Search the forum,

heat

In thermodynamics, heat is energy in transfer to or from a thermodynamic system, by mechanisms other than thermodynamic work or transfer of matter. The various mechanisms of energy transfer that define heat are stated in the next section of this article.
Like thermodynamic work, heat transfer is a process involving more than one system, not a property of any one system. In thermodynamics, energy transferred as heat contributes to change in the system's cardinal energy variable of state, for example its internal energy, or for example its enthalpy. This is to be distinguished from the ordinary language conception of heat as a property of an isolated system.
The quantity of energy transferred as heat in a process is the amount of transferred energy excluding any thermodynamic work that was done and any energy contained in matter transferred. For the precise definition of heat, it is necessary that it occur by a path that does not include transfer of matter.Though not immediately by the definition, but in special kinds of process, quantity of energy transferred as heat can be measured by its effect on the states of interacting bodies. For example, respectively in special circumstances, heat transfer can be measured by the amount of ice melted, or by change in temperature of a body in the surroundings of the system. Such methods are called calorimetry.
The conventional symbol used to represent the amount of heat transferred in a thermodynamic process is Q. As an amount of energy (being transferred), the SI unit of heat is the joule (J).

View More On Wikipedia.org
Recent contents Top users
  1. H

    Best way to clean a heat exchanger

    I have a central heating system in a 7yr old ‘Persimmons’ new build, that has several problems related to reduced flow. A nice retired engineer on these forums, has helped me, through extensive testing, identify the heat exchanger as the culprit. The boiler is a Glowworm Ultracom 24hxi, 10...
  2. H

    Voltage for Nest E Heat Link in the UK

    Can anyone confirm that a 240v central heating wall thermostat can be replaced by the Nest E Heat Link? According to Google, the wiring needs to be low voltage so it will not work but I have seen a few comments in forums that the European version is different to the US version and does work at...
  3. ndfred

    Range Rating: Just Add up the Radiators’ Heat Output?

    I have a Vaillant boiler and want to set d.0 to something sensible, right now it is set to auto and can range from 6 kW to 37 kW. Adding up my radiators' heat output from the Stelrad website gives me 25.7 kW and my hot water cylinder coil rating it 23.9 kW. The Heat Geek Range Rating Method is...
  4. J

    Heat exchange rate in cylinder

    Just a fast one for the experts Does say heating water entering coil in hw cylinder heat the dhw faster if say the heating presure is say a bar and a half as oppose to f and e. Also if hw cylinder was unvented would speed up heat transfer aswell?? Thanks in advance if i get a reply
  5. kevintrot

    Which is the best boiler vs heat pumps

    Hello, I am not sure about the boiler as well as heat pump. Please tell me which one I should put in to heat my home.
  6. S

    ACV Heat Master HM 60 N heating separate from DHW?

    I just moved into a house with an ACV Heat Master HM 60 N boiler in the garage, providing hot water for two heating systems (plus of course domestic hot water). One is an underfloor system for the ground floor controlled by a Honeywell CM67. The other is a radiator system for upstairs controlled...
  7. gingalig

    Unvented and boiler heat loss calcs

    I have a house with 14kw heat loss using the whole house method, ( Navien oil system boiler ) I aimed to use heat engineer software on acceptance of the quote but have been struck down with covid, the unvented cylinder is 300ltr due too a family from Ukraine living there ( 8 people living...
  8. grumpydad

    Ultra heat rads and EPH trv's any good?

    Hi all Been quoted to replace 12 rads and valves, when I asked what they use. He said ultra heat rads and EPH trv's. Anyone used ultra heat rads or EPH trv's? Would you expect them to be any better than Screwfix Kudos?
  9. R

    Baxi 105e plate heat exchanger upgrade

    Hi all New Diverter valve going in mid week ( subject to eng being available) and from my previous discussion, the dhw plate heat exchanger could also be causing the bypass to lift. So I have sourced a potential replacement dhw plate heat exchanger to go in at same time, but the original part...
  10. B

    Can a 12kw boiler ever heat a 4/5 bedroom house with 3 bathrooms?

    Hi - I'm a homeowner, not a DIY person. My 20 year old Gloworm boiler needs replacing. British Gas quote is ok at £6100 for a 24kw replacement -valiant ecofit 625 system boiler. The tank/heat exchanger and copper pipework bring the price up. OK so I object (rightly or wrongly) for the extra...
  11. J

    Heat and hot water suggestions

    Need suggestion for heat and hot water. New 1300 sf,2 bed 2 bath, 2nd home that will have daily and weekly renters.
  12. T

    Heat leaking out of hot water tank?

    Hi everyone Would love some advice! We have a hot water cylinder which lost 14 degrees (48 to 34) in four hours, with no demand/usage. So I think the heat is escaping. The circulation pump (which you can see in the photo) is off, so could passive convection be the reason? The pump is always...
  13. I

    Ideal Logic Heat 15 with FD error

    Hi all, Really hoping somone can shed some light on this. I have an Ideal Logic Heat 15 boiler with an FD error. However, the boiler doesn't have a pressure guage or pressure release valve, so I am unable to check the water pressure. I assume this model doesnt work in that way? I have water...
  14. P

    Can you use a heat battery for central heating?

    Hey all, Excuse me if I get some facts wrong, I'm a complete noob when it comes to anything other than replacing radiators. We're about to get PV Solar Panels (~6kw) and a large battery storage array (2xTesla Powerwalls for ~27kwh storage and ~10kw output). I'm looking to replace my old...
  15. urebaz78

    Using fire to heat radiators

    My current set up (images attached). I can heat my hot water tank (oldWood Fire.jpg) using the coal/wood fire , however how would I be able to use the fire to heat my radiators (7). I have recently moved into the house and I just cant see how its done. What would I need to buy to enable this...
  16. A

    Samsung Air Source Heat Pump

    My ASHP has been set to 55 degrees C for the legionella in the control panel but I thought it had to be set to 60. Engineer seemed to think this is ok. I note that in 6 weeks I have had error E919 which is telling me the unit couldn't perform the correct heat for legionella thus the error code...
  17. M

    Connect air source heat pump to 2 UFH(unused)ports on a thermal store?

    Would it possible to connect an air source heat pump into 2 UFH (unused) ports on a thermal store? The property is heated by oil and a wood stove. I have the option to use the ports that are connected to the wood stove as using the heat pump would be a more efficient and a better priority, I...
  18. K

    Air to Air heat pump

    Has anyone installed / worked with air-to-air heat pumps? I wonder if their running cost is also high? There’s no information on running cost and even the people handling the funding pots for Air source heat pumps, are not aware of the costing.
    • Katelina
    • Thread
    • air heat pump
    • Replies: 0
    • Forum: Renewables
  19. I

    Gas or Electric to heat water in a flat

    Hi, I have a two bedroomed flat that I rent which I am going to completely renovate. I have pretty much decided on electric radiators but not sure how to heat the water. Seems like instant water has problems with filling a bath and so will probably need a hot water cylinder. Should I be heating...
  20. C

    Heat Towel Rail Switch - Clicking Noise

    Hi there We have a heated towel rail in our bathroom - Heller brand (well the switch is anyway). Was installed about 10 years ago. We have on a timer, comes on in the morning and back again in the afternoon, overall works well. However the Heller Switch / controller has been making a...
Creating content since 2001. Untold Media.

Newest Plumbing Threads

BS 5389 Tiling Standards
Plumbers Forum - Plumbing Advice
Tiling Forum UK
Tiling Forum UK
DIY Talk
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock