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Calorifier consumption in KW when in heating circuit


Markinaboat

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Calculating radiator sizes to give me in excess of heater unit (TBD - new webasto thermotop Evo, refurbed thermotop C or Hurricane). Not difficult ... BUT I cannot find anywhere what a cold calorifier would equate to in KW draw within the circuit?

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Being an old git, I work in BTUs. British Thermal Units.     1 BTU is the heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit.

 

If you want watts then you have to play with joules ( see what I did there? ) and I can't be bothered.

 

So I work it in BTUs and convert to watts  1 BTU = 0.29 Watts

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Take a look here: https://sciencing.com/calculate-time-heat-water-8028611.html

 

From that site: “Pt = (4.2 × L × T ) ÷ 3600. Pt is the power used to heat the water, in kWh. L is the number of litres of water that is being heated and T is the difference in temperature from what you started with, listed in degrees Celsius.

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16 minutes ago, Markinaboat said:

Brilliant, now I know! ?

 

Poor Joules...

so to heat a 65 litre tank from 15c to 65c = 3.79KW?

Per hour.  Gets nearly the same as my old method, never mind joules, he is an upstart.  That is most of a well stoked up  Squirrel stove output.

 

There are heat losses but well lagged they will be minimal.

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12 minutes ago, Boater Sam said:

Per hour.  Gets nearly the same as my old method, never mind joules, he is an upstart.  That is most of a well stoked up  Squirrel stove output.

 

There are heat losses but well lagged they will be minimal.

So my total Rads plan is around 6kwh making a total of around 10kwh! Need 2 x ebersplutter.webasters

Edited by Markinaboat
typo
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14 minutes ago, Boater Sam said:

Per hour.

Kw per hour eh??

 

The power consumption tends towards zero with Delta T, so the power consumption reduces with time.

 

The calorifier manual or spec sheet ought to give the nominal heat load it presents to a boiler for a specified delta T. Domestic hot water cylinder spec sheets do. 

 

 

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5 minutes ago, Mike the Boilerman said:

Kw per hour eh??

:D

43 minutes ago, Markinaboat said:

so to heat a 65 litre tank from 15c to 65c = 3.79KW?

3.79kWh to be precise. However, Mike’s point is more relevant I think. 

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27 minutes ago, Mike the Boilerman said:

Kw per hour eh??

 

The power consumption tends towards zero with Delta T, so the power consumption reduces with time.

 

The calorifier manual or spec sheet ought to give the nominal heat load it presents to a boiler for a specified delta T. Domestic hot water cylinder spec sheets do. 

 

 

Tends towards zero? No, tends towards a low constant value (which is the heat lost from the calorifier’s imperfect insulation). But I spose I’ll let you off.

 

Edited by nicknorman
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4 minutes ago, Alan de Enfield said:

It'd be a guess, but I'm thinking 2kW/h, or 1kw per hour for 2 hours.

 

Would that be "Kw per kw per hour" (like 32 feet per second per second)

 

Well rather as an Amp is a Coulomb of electricity per second, or 3,600 Coulombs per hour, making the term Amps per hour a nonsense, a Watt is a Joule per second of energy, making kW per hour also a nonsense unit. 

 

So no not kW per kW per hour, saying 2kW/hr as your example would be saying 2,000 Joules per hour, per hour.

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5 minutes ago, nicknorman said:

Tends towards zero? No, tends towards a low constant value (which is the heat lost from the calorifier’s imperfect insulation). But I spose I’ll let you off.

 

Er, it won't be reducing when it starts to boil. Bit more than 3.79kW then!

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2 hours ago, Markinaboat said:

Calculating radiator sizes to give me in excess of heater unit (TBD - new webasto thermotop Evo, refurbed thermotop C or Hurricane). Not difficult ... BUT I cannot find anywhere what a cold calorifier would equate to in KW draw within the circuit?

I think in practical terms the calorifier can be ignored, certainly has been with all my installations ;)

  • Greenie 1
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Just now, Boater Sam said:

Er, it won't be reducing when it starts to boil. Bit more than 3.79kW then!

 

<Sigh> !

 

 

Just now, Loddon said:

I think in practical terms the calorifier can be ignored, certainly has been with all my installations ;)

 

Loddon has it right! 

 

I always ignore the calorifier loading when designing a heating system as the load is intermittent and varies and tends towards a negligible value. Not zero. (Ok Nick!!? )

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15 hours ago, Mike the Boilerman said:

 

Well rather as an Amp is a Coulomb of electricity per second, or 3,600 Coulombs per hour, making the term Amps per hour a nonsense, a Watt is a Joule per second of energy, making kW per hour also a nonsense unit. 

 

So no not kW per kW per hour, saying 2kW/hr as your example would be saying 2,000 Joules per hour, per hour.

Amps per hour can be a sensible unit - but mostly not in the situations one sees it used.

 

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12 minutes ago, Tacet said:

Amps per hour can be a sensible unit - but mostly not in the situations one sees it used.

 

I can not think of any use for Amps per hour, which is of course Amps divided by time (hours) so the longer you consume energy the smaller the result is.

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5 hours ago, Chewbacka said:

I can not think of any use for Amps per hour, which is of course Amps divided by time (hours) so the longer you consume energy the smaller the result is.

 

It is a rate of change of current, for the rare occasions one needs to know the rate at which the current in a conductor is rising or falling.

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