Calculating Heat Loss in a Home Heating System

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SUMMARY

This discussion focuses on calculating heat loss in a closed-loop home heating system using the temperature difference and flow rate of water. The formula for power loss is established as Power (in Watts) = Temperature Change × Specific Heat of Water × kg of water flow per second. Accurate flow and temperature measurements are critical for precise calculations, with a recommendation to convert flow rates from gallons per minute to pounds per hour for consistency. The conversation highlights the importance of understanding both metric and imperial units in these calculations.

PREREQUISITES
  • Understanding of thermodynamics principles, specifically heat transfer.
  • Familiarity with the specific heat capacity of water.
  • Knowledge of flow rate measurement techniques.
  • Ability to convert between metric and imperial units.
NEXT STEPS
  • Research methods for accurately measuring water flow rates in heating systems.
  • Learn about the specific heat capacity of water and its implications in heating calculations.
  • Explore the conversion formulas between metric and imperial units for fluid dynamics.
  • Investigate the Callender and Barnes experiment for practical applications in heat loss calculations.
USEFUL FOR

Engineers, HVAC professionals, and anyone involved in designing or optimizing home heating systems will benefit from this discussion.

marmulak
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Hi every body
This question came to my mind when I was looking at a Home Heating System.
The system is a closed loop. In this closed loop of pipe hot water is flowing.
I know the temperature of the pipe in the beginning and at the end of the pipe.
I also know the flow rate of water in the pipe.
I want to calculate the heat loss in this circulating system.
For example at the beginning of the pipe I have the temperature of 50 centigrade degree, and at the end of the pipe this temperature becomes 40 degrees, if the water flows at the rate of 8 ft/m, then how much is the heat loss in this system.
I am an electronics engineer and I don't know how to calculate this.
Thanks for your help.
 
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This takes me back to the Callender and Barnes experiment we did in the V1 form. If you know the temperature change and the rate of mass flow then that will tell you the Power being delivered to the house.

Power (in Watts) = Temperature Change X Specific Heat of Water X kg of water flow per second

Nots: it's not the speed of the water that counts - it's how many kg per second are going through. You will need to get out a bucket and a stopwatch! Actually, if you know the speed and the diameter of the pipe, you could work out the volume per second - which gives the mass etc. etc. Is the speed you refer to the speed of water in the main output of the boiler?

You can substitute imperial units and still get the answer. (SI rules in UK and most of Science and you would need an answer in kW, in the end. no?)
 
Your answer lies in the formula for Btu. 1 degree F x 1Lb of water= 1 btu.
T1-T2 x flow in Lbs/ hr will yield Btuh.
The tough part is 1) accurate flow measurement and 2) accurate temp measurement.
Remember to convert Gpm to Gph by multiplying by 8.33 ( Lbs/ gallons)
Sorry for the imperical units, its how I learned it and I'm too old to change.
 
All that remains is to count the cost in Pounds Shillings and Pence.
Can you really be that much older than I?
I did the Imperial thing at School - 32 ft/sec/sec and all that but it was more than 50 years ago.
 

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