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A cylinder (from Greek: κύλινδρος, romanized: kulindros, lit. 'roller', 'tumbler') has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. Geometrically, it can be considered as a prism with a circle as its base.
This traditional view is still used in elementary treatments of geometry, but the advanced mathematical viewpoint has shifted to the infinite curvilinear surface and this is how a cylinder is now defined in various modern branches of geometry and topology.
The shift in the basic meaning (solid versus surface) has created some ambiguity with terminology. It is generally hoped that context makes the meaning clear. Both points of view are typically presented and distinguished by referring to solid cylinders and cylindrical surfaces, but in the literature the unadorned term cylinder could refer to either of these or to an even more specialized object, the right circular cylinder.

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  1. B

    Another Regular Boiler short-cycling on Hot Water problem...

    Hope someone can suggest where I should looking to resolve this one... I have a Bosch 30Cdi regular boiler on an S plan system with a 180L vented, indirect hot water cylinder. Boiler Temperature is set to 5 (67c) and the stat on the Hot water cylinder is set just below 60c. A Honeywell DU144...
  2. J

    Vent pipe size for vented cylinder installed in 2005-6

    Hey, having searched this forum and last building regs (2000) from around that time... Any idea what the correct size is for a vent pipe for a vented hot water cylinder, gravity fed? I.e. the one that is continuously rising back up to the cold water feed tank for the cylinder? Have discovered...
  3. H

    Unvented cylinder for ASHP

    Hi all. I have an Isoflo CL170 cylinder with good few years life left in it in my system which has performed trouble-free other than the odd new immersion element. I'm getting a new ASHP fitted and the installer is recommending scrapping the Isoflo and replacing it with a Secon Trade Heatpump...
  4. R

    Unvented cylinder viability??

    I'm looking at getting an unvented cylinder fitted but want to know if it's viable before even getting a quote. My cold incoming main is only 15mm but I do get a good pressure and flow which doesn't change alot when another tap or shower is used. Would an unvented be possible?
  5. euge595

    URGENT Motorized valve or cylinder thermostate

    Hi, I have no hot water unless I put the CH on, I've changed the HW motorized valve which still needs to be opened manually and I've changed the cylinder thermostat, can anyone suggest my next course of action. Many thanks
  6. G

    Can I add a seperate header tank to a fortic cylinder?

    Hi I just bought a house with a combination hot water cylinder & cant replace the heating system yet as we have walls to knock down etc where the new radiators would be & the new layout will require different sizes. My GF needs a more powerful shower its a trickle atm. I ordered a pumped power...
  7. B

    Placement of a copper Cylinder for best effect

    I Cannot installa unvented cyclinder because my waterflow rate is too low. I am therefore thinking of using the old attic tank feeding a cylinder system. My query is, Which is the better of two cylinder placements. Water fed to a cylinder in the loft with hot water fed from top of cylinder...
  8. M

    Continuous noise from indirect water cylinder

    I have moved into a house with a Joule Cyclone CY200L indirect cylinder in my loft. Recently it seems to continuously be making a noise, as if it's filling up or heating up, I'm not sure which. The thermostat on the side is set to 55, when I turn it below 50 there is a click and then the noise...
  9. S

    Help with unusual tap with non-standard cylinder

    I have a leaky tap, so I thought I could fix this with replacing the washer, however, when I took the cap off, I could not get the wrench in there to grab hold of the nut to turn! This is because the nut part of the cylinder is sunk into the casing (please see photo in the attached links)! I...
  10. C

    Unvented Center cylinder no hot water

    Hi all, I’ve got an issue with no hot water from Center 300L unvented Cylinder on S Plan plus system. All Electrical controls working fine. Only way to get hot water to the taps is by using immersion heater. Any ideas what could be up? Thanks in advance.
  11. J

    Suitability of Unvented Cylinder

    Hi I've read through dozens of threads on here about unvented systems but was wondering if someone might provide some advice on an upgrade we are planning as part of a bathroom refurb Current Setup: Gravity fed system with cold water tank in the loft and hot water tank in the hot press (1st...
  12. G M

    URGENT Unvented Cylinder Gushing Water from Relief Valve?

    Hi folks, I hope someone can help me. This morning we noticed water leaking under the hot water cylinder in hotpress room. On closer inspection, the water was just gushing on to the floor and it was only by chance we noticed it. We turned off the heating system and spent the morning emptying...
  13. O

    Unvented cylinder - usage question

    We have an unvented cylinder with a Horstmann Electronic 7 timer. The cylinder only serves a wet room which is very rarely used. The rest of the house is served by a Vaillant combi boiler. The timer on the cylinder is set to heat up water 3 times per 24 hours, which I think it is the default...
  14. G

    New Eco 7 Cylinder - spluttering/air in system?

    We've just had a new Economy 7 cylinder put in and after 3 or 4 days we still seems to get spluttering out of the taps as thought there is air in the system Basic setup as follows - apologies for poor terminology as i'm not a plumber! Cold water tank in loft of bungalow feeds into the hot water...
  15. W

    Water shut off cylinder

    Is it possible to replace inside part of the water shut off cylinder without replacing whole cylinder?
  16. R

    Advantage of unvented cylinder outweigh the disadvantages?

    I have come to my decision I might as well do my G3, even if only for maintenance jobs. Question I have is WHY we are fitting so many of these unvented cylinders i.e. 27 gallons /117l size or above (I'm not disputing the need for 10l unvented 'cylinders'). They 'need' annual servicing by a G3...
  17. L

    URGENT Willis imersion heater

    Willis heater heats for 5mins and stops gate valve on cold feed between cylinder and immersion discuss options
  18. R

    Do I need G3 to repair a 10l unvented cylinder?

    Hi. Potential customer has a leaking 10l Ariston Europrisma cylinder. Probably just a flange gasket or the magnesium anode needs replacing. While I feel this is easily the sort of task I can tackle as I am very good at mending things, I get the impression I'd need my G3 to install such a...
  19. P

    Cylinder noise / Balanced Colds / Pressure etc

    I wanted to start a new more dedicated thread as I am on about 3 just now in one way or another trying to get up to speed with my problem. The issue is that my Gledhill Stainless Lite indirect unvented cylinder makes loud noises when heating - this is a bit random, but that noise is loud enough...
  20. R

    Vented indirect cylinder venting issue

    A customer of mine lives in an old cottage that has been extended. They have three loft areas that are completely separated. The CWSC is in one higher loft space, the hot water cylinder and shower pump live in another lower loft. They are on different sides of the building. There is single 22mm...