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Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the ambient pressure.
Various units are used to express pressure. Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre; similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and US customary systems. Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure and the torr is defined as  1⁄760 of this. Manometric units such as the centimetre of water, millimetre of mercury, and inch of mercury are used to express pressures in terms of the height of column of a particular fluid in a manometer.

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  1. P

    1st fix pipework for possible cylinder upgrade

    I'm renovating a property which after works are complete will be 5 beds, 4 bathrooms. All 4 bathrooms will have rain head showers and one will also have a bath. Incoming CW supply is in 25mm MDPE to internal stopcock and then 15mm to CW outlets. Pressure is 3.5bar Boiler is 32kW system boiler...
  2. J

    Ideal 30 Low Water Pressure

    Hi Removed radiator from wall for decorating, then refilled and bleed all Radiators. System now saying low water pressure Boiler saying 1. Fill System to 1 bar.. although after topping up now showing 1.5bar 2. Bleed radiators - done all 3. Contact Installer!!.. Is there anything i can do check...
  3. F

    System pressure loss

    I'm an amateur with an interest in plumbing - installed 2 systems in the 60s and 70s and modified others for self and family until banned in 1991. Current problem relates to daughter's system. She had an Ideal Logic 35kw combi installed under Government scheme some 8 or so years ago. At the same...
  4. D

    Pumps to boost pressure for combi boiler flat?

    Hi, I live in a 4th floor flat, with 2 recently refurbished showers and a combi boiler. The pressure in the showers was poor, so after getting some reassurances that a gravity fed pump was still ok for my flat, I had a gravity fed salamander pump installed, but after a few weeks of it working...
  5. K

    Boosting Water Pressure

    Hi, I have just had a bathroom installed on the third floor of the house in a room which used to be a bedroom. The problem is, the water pressure/flow isn't very consistent. Its acceptable sometimes and we get flow rates of about 10-15 l/min but at other times it drops down to about 5l/min or...
  6. J

    Landlord Gas safety check. Operating pressure

    So I was doing a gas safety landlord check on a vaillant ecotec 835 and the meter was so far away from the flat that by the time I got there the boiler got to temp and would momentarily shut off and I couldn’t get a full reading for a gas rate. I tried numerous times. In the end I got the...
  7. S

    Low pressure light on electric shower

    I have a low pressure light on a tenants electric shower, it completely cuts the water off. They say they have not had any other appliances on and it is now getting worse. The boiler is a condensing boiler. Any help welcomed.
  8. I

    Low pressure taps help

    Hello, I'm wanting to buy a low pressure mixer tap for my bathroom Basin. I see there rated by Bar, what Bar of pressure should I get? Thanks
  9. I


    Hello, I have a low pressure system, but it seems I have a high pressure tap. I have amend some of the pipework to the tap anf put a full bore 15mm isolator on pipe to help keep the full flow, but the flex from the mixer are really small in diameter how can I over come this, or do I just need...
  10. O

    Domestic gas pressure

    I’m curious why gas is regulated to such low pressures when it enters a dwelling. My gut instinct says this is for safety but then there is an argument smaller pipes could be made from stronger materials, have smaller leak paths and are less likely to be damaged. Given this seems to cause...
  11. U

    V&B shower mixer - restricting pressure?

    Hi, Just moved into a house with a villeroy & boch shower. Water flow out the showerhead and the handheld are both equally terrible. The pressure and flow at the bath downstairs is OK at about 15L per min. There is a megaflo cylinder. I'm thinking that the problem must be the shower mixer or...
  12. A

    Concerned about fix made to pressure on Heatrae Sadia Megaflo unvented system

    I already posted a question about this to the MyBuilder.com Ask a Tradesman section but I'm unable to post follow-up questions. Someone has kindly replied that the fix made to my system is dangerous and should be replaced and I'd appreciate it if someone here could validate this advice. I have...
  13. N

    Water Pressure for new Garden Tap

    I currently have ½ inch supply to my main outside tap. If I create a T, in the main feed, and run a 1 inch pipe to a new tap from the ½ inch feed, will this contribute to a greater flow rate at the new tap?
  14. M

    Boiler constantly increasing pressure.

    Hi guys, So a couple weeks ago I had a problem on my boiler where I was losing .1 of a bar of pressure every two days and the built in filling loop knob wasn’t allowing any water back into the boiler. So a plumber came out and replaced the filling loop valve because there was a blockage of some...
  15. A

    Low hot and cold water pressure

    Hello, I have been experiencing low water pressure from both hot and cold taps throughout my property. It is all electric no gas and I have a cylinder in the airing cupboard. I do not have any instructions on how to repressurise and really struggling to find a solution online that have worked...
  16. S

    recommended pressure accumulator for longevity

    Hi, We have good pressure but not so good flow, so considering a pressure accumulator. I live in a hard water area - near Cambridge - if that matters. We'd be replacing a static header tank in the loft. There seem to be a number of brands, like Zilmet, GWS, Grundfos, APS and others. I've...
  17. N

    Air accumulating in system. No pressure loss...

    Hello, I'm hoping someone can help... I have a system boiler (Worcester Bosch 18i - Unvented) in my garage. I am having to bleed top towel rad in house and magnaclean next to boiler daily. Air is getting into the system. I have no loss in pressure. I have removed the lower level rads in house...
  18. D

    Hot water flowing out of electric water tank through pressure-release/overflow pipe?

    Hi guys, I'll try to describe my issue as best I can but I've attached a video and linked to some images below that might do a better job of explaining. Edit: Just noticed the video didn't upload. I'll try to upload to an external site and pop a link at the bottom when it's done. In the...
  19. D

    WB HEATSLAVE 18 25 losing pressure

    Hi all I am new to this forum so if I put in too much information please forgive me. I have a WB Heatslave 18 25 oil combi boiler. I have had it for a number of years. I know WB has a great reputation which is why I bought this boiler but it has been temperamental, to say the least. It has...

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