9:54 PM GMT-5
Heating the Boat
Location: Sidney, British Columbia, Canada
Coordinates: 48° 40.170’ N 0123° 24.449’ W
I posted a recent blog on Friday Harbor in which I briefly described the challenges of heating the boat in the Pacific Northwest this time of year. I referred to a project I did to isolate our electric heaters onto their own circuit. I received several requests for more information about the arrangement, so this post describes what I did. If you’re not interested in HVAC or electrical circuits, you can stop reading now. :)
First some relevant history: My dad is a heating, ventilating, and cooling (HVAC) engineer, so I grew up being more aware of heating and cooling than the average kid. He worked on HVAC projects from automobile factories, to regional hospitals, to professional stadiums. A few years ago we attended the NCAA Men’s Basketball Tournament Final Four at the new Ford Field in Detroit, and we spent quite a bit of time discussing the heating and cooling of the cavernous building. When I was in high school we took our Starcraft tent-trailer camping in northern Michigan in the dead of winter to go snow skiing, but not before spending several weekends engineering the insulation and heating system. You get the picture: I’m a bit of a ventilation geek. Thanks for everything you taught me, dad!
As we began moving up the west coast toward the Pacific Northwest, where we planned to spend the winter, I was pretty sure our reverse-cycle air-conditioners would not provide sufficient heating. I theorized that two well-placed electric heaters should be able to heat the whole boat: one in the master stateroom, as far from the door as possible; and one in the salon, as far astern as possible. The heat from both heaters would flow upward, and eventually it would all end up in the pilothouse, so there would be no need to heat the pilothouse. This arrangement has worked out pretty well. Ayla’s forward stateroom doesn’t get quite enough heat because the heat goes up the stairs when it exits the master stateroom. This isn’t an issue while she’s away this semester—we just keep her door closed—but when she gets back in January we’ll use a small supplemental heater in her stateroom. We’ve tested this, and the small supplement is enough to keep her room at a nice temperature.
I don’t like fans—I find the noise annoying—so I wanted to use heaters that would produce and radiate the heat naturally. The first set of heaters we bought were Honeywell baseboard-type heaters, and although they heated quite well, there were two problems. First, they are like toasters, using heated electrical wires inside a metal cage to produce the heat. Once we started using them they felt like a fire hazard. They also smelled terrible whenever dust particles would drop through the metal grating onto the heating elements—yuck! And the final blow came when one of them simply stopped working with no warning. (My dad worked for Honeywell’s main competitor, Johnson Controls, for many years, so I’m sure he’s not surprised at this premature failure.)
So when we got to Friday Harbor I went to the local hardware store, and spent quite a bit of time talking with one of the clerks about their vast collection of electric heaters (obviously people use supplemental heat on San Juan Island). I decided to try one of the Pelonis oil-filled radiator heaters, which we have now grown to LOVE! It’s a bit old-fashion looking—Kathryn says it reminds her of Lucy and Ricky Ricardo’s apartment—but it produces efficient and even heat. After using it for a few days I went back and bought a second one, and they’ve been excellent. The Honeywell heaters are being returned.
Another problem has been power management. Our boat has two 30-amp outlets that can be connected to shore power. The main circuit provides power to most of the boat’s electrical equipment, including the inverter/battery-charger, water heater, convection microwave oven, washer/dryer, and all the lights and plugs. The second circuit provides power to the three air-conditioners. Since we began using the electric heaters they have been plugged into normal outlets, which means they’re running on the primary 30-amp circuit (and through the inverter). We’ve had to constantly juggle heaters, water heater, oven, etc. to make sure we stayed under 30 amps. And I was always worried that when the two heaters were drawing maximum power (about 12.5 amps each), the hot-water heater would spontaneously turn on and blow the circuit breaker, leaving the heaters to quickly drain our house battery bank. This was not a sustainable situation.
Then I got the bright idea to isolate the heaters on our second 30-amp circuit; the one dedicated to the air-conditioners, which we weren’t going to be using at all this winter. Although many of the docks here in the PNW provide only a single 30-amp circuit for each slip, this time of year we often have an empty slip adjacent to us. Whenever a second circuit is available we can use it, and when we’re limited to a single circuit we can go back to juggling with a single circuit. All I had to do was install a couple of plugs that would draw their power from the air-conditioner circuits. I put the salon plug on the salon air-conditioner circuit, and the master stateroom plug on the stateroom air-conditioner circuit.
At first I thought I would do a “home run”, fishing a new 3x12-gauge wire from the each circuit breaker in the pilothouse to where I wanted each plug, but that was going to be quite difficult. Then I realized that the air-conditioners already had 3x12-gauge wires providing power to them. Why not just take the power from there to the plug? I installed two 6-terminal wiring blocks (terminal blocks) next to each air conditioner to split the wire into two wires: one went back to the air-conditioner, and the other wire went to the new plug.
There was already a plug in the salon near the heater location, in the same chamber as the air-conditioner, so this was an easy one. I wired the top plug to the new circuit, and I left the bottom plug wired to the original circuit.
There was not a suitably located plug in the master stateroom, so I installed a new one at the base of our berth. The wire run from the air-conditioner chamber in Ayla’s stateroom to this location was very easy: all the holes already existed, and I just had to string the new wire (it always makes Kathryn a little nervous whenever I drill or cut holes in our boat, so this was a double win). I installed a new box and plug, and I was done.
There are a couple things I really like about the solution. First, the heaters are no longer running through the inverter, so if the power goes off, the heaters go off. Second, when we have a second 30-amp circuit available to us we can completely isolate the heaters from the rest of our power consumption, allowing us to live more normally than when they’re all sharing. And with the flip of a switch we can tie the second 30-amp circuit to the primary 30-amp circuit, so they share a single source of power (which is how we’ll run it when we’re using the generator). It’s all good!
One funny tidbit: Dilly now likes to sleep on the aft edge of our bed, which is where all the heat flows up and over. It’s amazing how cats quickly find the warmest place in the house!
• • •
We cruised from Friday Harbor to Sidney, British Columbia today, and we’re moored at Van Isle Marina. We’ll meet with Raven Marine this week to finish arranging the work to be done on Three@Sea. It’s fun to be in Canada again; last time we were in Canada on Three@Sea was in Nova Scotia, which is a long way from here!