LPG Fireplace Safety Guidelines

Posted by Darrell Nicholson with Drew Frye at 03:32PM - Comments: (8)

Drew Frye
Drew Frye

PS Tester Drew Frye's installation on his PDQ catamaran required a slight bend in the chimney. Ideally, any installation should strive for a straight exhaust.

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. 

 

Comments (8)

Great article, but what about the LOW-PRESSURE REGULATOR AND SOLENOID?? If you WANA see a LPG system that's done correctly? It's done to code, and then some, the Dickinson LPG Caribbean & the Cozy Cabin propane heater each have a dedicated High strength hose with HD connection fittings, secured to the bulkheads & double the insulation through the floors and walls!! We have 2-20# tanks & 2-6# tanks!! The stove isn't as thirsty as the heater, but not by much!!!

Posted by: Gary Larsen | April 18, 2019 11:39 AM    Report this comment

Drew
My 1983 Catalina 36 had a Dickison Propane heater much like yours - I upgraded the installation in several areas to improve safety.

1) I added a computer muffin fan behind the flue as it left the stainless back of the stove. These fans can be very quiet and run on 12 V - This takes flu temp way down and really improves heat distribution. hung like a diamond - a pair of #6 fender washers capture the stainless back at the bottom of the fan, and a single wood screw with a 1" standoff secures the top. I wired to come on when ever the propane switch is on.
2) I added the Exhaust Guard - this keeps the sheets from catching in the multi layered exhaust hood.
3) I added a propane alarm - haven't gotten to hooking it to the solenoid yet but its on the to do list.
4) In addition to running rigging - inflatables on deck of necessity sit on or very close to the exhaust - so don't punch 5" holes in the dink by forgetting it up there - don't ask.

Posted by: LeslieTroyer | April 18, 2019 10:32 AM    Report this comment

ABYC requires that there be a solenoid valve on the propane with a manual switch located in an appropriate location inside the cabin. ABYC also requires that there be propane sensors. ABYC does not require that they be linked together as indicated in this article. Personally, I think that it is a good idea to have a system where the propane sensor automatically shut off the propane solenoid. However, the last time I checked, the link is not required by ABYC

Posted by: Wes | April 18, 2019 9:44 AM    Report this comment

When recently exploring a unit to replace our dreaded Force 10/Cozy Cabin heater. The FOrce 10 diesel/kerosene stank up the cabin, left soot on the headliner, and didn't put out much heat. If used incorrectly, it also posed a severe fire hazard. In considering replacements, we considered the various Espar Hydronic and Webasto units, but we finally focused on two alternative Dickinson units:
1) The Dickinson P12000 propane with coaxial chimney tubing. The coaxial chimney stack brings in fresh external air in the outer tube, and send exhaust out through the inner tube. This greatly improves the persistent problem of high humidity due to combustion of propane to Carbon Dioxide and lots of water. But the total heat output is limited, and it meant yet another propane appliance, with the associated dangers. The heat output is a modest 5,500 BTUs. Installation is relatively simple.
2) The Dickinson Newport Diesel heater, mounted on the bulkhead. Our concern was that it would emit irritating diesel odors. However, the recent design burns without release of diesel odors. It puts out over 16,000 BTUs, burns cleanly, uses the same diesel fuel used in the engine, and can also be used to heat circulating hot water for use in the galley and head. The installation is a bit more complicated, but provides large amounts of heat. Igniting the burner is a bit more complex than the propane, but with practice is easily achieved.
I installed the Diesel Newport heater in the same general location as our old Force 10 diesel/kerosene heater. I have been very happy with the results. It puts out lots of heat, absolutely no diesel fumes. The hot water coil built into the heater is moderately efficient. I like the idea of having hot water in the head on a chilly morning without having to run the engine. But it is a slow procedure with this unit.

Posted by: hjkarten | October 25, 2015 6:40 PM    Report this comment

Drew,

Unattended is not necessarily your activity it is a definition of a type of appliance under the standards. An oven/stove is considered an "attended" appliance. The type of appliance determines where it fits into the ABYC standards definitions, and what it needs to comply with. Regardless of how it is used by an owner, a heater, gas refrigerator or gas water heater is considered an "unattended appliance" and thus should be "room sealed combustion" just as the P9000 is.

The Dickinson Propane models do have room sealed combustion and are beautiful and cozy little propane heater/fireplaces. As for leaving a heater running unattended, I don't even leave my Espar running when I am not on-board. The Force 10 /Cozy Cabin heater that was on-board our boat when we purchased her was immediately disconnected and removed. You are spot on about the level of humidity non room-sealed LPG heaters can create and that, on top of not meeting the safety standards, is why we removed it.

Posted by: RC Collins | October 23, 2015 11:39 AM    Report this comment

Silver Heels. This past week I was out for 4 days, running the heat much of the time. The humidity ranged from 40-50%, confirming that a sealed heater means a dry cabin. The Cozy Cabin is not sealed and tends to increase humidity dramatically, as well as CO2.

RC Collins. I do not operate the Dickinson P9000 unattended and would not suggest that practice, even though it does include sealed combustion. When I leave during the day it is off, and it is off at night (lots of blankets--I really like a cold sleeping cabin). I also seal my boat up pretty tight in the winter--storm windows and extra weather stripping. It is a much smaller space than a house, and so the risk of CO build-up is simply too great for my personal standard.

Posted by: Drew Frye | October 23, 2015 11:21 AM    Report this comment

One major point that often get missed is the definition of an "unattended appliance". Under ABYC standards a cabin heater, gas refrigerator or water heater is considered an "unattended appliance" regardless of the safety features built into it. As a result any heater, refrigerator or water heater should comply with the minimum safety requirement for an unattended appliance.

ABYC A-26:
26.5.10 Unattended appliances shall incorporate a room sealed combustion system.

ABYC A-26 Definitions:

26.4.4 Unattended Appliance - Appliances intended to function without frequent attention by an operator, and that may cycle on and off automatically, such as refrigerators, thermostatically controlled cabin heaters, and water heaters.

26.4.7 Room Sealed Combustion System - A combustion system in which incoming air, the combustion chamber, and the outgoing products of combustion are sealed from the boat interior.

There are many cabin heaters out there that do not meet the minimum requirements for safety on board a boat. The Cozy Cabin heater is one of the most prolific. Here is the disclaimer from the manual.

Cozy Cabin Heater Disclaimer:
"Caution: This heater consumes oxygen. You must supply sufficient outside
air to replace the oxygen used by the heater. This unit is equipped with an
oxygen depletion device which will turn off the pilot flame when the oxygen
level drops to 95% of normal. This, in turn, cools off the thermocouple,
which shuts off the main valve."

As a DIY reading this disclaimer you might actually assume it meets current boating safety standards, yet it does not, because it is not a room sealed combustion design and it is an unattended appliance.

There are also numerous on-demand water heaters using extremely misleading marketing that also do not meet the minimum safety standards. I have actually had to remove a few on-demand water heaters to satisfy an insurance survey.

Like anything this market is buyer beware and surveyors are playing a very close game of CYA these days. All gas "unattended appliances" should incorporate "room sealed combustion". Don't risk failing an insurance survey because your installed appliance is not in compliance with the minimum accepted safety standards.

Posted by: RC Collins | October 23, 2015 8:11 AM    Report this comment

Gas fireplaces can cheer up a crew on a damp evening. This type of gas fireplace takes in outside air, sending its exhaust back out via a coaxial flue, sharing the same basic path with the air intake. This means that it does not consume inside air. As veterans of four frigid Canadian winters aboard our boat, we know that the solution to humidity buildup inside a boat is to increase outside air exchange by consuming damp inside air and shooting it up a chimney. The definitive text on cold weather boat heating is " The Warm Dry Boat". Search for it if you'd like to extend your yachting season into the fall and early spring.

Posted by: Silverheels III | October 22, 2015 5:51 PM    Report this comment

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