Posted by Darrell Nicholson with Drew Frye at 03:32PM - Comments: (8)
One of our contributors in northern Michigan reported another dusting of snow last week, reminding me that while the summer pattern of afternoon seabreezes is beginning here in Florida, spring sailors in other parts of the country still need ways to heat their cabin.
Back in 2013, I wrote about the various types heaters that Practical Sailor has examined. Our most recent full-blown product test involved small electric space heaters, but past reports have also looked at wood-burning, pot-belly stoves, diesel heaters like the Wallace stove/oven, modular air-heating systems like Espar and Webasto, and gas heaters that run on liquefied petroleum (LPG). In the December 2015 issue of Practical Sailor we revisited the venerable Dickinson Propane Fireplace, a compact LPG heater that has been around for decades, with some small improvements over the years. Although compact, the Dickinson is part of a relatively complex LPG system, requiring special precautions during installation. The use of LPG to generate an open flame also raises certain safety concerns while in use, as with an LPG stove.
As part of this report "Playing it Safe with LPG Heat," contributor Drew Frye provides an in-depth look at a do-it-yourself installation, with special emphasis on safety. The following are important safety tips that generally apply to any propane heating system. These guidelines focus primarily on the items downstream from a properly-fitted LPG tank and locker, which we’ve described in detail in our report, "Some Propane Dos and Donts." As I pointed out in a related report on a fatality aboard a sailboat in Guatemala, ignoring basic safety sense with regards to LPG can have devastating results.
The American Boat and Yacht Council’s Standards and Technical Reports for Small Craft offers explicit guidance on LPG systems like the Dickinson. In addition to following the ABYC guidelines and any guidelines provided by the manufacturer, you will also want to consider the following tips from Frye:
- A proper propane locker housing the regulator and shut-off solenoid, and providing overboard drainage for any gas leakage, is a must. Alternatively—though less desirable—cylinders can be mounted above decks, so long as the gas flow path is overboard and not into the cockpit or any locker.
- A cut-off solenoid connected to cabin gas sensors and a control panel is required. Our test boat, a catamaran, has a sensor in each hull, near the appliances; these must be as low as practical.
- A separate gas line is required for each appliance, with connections only in the propane locker and at the appliance. The test boat has four lines for four appliances (refrigerator, stove, water heater, Dickinson P9000). These lines are supplied in pre-made lengths with the fittings attached.
- The gas line must run through a vapor-tight fitting from the propane locker into the cabin. This is a standard item through West Marine, Defender Marine, or Dickinson. Pre-assembled with 3/8-inch flare fittings on each end, it is a bit fat; the fitting will accommodate these. The line should be well secured to reduce motion.
- A 12-volt electric supply, preferably via a dedicated breaker, is required for the unit’s fan. The Dickinson will run without it, but the heat output is considerably less and not well distributed. The safety shut-off is not dependent on electricity.
- Side clearances are quite small for this unit (two inches), because the fan circulatescold air around the firebox, keeping it cool. Additionally, the combustion air is drawn through the deck, and around the flue via a double-wall pipe. Thus, the flue never really gets hot on the outside (measured at 175 F) and requires no additional insulation where it passes through the deck. Two-inches of side clearance in the cabin is enough. Other cabin heaters may require greater spacing and flue guards.
- Because of the weight and vibration of the heater, through bolts are preferred for mounting.
- Any heater will produce exhaust hot enough (measured at 329 F, but most heater stacks are hotter) to damage running rigging. This will require a line guard to keep running rigging from snagging (and possibly burning) on the chimney. We built our own guard, as the stock deflector can still snag some lines. Without the deflector, the chimney will catch and hold every line that comes near.
- Check all gas connections for leaks with diluted dish washing liquid and a brush.
- Periodically test the system for leaks by shutting off the tank and all appliances; pressure should maintain for at least two hours. For more details for leaks detection, see my blog post "Double Check for Propane Leaks."
- Test the propane leak sensors by exposing them to propane (use a cigarette lighter with flame not lit). The tank solenoid should cut off appliances. If you suspect that your propane detector is producing false alarms, check for possible other sources, such as solvents. For more details on false alarms in propane sensors, see our recent report, "Boat Gas Detectors and False Alarms."
- While the unit is equipped with a flame failure switch and is sealed from the cabin, a CO monitor is an important addition on any boat that uses fuel for cabin heat. We tested several of these over the years (Google "Practical Sailor CO detectors" for past tests.