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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. F

    Expansion Tank sounds like a foghorn

    We recently dropped the house water pressure from 70 to 60 psi and increased the pressure in the expansion tank from 40 to 60 psi as I was told that they should be the same. The hot water tank and the expansion tank are 3 months old and there were no issues when the house pressure was at 70 psi...
    • FlyersFan
    • Thread
    • america expansion sounds tank usa
    • Replies: 0
    • Forum: USA
  2. P

    Thermal expansion issues

    Hello all! I'm located in the US. I had a water pressure issue (150PSI) until I replaced the water pressure regulator (replaced the faulty one with a WATTS LF25AUB-RK,) which came preset to 50PSI. It held that pressure for about a week. Slowly but surely, the water pressure's been creeping up...
    • Plumber_Wannabee
    • Thread
    • america expansion issues thermal usa
    • Replies: 0
    • Forum: USA
  3. L

    Expansion tank pipes

    Hello, I'm an electrcian who is just trying to grasp some knowledge of heating systems as I've got some S plan jobs coming up. On older installations what is the pipe used for that runs from the header tank into the flow pipe? Expanding water?? How come this set up is not required on combi...
    • Loubanez
    • Thread
    • america expansion pipes tank usa
    • Replies: 3
    • Forum: USA
  4. N

    Groaning Expansion Vessel

    The tundish near the expansion vessel started dripping, plumber came and pumped up expansion vessel and dripping stopped, great. However now, every time we flush any of the loos we get a strange heavy vibration noise through the expansion vessel for 1-2 seconds. We also recently discovered it’s...
    • Notveryhandyman
    • Thread
    • america expansion expansion vessel usa vessel
    • Replies: 8
    • Forum: USA
  5. M

    Screwfix Expansion Tank

    Anyone know weather you leave in the plastic insert in the expansion tank threaded connector?
    • Marty111
    • Thread
    • america expansion screwfix tank usa
    • Replies: 0
    • Forum: USA
  6. M

    Expansion vessel insert, should I remove?

    Has anyone installed a Refix potable expansion tank? There's a plastic insert inside the 3/4 threaded connector - should it be left in? I though it maybe to space the diaphragm off the inlet point, but not sure if it's just a protector insert which will stop the tank operating - nothing in...
    • Marty111
    • Thread
    • america connector expansion expansion vessel fitting insert remove should tank urgent usa vessel
    • Replies: 7
    • Forum: USA
  7. J

    greenstar 24i expansion vessel hose

    I have removed an old expansion vessel from a Worcester greensatr 24 i. I am now trying to reconnect the hose but I am having great difficulty. Its so tight inside the fitting. Is there an easy way to reconnect it? Thanks
  8. M

    HW expansion vessel pressure and sizing

    Afternoon, I am not a G3 engineer but am using the downtime during COVID to do some extra learning. Is there a calculation to use to correctly size the expansion vessel and have the correct pressure in the vessel on unvented HW systems? Thanks
    • mc0911
    • Thread
    • america expansion expansion vessel pressure sizing usa vessel
    • Replies: 1
    • Forum: USA
  9. M

    What pressure to charge HW expansion vessel?

    Afternoon, this is purely a query and learning benefit. I am not a G3 qualified engineer, however am just using the down time during COVID to take on some extra learning. Would anyone know if there is calculation or something to determine what pressure and size the vessel should be on an...
    • mc0911
    • Thread
    • america charge expansion expansion vessel pressure usa vessel
    • Replies: 8
    • Forum: USA
  10. M

    Zilmet expansion tank block?

    Brand new 18l Zilmet expansion vessel (red) and the neck seems to be blocked by thick black rubber. Is that the bladder, tank is pressurised but can’t be pushed in with a finger. I just want to check as by the time an engineer comes it’s going to be too late to replace? Matt
  11. M

    To fill expansion vessel with water?

    Hello! I’m wondering which will cost more - to run our heating system with an inefficient/broken expansion vessel for a minimum of six months from now, or to call out an engineer (£100 excess). Our house is a new build and still under warranty. I noticed the pressure in our unvented system...
    • Mouton
    • Thread
    • america expansion expansion vessel usa vessel water
    • Replies: 11
    • Forum: USA
  12. J

    Why would cold mains feeding the boiler need an expansion vessel?

    British gas fixed a leak in the boiler and said the due to the recently installed water meter the fluxuation in pressure caused the leak. They advised to get a expansion vessel on the the cold mains entering the boiler. I read on here someone say that Worcester wouldn't warranty boilers being...
    • Joef
    • Thread
    • america boiler cold cold water expansion expansion vessel feeding main mains usa vessel water
    • Replies: 5
    • Forum: USA
  13. Lumen

    Lowering Expansion Vessels on Unvented System

    Hi Chaps, Wife has been nagging me about having shelves in an airing cupboard for about a year now. We've had unvented cylinder fitted last year and both expansion vessels are very high to fit a towel shelve (as it will be just below the top of door frame). Can the expansion vessels be lowered...
    • Lumen
    • Thread
    • america expansion system unvented usa
    • Replies: 5
    • Forum: USA
  14. N

    Wilo pump & expansion tank - need to repressurise

    I live in Azerbaijan where I have a Wilo MC605-EM pump attached to a Wilo LRS 50/10H diaphragm expansion vessel, which pumps water into my house on demand. We have a large water storage tank sitting between the mains and the pump so there is effectively no water pressure, the pump sucks water...
    • naylorpd
    • Thread
    • america expansion pump repressurise tank usa wilo
    • Replies: 4
    • Forum: USA
  15. N

    Best solution for a failed expansion vessel?

    I have a Vaillant Turbomax Plus boiler, fitted in 2005. Recently it's locked out several times due to low pressure, which prompted me to check the expansion vessel. When I pressed the Schrader valve I found that water, rather than air, was released. That suggests to me a failure of the...
  16. J

    Repressurise white expansion vessel

    Hi all, I've got my G3 card. First time I've attempted to re-pressurise the white, expansion vessel above an unvented cylinder. I first turned the water off, ran the taps to relieve the pressure. The vessel (it was flat). I managed to pump it up to 1.2bar with no issues. But then it was...
    • Jennie
    • Thread
    • america expansion expansion vessel repressurise usa vessel white
    • Replies: 12
    • Forum: USA
  17. B

    Expansion Tank Tap/Valve

    This tap sits below my Potterton Combi Expansion Tank, I think its the cold water inlet valve Should the tap be ON or OFF To me is looks currently in the ON position
    • bures
    • Thread
    • america expansion tank tap usa
    • Replies: 2
    • Forum: USA
  18. B

    URGENT water level changes significantly in expansion pipe (open vented system)

    I have made some adaptations to the layout of an existing open vented one pipe system. The pump is now some 6 or 7 metres away from the boiler. The cold feed is on the negative side of the pump as is the expansion pipe. The order of fixing is expansion pipe - cold feed - pump. When the pump...
  19. F

    Best CH expansion vessel

    Hello again from enthusiastic amateur. Previous request for help re daughter's pressure reducing Ideal boiler helped me to get it sorted economically. Today my query is re my own system with Worcester Bosch system boiler where I think the built in expansion vessel is inadequate or faulty. I...
    • fiddler3
    • Thread
    • expansion expansion vessel vessel
    • Replies: 5
    • Forum: Australia
  20. H

    Kerosene Boiler Worcester 12/18 Heatslave "hot water expansion" !

    This heating system is new to me, in reality about 8 years old and in good condition. In the tail end of last winter's heating season, I think I shot myself in the foot. With more bedrooms than occupants and a water cost of about £4/tonne, I had a water meter installed. It might have been a...
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