The Norcold Refrigerator 876EG2 *or* Electrics (Part III)

After getting the AC breaker box and converter installed and working, I set about getting our fridge in place and powered.  The 4-4 1/2 cubic foot fridge that we salvaged from our friends’ trailer was what we wanted in terms of a small three-way unit, but unfortunately, it didn’t work.  First, the controller card wasn’t responding, and even though the ammonia system was sealed and I could force the AC heating element to fire up and run, the fridge just wouldn’t cool.

Now, if you’re only used to our modern, AC, compressor refrigeration systems, the ammonia-based systems of a heat-powered system may seem odd. But they are super-quiet (aside from the occasional gurgle) and great for boondocking.

Here’s a nice introductory video on non-mechanical refrigeration systems:

If watching the video is too long for you, essentially the three-way (two electric heating elements or the LP gas heater) system works non-mechanically (no compressor to force-chill the liquid/gas coolant) to cool the interior of the freezer and fridge through heating ammonia to a gas, then taking advantage of the fact that it will condense back to a liquid and the chilled liquid ammonia will become the cooling factor for the freezer and the fridge.   Ammonia boils (and thus condenses back to liquid) at -28°F, which is more than enough to keep things freezing in the freezer.

Think of the ice machine in The Mosquito Coast

Now, in getting a second-hand non-mechanical fridge system, there are some trouble-shooting things you need to do, unless the owner you’re getting it from can demonstrate that it definitively works.  One is to tip it on it’s back for several hours, then raise it up slowly.  This is done as an attempt to insure that all the liquids are back down in the reservoir so that the ammonia can be boiled off, and thus cool the interior of the fridge/freezer.  The other is to bypass the thermostat’s circuit board and put a heat source (like the electric heater that is installed on the unit or an LP source, like a low flame propane torch) to see if the ammonia will boil out and chill the system.

The most important part of the system is the cooling system, and many old fridges can be rehabbed by purchasing a new cooling system (most for around couple hundred dollars).  After I tested the salvaged unit for a couple of days and found no temperature change in the interior at all, I considered this, and started in to do my research, finding out that the shipping charges for these rebuilt/recharged systems can be costly.

It turned out that for us that a (relatively) local seller on Craigslist was selling a 6 cu ft Norcold Refrigerator (model 876 EG2) for about what it would cost for us to get the rehabbed cooling unit for the smaller salvaged unit.  And, the seller had it running and cooling when I came to pick it up, so I knew that it was good.  (He was also the one that threw the converter in for a song.)  This was a good deal, as a comparable new unit like one of these is much more expensive:  

Norcold Inc. Refrigerators N641.3 3 Way 2 Door Refrigerator (Automotive)

List Price: $1,230.89 USD
New From: $1,230.89 USD In Stock
Used from: Out of Stock


Norcold NXA641.3R RV Gas Absorption Refrigerator

List Price: $1,846.80 USD
New From: $1,767.81 USD In Stock
Used from: Out of Stock

The Freezer ...
The Freezer …

The 876 model is a two-door unit, which was a change from the salvaged one, which had a small metal enclosure for the freezer that helped to cool the rest of the fridge.

The Fridge area ...
The Fridge area …

The two door unit makes for a much more energy efficient and manageable freezer and fridge in terms of temperature.  You don’t get ice in the fridge area and the freezer stays really cold.

However, the 876 is taller and slightly deeper than the salvaged unit, which threw a bit of a wrench into my plans.  As you might remember from my floorplan, FloorPlans2 there was a covered window behind the fridge, as the fridge needed air space for the cooling vents, and for the heat and exhaust to be vented  outside in order to function.  One of the major reasons why absorption refrigerators don’t work has to do with insufficient ventilation and blockages in the heating system.

With the smaller, salvaged fridge, I had expected to cut vents into the skinned window and not have to cut the roof, even with the fridge sitting up over the wheelwell (I had expected to use the seat-rail as a support).  However, with the much larger 876, I would have to cut off the seat-rail, and rebuild the wheelwell cover in order to lower the fridge as much as possible, and then cut a vent hole in the roof.  I had also planned to cut vent holes in the floor to gain air flow and O2 for the LP burner, but with the depth and base construction of the 876, I wasn’t able to do that, so I would have to also cut into more of the skin of the bus in order to get good air flow (and I was nervous about both of these cuts, since I hadn’t done anything to the exterior up to this point!).

Now, I knew that the fridge cooled nicely on 12 VDC, and wanted to verify that it would run well on AC, and was upset when I plugged it in and got no response! But that was because the thermostat circuitry is all 12 VDC, and must have power to run so the AC can kick on the heating element.  Once that was rectified, I confirmed that the fridge would automatically switch from a DC source to an AC source (and back) when the AC was available for the heating element.  This is kind of a big deal as the electric heating elements are not as efficient as the LP burner, and when available, shore power is your friend for cooling.  The DC power is important for while you’re driving (and perhaps for regular running when all the solar panels get installed), and the LP is good for extended boondocking.

The gas line to the burner had corroded/worn to the point that it had holes and broke upon finger pressure.
The gas line to the burner had corroded/worn to the point that it had holes and broke upon finger pressure.

But before I could check and see if the LP worked, I had to replace the gas line from the solenoid and, as it turned out in dis-assembly and cleaning, a new burner.  The new burner was easily available 

Norcold 621957 Burner and Orifice (Automotive)

List Price: $58.64 USD
New From: $30.61 USD In Stock
Used from: $53.51 USD In Stock

(though it used to cost less than it does now!) and needed a new compression fitting at the end of the tubing.

The new, steel LP line for the burner on the fridge.
The new, steel LP line for the burner on the fridge.

Luckily, I had bought a really nice set of tools for flaring compression fittings to redo the brake lines in my wife’s Daewoo, and it turned out that the gas line was a 5/16″ line that I had a bunch of, so I cut and formed up a new line that sealed up nice and tight, and all worked well.

Oak facing on the fridge (and freezer) doors.
Oak facing on the fridge (and freezer) doors.

Unfortunately, as the 876 had been pulled from an RV that had been sitting unused, it was from a unit that had been built in the late 80’s or early 90’s, and had this horrible beige padded covering that stuck out and made the fridge even that much bigger.  I had examined the doors and found that the hinges could not only be moved to the right side (from the left where they had been), but also that with the removal of one of the edges the padded facing could be easily removed and replaced with some stained oak plywood, which fit a lot better with our overall look.

I trimmed the existing wheelwell covering and removed the pieces that held it up.  Some 2×3’s built up a new floor for the fridge and then I could measure for the area that it would need for the air venting intake and then the hot air exhaust.  These presented some problem as the opening I wanted to cut would have gone right through one of the rub-rails.  I wanted to preserve these as much as possible so that the bus would keep as much of it’s structural integrity as possible.

The air intake vents cut around/between the rub rails.
The air intake vents cut around/between the rub rails.

To deal with this, I cut the skin between the rub rails to get the opening necessary for the air flow.  This was reckoned from the venting salvaged from the old trailer.  I ended up cutting down the locking casing for the smaller area so that I could get in and clean out the burner, then cut the vents so that the upper area could be screwed in place and sealed.  This makes it removable if necessary, but not with the ease of access of the lower area, yet also keeps the rub-rails intact.

The roof, cut and welded to make a vent opening that would not let in rain.
The roof, cut and welded to make a vent opening that would not let in rain.

For the top, I, with no small amount of trepidation, cut into the roof.  Three cuts allowed the roof to spring up above the reinforcing plates inside, and two triangular metal pieces for the sides created a nice opening for the heat to exit the bus and create a nice draft to pull cool air over the cooling fins of the fridge.  It has window screen over it to keep insects out, and will (eventually) get a nice sheet metal cover to keep the rain out.

The access hatch for getting to the airflow area at the back of the fridge and the roof vent.
The access hatch for getting to the airflow area at the back of the fridge and the roof vent.

Inside, the air was channeled to the outside by some wooden ducting, sealed with weatherstripping and screwed in place.  The actual flue from the LP burner would run up against the metal, keeping the burning hazard at a minimum, and allowing for plenty of air movement.

Wires were run for the DC and AC power sources and the fridge now runs like a top, even bringing some pop-ice sticks to a frozen state within a few hours.

Problems with getting things done on the bus …

Every job has its problems.  Some of those on the bus are relatively simple to deal with, like the curved roofline.  To combat that, I made up a template using one of the interior endcaps and some sturdy MDF.  Voila, I can now cut a curve for wall paneling or shelf ends that will fit any section of the interior roof to a shape that will fit pretty well.

But some things are bigger problems.  Like in working on the electrical system, I’m up to the point in blogging where I *should* be installing the DC Circuit Breaker box.  It’s a wonderful thing from Blue Sea marine rated so it’s good with moisture, separate wiring for backlighting, and available in 12 or 24 volts, and you can have all the breakers wired to one power source, or source them separately (which is what I’ll do).  

Blue Sea Systems WeatherDeck 12V DC Waterproof 6-Position Circuit Breaker Panel, Grey (Sports)

List Price: $142.46 USD
New From: $96.92 USD In Stock
Used from: Out of Stock

But I can’t put that in the system yet.

The breaker box in place in the frame of the wall between the captain's chair and the rear-facing bench seat in the passenger area.
The breaker box in place in the frame of the wall between the captain’s chair and the rear-facing bench seat in the passenger area.

Why, you ask?  Because it has a cascade of other jobs that need to be done before I can get there, each job hinging on the one before it.  The circuit breaker job, for example, needs to have paneling up before it can be installed in place.

Some nice flat panel wainscoting in the galley/bathroom wall.
Some nice flat panel wainscoting in the galley/bathroom wall.

Now, I’ve been doing some nice flat panel oak wainscoting on the walls, and was planing on doing more of it for the area behind the captain’s chair, so it would need to be built to fit around the existing electrical outlet, captain’s chair back, & AC breaker box.

Just to port of the captain's chair all these lovely toggles connect to what seem like miles of wiring!
Just to port of the captain’s chair all these lovely toggles connect to what seem like miles of wiring!

Oh, and around the housing for the electrical panel and  bus wiring that’s just to the port side of the captain’s chair.  Under the plastic there’s lots of empty space and I need to decide how much needs to be taken up with what and how best I’ll get access to the wiring that will still reside in there.

And of course, I have to build the paneling and enclosure around the vents for the defroster (by the port window) and the vents down by the floor for the driver’s heater outlet.  Oh, and the control for the heater core fluid flow.

Unlike modern school buses that have a dial like your car that opens and closes a vent that allows air to flow through or around the heating core (a miniature radiator), our bus has a 1/4 turn valve that allows or restricts (or stops) the hot coolant from flowing into the core, which is mounted just under the big panel of toggles and switches.  Unfortunately, it’s a little thing with short wings, and is really difficult to turn on or off while driving.  As such, I have the body for an old ratchet that I need to weld to the valve  for better control.  And this needs to be built into the paneling in such a way that the hardware of the valve can be attached to the back so it doesn’t move about.

Battens, insulation, & new subfloor.
Battens, insulation, & new subfloor.

But before I can get to working on this paneling, I need to deal with the floor.  I took apart all the original floor up to the captain’s chair and replaced it with batten strips, insulation, and plywood underlayment. But the floor fore of that, is still the old rubber and marine-grade plywood.

Some of the remaining old flooring, with the edge of the transmission cover plate on the upper left.
Some of the remaining old flooring, with the edge of the transmission cover plate on the upper left.

Which is held in place in the front with metal plates. And there’s also a big plate that covers the opening over the transmission for the shift lever to come through, with a nice rubber boot to seal it all up.  And, of course, the plate needs to come up so that the floor can be replaced.  But to take the plate up, the boot needs to come all the way up the lever and off over the shifter knob.

Five speed manual transmission shifter - steel plate and boot on down at the bottom of the lever.
Five speed manual transmission shifter – steel plate and boot on down at the bottom of the lever.

Said shifter knob needs to be removed so the boot can come off the lever, but has (so far) resisted all my attempts to unscrew it.

And then, last but not least, is the captain’s chair itself.  The chair has six bolts holding it down, and the seat belt is held down by two more bolts.  While these really shouldn’t be a problem , there’s a more complex chassis configuration in this area, and it’s rather hard to get to some of the bolts from underneath.  And I’ll actually have to drill up through the new floor in order to put new bolts in the right places to reseat the chair and seat belt hardware.

All to install a DC circuit breaker box …

(That said, I will be getting things done …)




At The Terminal – Snow & an Accident (not mine!)

So, more lessons from being a real school bus driver, not just a skoolie.

I have to start with a news story from last Thursday (December 11), where a school bus driver slid the back of his bus into the open door of a parked car, catching a pregnant woman’s arm as the door was forced closed  (and another report).  The weather was snowy, with rain that had turned to snow overnight.

Bus Accident 12/11/14  The video from the surveillance camera (in the first link) really nicely shows what happened.  It’s obvious that the driver had the bus in drive and the wheels spun as the bus tried to get going, but then they caught, and then spun again, causing the bus to slide into the woman’s car and catching her arm.  Now, for people who are used to gasoline powered cars, it must look like the driver stepped down hard on the pedal, let off, then stepped down hard again, but that’s not likely to be the case.  The diesel engines in these buses are slow to ramp up.  Yes, you can step down hard on the pedal, and the bus will go, but it’s not as reactive as a gas engine.

    You might also ask if the street is slanted.  I used to drive the route and the driver is only on that street for one block (unless they’ve changed something serious since October), and the street is nice and flat.  Why then would the bus slide like that?  Well, for one thing, it was empty (the driver is out of my terminal, and I heard the report on the radio), he being almost an hour late due to the weather and not having had his first stop’s student on the bus (otherwise, as you can see in the video, he wouldn’t be able to get off the bus).

Now, you might not think that the kids on the bus weigh alot, but the buses that size can now carry 58 students (they were standard 65 student buses, but the upgraded seats that all have three-point harnesses cut that down), and we carry all the spectrum from pre-kindergarten to eighth grade students.  If you figure a simple 85 pounds per student, you’re looking at just about  two and a half tons of kids in the buses weight.  This makes a huge difference not only in acceleration and braking speeds and distances, but also in handling, as these buses are rear-wheel drive, front-engine buses.

As it was for my run on that day, I ended up getting to my school fifteen minutes late, and spent most of my run 10 minutes late, but not because I felt the roads were so slippery.  Coming out of our yard and heading to the start point of my route (in my empty bus), I noted the slippery aspect of the roads, and dropped my gearing from drive (which worked fine in the gravel of the bus lot) down to second, due to the thin film of slippery slushy snow under all the fluffy snow of the five or six inches that were on the roads.

One of the things this did was limit my buses’ top speed down to 25 miles per hour (which isn’t a big deal since the speed limit in the city is 30 mph), but also kept the bus from shifting down as quickly.  This made it easier to get and keep traction.  I also started braking a little earlier, since people stomping on the brakes to stop suddenly and then stomping on the gas to get going at intersections makes them extra slippery.  But here’s a place where driving the bus actually helps – your drive and dual braking tires are in the back, farther behind where cars tend to make slippery.  So I actually found the driving to be fine.  No slips, no slides, no being out of control.  And the more students I picked up, the better it got, as I got more weight over my drive wheels in the back.

My lateness was due to accidents that I had to pass and other drivers who were not driving safely.  And while I understand that not everyone is as comfortable in winter driving as I am, everyone should be as aware of how to drive  in these weather conditions, just in case.

It also makes me much more comfortable with the prospect of driving the skoolie through inclement weather.  Due to the built in nature of the furniture and appliances (and the water tank, when that goes in), there should be plenty of stable weight to maintain control.  Plus, manual transmissions help out a lot in situations like this.  If I could go back to Thursday and change my bus from an automatic to a standard, I probably would have had an even more enjoyable day, driving-in-that-weather-wise (but probably not for the amount of stop-signs on my route!).

But the bus accident above was another really good reminder of how a driver has to be really careful all the time.  As much as the street the driver was on was a one-way street, he should never have been that close to that car anyhow.  The video certainly makes it look like he could have been another foot or more over toward the right side of the street.  Does that accident come down to poor judgement and the bad luck to hit an extra-slippery bit of street?  Probably.  But that sort of thing scares me silly, so I try to drive carefully.

As we all should.