dsi water boiler for brunnhilde

Strangely, the motivation for my wanting to replace the pilot-light lit water boiler in Brunnhilde to one with direction spark ignition (DSI) is not so much for the ability to remotely turn on and off the boiler at will. I really don't find it a bother to having to light the pilot-light with a match. Though it may be a difficult if there is a stiff breeze.

My reason is each time I open the access panel to light the pilot, or to turn off the boiler, I grew increase uncomfortable with the flimsy nylon locking latch of the Suburban boiler. I always have this fear that the latch decides to fail when we are travelling a highway speed. Also it is susceptible to someone with a ill spirited prank to unlock it while leaving the door stay in the shut position. That will cause a lot of paint finish damage should that ever happen. With a DSI one, there is no need to open the access door. One can turn on or off the boiler from inside the cabin.

From the research I did I knew the 4-gallon DSI model will not be a simple drop-in replacement for the 3-gallon pilot-light lit stock boiler.

I purchased the SW4D from Panther RV in Vancouver, Washington. I have taken notice of this RV parts supplier for a long time. It is the first time I work with them. They were very responsive and gave me a price lower than any. It was a special order so it took nearly a month to arrive. I suspect Suburban built this to order because the demand of 4-gallon water heater is next to non-existent in the US.

i couldn't wait for them to ship to me because i was very eager to check out the dimensions and assess any potential show-stoppers

that is it coming out of the box

the wiring diagram on the side - this is all i need

yes! the external dimensions are exactly the same as the 3-gallon factory boiler

the main challenge is the location of the gas connection is different

the gas connection on the stock boiler is about 2 1/2" lower

the steel gas supply line

the routing of the gas line to the boiler is very tight so there is not much room for error

Westfalia did not let us down - they designed the fitting on the other end making the removal of the gas line possible

making a smoked brisket

i wasn't going to take a risk to remove the perfectly good boiler only to find out the new boiler is defective - so i performed a live bench test (with the boiler bone dry)

the only way to drain the water completely is to force air into the boiler

a heat gun help soften the stiff PVC water hoses

i was surprise servicing the simple boiler tested my collection of specialty tools

removing the old boiler involves some struggle

i would realize later the job would be a lot easier if i remove the gas line completely first

the US RV water boiler was not good choice for uni-body van chassis like the Sprinter; they were developed for RV that were build with 2x2 lumber; i really dislike this opening that cut through the reinforcement ribbing

just like bad plumbers that cut your load bearing joists to run their pipes; thus is US RV industry practice

who say i cannot multi-tasking?

it is nice to be able to get an accurate temperature

button up for the night

here you can see the gas connection are at different height; actually the horizontal angle is also different due to the vertical axis of the fitting is at different locations

i could not find any of the American fittings compatible with the factory gas line - it looks to be imperial but has very coarse thread

my protein laden breakfast

i am not going to cut any hole for the panel; i plan to eventually rid the POS Onan Cummin' generator and mount the boiler control at where the generator's

i plot the routing of the wiring; i didn't need to drill any new holes and was able to using the existing wiring chase up through the closet to the top, across and then down to where the generator control panel is

this is the butcher job Airstream did mounting the POS generator control panel

i took this photo to note the position of the gas line WRT the plane of the body panel, as well as the bend angle

carefully checking, i decided this is the best location for the control electronics module

i doubt that one can procure this weather strip should it be necessary

nice and square; it is within the reach of the water boiler wire harness and the high voltage cable

next i tackle to modify the bends of the gas line; in need to raise it horizontally by 2 1/5" while keeping the end of the fitting at the same position WRT the plane of the body panel

the steel gas line is very stiff and you don't want to do a monkey job by bending it in-situ; i did all my bending on a vice with a lot of different improvised implements

this is one of many challenges and this would took many trials and errors to get just right

unlike copper tubing, you cannot "adjust" the steel tubing by hand unless you are willing to risk putting kinks into the tubing; the entire tubing must be just right before you try to install it

finally

reconnecting the water connections and doing the electrical wiring are the easy parts

making connection to the cable to the switch panel in the cabin

the wiring diagram

this is just a temporary setup until i remove the generator control panel to make room for this

in need of a fuse holder i don't have, i came up with this solution

i also painted the rusty steel rim of the boiler mount

strain relief for the high voltage cable; not a good idea to leave it dangling and the last thing you should do is to run it near any wiring

my home made fuse holder - i couldn't find the only one i have laying around

all tidied up with the electronics module hidden out of view and harms way; you cannot tell it is not factory

I tested the boiler from a cold start till it reach set point. The temperature is piping hot, higher than I would set on the pilot-light unit. I then consumed enough hot water to trigger the heating cycle. At this point the water temperature does not feel not hot enough at all.

The conversion was exactly as I have envisioned. The modification of the gas supply line was the most difficult part of the project as I identified before begin the conversion. All went as planed and I am very happy with the result.

I have to admit I am quite impressed with this Suburban product other than there are a number of things I dislike about the inherent nature of the original design template that paved the legacy. I am impressed with the low cost (due to value engineering) and simplicity. What I don't like is the inherent nature of steel tank's eventual, usually catastrophic failure, and the jumbo size cutout required to install it. I have read that the original Truma boiler has been troublesome. Given a choice I would rather live with a more finicky and more sophisticated design that is more complex but without the jumbo size cutout required.

here is a photo of the James Cook with the original Truma high tech boiler - the combustion port is the rectanglar port at the right of the third brake light on the high top; no ugly jumbo size plumber's hack job cutout on the Sprinter body