HeatingCalculation - Revision history

DavidShaw: /* Method */

2015-10-07T13:47:48Z

‎Method

DavidShaw: /* Method */

2015-10-07T13:43:59Z

‎Method

DavidShaw: /* Method */

2015-10-07T13:02:05Z

‎Method

DavidShaw: /* Summary */

2015-10-07T13:00:25Z

‎Summary

DavidShaw: /* Summary */

2015-10-07T12:57:44Z

‎Summary

DavidShaw at 23:04, 6 October 2015

2015-10-06T23:04:38Z

DavidShaw: /* Heating Calculation */

2015-10-06T22:59:36Z

‎Heating Calculation

DavidShaw: /* Heating Calculation */

2015-10-06T22:56:43Z

‎Heating Calculation

DavidShaw: Created page with "= Heating Calculation =
Download spreadsheet: [tbd]
Methods of calculating requirements for both heating and air conditioning tend to the..."

2015-10-06T22:43:48Z

Created page with "= Heating Calculation = <div id="spreadsheet"><i>Download spreadsheet:</i> [tbd]</div> Methods of calculating requirements for both heating and air conditioning tend to the..."

New page

= Heating Calculation =

<div id="spreadsheet"><i>Download spreadsheet:</i> [tbd]</div>

Methods of calculating requirements for both heating and air conditioning tend to the arcane or the very simplistic. There are too many variables to consider, e.g., the colour of the deck paint affects the amount of heat gain inside. The provided [[#spreadsheet]] application tries to strike a balance between simplicity and accuracy. When calculating heating requirements, it ignores heat gain through southern exposure windows in the daytime and heat loss through all windows at night. It also ignores sporadic heat gain from equipment and appliances.

The spreadsheet uses the following formula to determine heating requirements in British Thermal Units per hour (BTU/h):

<pre>BTU = V * T * K * B</pre>

where:

<pre>V = volume of the accommodation in cubic metres

T = temperature differential in degrees Celsius

K = dispersion coefficient (how heat ‘lossy’ is your boat)

B = 4 (conversion factor to BTU)</pre>

To calculate the Volume, for each living space multiply Length * Width * Height in feet as shown in the below table. Use judgement in deciding whether to list each space individually or as part of a section. The calculator will do the conversion to metric.

For T, if you need to convert degrees F to degrees C, the formula is:

<pre>C = (F – 32) * 5/9</pre>

The dispersion coefficient K is adapted from housing construction as follows:

<pre>K = 3.0 - 4.0 (Simple construction, simple windows - Not insulated)

K = 2.0 - 2.9 (Simple construction, simple windows - Poorly insulated)

K = 1.0 - 1.9 (Standard construction, double-pane windows - Moderately insulated)

K = 0.6 - 0.9 (Advanced construction, triple pane windows - Well insulated)</pre>

With K=3, the calculator yields 19 BTU/ft-sq while experts recommend 20 BTU/ft-sq, so we have good agreement at one end of the range. How aggressive you should get towards the other end is impossible to say. However, with the three heating systems specified for the boat there should be ample scope for increasing or decreasing the heat without upsetting the balance of the system.

In a system that is under-sized, the furnace will run for long periods. In an over-sized system, the furnace will cycle frequently and run for very short periods. In general, a heating system should be sized 154% of the requirement so it runs at about 65% duty cycle.

Typical furnaces are 80-90% efficient, so if you need 100,000 BTU output you will need one rated at, say, 125,000 * 154%.

<table width="80% border="1">

<tr>
<th colspan="5">Accommodation Space Calculation</th>
</tr>
<tr>
<th>Area</th>
<th>L<br>(ft)</th>
<th>W<br>(ft)</th>
<th>H<br>(ft)</th>
<th>V<br>(cu ft)</th>
</tr>

<tr>
<td>Forward</td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>Aft</td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>Pilothouse</td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr>
<td>Salon</td>
<td> </td>
<td> </td>
<td> </td>
<td> </td>
</tr>
</table>

@@ Line 9: / Line 9: @@
 == Method ==
-<div id="spreadsheet"><i>Download spreadsheet:</i> [[Media:CalculatedHeatAC.xlsx.xlsx|Microsoft Office xlsx]] | [[Media:CalculatedHeatAC.xlsx.ods|Libre/Open Office ods]]
+<div id="spreadsheet"><i>Download spreadsheet:</i> [[Media:CalculatedHeatAC.xlsx|Microsoft Office xlsx]] | [[Media:CalculatedHeatAC.ods|Libre/Open Office ods]]
 </div>

@@ Line 9: / Line 9: @@
 == Method ==
-<div id="spreadsheet"><i>Download spreadsheet:</i> [tbd]</div>
+<div id="spreadsheet"><i>Download spreadsheet:</i> [[Media:CalculatedHeatAC.xlsx.xlsx|Microsoft Office xlsx]] | [[Media:CalculatedHeatAC.xlsx.ods|Libre/Open Office ods]]
 Methods of calculating requirements for both heating and air conditioning tend to the arcane or the very simplistic. There are too many variables to consider, e.g., the colour of the deck paint affects the amount of heat gain inside. The provided [[#spreadsheet]] application tries to strike a balance between simplicity and accuracy. When calculating heating requirements, it ignores heat gain through southern exposure windows in the daytime and heat loss through all windows at night. It also ignores sporadic heat gain from equipment and appliances.

@@ Line 5: / Line 5: @@
 == Summary ==
-Methods of calculating requirements for both heating and air conditioning tend to the arcane or the very simplistic. There are too many variables to consider. The provided method is based on volume of the heated space, differential with the external temperature, and a dispersion coefficient (heat loss) to give the required heating in British Thermal Units (BTU). It correlates well with industry practice for calculating heating for homes.
+Methods of calculating requirements for both heating and air conditioning are usually based on floor space and rules of thumb. The provided method is based on volume of the heated space, differential with the external temperature, and a dispersion coefficient (heat loss) to give the required heating in British Thermal Units (BTU). It correlates well with industry practice for calculating heating for homes.
 == Method ==

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 = Heating Calculation =
 == Summary ==
 == Method ==

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 To calculate the Volume, for each living space multiply Length * Width * Height in feet as shown in the below table. Use judgement in deciding whether to list each space individually or as part of a section. The calculator will do the conversion to metric.
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 </tr>
 </table>
 == Related Pages ==

← Older revision		Revision as of 22:59, 6 October 2015
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	= Heating Calculation =		= Heating Calculation =
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		+	== Summary ==
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		+	== Method ==

	<div id="spreadsheet"><i>Download spreadsheet:</i> [tbd]</div>		<div id="spreadsheet"><i>Download spreadsheet:</i> [tbd]</div>

← Older revision		Revision as of 22:56, 6 October 2015
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	</tr>		</tr>
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		+	== Related Pages ==
		+
		+	[[VentilationCalculation\|Calculating Ventilation Requirements]]
		+
		+	[[AirConditioningCalculation\|Calculating Air Conditioning Requirements]]
		+
		+	[[Category:Heating]]

HeatingCalculation - Revision history

DavidShaw: /* Method */

DavidShaw: /* Method */

DavidShaw: /* Method */

DavidShaw: /* Summary */

DavidShaw: /* Summary */

DavidShaw at 23:04, 6 October 2015

DavidShaw: /* Heating Calculation */

DavidShaw: /* Heating Calculation */

DavidShaw: Created page with "= Heating Calculation = Download spreadsheet: [tbd] Methods of calculating requirements for both heating and air conditioning tend to the..."

DavidShaw: Created page with "= Heating Calculation =
Download spreadsheet: [tbd]
Methods of calculating requirements for both heating and air conditioning tend to the..."