Parking Heater (Part 4)

Picking up where I left off last time, I was in the middle of the install of one of those cheap eBay parking heaters that are a rip-off of those $1000US jobs. I have a partially constructed custom heat register, the fuel line run from the engine compartment through the fuel pump to the heater unit. I have holes bored for the combustion air intake and exhaust. Last, I have the unit grounded and the 12V source almost together. So, while lots of things are not done, they are all just a few steps away. I didn't quite finish it today.

Exhausting

making register

I had already worked the combustion air intake hose up through the holes from under the bus. This took a few trips in and out of the bus to get the hose to bend and not hang up as it passed through. If you have a helper, even a reluctant one, this is where s/he would really give lots of help for very little effort. With sufficient hose pushed through to the inside of the cabin (I gave myself about 6"), I switched to the exhaust. First, I slid the bendy stainless steel hose into the heat sleeve. The sleeve is 3' long, and it is much longer than the stainless steel exhaust hose/pipe; I will have extra. I got the sleeve as tight around the pipe as I could and slid it up through the holes from under the bus. These holes were more aligned and a little larger than the intake, so it went through with little fanfare.

Once through, I could start connecting the air and exhaust to the heater. The air hose was more willing to be managed, and connected without much effort. The exhaust, however, took some doing, but I got it on, and the sleeve pulled all the way to the top, and then clamped the pipe and sleeve to the heater output with one clamp. In the process, the fuel line popped off, so it needed to be re-attached. For now, the exhaust and intake pipes are laying on top of a car-ramp so they aren't sitting on the pavement in the rain. I'll button them up to the underside once everything is working and after the noise experiments indicate what muffler solution to use.

Heater In

heater in

With the underside connections to the heater all buttoned up, I was ready to press the heater into place. First, I set the heater above the hole and pushed a little bit. Say, 10 pounds of pressure. Then, similar to the run-around I did for the air intake, I got under the bus and tugged on the hoses a little bit. Again 10 pounds of pressure or less. This took some of the excess bends out so I could then press the heater home from inside. I checked again from below just to be sure. I then attached the unit to the bottom of the cabinet with a pair of wood screws and then tried to shake the heater. It wouldn't budge.

Fueled
Next, I needed to complete the connections for the fuel. I had intended to locate the "T" close to the front (front is front) of the engine compartment, but once I got in a position to work on it, I made a small change. The large clear filter was already in a fairly good space, and I figured that I could fit the "T" just downstream of the filter without cutting any fuel hoses. I took the "T", pressed on a short (2" long) stretch of hose on one end, and a 2" stretch of 4mm hose on the small part of the "T". I clamped the other end of the 4mm hose to the trimmed end of the heater fuel line. Then, I squeeze-sealed-off the hose between the clear filter and the large filter with a vice-grip. I was now able to remove the line from the clear filter and then quickly connected the short stretch of hose from the "T" to it. To the other end of the "T" I connected the vice-gripped line. All clamps were snugged down and then I removed the vice-grip, but fuel didn't really move around. The net result has fuel leaving the small clear filter and immediately enter the "T" fitting. The large end of the "T" continues on to the Caterpillar filter while the small (4mm) end of the "T" routes to the heater.

Priming

foamed and screwed

I should note that the picture in the last post of the fuel pump needed to change. The directions give no indication of the fuel flow direction, and that pump is one-directional, pulling towards the end which shares the electrical plug. That's the case with mine and while they may not all be the same, my viewings on YouTube of the little heater professor (John McK) implies that they are all the same. I was also alerted (again by Hal) about the orientation of the fuel pump in my post a few weeks back. So, I re-checked it, and he was right, I had it practically horizontal, and they need to be approaching vertical for the fuel to lubricate the piston inside the pump and for the little bubbles created during the pumping to float up into the heater. I disconnected the heater-side from the pump, shifted things around, and re-connected.

I left the fuel line at the supply-side of the fuel pump disconnected, however. To this line, I connected the Mity-Vac to fill it with fuel. Once the Mity-Vac jar was steadily filling, I stopped the vacuum and quickly reconnected the line to the pump. I checked the clear filter in the engine bay and it was full, so we should have a nice tight system now.

Complete Heat Register
When I last touched the heat register, it was a box, but it needed to be sealed and it still needed a 3" pipe connection. I got a 4" connector from Home Depot, and cut it open. I could have probably used some basic flashing, but thought the dimples and wrinkles would help hold the air hose on. I fit the cut connector into the hose, marked with a pen and then cut the connector so it fit a 3" diameter hose. I also cut about 1-1/2 inches off the end to make more maneuvering room in the cabinet. I fit the connector into the register from the inside, and pushed the seating tabs down. Once set, I used metal HVAC tape on all of the seams on the register, including the connector. You can see the finished result in the top picture.

register completed

My rough forming of the register resulted in the outlet not being completely flat. I tweaked it for a few minutes and got it close, but I knew I couldn't get it perfectly flat. To resolve, I put a thin strip of foam along the edge which would be pressed against the cabinet. Then, I threaded one screw per side through the register edge to hold it to the cabinet. I took it out to the bus, and pressed it into service.

Last for the heat outlet, I needed to run the air hose from the heater to the register. This was relatively simple. I laid out the hose to check length, cut it with a pair of scissors, and clamped it in. It took some wrestling.

Finish Electrical
With the fuel ready and the heated air routed, all that was left was connecting the final electrical bits. First, I completed the wiring from the fuel pump. By now, the switch I had ordered had arrived, so the rest was just as easy. I connected the center post to the heater supply-side and the fused 12V from the main battery to one of the outer posts. Then, I plugged in the controller and the heater.

Tests

The moment had arrived. After charging the battery, I flipped the switch, and heard the fuel pump fire up. Then, the fan on the heater started. Cool air blew through the register and out onto my boots. I felt the air flow and there was positive, consistent air movement all along the grate. But, the air was not warming up. Huh. So, I tried to figure out the interface, and I really couldn't. I knew from John McK's videos that the way you changed the temperature was to increase the speed of the fuel pump, so I messed with that a little bit. Turned out, I was just impatient. Once the glow plug was up to temp and fuel had made it down that last stretch of hose from the pump, the diesel started to fire and I started to get heat. Curious about the noise, I checked the driver side of the bus. It sits below 65dB, floating up and down depending on the fuel pump speed. At the lowest setting, my little phone app decoded the dB to "quiet house". At the mid-setting (3.3 on the pump speed) is decoded to "quiet street". This is without a baffle on the air intake, and the exhaust without any muffling while I was standing, semi-stooped over with a phone a few feet away from the hose ends. More on how these ends are dealt with next time.

Thanks, as always, for following along--