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== Control Zones ==
For heating, ventilation and air-conditioning distribution and control purposes, the boat is divided into the zones in the below table. With a K=1, the boat requires approx. 37,810 BTU/h of heating. The main diesel furnace supplies this, sufficient for the coldest weather.
<table width="80%" border="1">
<tr><th colspan="5">HVAC Zones</th></tr>
<tr>
<th>Description</th>
<th>Zone</th>
<th>Distribution</th>
<th>Air<br> Conditioning<br>BTU (K=1)</th>
<th>Heating<br>BTU (K=1)</th>
</tr>
<tr>
<td>Forward cabin</td>
<td>1</td>
<td>44% </td>
<td>24,349</td
><td>16,637</td>
</tr>
<tr>
<td>Aft cabin</td>
<td>2</td>
<td>17%</td>
<td>9,408</td>
<td>6,428</td>
</tr>
<tr>
<td>Pilothouse</td>
<td>3</td>
<td>18%</td>
<td>9.961</td>
<td>6,806</td>
</tr>
<tr>
<td>Salon</td>
<td>4</td>
<td>21%</td>
<td>11,621</td>
<td>7,940</td>
</tr>
<tr>
<td>Engine room</td>
<td>5</td>
<td>-</td>
<td>-</td>
<td>?</td>
</tr>
</table>
But what happens in an emergency? In the event the furnace fails, the Bristol Pacific model diesel stove in the galley can provide 6,500-16,250 BTU to heat the forward accommodation. At the lower heat setting it could maintain a temperature differential of 21 C, while the higher one maintains the design differential requirement of 55 C in the forward compartment.
At the lower setting, water pipes, etc., are protected down to -20 C, a not infrequent winter temperature, which is why the design requirement is the higher 55 C differential. Because the galley stove alone cannot heat the whole boat in the event of a furnace failure, additional heat has to be supplied by the diesel fireplace in the salon. A fireplace such as the Bubble produces only 3.5 kW (11,946 BTU), good for a 17 C differential overall. So it will only heat the pilothouse and salon, not the aft cabin.
Therefore in an emergency in the coldest weather we have a heating shortfall of 21,560 BTU (6 kW). This is not critical above deck in the salon and pilothouse, since there are no water pipes there. But it is critical in the aft head.
Finally, some heating has to be provided to the engine room to keep water tanks and pipes from freezing. Obviously some further development is required in the design of the back-up heating. Increasing the output of the diesel stove is not a good option, as this would tend to make it less useful as a cook stove. Perhaps the Bubble should be re-located to the aft cabin, but this negates its lifestyle purpose. More practical solutions are to shut off the water to the aft head and run the engine to keep the engine room warm. Another solution is to have an aft engineroom and a contiguous forward accommodation space.
→Control Zones
</tr>
</table>
== References ==