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In addition, to provide backup in the case of failure in a severe cold spell, a diesel bulkhead fireplace in the salon, such as the Kabola Old English Diesel Room Heater [4] or the Harworth Bubble [5] is also plumbed into the distribution system. Other types of bulkhead heater are available from Dickinson [6], Refleks [14] and Sigmar [15].Initially a fireplace was desired for lifestyle reasons, but as the design evolved it became a backup system. The Dickinson Bristol Diesel Cook Stove [6] in the galley can also heat the forward accommodation, but it is not part of the main distribution system. The main distribution system also routes through the towel rails in various compartments. These are switched out of the circulating water system in summer and heated with AC elements.
== Heating == 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 author has developed a spreadsheet application that 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 invBritish Thermal Units per hour (BTU/h) [1]: BTU = V * T * K * B where: 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) 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: C = (F – 32) * 5/9 The dispersion coefficient K is adapted from housing construction as follows: 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) 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.
== Ventilation ==