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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. J

    Hot water pump runs continuously

    I have a Potterton Precision boiler fitted by British Gas 8 yrs ago. All good up to now but in the last few months it has failed to come on a number of times when required by the thermostat. I have had to press the reset button. The pump has also recently started to show it is running at low...
  2. A

    Combi Boiler heats radiators when hot water only is selected.

    My combi boiler has started heating the radiators when I select hot water only. Any ideas ? The system has been in for maybe 10 years.
  3. will-i-am-sam

    URGENT Cold Shower/ No Hot Water

    😒😒😒 Hello there, we have a Bristan Bliss electric shower, yesterday morning it was working fine, my husband and my daughter both had a shower no problem. We had a plumber round to relocate our bath pipes and sink pipes & to fit the new toilet, ready for our new bath and sink to be fitted, but...
  4. N

    Hot water zone valve issue

    Hi I’ve been having problems with my boiler tripping my electrics For a while which has got worse.. I now have no hot water and my boiler won’t turn on for more than 5 Mins without tripping. A gas engineer attended yesterday and said it was water damage from the pipes and the hot water zone...
  5. B

    Hot water only when heating radiators.

    Hello. I have a Worcester Greenstar 24 Ri boiler linked to a Megaflo cylinder. The boiler heats water for central heating but when I want hot water only the boiler does not fire up. I can get hot water when the central heating is on, but not ideal in the summer. The boiler is only 18 months old...
  6. Stanios

    Promax/ Performa hot water switch

    I am sure everyone is familiar with these and the common diaphragm replacement cure for drips and no hot water fix. Just the other week replaced a diaphragm it looked pretty good I put new one in anyway. The pin did come out but only when the tap was half way on at least. Pressure in the house...
  7. M

    Secondary hot water T

    Hi Lads. I'm working on a large house and we need to tap into the secondary hot water pipe to extend it to the new part of the house. Silly question but I have never had to T in more than once and was checking this would be okay to do.
  8. R

    Fluctuating hot water after new rad.

    Hi, Just after some advice from someone that knows more than i do please . Boiler is a viessmann Combi boiler less than three years old. I recently replaced an old radiator and moved the location, I have cut and capped the old pipe work and added new. I froze the pipes to cut but one of the...
  9. S

    baxi duo-tec2 fault code e385

    as above driving me insane about ten people from 27/4 rescue looked at it can not find problem,i get hot and ch but it takes a while for it to come through all the time flashing 385 then all of a suden will fire up and be fine
  10. Z

    No switched live to boiler when hot water tank thermostat demands heat + CH staying on.

    Hi folks. I have a couple of issues, any help advice much appreciated. 1. When my hot water tank thermostat demands hot water (wired into Honeywell wiring centre), I do not get a switched live to the boiler. I get 69 volts ac for both on and off wires from the tank stat. I have fitted a new tank...
  11. G

    URGENT Overflow running when heating or hot water on

    Hi all, I have a customer with open vented system,cold feed from f&e tank is teed into flow just above cylinder coil where in enters attic as expansion/vent which terminates through roof The tank overflows whenever heating or hot water is on and stops as soon as boiler/pump goes off,so it’s...
  12. M

    Combined direct vented hot water cylinder

    Hi, I have a combined direct vented hot water cylinder installed in my flat and it works on economy 7. Just recently I have noticed that when I open a hot tap the water didn't come out warm and also after about 2 minutes the cylinder or pipework to it started juddering. Just in case the heating...
  13. Z

    Shower is not activating hot water?

    Hello all, first post here. My shower has been playing up lately. It feels like it's lost pressure and goes cold after a couple of minutes. The copper pipe for the hot water from the combi boiler is cold so it's not activating the hot water for some reason. If I run the tap that activates the...
  14. C

    Hot water variations

    We have a weird problem with the hot water in the house. The system is only three years old with a Potterton Promax Combi and a Megaflo cylinder on the ground floor. Around three weeks ago our mains pressure was fluctuating due to a mains problem and our hot water has been all to hell since...
  15. H

    Why is the water pressure non existence for hot water supply to shower?

    We bought an Edwardian semi detached house just over a year ago (previously a hotel, converted in the mid 90s). The shower (not power or pumped) had low pressure for hot water which got worse over time, then out of nowhere (hadn’t got round to getting anyone to look at it) it was great, better...
  16. G

    Replacement hot water cylinder query

    I'm going to replace my hot water cylinder with as close as I can to like for like. Replacing as it doesn't have an immersion heater. It's a copper vertical 140Litre tank in an indirect vented system and the inlets and outlets seem pretty standard, except it has an outlet for the shower that's...
  17. M

    Baxi Duo Tec 40 HE A Fluctuating Hot Water Temperature

    Hello All, I am currently having an issue with my Baxi Duo Tec 40 HE A not maintaining a constant temperature for the domestic hot water. With a thermometer under a tap & the domestic hot water thermostat set to 43 °C I get a fluctuating temperature from 51 °C to 38 °C which is clearly not...
  18. F

    No hot water can’t repressurise

    Hi I desperately need some help please. We have an oil fed heating and hot water system that has decided to stop working today. Done the obvious checks on the oil, which is fine. But they system is below 1 bar pressure. So suspect this to be the main issue. However I can not seem to be able to...
  19. 4

    Installing Shower Booster Pump

    My Son has converted a spare room into Bathroom in an extension of a long Cottage. The room is remote from the Boiler and Cylinder which feeds the existing Kitchen and 2 Bathrooms. An Inline Powerstream Water provides Hot Water to the Basin and Shower direct from an extended cold feed. This...
  20. A

    Is this pump installed correctly? Pictures keep getting air though the hot water.

    Hello everyone I was wondering if you could help me solve an issue I'm having with air in my hot pipes. I had a positive head pump installed in the airing cupboard as shown in the picture but it would not start without putting the shower head in the bath to increase the pressure. After a month...

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