NEW Propane Refrigerator Installation

I have long searched for an acceptable fuel source to eliminate the dependence our refrigerator had on recharging the house battery*for those times we wanted to remain quietly at anchor for more than 24 hours.

Propane looked like a good idea, but until now, I have been a bit leary of it from cost and safety perspectives.* I bit the bullet on cost and resolved my safety concerns with my new setup.* For those who pooh-pooh or tut-tut at the idea of propane installations in boats, I understand, but I think a safe installation of a propane/electric fridge is a truly liberating experience, IF YOUR BOAT IS CONFIGURED IN A MANNER TO EASILY ACCEPT IT.

Let me expound.* My reefer backs up to the cabin side with nothing but open deck behind it, allowing me to open up a large area for ventilation.* In addition to the intake vent with ducting to direct incoming air to the bottom of the reefer, the exhaust vents are fitted with two thermostatically controlled 120 VAC brushless muffin fans.* A galley-down installation is not impossible, but it is probably something*I would not attempt or recommend.* In my case, the whole reefer enclosure is sealed from the rest of the boat eliminating any possiblity of exhaust gases or unburned propane from entering the boat.* We also have CO detectors aboard.

I also added a couple of inches of insulation to the top, bottom and sides of the reefer because the space was there.

Close by the reefer's propane burner box is one of two propane sensors of the Xintex S-2A propane sensor and control panel, which is mounted beside the reefer.* The other sensor is directly*below the unit in the engine room.* If the burner flame were to somehow blow out, the reefer thermocouple switch would shut off the gas supply at the reefer.* if that failed, or the propane line ruptured, the S-2A would sense the gas and shut off the supply at the solenoid switch in the gas bottle locker on the flying bridge.

The dual 20-pound*propane bottle locker from Trident is a nice piece of gear and will also serve as a handy foot rest or table top for the port side aft-facing bench seat on the bridge.* It came with a single regulator, but I opted for a twin unit which automatically switches over from*the empty to the full bottle.* The locker is sealed and came with the necessary fittings to mount it internally.* Had*i done so, one of the two propane sensors would have been mounted there instead of in the engine room.

My operating plan will be to run the reefer on electrical power (no compressor, just a silent electric heater instead of propane warming the amonia refirgerant) while 120 VAc is available through the inverter underway or with generator running for extended periods like*when air conditioning required.* It will also be on electric when we have shore power.

Based on initial usage,*i am guessing this undercounter RM2410 Dometic refrigerator will have enough propane to run a very long time.

It sounds like you've covered every safety feature needed for the installation. I hope the propane usage is small enough to be practical.

The biggest downside I see from this, is as time goes by and you or perhaps the next owner are so comfortable with the setup, the safety features you've built in get compromised. Such as the sealant around the bottom isn't replaced after servicing, the vent fans or monitor system become too much maintenance and aren't kept up, etc.

If you can avoid complacency, I'm envious of your system.

I do have one question, the bottle locker is sealed? Or does it have a "drain" out the bottom for escaped gas? Most of those I've seen have a vent out the bottom which needs to be directed to a place where the gas can't get into the boat. Sometimes this is difficult to do and make it look nice. If the bottle locker is indeed air tight, what happens if a leak occurs? Is it able to hold the pressure of a full bottle as it releases? Or does the gas eventually overpower the seal and then flow wherever it wants? Maybe an additional sensor in the box isn't a bad idea. I wouldn't take the one out of the bilge though.


Ken Buck

If you drain on a deck, the openings in the deck , must be setup to drain ant gas overboard.

Pour a gallon of water in the inside catch tray and see that EVERY drop goes overboard.

We have been using propane for decades, so I have a few sugestions.

First if you havent bought the unit purchase a Sevelle , made by the same folks but for houses (more space) so the insulation is thicker , and NO electric.But its a full sized not under counter.

If you own the unit purchase a Dinasoar replacement circuit board , there about $125 and mill spec construction.

Hook the unit up with at least #10 wire , the stock boards die from low voltage in a NY second.

My 35 -40 year old unit is reliable , but eats a pound a day.

The new units will eat 1/4 that.

For most the electric option is only used at dockside , on DC its about 25 to 35A , inverter AC add 10% , so folks never bother to make the switch, to save some part of 1/4 lb a day.

Enjoy months on the go with never ever a dead battery!

FF

-- Edited by FF at 04:59, 2008-02-18

1/4 pound per day sounds great. Ours, a Norcold RV unit, runs 21 days (in the Bahamas or South Florida)*on a 30 pounder. You could set your clock by it.

Gas or electric all these crappy RV jobs can be helped a bunch with extra insulation glued on the outside of the box.

I am currently experimenting with a Sub Zero freezer , by installing a refrig range thermostat , and blocking the coldest section into a freezer section,

I hope to use the much finer/thicker insulation to reduce run times in our battery limited RV.

FF

FF - We have a standard Sears "under-counter" AC fridge on our boat which runs from the inverter.
I added 1 inch styrofoam insulation board to the sides and installed a small computer fan that comes on with the compressor and found the run times and power used dropped dramatically. We went thru 2 RV type 12/120 units in just a few years and picked the current one up on sale at the local Sears store. It's nice as it does not have a freezer compartment so there is a lot more room inside it and we use a separate under-counter Sears deep freeze with added insulation and a fan as well. Both these units run from the inverter or shore power only and we have increased our available time "on the hook" dramatically. These units have been in service for over 8 years.
The electrical circuits on the RV fridge were pathetic even though it was from one of the big manufacturers. Parts and service were almost non-existent here on the island so the Sears units were a no brainer move.
John Tones "Penta"
Sidney, BC

I vote for Penta and FF.* A small 120/60 box, an inverter (it can be surprisingly small), and a suitable battery bank (which should be on board anyway) beat the risk of a propane application that is definitely NOT approved and equally UNSAFE (regardless of the planning and design surrounding the installation) is by far and away the better approach -- and cheaper by to boot.

Even when every circumstance is considered, there is always that unconsidered situation that will arise, sooner or later, that in this instance could result in the loss of the boat and serious injury to those aboard.* KISS.

DS

I also replaced a AC/DC refrig with a Sears under counter unit. (120V only) I run it off my inverter (No gen on my boat) and I also run a 120v ice maker and a small microwave. All this off of 2 8D AGMs. I admit its a management problem but it's no hill for a climber.*

"and a suitable battery bank (which should be on board anyway) beat the risk of a propane application that is definitely NOT approved and equally UNSAFE (regardless of the planning and design surrounding the installation)"

Nonsense , propane fridges have a good safety record going back 4 or 5 DECADES.

Propane is the ONLY way a cruiser can go for long periods of time , with out noisemakers ect.

Our boat is kept at a mooring in CT when not in use ,

ever see a bat set that can handle a large fridge/ freezer for a MONTH!!!

Don't knock equipment and techniques you are unfamiliar with or do not understand, and have no experience with.

If I were a cruiser, which I'm not.....I would definitely have a propane reefer on board.

While propane is good, I have to praise my Rich Beers cold plate refrigeration system on board. It runs off 110V, so when out cruising I have to run the genset 2-3 hours a day normally to keep it cold. However, if you don't open it, it will stay cold for 48 hours without any power. Discovered this when we had the fire at the marina last year, and the power was out for two days. The freezer was at 34 degrees F after two days... it normally swings between about 5-18 degrees F.

And yes, FF, I only run the noisemaker during the late morning hours!

I worked for Adler Barbour during a furlough and have their gear on board our 90/90.

It works fine for the ACTIVE cruiser , but is useless at a mooring , or whenever the eutetic fluid finally melts.

In New England cruising we would change harbors every 3rd day , as on the 4th the ice cream would start to go soft (above +5F).

2 hours of engine time every 3rd day is hardly a burden IF the boat is being cruised , in the Bahamas we had ice cream after 2 months!(its a big freezer).

Dockside , no sewat a tiny AC can would keep everything fine.

BUT on a mooring , unless you are willing to go aboard and run the engine with almost no load every 4th day , you have nothing.

FF

I have been a long time getting back to this, but I should note some of you have either misread or just skimmed my article and went on about typing up your own thoughts - been there too .

I was reporting on a recently installed system, not something I am contemplating.

The SEALED propane locker is on my flying bridge and has a drain into the open air there. Water flows from that area off the back end of the flybridge into open air. There is no openable door or window anywhere near that point. So although it is sealed, it doesn't need to be in this application.

The system is so safe that parts of it can fail and not compromise the vessel. For instance, the fans I added are for increased efficiency, not safety. I have even figured that with an explosion behind the unit, the huge ventilation hole behind it means that all the flame and smoke will go that way because the front is sealed. If the sensor were to go toes up AND I were to have a propane supply hose rupture behind the reefer (very little hose is actually inside the boat), the propane will exit via the deck-level louvered vent behind the unit. There is no auto-relight feature on the reefer; one has to press a couple of buttons; so there is no chance of an undetected leak getting set off by the reefer trying to restart itself.

The heart of the safety system is the propane monitor, which is dead simple. "Degradation" of it is not possible - it works or you don't get propane. The unit runs a test on the two sensors when energized. No green light for BOTH sensors, no "turny on." If the sensors go bad, a red light shows up, and you get no prpane. If the panel goes bad, a yellow light shows up, and you get no propane. Kinda hard to ignore that, plus you have to press a button on its panel, while looking at all those lights, to open the propane solenoid valve.

With the additional feature of the thermocouple shut-off on the reefer itself, which senses lack of flame in the propane mode and shuts off the reefer's own propane valve, the system is actually looking for a way to fail and NOT send propane to the burner.

If propane systems are safe on rattle-trap RVs bouncing along the roads.... nuff said. So far I have heard about one recent propane explosion on a boat, and it was a sailbote with the unit poorly intalled and below decks. And looking at my initial post, you will see that I do not recommend a below-decks instalation. I expect mine will be working fine years from now when frayed electrical wiring behind 120-volt-only refrigerators has burned down many another boat. I say this tongue-in-cheek knowing full well my propane/electric unit will likely be pwered many more hours on 120 volts than propane.

Until now, I have been doing the 120VAC-reefer thing (with insulation glued to their exteriors and muffin fans for added ventilation of the compressors/coils) for 22 years, and let me tell you, the idea sucks big time with 12-Amps (at 12 volts) being drawn off the house bank - that's 144 Amp-hours at 50% duty cycle in hot weather. My four T145 golf carts are going to go flat dead in about 2-3 days with those things. You would do better with a 12-volt only model drawing 2-3 Amps directly off the batts. I cannot replace the unused undercounter Sub-Zero 120 VAC freezer with another propane refrigerator because there would simply not be enough clearance behind the unit to accommodate my safety requirements; so some time later in the year I will be getting a 12-volt only reefer to go in that slot. With the propane unit running along with this 12-volt unit, I expect to draw less than half the Amps required by the single castoff 120-Volt unit running for a week. Once we use the groceries in the 12-volt unit, it gets turned off.

you will see that I do not recommend a below-decks instalation.

Below decks is fine BUT the bottom of the fridge must be above the water line , and installed in a sump that will directly lead a good volume of gas overboard instantly.

Simulate with a pail of water in the sump.

Pretty EZ to do on a newbuild , or with a pilot house galley ,

lots more "figgurin" if well belowdeck.

FF

OK, so SEALED means there is a gasket on the lid to keep water out. If there is a hole to allow gas leakage out then the box isn't airtight, gastight or watertight. The concern I had was one of overpressure from a leaky hose or valve.

"I have even figured that with an explosion behind the unit, the huge ventilation hole behind it means that all the flame and smoke will go that way because the front is sealed."

Anyone who believes that the explosion will all go out the huge ventilation hole please sit down and do some research on explosions. I quote from New Mexico Tech energetic materials textbook:

"From this moment of detonation a shock front emanates radially outward from the seat of the explosion with a positive blast pressure behind it. Explosive quantity dependant, as these gasses expand at up to 13,000 mph (mach 17.6) they will create pressures at the source up to 700 tons/in (95,000 atmospheres). High heat is generated. At the Oklahoma City bombing temperatures reached 2000 degrees F. The fragments from the containers and the shrapnel associated with the ball bearings will accelerate outward at initial speeds up to 2700 fps (as fast as a rifle bullet)."

This particular passage is dealing with explosions designed to do harm to people using ball bearings as shrapnel. However, any material in the area under the refer during the explosion will become shrapnel quickly. Explosions expand in all directions and the "sealed" front, unless made of thick steel will not protect the inside of the vessel.

The best way to avoid a big explosion is to keep the size of the explosion chamber (gas/air mixture) small. If you'd like to see what a big propane explosion is like, google "Propane BLEVE Tacoma" and watch the video of an 8000 gallon propane tank truck exploding in the middle of an industrial area in WA state. I can also provide close up pictures of what that 3/8 inch steel tank looks like after the explosion.

Having said all that, I think you have done a good job of installing your refer. I would be afraid of saying that nothing can go wrong. Mr. Murphy is very inventive and he is constantly looking for people who feel safe.

Ken Buck

It's a pretty small place behind the reefer where any gas could collect.

I have seen a few explosions in my day (not propane) and I quite believe what I said about expecting a propane explosion back there to be more of a puff out the vents than a rip roaring explosion with the brisiance of high explosives. But firstly, I fully believe that anything less than a fully cut-through gas line is going to have a hard time generating anything like an explosive mixture back there because the huge vent there makes it almost like the darned thing is sitting in the open air - something a below-decks reefer cannot boast.

Just watch the Myth Busters shooting tracer ammo through a cloud of released propane to see how hard it is to create an explosion.

Mr Murphy is why I have installed the redundant safety of a propane sensor with auto-shutdown in addition to the reefer's own auto-shutdown system.

He is also why every inch of supply hose is extremely well guarded against chafe.

The flammable range of propane is 2.5% - 9.6%. If you can see the cloud, you can't ignite it. That's how the natural gas folks weld on charged gas lines, too rich to burn. But then that doesn't make for good TV shows. Have you seen the trick where you move your finger thru a candle flame without getting burned? That must mean that the flame isn't hot enough to burn your finger.

Ken Buck

Oh, I almost forgot, the boat fire a week ago was caused probably by a can of acetone. The boat was being readied for charter service in Alaska this summer. I looked at the collateral damaged boat on Thursday on the hard. It will most likely be sold for salvage, but there isn't much worth saving. It was a very nice sport fisher.

The 60 foot boat which initially caught fire was scheduled to be hauled that afternoon but we were busy at an oil spill and didn't get back down there.

Ken Buck

While I understand the benfits of propane - I had one on a previous boat that worked well, many folks are understandably nervous about having it on-board. I am not since we have a propane stove anyway.

But you can do DC refrigeration which will last a month anchored out or on a swing mooring with the right systems.

Power outages at our marina are quite common and never concern me since our two fridges and the freezer will run happily on two 80W solar panels. The batteries (200Ah x 24V) are only needed at night and then get topped up the next day. after sunrise.**The fridges and freezer aren't opened as much at night and the ambient temp is lower.

Efficient Danfoss compressors
Good quaility insulation
Two 80W solar panels
200 Ah house bank

We also have very efficient charging systems but rarely need to use them.

Jeff b

Hi Fred,*
Lat 37deg S.
In our experience...
Overcast is OK. From October 1 to*March 31, there's always enough light, even if it's raining,*between 0900 and 1700 at to produce at least a*2.5 amps with Monocrystalline panels.
Our average total refrigeration*draw is 2.1 amps,**all at a nominal 24V (actually closer to 26V).*

I wouldn't*expect to be able to do this in winter - but we only do*short (3 day max) cruises then.**
Best regards,
Jeff b