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A valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure. The word is derived from the Latin valva, the moving part of a door, in turn from volvere, to turn, roll.
The simplest, and very ancient, valve is simply a freely hinged flap which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction. Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems.
Valves have many uses, including controlling water for irrigation, industrial uses for controlling processes, residential uses such as on / off and pressure control to dish and clothes washers and taps in the home. Even aerosols have a tiny valve built in. Valves are also used in the military and transport sectors.

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  1. J

    Thermostaic Valve Replacements

    Just ordering a new set of thermostaic taps and I was wondering is the cost of the thermostatic cartridges getting to the point where its cheaper to replace the whole unit than just the catridge itself?
  2. R

    Leaking isolation valve

    A leak has developed around the top nut of isolation valve in bathroom where the pipe feeds into toilet cistern (see photo) I have tried tightening the top nut and adding PTFE tape around the thread but this does not help. So I guess I have to replace it ? Problem is that the bottom nut won't...
  3. R

    Viva Skylo Unifill Fill Valve - problems?

    Anyone else had a bad experience with these? I bought one on the premise that one part fits most and stuck it in the van. Then, appalled that a spare diaphragm washer for it was expensive and rare, I decided against fitting it in any customer's house and it eventually ended up in my own toilet...
  4. A

    Replacing Fordham Flush Panel toilet fill valve

    Has anyone replaced a Fordham Flush Panel toilet fill valve with modern one with integral overflow mechnism?
  5. R

    Fernox TF1 compact valve leak

    I've got a Fernox TF1 compact fitted in the airing cupboard, and discovered this evening after the boiler had no pressure that it is leaking. I've seen previous threads about this where it leaks from the cap however mine appears to be leaking from the bottom inlet valve, not on the filter itself...
  6. G

    Toilet fill valve filling from tiny hole near the top?

    I installed a new toilet fill valve a few months back, it came with a plastic tube to connect to the tiny hole and I figured that's how it must fill. Looking at my other toilet after it had a problem, no water comes from the hole at the top at all and there's no plastic tube there. So I feel...
  7. C

    How to remove diverter valve handle and faceplate

    My shower hose connection has popped out of the diverter value You can see it here: Imgur I've found the manual for it, here: Imgur But I have no idea how to remove the handle and faceplate so I can tighten the screw into the notch on the shower hose end connection. Any ideas?
  8. Roverspete

    Toilet Flush valve brand.

    Hi All, Sorry being really lazy today, has anyone got a clue which brand makes this Flush Valve and fill valve please? Customer could only say it was made by WRAS lol If not it will be Viva’ed up new Friday. Thanks in advance. Pete
  9. N

    Toilet Cistern Overflowing (Picture Included)

    Quick question please, the toilet cistern is constantly over flowing and I need to adjust the fill valve. Am I right in assuming that the part circled should turn so that it can be adjusted? Or do I just need to bend the ball cock arm? Thanks Phil.
  10. T

    Is it a problem with Diverter Valve?

    My 5 year old Bosch system has recently started the CH sytem when the heating side of the controller is in OFF periods. The HW side still working to set times, and although not getting full heat on the towel rails, some heating is occurring outside the CH times set. I turned off CH side for 24...
  11. J

    Radiator valve tool - better options please

    Anyone got a better tool/plan/idea that using a small spanner when opening and closing multiple rad valves? PS on a powerflush... Cheers, J
  12. cdel2005

    10l water heater pipework check valve

    Hi guys Should the check valve be after pressure reducing valve and before expansion vessel Picture shows existing pipework with check valve before pressure reducing
  13. B

    Grohe tap fitting 15mm flexi vs 21(?)mm valve thread

    Hello, I’m trying to fit a new Grohe tap. Flexi hoses are 15mm and don’t fit the 21mm (guessing it could be 22mm?) existing thread on the water feed valves. See pictures attached. Is there an adapter I can buy? Or do I need to replace the valve for a 15mm one? The copper pipework itself for...
  14. K

    New home help! Not sure what this is?

    Hi, I have moved into a new home and have the following part connected? I don’t know what it is... and what it does?
  15. P

    Pneumatic flush valve failing

    Hi all, I've got a problem with a Gerberit pneumatic dual flush valve. It has two buttons on the actuator plate, when pressed individually they do nothing, you now need to press them both at the same time in order to get it to flush. The toilet was installed around 5 years ago with no problems...
  16. G

    Valve ID`s required please?

    Can anyone tell me the make and model of these valves please?
  17. J

    Leaking radiator drain valve leaking

    Hi. I've started draining the central heating system to make a repair and now have three of these drain off valves leaking. Please say there is an easy repair without removing the whole unit. Water is pooling in the top, where the screwhead is and I think, dripping from the outlet too. I've not...
  18. Bogart

    Fire valve requirement

    How long has it been mandatory to install a fire valve in the fuel line when installing a new boiler to comply with Part J? Now could someone hazard a guess as to roughly how long to do the following. 1 Remove an old oil fired boiler. 2 Replace with a new oil fired boiler 3 Install a 3m remote...
  19. RobG

    Wheelhead Gate Valve unscrewed but won't slide off pipework

    Hi, this is my first post to this esteemed forum so please excuse any faux pas. The red wheel head gate compression valve has seized half on-half off so I have unthreaded the nuts holding it in place (wasn't easy) ready to replace with a 22mm Pegler ball valve (bought from S...x - the only chain...
  20. Simon42

    Help identifying tap valve

    I have a dripping valve on my towel rail, but when I removed the cartridge it doesn't seem to be the standard one, and I don't know how to find a replacement. I'll attach a photo. Any help welcome.

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