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expansion

Thermal expansion is the tendency of matter to change its shape, area, volume, and density in response to a change in temperature, usually not including phase transitions.Temperature is a monotonic function of the average molecular kinetic energy of a substance. When a substance is heated, molecules begin to vibrate and move more, usually creating more distance between themselves. Substances which contract with increasing temperature are unusual, and only occur within limited temperature ranges (see examples below). The relative expansion (also called strain) divided by the change in temperature is called the material's coefficient of linear thermal expansion and generally varies with temperature. As energy in particles increases, they start moving faster and faster weakening the intermolecular forces between them, therefore expanding the substance.

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  1. G

    USA Expansion Tank Issues

    Every time I flush my toilets, I hear a popping sound from my expansion tank. I have drained the water from my electric hot water heater. I have shut off all the water going into the house, cut my faucets on to drain them to get any air out my lines. Im going nuts trying to figure this out...
  2. tonyt

    Vented system - Expansion / fill pipe or pipes?

    Hi, I'm coming to the brainy forum for a proper answer! Scene - vented system, was originally gravity with Aga, then oil boiler with integral pump, then new oil boiler last year with fully pumped "Y" system. I have problems with air in radiators. I find there is a single 22mm expansion/fill...
  3. A

    Expansion vessel

    If there is an unvented cylinder being installed in the loft, System boiler downstairs, how would you decide what size expansion vessel to put on the heating side and how will you configure the Pipework for heating expansion vessel in the loft. As there will be an expansion vessel in the boiler...
  4. I

    Expansion Vessel Vibration

    First post after a lot of browsing and hoping for some insight into an on-going issue. I have a Glenhill unvented cylinder setup on my house. Installed 5 years ago (I’ve lived here for a year). Backstory: The expansion vessel was replaced in November as the last one had started to leak. No...
  5. J

    European / international water heaters, no expansion vessel

    I've seen and heard about this a couple of times. When installing an un-vented water heater some parts of the world seem to fit an expansion valve and just allow it to blow off each time the water is heated. No expansion vessel is fitted on the incoming pipe work, they either fit it to a...
  6. Riley

    Exploded expansion vessel

    From the start I will say this is not installed by me. I was called out last night where an expansion vessel on an unvented cylinder has rusted through and gone pop. Serious flooding etc. Went over and made safe and I’m now trying to source replacement parts. I note that rather than using...
  7. 999

    Accumulator or expansion Vessal

    Hi All Ive been looking at accumulators online and ended up buying a Reflex potable water expansion vessal. I orginally googled for potable water accumulators and had a load of pages open and purchsed what might be the wrong item. Can someone confirm an expansion vessal is not the same as a...
  8. M

    Expansion vessel change on a viessmann 200wv

    hi guys. I’m after some advice on replacing a viessmann expansion vessel if anyone has any? I’ve never worked on one or installed one. I don’t normally do part replacements at all if I’m honest so any help would be appreciated please. Cheers
  9. Wetbandit

    Does this expansion vessel need supporting?

    Just noticed this on a job and wondered how dangerous it is if any of you knowledgeable people can tell me if it's supposed to be supported? Cheers wet bandit
  10. R

    Expansion Vessel Combined Boiler

    Got a weird one, no water on on valve and tested integrity using LDF and all fine. Drained down system and left drain off open and pumped to around 1 bar. It’s not holding any pressure but not showing any other of the normal symptoms of a broken membrane. My thoughts are vessel but I’m not...
  11. D

    Adding a second Expansion Vessel?

    I was at a job looking at an unrelated issue when the lady mentioned her blow off keeps running outside. Apparently the last plumber replaced expansion vessel(and checked the precharge was 3bar) on the cold feed into the cylinder, 3bar pressure reducing valve and 6bar blow off in the hope to...
  12. M

    Worcester Greenstar Expansion vessel

    Hi, Serviced a boiler today that was over pressurising when heating up, so thought it would be a simple case of drain down and re-pressurise the vessel. tried that and found that the vessel would not take any pressure as if the valve was blocked, I removed the schrader valve but no change...
  13. A

    HE24 Expansion vessel location

    Hi, Can anyone tell me where the expansion vessel is located on an Ideal HE24 boiler, please? I have an issue where the pressure drops when the heating has been on because the water is leaking from the outside pipe and some other threads I've read advise to check for pressure in the vessel but...
  14. MikeJhn

    Flat 12L potable expansion vessel

    I can find lots of the above for Boiler installation, but assume for potable water they would be different internally (lined) due to possible cross contamination to the drinking water, anyone know where I can find one?
  15. Inverness

    Vokera linea24 replace expansion vessel?

    hi guys, any one hot experience in replacing the expansion vessel on a vokera linea ? It has to be a striaght swap. Experience and thoughts appreciated.
  16. B

    ** Heatline Monza 28 expansion vessel **

    I had a Heatline Moza 28 boiler fitted around five years ago. It had some pressure issue from very first year. I used to top it up manually. Then last year, it stopped working altogether and boiler engineer had to pump up its expansion vessel. my boiler worked fine for whole year. Now it am...
  17. H

    Expansion Vessel Upside Down?

    Hi, Has this expansion tank been installed upside down? - The cold water expansion tank is install this way as well... Or is there something special about the configuration that I haven't understood? Surely air gets trapped with the expansion tank fitted this way? I still have noise in my...
  18. Steve weightman

    Expansion vessel in a domestic house

    Any reason why this cold water expansion vessel would be found in a domestic house it's massive
  19. J

    Expansion vessel appears ok, but boiler operating pressure at 3 bar.

    Hi. It would appear that the expansion vessel is ok, and yet the boiler pressure is operating and exceeding 3bar. The PRV does leak before 3 bar and I know needs replacing, but what could be causing the high operating pressures. Thanks
  20. D

    Unvented Cylinder Expansion Vessel - advice sought

    Hi, I am a homeowner, I had a new unvented cylinder (OSO DC 300) fitted in August, and had a small problem yesterday with the pressure valve dumping water and making a lot of noise. Eventually this was resolved. However, during my conversations with plumbers it appears that I have a red...
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