. D

    House pressure reducing valve cold water hammer

    Having issues with water hammer, I have a megaflo with balanced hot / cold using a heat stadia 3 bar prv, this seems ok as getting 3 bar at taps with test gauge, the outside tap is between the house incoming stop valve and the 3 bar PRV and that is showing just over 4.5 bar. If I switch a hot...
  3. D

    Megaflo Pressure Reducing Valve Clunking

    I have a loud clunking noise coming from the PRV when the cold water is shut off. It has been doing it for at least a year now but its getting annoying and I have noticed in the night (when the water pressure rises) I am getting random clunks from this valve after about 11pm at night. I am...
  4. M

    Pressure reducing valve on boosted hot water?

    Afternoon everyone I have gravity fed hot water - downstairs taps are 4.4m below tank. Upstairs 1.5m. The hot at the new minimum 0.3 bar monobloc kitchen tap is delivering a flow rate of just 4 L/min. So I am thinking about fitting a single impeller booster pump. This will be ideal for...
  5. P

    Pressure Reducing Valve

    Hi All, I've recently installed an unvented Andrews 270 litre gas-fired water heater in a ten-flat hmo and to reduce the chance of leaks I put in a pressure reducing valve. I went for the drop-tight design which is supposed to limit the pressure under no-flow conditions . . . except it doesn't...
  6. M

    Can you fit any pressure reducing valve/ multiblock on unvented.

    Assuming the pressures are the same can I fit a standard pressure reducing valve/ multiblock or do I have to fit manufacturers specific? At the moment i have a grant duowave with a megaflo multiblock but the block is leaking the grant one I can get in a couple of days but I can get a standard...
  7. D

    Caleffi pressure reducing valve

    I have a caleffi valve on my system. It has worked well for some 10 years. Recently I noticed it is not regulating, with no flow sits at mains pressure. With flow it regulates. Replaced cartridge but just the same. It is a Caleffi 5350, i.e a static regulator. Any ideas as to why performance has...
  8. R

    Pressure reducing valve - is this normal?

    Hi. Just been shown a job by an engineer friend who likes to mess around with things. He's fitted a pressure reducing valve to the supply pipe to a heated outbuilding. The mains pressure is 5 Bar, the valve has a gauge on it showing 2 Bar when taps are closed. He helps me out, so I don't...
  9. M

    Herz pressure reducing valve issues

    Hi one n all. I run maintenance for a building with 456 rooms in it. For each 2 rooms there is 1 riser with a PRV on the hot water supply. I'm constantly getting valves that seem to be sticking closed. In the 6 months since we opened, we've attended probably about 70 valves, and about 25 of them...
  10. S

    Noisy megaflo pressure reducing valve

    hello there, I have a megaflo unvented system everything works fine apart from the prv valve shown on the pic. Every time a tap opens or toilet flashed this prv makes noise. Spoke to guy who fitted the system and he said dont have much to say other than replacing with e new one. Just...
  11. D

    Pressure reducing valve

    Hi all, My pressure reducing value has failed on my unvented cylinder, my plumber has already changed the potable expansion vessel and prv and cold water is still running through the tundish. I hate being the annoying Googling customer, but I've found a Honeywell pressure reducing value on...
  12. A

    Megaflo pressure reducing valve

    Hi everyone, Was called to a megaflo last night, no water coming from any taps. Followed the recharge instructions but made no difference. I heard gurgling but no discharge appeared and the gurgling stopped after approx 3 minutes. I spoke to heatrae sadia who recommended new pressure...
  13. K

    Choice of Pressure reducing valve

    Renovating bathroom just now and the wife wants mixer taps throughout. Normal single handle hobbj on the sink and a fancy traditional style beast on the bath. Hot water is supplied from unvented cylinder at 2 bar closed pressure, 1.5 bar ish when flowing full tilt. Cold is supplied from mains...
  14. Inverness

    Oil pressure reducing valve

    hi guys, I'm planning to locate a new oil tank but the problem is the height will most likely to be greater than 4 meters from oil pump. I know you can use a oil pressure reducing valve have anyone used this before?.
  15. R

    zip pressure reducing valve operation

    Thought I had a problem with an Ariston 30L water heater in a village hall whereby the hot water flow has steadily reduced to almost nothing over a period of a year. When you open the hot water tap you get a burst of water then it slows and stops after only a small amount has come out...
  16. A

    Flamco pressure reducing valve

    This is a pressure reducing valve correct?
  17. S

    Megaflow 3 bar pressure reducing valve placement

    Hi, Have lived in our house for around 10 years and always had bad pressure if more than one tap is running, toilet is flushed etc(hot and cold). We have (what I believe to be) a mains pressure system with a non vented Megaflow cylinder. We are about to install a new thermostatic shower and...
  18. P

    Fog Horn noise when using Hot Water - Pressure Reducing Valve recently replaced

    A few months back the expansion vessel from the mains water supply failed and I had the vessel and the pressure reducing valve replaced. As part of the replacement the expansion vessel was fitted with a copper tube instead of the flexible hose that was originally used. Since the work was done...
  19. P

    flamco pressure reducing valve?

    Hi chaps and chapesses I have a customer with a leaking Flamco pressure reducing valve see pics it seems to be leaking from the gauge which is full of water. looks like it was fitted as an afterthought the way the pipework runs. customer now has a combi in so probably has a new prv fitted...
  20. S

    pressure reducing valve cartridge leaking

    Hi all, I think the pressure reducing valve cartridge on my pressure reducing valve is leaking. The pipe size is 22mm. Where can I find a replacement for it? I am clue less about what pressure and type it is. here is a picture https://goo.gl/photos/3UeYrT7gdt3rmhgcA Thanks Seb
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