This page covers the installation of the propane system that powers the furnace and the stove on our DIY ProMaster camper van conversion.
Propane Tank Type and Location
We had a commercial van conversion RV some time back that had the propane tank mounted under the van. While this setup was OK, it did have some disadvantages: 1) the tank was always dirty from the road and tire splatter and all this dirt and mud made for a short life for the components like valves, gauges, and regulators, 2) the tank was one of the low points on the van and it seemed like it could be damaged, especially on back roads 3) the tank was difficult for the propane guys to fill due to its location and dirt, and 4) you had to find a place that refills cylinders and wait for them to find someone with the time to do the refill.
On this conversion, we decided on using a standard 5 gallon refillable cylinder (e.g. a standard BBQ cylinder) and to locate it in a sealed compartment within the van that is vented to the outside.
On the plus side, this arrangement 1) keeps the entire propane system out of the weather and mud, 2) allows you to either refill the cylinder or just trade it for a new cylinder at one of the many places that offers this service, and 3) its much cheaper than using one of the under van tanks.
On the negative side, 1) it takes up some space inside the van, 2) the capacity is only 5 gallons as compared to (typically) 8 gallons for the under frame tanks, and 3) some may feel there is a safety issue with having propane inside the van (see below).
My guess is that the five gallon capacity will work out to be fine. For warm weather trips with little furnace use, the propane usage for just the stove will be small and the tank should easily last several trips. For cold weather trips, the van is small and pretty well insulated — I believe (based on a little testing) that the propane usage per night at 32F will be about half a gallon, so the change tank interval should be at least a week. But, if you are doing the Dempster Highway in the middle of winter, you might want to carry an extra cylinder.
Another consideration for propane is that if you make a ferry crossing, the propane tank will likely have to be turned off at the tank shutoff valve.
There are some potential safety issues both plus and minus to this arrangement. On the plus side, 1) the tank is protected from physical damage, 2) the propane compartment is strong, securely attached to the van, vented to the outside, and separated from ignition sources, 3) the whole propane system is inside and not subject to malfunction caused by dirt/mud/debris.
On the negative side, you have the propane tank inside the van. All stuff for YOU to consider, research and make up your own mind about.
There will, of course, be propane and CO alarm system to detect any leaks and incomplete combustion — as there must be with any vehicle that uses propane (or any fuel).
Some Information on 5 Gallon Propane Tanks
The 5 gallon or 20 lb propane tanks are very widely used — mostly to power gas barbecues, but also for many other things like cooking, heating, weed burning, …
They can be refilled at places that sell propane or there are many exchange services (e.g. Blue Rhino) that will exchange your empty tank for a full tank.
While the tanks have a nominal capacity of 20 lbs of propane, the overfill protection (OPD) float and valve limit the capacity to 17 lbs. And, many of the exchange services (e.g. Blue Rhino) only fill the tanks to 15 lbs. Propane weighs 4.2 lbs per gallon, so 15 lbs is 3.6 gallons — if you get a full 17 lb fill, that’s 4 gallons. The tanks are only filled to 4 gallons max so that there is always a gas space above the liquid propane to allow for expansion if the tank is subjected to a hot environment.
A gallon of propane has a heating capacity of about 92,000 BTU, so a full tank gives you about 330,000 to 370,000 BTU total.
The empty weight of each tank is stamped on the collar of the tank — usually about 17 lbs. If you have something like a 50 lb fish scale, you can weigh the tank to get an idea how much propane is left. The tanks start at about 32 to 34 lbs full, and go down in weight as the propane is used. When the total tank weight is down to about 17 lbs, you are about out.
Update 12/7/16: Tried this Grill Gage for checking how full the tank is. Found it to be very handy. You don’t have to lift the tank up high enough to see the gage scale, as it records the reading.
On the safety front: the tanks have overfill protection that prevents filling to more than 17 lbs of propane so that there is always a gas space above the liquid to limit the pressure inside the tank if the tank should be moved to a hot environment; there is a pressure relief valve in the tanks that blows out releasing the propane if the pressure inside the tank reaches a very high pressure; there are controls on the manufacturing of the tanks, and they have to be recertified after 10 years; there is a safety control in the tank valve that turns off the flow of propane if the flow exceeds a certain value (e.g. from a broken line). All this is good, but propane is dangerous and you should treat it with the utmost respect, and have a propane and CO alarm in your RV.
One caution about the Blue Rhino tanks — some of them can only be refilled by Blue Rhino… This could be a big inconenience if you take your RV to a place where a Blue Rhino exchange is not available.
Update: January 2017
It appears that my statement above that the OPD valve on a 20 lb tank prevents it from being filled to more than 17 lbs is not correct. It appears that a 20 lb tank can actually be filled to 20 lbs, and that the nominal 20 lb tank when filled to 20 lbs is only 80% full and has the required 20% vapor space. There is quite a bit of conflicting info out there, but this link appears to give truthful data.
I have found a local propane tank exchange that actually fills cylinders to 20 lbs. This is clearly stated on the label, and I’ve weighed a full cylinder and it showed 19.6 lbs. This is in contrast to the very common Rhino tank exchange cylinders that are only filled to 15 lbs. You get an extra 25% more propane, which extends the time between exhcanges and means that in cold weather you can run more nights on a tank without refilling. They don’t charge anymore for these full 20 lb tanks than Rhino charges for the 15 lb exchange tanks.
The picture above shows the tanks I’ve been getting. It clearly states that you get a full 20 lb.
These tanks are equipped with the usual overfill protection valves (OPD valves).
So, its worth looking around for a place that does 20 lb fills rather than the 15 lb fills that Rhino (and others) do. Maybe if enough of us do this Rhino will get the message and start doing full fills.
Another option is to have your tank refilled at a propane place — they should be able to fill it to the full 20 lbs, and you also won’t be “losing” the propane that is left in the tank when you take it in.
Installing the Propane System
Our propane tank lives inside the van in a sealed, strong and well anchored compartment that is vented through the floor to the outside. Its a regular 5 gallon barbecue to minimize the refill/exchange hassle when more propane is needed — its also a very inexpensive tank.
The Propane Tank Compartment
The propane storage compartment is built into the aft end of the driver side bed unit. It is made with 3/4 inch high strength Medium Density Overlay (MDO) plywood and is bolted down through the floor in several places with 3/8 inch steel bolts.
The compartment is made so that the cylinder just fits inside of it, so there is no need to fasten the cylinder to the compartment as there is no place for it to go — this makes it easy to do swap outs when the cylinder is empty.
The lid of the compartment is easily removable so that the propane cylinder can be removed for refilling or swapping out with a new cylinder. The lid is 3/4 MDO and is secured in place with 4 carriage bolts with wing nuts and washers on the bottom side — takes about a minute to remove the lid and get the cylinder out.
The tank is a regular BBQ cylinder and the gas connection can be disconnected or connected by hand without tools.
The next few pictures show the finished propane tank compartment and the removable lid that provides access to the tank when you want to put a new tank in.
The 2 by blocks being glued and screwed in place provide a place secure anchor for the carriage bolts that hold the lid down.
Update: While the above tank compartment lid works fine, I’ve since changed it so that the aft end of the lid is secured with a piano hing, and the forward end of the lid is secured with two over center latches. This makes it faster to swap out tanks.
Venting the propane compartment
The compartment is vented with a 3/4 inch plastic line that goes from the bottom of the compartment straight down through the floor and is open at the bottom.
The regulator and hose arrangement is a standard BBQ style unit. It screws onto the cylinder by hand — no tools required. I have read that there are some advantages to using a 2 stage regulator, and I’m going to look into upgrading.
The rest of the propane plumbing is 3/8 inch flexible copper tubing with flare fittings used for the connections.
There is very little plumbing. A single 3/8 inch line runs forward from the tank along the drivers side near the van sidewall to a Tee that is located behind the furnace. One 3/8 copper line goes from the Tee to the furnace, and another goes from the other connection on the Tee to the propane stove.
Connection of rubber hose from propane tank to the 3/8ths copper tubing.
This is the first time I have used the flare fittings, and they seem relatively easy to make up correctly, quite secure mechanically and gas tight.The flare fitting procedure is: 1) slide the flare nut onto the tubing 2) use the flare tool to flare the end of the gas line, 3) thread the flare nut onto the flare fitting.
I checked all the connections with gas leak fluid — no leaks.
When to Refill?
I use a fish scale to measure how much propane is left in the cylinder — an empty cylinder weighs about 17 lbs (empty weight is stamped on the cylinder) and a full cylinder is about 38 lbs. The weighing is done by hooking the scale on the loop of cord around the valve plumbing — does not require removing the cylinder from the compartment or disconnecting the hose. A gauge of some sort would be handier, but have not had a chance to look for one.
Note: this Grill Gage for checking how full the tank is works quite well and is much easier to use than a fish scale in that you don’t have to lift the tank up to eye level.
In order to have some backup propane in case I screw-up and run my 20 lb cylinder down to nothing, I now carry a couple of 1 lb propane cylinders and an adapter that adapts the 1 lb cylinders to the regulator that my 20 lb tank normally plugs into. The one lb cylinders supply enough propane for hours of cooking and even for limited space heating.
If I were doing the compartment that holds the 20 lb tank again, I would allow slightly more room so that it would hold the 2o lb tank and a couple of 1 lb tanks. This would take very little more room as there is already some dead space in the corners.
Cost, Weight and Time
|Item||Cost ($)||Weight (lb)|
|5 gallon propane cylinder||$0 (on hand)||20 empty, 37 full|
|3/8 inch copper line and fittings||$40?||5 lb ?|
|Regulator and hose||$20||3 lb?|
Installing the propane plumbing took a couple hours. The fabrication of the compartment for the propane tank is included in the Beds/Storage section.
November 30, 2014, June 24, 2015