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hot water

Water heating is a thermodynamic process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.
Domestically, water is traditionally heated in vessels known as water heaters, kettles, cauldrons, pots, or coppers. These metal vessels that heat a batch of water do not produce a continual supply of heated water at a preset temperature. Rarely, hot water occurs naturally, usually from natural hot springs. The temperature varies with the consumption rate, becoming cooler as flow increases.
Appliances that provide a continual supply of hot water are called water heaters, hot water heaters, hot water tanks, boilers, heat exchangers, geysers, or calorifiers. These names depend on region, and whether they heat potable or non-potable water, are in domestic or industrial use, and their energy source. In domestic installations, potable water heated for uses other than space heating is also called domestic hot water (DHW).
Fossil fuels (natural gas, liquefied petroleum gas, oil), or solid fuels are commonly used for heating water. These may be consumed directly or may produce electricity that, in turn, heats water. Electricity to heat water may also come from any other electrical source, such as nuclear power or renewable energy. Alternative energy such as solar energy, heat pumps, hot water heat recycling, and geothermal heating can also heat water, often in combination with backup systems powered by fossil fuels or electricity.
Densely populated urban areas of some countries provide district heating of hot water. This is especially the case in Scandinavia and Finland. District heating systems supply energy for water heating and space heating from waste heat from industries, power plants, incinerators, geothermal heating, and central solar heating. Actual heating of tap water is performed in heat exchangers at the consumers' premises. Generally the consumer has no in-building backup system, due to the expected high availability of district heating systems.

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  1. M

    Hot water cylinder drain valve.

    Hi all, Looking for some help, I am a complete novice when it comes to plumbing so any help would be appreciated. Today i had to drain down the central heating system to change a radiator valve in the lounge that's leaking which was fine. But just as i was about to fill the system again i...
  2. B

    hot water cylinder return valve setting

    h all , i have a faily old s plan fully pumped system with a worster bosch r 18 heat only boiler, the boiler was replaced about 4 years ago had a potterton neta heat before. 16/18 i think, what i want to know it has a gate valve coming from the cylinder back to the reurn to the boiler , what...
  3. B

    Leaking joint on hot water outlet pipe of unvented water heater

    Hello All, I've got a small leak where the pipe of the hot water outlet of an unvented water heater joins the valve. I'm attaching a couple of photos to give an idea of the set up. Is there a good solution that doesn't involve resoldering the joint? Many thanks.
  4. T

    Hot water tank not working after smart meter installed

    Hi I recently had a smart meter installed and shortly after my water tank stopped working - it is an electric tank, I have no gas supply. As part of the smart meter installation they turned off the electric supply. I have attached a picture of one of the front parts of the water heater. I am...
  5. Rogerf

    If we go to lockdown.

    If the government puts us in lockdown, customers with no heating or hot water ,what are we as engineers supposed to do. Doesn’t seem right to just say sorry but can’t attend
  6. S

    Help with hot water wanted please

    Hello, I'd be grateful for any thoughts or help on the following. I have next to no plumbing/boiler knowledge (limited knowledge and parts identification below come from reading the manual): Worcester 35CDi II Combi boiler pressure appears within normal range We have inconsistent hot...
  7. R

    Hot water and heating come on together.

    Hi guys. My heating and hot water both come on together no matter if i put hot water on or heating on. Can't find a 3 way valve anywhere but I've found this in my airing cupboard. Is it meant to have a motorised head on it?
  8. J4M13UK

    Hot Water Pressure Kitchen Sink Intermittent

    Hi folks! I’ve just had this video from a friend who lives in a block of flats. This video is the hot tap from his kitchen sink. As you can see the flow rate is perfect the suddenly drops a fair bit but continues flowing then it goes back to flowing a lot a few seconds later and continues to do...
  9. B

    Sime Murelle HE300 not getting to temperature

    Hi, have a Sime Murelle HE30 boiler on traditional CH 15 rads plus hot water tank circuit. Boiler gets to about 60 then modulates, drops to 50 ish but fails to reach demand temp of 75. Pressure is ok (although could do with a bigger expansion vessel). It was fine last week! Any ideas?
  10. B

    Why Does My Hot Water Circulating Pump Bang When It Starts Up?

    I have recently had a new boiler and circulating pump installed keeping the hot water cylinder. I have the hot water timer set to come on for an hour each morning but when the time is reached, a loud bang comes from the pump which can be heard all over the house. Can anyone please suggest what...
  11. L

    Help... intermittent hot water issue

    My heating has developed a new and unwelcome quirk just recently, which is that it's sporadically failing to provide hot water. This is something that happened a few weeks back, but it seemed to go back to normal, but in the past couple of days it has happened again each day. We have a...
  12. S

    Vented Hot Water Cylinder Without Vent Pipe!

    After calling a plumber to look at our leaking power shower he discovered that there is no vent pipe coming off the hot water cylinder . The cylinder is an old indirect vented cylinder heated from the central heating boiler and has a secondary electric immersion heater that is disconnected...
  13. T

    Worcester Greenstar 30CDi info please

    Hi Is the Eco button for the heating of the radiators, or the domestic Hot water? The reason i ask is there is also an E setting on the Hot water control Knob. When i had a Baxi(old house), the domestic hot water always had priority. which seems logical. How does a worcester bosch handle it...
  14. M

    Hot radiators remain when heating goes off - maybe from hot water storage cylinder ?

    Hot water coming out of the hot water storage cylinder into upstairs radiators after heating/HW turns off and running out of hot water in the mornings. I have a Glow Worm 24HX Condensing boiler on the ground floor with a pump in the same cupboard, a hot water storage cylinder in the airing...
  15. L

    Question on upgrading hot water cylinder

    Hello, I am looking into upgrading various parts of my residential block's heating and hot water system, which serves 12 flats that resulted from the conversion of two adjacent terraced houses. Our current hot water cylinder has 1000 lts capacity, is vented, is heated indirectly through a gas...
  16. elvis80

    PEX-AL-PEX for hot water return (manifold system)

    (Bear with me this is my first post on here...) We're putting in a manifold system for the H+C in the bathrooms of our new house (self-build). What are everyone's opinions on using PEX-AL-PEX pipe for our hot water return system, please? Good or bad idea? The pipe says: Tmax 95 degrees C / 10...
  17. S

    Getting a Remote Control RFWRT thermostat talking to a Worcester Boiler 28i

    Getting a Remote Control RFWRT thermostat talking to a Worcester Boiler 28i, changed the batteries, no heating, hot water working ?
  18. M

    Thermal store combi boiler, hot water flow rate.

    Can anyone tell me the hot water flow rate on a thermal store combi boiler? As opposed. To a 40kw combi that will deliver nearly 16litres per minute. And any recommendations for a good thermal store boiler thanks.
  19. C

    Heating / hot water glitch ?

    Good day . The heating and hot water on my vaillant boiler work fine independently . If my heating is on and a hot water tap is opened or shower used - the heating [ if on ] refuses to come back on and if left will stay off . If I hit the reset button the boiler will fire and the heating comes...
  20. C

    Heating won't come back on after using hot water tap / shower

    Good evening . I have a Vaillant boiler that although the heating and hot water work perfectly independently the heating if in use will not come back on after using a hot tap or shower . If I press the reset button the heating will come back on but will not do so on it's own accord . Any advice...