Calculating Heat Loss in a Home Heating System

[marmulak]

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.

 

[sophiecentaur]

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?)

 

[Burnerjack]

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.

 

[sophiecentaur]

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.

 

[sardar]

I can provide information and guidance on how to calculate the heat loss in a home heating system. Heat loss in a closed loop system is typically calculated using the following equation: Q = U x A x (T1 - T2), where Q is the heat loss in watts, U is the overall heat transfer coefficient of the system, A is the surface area of the piping, and T1 and T2 are the temperatures at the beginning and end of the pipe, respectively.

To calculate the overall heat transfer coefficient (U), you will need to determine the individual heat transfer coefficients for each section of the system, such as the piping and any insulation. These coefficients can be found in tables or calculated using known values.

The surface area (A) of the piping can be calculated by multiplying the length of the pipe by its circumference. In your example, if the pipe is 8 feet long and has a circumference of 1 foot, then the surface area would be 8 ft^2.

Once you have all the necessary values, you can plug them into the equation to calculate the heat loss in watts. This can then be converted to other units, if needed.

It's important to note that this equation is a simplified calculation and there may be other factors that can affect heat loss in a home heating system, such as air infiltration or heat loss through windows and doors. It may be beneficial to consult a heating and cooling specialist for a more accurate calculation.

I hope this information helps you in your calculations. If you have any further questions, please don't hesitate to ask.