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. K

    Running out of hot water after 3 minutes

    I’ve had a new bathroom put in and having problems with the shower. The pressure is awful and runs cold after about 3-4 minutes. The hot water still comes out of the taps and we have another shower which has never run out of hot water after 15/20 minutes plus and is still working perfectly. The...
  2. S

    VENTED central heating system - water circulating through header tank

    Two years ago, I requested a fully qualified plumber to change the location of the hot water cylinder in a vented central heating system. I wanted to move it from the first floor to the loft, which he did. During the last two years, I have often noticed when I have been up in the loft that the...
  3. M

    Hot water not working

    Hi. My Potterton Suprima boiler stopped working- red light on constantly. I replaced the PCB with a new one. Then the boiler worked fine but no hot water. Heating working normally. S plan system. The water would only work if I put the 2 port valve on manually. So I changed the actuator - Danfoss...
  4. S

    Problems with hot water on a gravity fed system.

    Asking for a neighbour. He has an old style gravity fed heating system with tank and immersion heater. He has just changed the pump and three way valve actuator. His heating works but if he selects hot water it turns the heating off. Any suggestions would be appreciated, thank you.
  5. M

    Hot Water Mystery

    I'm hoping someone can shed light on this mystery for me. My son has moved into a rental flat and, not being very savvy with central heating controllers, I'm trying to help him understand how it works. And I'm trying to help him remotely which is making it very difficult. His flat has a combi...
  6. P

    Is my CH/HW fully pumped? Is it two-pipe?

    Hi, I'm having problems understanding the exact configuration of the CH/HW piping in my house. In particular, I have to understand where and how to place piping for additional radiators at the upper floor. My configuration is the classical one: loft cistern, indirect cylinder on the upper...
  7. T

    Hot water not up to temperature

    Evening all, hope someone can give advice. I have a Baxi duo etc 24 HE A combi boiler and over night the hot water is not going above the digital display of approx 48 degrees. The burner and light does come and goes off, this still happens when the hot water dial setting is at max but the temp...
  8. A

    Very hot water and radiators after Summer.

    Suggestions please. I have an puzzling problem. I switched off hot water and CH in Summer. Baxi boiler. After a short period of turning hot watertap on the water was scalding. Assuming hot water coming from hot water tank? I switched on hot water and CH but hot water is still scalding and...
  9. I

    Towel Rail on Hot water system

    Hi all Hope you can help... firstly, I'm not a plumber, but l like to be hands on If possible and try to understand things if I can. The problem I have is I had a new radiator/towel rail replaced in my bathroom which I tiled a while back. I had a local plumber plumb the radiator in which I...
  10. T

    Is it the tap or the vented hot water system?

    Hi all, I've got a customer with an Edwardian bath/shower mixer which gives her water that's either too hot or too cold. The taps are quarter turn, so ceramic disks of course, but even I couldn't get the hot water to come out at a safe temperature. I'm wondering if this is down to a failure...
  11. P

    Not hot water

    Hi.. I have a Trianco combi external oil boiler.. the problem i have is that i cannot get any hot water unless I turn the central heating on. If i turn any of the taps on ( mixture between normal and mixer taps) the boiler wont kick in. I have had the diveter internals changed but no joy. It...
  12. M

    Horizontal Vented Hot Water Cylinder

    Is a horizontal cylinder (indirect) as efficient as a standard vertical cylinder? No choice but to use use a horizontal but just asking the question to those who have experience .
  13. C

    Hot water and heating on at the same time

    Hi. We have a baxi boiler conventional hot water system. We noticed that when the controller has hot water only selected that the radiators too get hot. I put this down to a faulty midway valve as the indicator on the valve was on w but both outlet pipes were hot. So yesterday we got a man in to...
  14. L

    Slow hot water after fitting new immersion tank

    Can someone please tell me what I have done wrong. Fitted a new tank exactly as old one recently but since then the hot water pressure up and downstairs has been really low. (E.g. A good 10/15 mins to fill kitchen sink) It is a gravity fed system. No gas. So far tried to clear any airlocks...
  15. P

    Worcester 42cdi Hot water problem

    Hello, I have a problem with my Worcester Greenstar 42cdi. It was working fine until yesterday. when I noticed that the hot water would not get hot. upon further investigation, I am even more baffled. The boiler is in the upstairs bathroom. 1. Bathroom sink, (closest to boiler) gives warm water...
  16. P

    Hot water cylinder making squeaking and running water noise.

    Hello, I am in South Devon and have a Daikin monobloc air source heat pump with HW cylinder which provides CH & HW. Currently CH off and just supplying HW. Once a week (SAT) the system heats up to 70c for sterlistion etc. It has been doing this in almost silence for 3 1/2 years until today...
  17. A

    No hot water combi

    Baxi main eco elite. Call for hot water , no fire up. I have a service contract but as the fault is erratic and may not be evident when an engineer calls, he will not touch it while it's working, and I will have to pay £95 excess regardless. No fault code as yet. Can anyone help as to what could...
  18. T

    Aqualisa very hot water low pressure

    Hi All, this is my first post and need help. I recently developed a fault with my Aqualisa Quartz electric shower 8.5kw. When you start the shower the pressure is really low and you can hear the water heating up. However the water is extremely hot and the pressure is really low. It then makes a...
  19. C

    LPG instant hot water boiler advice

    Hi, I'm trying to setup a campsite and need to provide a shower and 2 or 3 sinks for the compost toilets and kitchen area. The field has a 1/2" water supply but no electric. I had thought of using a horse shower that runs off a LPG bottle but I'm guessing that will only cope with the shower...
  20. P

    Main Combi HE 30 boiler

    Hi Everyone. My boiler has recently started playing up. When using the shower or hot water the boiler fires then cuts off for a couple of seconds then fires again. Resulting in Luke warm/cold water. I’m guessing it might be the heat exchanger as the boiler appears to be louder than usual. Any...
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