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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.: 445  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 (N/m2); similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and U.S. 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. B

    Elevated moisture on floor despite pipe pressure test ok

    Hi. I had a pressure test done on the toilet connection tap. Test showed no leak. However, thermal imaging showed elevated moisture levels around the tap (& toilet (on the floor). I am wondering if it is possible that there could their have been a long time (ie years) slow leak from the pipe /...
  2. MichaelO

    Water supply line pressure: one too low, one too high

    Two connected houses in our 70s condo development, everyone served by one water meter at the road. 833 has 40 lbs of pressure while attached house 835 has over 100 lbs. -- no problems in either house or immediately outside -- and no pressure relief valves or shutoffs. Plumber traced the...
  3. I

    Combi boiler question regarding usage with no pressure

    Hi, just a quick question. Do I need to fill my combi boiler to run it for hot tap water only? I'm planning to drain the system and leave it drained a while so I can decorate and change some pipes and rads.
  4. A

    Water pressure reduced when other appliances are on

    Hi all - hoping to get some advice here on a plumbing issue in our house. When we are showering / filling the bath and another appliance draws water (toilet cistern filling after flushing, tap being turned on or washing machine filling etc), the water pressure / flow to the other appliance...
  5. D

    Best options for finding a CH pressure leak

    I have a pressure leak on my CH system. Our piping is buried in the walls (maybe a mistake) and the room-to-room pipes are now covered by flooring making it difficult to detect any leaks if there is no yellowing happening on the ceilings below. We have noticed that we need to top up the system...
  6. C

    Water pressure for block of flats

    Hi, I will try to explain best I can, please bare in mind I am currently in a learning stage so just trying to understand the process behind things. A building with three floors and 69 rooms. How do you work out the pressure needed on the hot water system? I’m sure there is a calculation to...
  7. R

    UFH loss pressure 0 when off

    Just recently installed UFH .When all radiators and Ufh are on pressure normal floors are warm radiates are warm .When anything is turned off pressure drops to 0 with Worcester boiler flashing I have isloated it to the UFH and not boiler or radiatets could this be anything other than a leak...
  8. Z

    Faulty pressure gauge?

    Hello. Today I have installed a new radiator upstairs. A little bit bigger so I had to make new pipe work. Before that I flushed as much water from heating system as I could. Only one leg (3 legs downstairs) had valve which allowed me to flush water from radiators upstars, all of them. Only 3...
  9. D

    Low pressure on boiler, causes water leaks?

    Hello All. Sorry, im new to the forum and had a quick look around, but I couldnt find any answers. I have an HE35 Isar boiler and over the past few weeks. Ive noticed a leak coming from pipes near my toilets. Ive checked the boiler pressure and it is near zero. Could this be a the cause of the...
  10. Z

    Boiler Pressure Keeps increasing - Vaillant Ecotec Plus 838

    Hello everyone, I have a Vaillant Ecotec Plus 838. The issue i have is after the heating is switched on and then left it to cool over night i see the pressure has gone up. For example yesterday it was set at 1.3 heating was switched on and when it reached its temp it went upto 1.9 so no issues...
  11. Prof Yaffle

    Combi boiler losing pressure - No leaks, many new parts, but still...

    I'll pop this into the general advice forum as it seems the most active, but mods - feel free to move if there's somewhere more appropriate. Thank you! --- Apologies, but yet another "boiler losing pressure" thread - I've read many others, but am no closer... Not my boiler (parents), so...
  12. P

    Yet Another Boiler Losing Pressure Issue

    Looking for some help here - not my boiler, so consider me a proxy. I'm also by no means a heating engineer: I'm just looking for pointers, as the owner of this boiler is now caught firmly between "not us", "not us" and "not us" - nobody will take responsibility, and just calls into question...
  13. I

    Boiler pressure issue

    Hello people Need help git issues with my vailiant ectoec Was having plastering done removed some radiators this is when the problem started . The boiler pressure kept dropping and when heating was on pressure would go to high . Had the expansion vessel re-pressuried and pr valve changed...
  14. T

    Rainfall shower pressure problem

    Hi we have a rainfall/riser shower fitted over the bath, on a agravity fed system. We have 2 showerboosterpumps under the bath which supply the hot water in the kitchen below and the bathroom hot water. The problem is the shower won't kick in when turned on, pressure is good on all other taps
  15. M_Nash95

    Ideal System 15 losing pressure; pressure dial violently twitching

    Hi there, I am renting at the moment. Our boiler is an Ideal System 15. Within an hour or two of moving in and turning the heat on the boiler lost pressure. Now it loses pressure any time that it is turned on. If the boiler pressure is set below 1.5 bars cold it will lose all pressure in about...
  16. S

    Ideal boiler had the F1 code, so topped pressure up but code persists.

    After researching as much as I can to sort this problem, I keep reading that if your Ideal boiler has an F1 code and the pressure is low, it needs topping up. If it has an F1 code but the pressure is fine, then this indicates a potential pressure sensor fault. What if it was low (completely...
  17. E

    Hot water low temperature and pressure. (Diagram and data provided).

    Hot water temperature is low. This varies at different flow rates. At 8lpm it is around 37deg (c) At 2lpm it is around 49deg (c) 8lpm is around the max flow rate. It is around the same flow rate / temperature at all taps (upstairs bath / upstairs sink / downstairs kitchen / downstairs...
  18. P

    Loss of pressure & High Pitch Whistle in bathroom

    Equipment The shower (a cold feed electric unit) and the Kingspan tank are on the top floor of a 3 storey building. The Ideal Boiler Logic Heat 15 boiler is on the ground floor. The house is 9 years old in May. Both the boiler and Kingspan tank have been serviced in the last month. The shower...
  19. G

    Water pressure suddenly dropped

    Recently we had reason to replace our boiler. It was on the blink and you could only con it into coming on by first turning on the hot water and then the heating. Whilst waiting for the installation one day randomly the electric shower stopped heating the water. It flashed low pressure -...
  20. S

    Auto Bypass Valve OR Proportional Pressure pump mode – how to choose?

    I have read that an Auto Bypass Valve (ABV) is not compatible with a pump set to Proportional Pressure (PP) mode. I have a recently fitted Vaillant EcoFit Pure 430 heat-only boiler + Vaillant SensoComfort weather sensing controls + 15 rads (12 with TRVs) across 2 CH zones + a static bypass...
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