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combi boiler

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. P

    Alpha Combi Boiler Settings

    Please can somebody tell me what the correct settings should be for my Alpha Combi Boiler Eco 2 Plus and Thermostat. Please see the attached photograph with all my current setting. Currently, my daily electricity usage seems to be higher than normal and it just was serviced. kind Regards...
  2. M

    Combi boiler pressure issue

    Hi, hoping for some advice on problems I’ve had with a combi boiler. I have a Vaillant ecotec plus 831 serving 4 radiators and 1 towel rad plus water to a bathroom and small kitchen. Only recently bought the house and there were signs of leaking at all rad thermostatic valves and the stains...
  3. A

    Unvented System vs Combi Boiler

    Hi folks, new member to the forum here. Me and my wife are in a bit of a dilemma with our hot water/heating system we currently have. We are planning to do a kitchen extension at the back of the property (currently the kitchen is at the front, with the boiler in a cupboard), + add one more...
  4. E

    Ideal Logic 30+ combi boiler - no heating

    Hi all, Looking for some advice as to why my central heating is not working. We have recently moved 2 radiators, replacing one with a new one. When turning the boiler back on there is now no heating. We have hot water, we have checked the pressure, bled the radiators, reset the boiler. We do...
  5. S

    New thermostat doesn't turn on combi boiler

    Hi, The house I've bought came without a room thermostat. Just a combi boiler with a timer. So I bought a room thermostat, installed it, but it doesn't turn on the heating. Here are some photos to illustrate. So as you see I've piggybacked of the Live and Neutral input from the boiler to...
  6. S

    Boiler not turning off

    Hi there I've got a Valliant echo plus 28 combi boiler and what I've noticed is that when I set the thermostat target to say 20 it keeps on going( not everytime tho) I changed the stat to a nest thinking that might be the problem but noticed that again when I set it to 20 I would look an hour...
  7. M

    Worcester Greenstar Junior 28i combi boiler - no green light or heating

    Hi all, First of all, I hope I have posted this in the correct place (apologies if not). I haven't used my boiler throughout the summer and have gone to turn the heating on. The hot water is fine and no problems but the green light does not come on my boiler and there is no heat. The blue...
  8. P

    New Combi Boiler Hum

    We had a new Worchester Combi put in our loft yesterday, before agreeing to put it in the loft we asked the plumber if there would be any noise issues in the bedrooms below. He said there wouldn't be. After installation, in the bedrooms we can hear a lo whir when the heating clicks on, which...
  9. N

    Will a combi boiler be adequate for my house?

    We recently moved into a new home that currently has a Super Hot MG-100 Hydronic Boiler (installed in 1986, when the house was built). Clearly, the boiler is way past its life expectancy and in need of replacement. We had a couple of boiler companies come give us a quote and one of them...
  10. S

    Combi boiler constantly filling up

    Hi all my Combi boiler a Worcester 28i junior the old one is constantly filling up and over pressuring and the overflow is running like a tap the filling loop is disconnected this happens with the boiler on or off the pressure drops when the hot bath tap is on dose anyone know what’s up with it...
  11. H

    Shower going from hot to cold - Main Combi 24 Boiler

    Hey everyone, I'm hoping for some help/advice with my shower. I've a Main Combi 24 boiler, and my shower is from a mixer tap over the bath. When the boiler flame lights, the shower will be hot almost instantly, but a few minutes into the shower it'll go completely ice cold. I'm then soaped up...
  12. C

    New Boiler - Pressurised System or Combi Boiler?

    Good evening, We are having issues with our current system, mainly around the water pressure being low and having to rely on shower pumps to get enough pressure for our showers - our second pump in so many months has just died so I'm sick of it and figured It's probably worth it in the long...
  13. Dame1701-

    Refill a Baxi combi boiler (24 series)

    Hi guys, We have a baxi combination boiler which needs to be re-pressurised (error code 119 I believe). I've done this several times on different boilers using the tap on the front. I just want to confirm that we need to turn the two taps at the front to repressurise. From what I understand we...
  14. D

    Pumps to boost pressure for combi boiler flat?

    Hi, I live in a 4th floor flat, with 2 recently refurbished showers and a combi boiler. The pressure in the showers was poor, so after getting some reassurances that a gravity fed pump was still ok for my flat, I had a gravity fed salamander pump installed, but after a few weeks of it working...
  15. M

    Combi boiler shower hot and cold

    I had a plumber out to service and do a gas certificate for my combi boiler. Since then my shower that runs off the boiler will not stabilise temperature. When I twist the single lever mixer tap the shower goes too hot or too cold. He says this is not his fault and will not come back. I say it...
  16. L

    Combi boiler modulation for low heat output

    I'm looking to buy a 24kW combi boiler with only 4 radiators rated at 1.7kW each, so I can later expand and add more radiators. I expect relatively low heat dissipation from the heating circuit. If I run the boiler from cold, the water heats up to say 40 degrees in the heating circuit and the...
  17. J

    Will a new Combi boiler improve shower flow??

    As the title says. I have been going round in circles deciding what to buy or get fitted (with a raft of various advice)...the short story (so far). I have an old Combi boiler needs replacing and, I am having a new bathroom installed in October but, I want to improve the all round shower...
  18. B

    Issues with Thermostatic Shower / Noisy Pipes

    Hi folks We have a weird problem. Our shower is a Triton thermoststic run from an Alpha combi boiler. The pipes began making a noise when the hot water was turned on (any tap) and we realised if the shower thermostat was turned to coldest setting this resolved the noise. But .. now the hot taps...
  19. B

    Thermoststic Shower - Hot Water Pipes Bang

    Hi folks I have a problem. Our shower is a Triton thermoststic run from an Alpha combi boiler. The pipes began making a noise when the hot water was turned on (any tap) and we realised if the shower thermostat was turned to coldest setting this resolved the noise. But .. now the hot taps...
  20. D

    Gettting CH but not HW

    Hi I have a Ideal Combi 35 boiler, we are getting CH but not HW. I have been looking around and seem to think it’s the diverter valve. Any suggestions would be great fully appreciated. Cheers