Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00 K on the Kelvin scale, an absolute thermodynamic temperature scale. This corresponds to −273.15 °C on the Celsius scale, −459.67 °F on the Fahrenheit scale, and 0.00 °R on the Rankine scale.
Since temperature relates to the thermal energy held by an object or a sample of matter, which is the kinetic energy of the random motion of the particle constituents of matter, an object will have less thermal energy when it is colder and more when it is hotter. If it were possible to cool a system to absolute zero, all motion of the particles in a sample of matter would cease and they would be at complete rest in this classical sense. The object would be described as having zero thermal energy. Microscopically in the description of quantum mechanics, however, matter still has zero-point energy even at absolute zero, because of the uncertainty principle.

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  1. Stigster

    Cold booster sets

    Hi Everyone, For those who like a long read but I could rally do with some advice. Might be a bit long this. For background. A gardener/landscaping friend of mine is going to install an irrigation system in a customer's garden. He asked me to pop around and measure the pressures and flowrates...
  2. surfsup

    Outside tap lost pressure since cold snap

    My outside tap has had really low pressure after the cold weather a few weeks ago. Its connected from under the kitchen sink, and can be isolated from turning a flat head screw type thing a quarter turn. Any help or advice would be much appreciated!
  3. N

    Power Shower Working OK then runs cold.

    We have a pumped shower with a thermostatically controlled mixer valve. My wife complains that when she is having a long shower (hair wash etc) the shower runs at the right temperature for much of the time but suddenly changes to run cold, usually during the hair rinse time, for no apparent...
  4. B

    Yellow water in cold and hot taps

    Can anyone help me with an ongoing issue I've had since I had an annual service on my combi boiler, which is a Potterton Performa 24. Literally after they left I started experiencing yellow water (pale) from all my taps - hot and cold, including the toilet. This was intermittent and then...
  5. T

    rads cold no indication of boiler fault HW fine (pls urgent)

    Hi All Bit of an urgent one being that time of year and can't get a plumber out until after xmas even on an emergency callout I have just tried to turn on my CH for the first time this year as I have a number of guests coming for xmas dinner but even after an hour all the rads are stone...
  6. S

    Mira Combiflow random cold water

    I’m after some advice. I’ve inherited my parents house. In the process of doing it up. My dad got a Mira combiflow installed about 15 years ago. Over the last couple of months every so often when it’s turned on the water runs ice cold even if I turn the handle to hottest temp. All other taps...
  7. T

    URGENT Hot water is cold. Boiler or valve

    Please advise me. I am a disabled pensioner. I had a wet room fitted just over a year ago using a local authority grant. Builder was employed by local authority. I had no say in who carried out the work. I have called the builder out under the guarantee several times for water leaks. The shower...
  8. W

    BRISTAN SHOWER runs cold

    Hi I've seen a previous thread that is closed now regarding this subject but the end result I could not see. Our Shower runs hot for 30 seconds then cold. I have changed the thermostat and it still runs cold after 30 seconds. If we run the hot tap it is better but at best, luke warm. We have a...
  9. D

    Shower(s) water is cold

    HI Iam hoping someone can provide guidance on a heating problem. I have a (old) Ideal isar HE35 where there is no hot water for the 2 showers at the property, there is water flow but not warm. I can confirm there is hot water from the sink/bath (downstairs and upstairs). I noticed that the...
  10. J

    Hot water running cold

    Hi all Hope you can help We have a Gloworm Ultracom 38CXI combi boiler. During the Summer the taps and mixer shower run hot water consistently hot for as long as need be, but now during the Winter when the radiators are on the taps and mixer shower will run hot for only a few minutes and...
  11. O

    My kitchen tap is leaking from the cold lever

    Hi I have a leak on my kitchen tap it is coming out off the bottom of the cold lever. How do I get the lever off? Also would this tap have a cartridge in the cold & hot or will it be just tap has had it & I need to get a new one?
  12. Jimmu0161

    Cold water at the hot tap

    Got intermittent hot water coming the from a combi boiler to kitchen mixer tap when it hits the T junction for the upstairs bath it's hot, but on the other of the T junction to the kitchen mixer tap it's stone cold, anyone any ideas ?
  13. T

    Distance between cold pipe cross over hot

    Hello I need to cross over an existing copper hot water pipe with a cold 15mm mains copper pipe. Is there a standard I need to adhere to in terms of clearance?
  14. M

    Pipes going to UFH cold

    bit of an odd one. UFH been working fine for about a year or two now. today the pipes going to it before the zone valve are stone cold. its a very basic system with Hive thermostatic valves controlling the rads upstairs and the zone valve downstairs. Could the pipe be blocked?
  15. S

    Shower valve issue. Hot and cold mixed up.

    Hi all. My hot water feed for my shower is on the left and the cold is on the right. My understanding is that this is correct and this is also stated in the instruction manual for my valve. However when I turn the mixer clockwise cold water is coming out the shower instead of hot water. When...
  16. Zach054

    Balanced Cold. Electric Shower.

    Good Afternoon. Just wondering if it would be fine to connect an electric shower to the balanced cold supply from an unvented cylinder. Replacing an old Bath mixer tap with the shower hose built into it. Regards
  17. C

    Bar Shower hot on right cold on left

    Hi everyone, I am looking to see if anyone has purchased a bar shower where the hot is incoming from the right and cold coming from the left, really struggling to find a bar shower and riser kit to accommodate this, any advice be much appreciated thanks
  18. R

    Unvented cylinder no cold water to multiple outlets

    Hi, I’m having issues with cold water to multiple outlets. Taps, showers, toilets cold water is fine at the kitchen sink. The hot water system is a Glenhill unvented cylinder. Hot water is fine at all outlets. I assumed the cold outlets not working were from the balanced cold from the...
  19. M

    Heat pump unvented install balanced cold

    If changing a combi boiler system to a heat pump. What do they usually do with the balanced cold connection on the hot water cylinder? Cap it. And put a pressure reducer on the mains so they have equal hot and cold pressures? I can't see them repiping a balanced cold from the cylinder to each...
  20. M

    15/22mm cold feed to boiler

    I'm in a house with the cold feed coming up in the kitchen. In 25mm mdpe. The boiler is in the garage adjacent. I plan on running the cold from the sink in the kitchen under the kitchen units to the garage to feed to boiler. And the 15mm coming back from the boiler to the sink. Would there be...
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