Parking Heater (Part 5)

How this concept took more posts to cover than the rebuilding of the front end of the MGB, I don't know. But, here we are, a fifth post about it. Wow. Let's start with re-capping what the prior 4 posts have covered.
Part 1 - why I'm doing this and what's in the box. Also some early, uninformed ideas about needed upgrades
Part 2 - planning, ripping up the old refer cabinet, placing the fuel line and fuel pump
Part 3 - planning a heat register, connecting the fuel line to the heater, sourcing the power and then an air filter boondoggle.
Part 4 - connecting the exhaust, installing the heater unit, completing the fuel system, completing the electrical and the heat register

So, what's left? Routing the exhaust, the inbound combustion air and running some tests.

Exhaust Wrap'd

fuel pump gets vertical

Until now, the exhaust has simply flopped on the ground. Obviously, that is not a viable long-term solution. So, after watching some interesting video footage of various muffler styles (courtesy of John McK), I made some decisions. JohnMcK stressed that the intake and exhaust must be left as open and clear as possible for long-term health of your heater. It was this advice that had me abandon any muffler wadding. He was also confirming what Hal said. JohnMcK was the source of the info to orient the pump as vertical as possible as well (see picture to see how mine is now oriented). I was going to conduct a bunch of noise experiments, but JohnMcK already did that for us. I encourage you to watch his videos; he is super-dedicated to these things.

So, post JohnMcK love-fest, I decided to use 2 of those little thought-they-were-garbage "muffler"s. Based on JohnMcK's findings, they each drop the dB by about 10% and when placed in series that continues (so 60dB drops to 54 which then drops to around 50). I had already acquired a flow-thru motorbike muffler, and John tested one of them also. They didn't seem as impressive as they looked, but I intend to use one anyway, since it will help to hide the others.

only shiny things in sight

The "muffler"s need to hang vertically because they each have a drain to let out moisture and/or unspent fuel. Unfortunately, they are hard to hide, especially since they are shiny and there's practically nothing shiny on this bus. The underside is particularly NOT shiny, so these "muffler"s will be very visible. Consider that the heater exhaust exits the bus a foot or so forward of the rear driver-side wheel, fairly close to the outer edge/lip along the side. Because of the short distance between the exit point and the wheel well, in order to route sound muffling, the pipe needs to run forward and then turn back on itself (exhaust must point rear and down or the air-flow from driving will create back-pressure). JohnMcK stresses the importance of having no more than 270* of bend in your exhaust or you may create too much back-pressure. So, this gets interesting. I planned the locations of the "muffler"s and pre-drilled holes in the belly pan to hold the "muffler" hangers. They are about 6 inches inboard of the outer lip.

wider context view

As the pipe leaves the bus, it turns 90* towards the front. I cut it off at that point with a hacksaw, cutting the heat sleeve with scissors first. With the help of a stainless steel reducer (3/4" to 1" with the 3/4 inch inside the cut pipe), I mated the cut-off pipe to 2 "mufflers" in series, connected by a cylinder of HVAC flashing held in place with pipe clamps. Yes, that sounds hinky, but it is actually quite solid. To the end of the second muffler, I slid on the clean end of the included exhaust pipe I had just cut off over the "muffler" end, leaving the ragged cut end free. I added more heat sleeve and another clamp at the "muffler". I then turned the pipe into a "J" so it faced more towards the rear and stopped to test, and to get noise readings. The pictures here paint a better picture than my prose.

Inbound Combustion Air
Apparently, these heaters don't need an air cleaner. I find that very hard to believe. Still, going with it, I decided to remove the air hose from the intake side of the heater, using the large cavity between the floor and the belly pan to act like an insulator against really bad stuff getting in there. I was having fit issues anyway, and this removed the thing that was in the way. I will be attaching a bit of window-screen to the intake, but for testing purposes, it currently has no filter. That's how JohnMcK does it without a filter, so I'll not argue. As it is, there are a few spots where air could get in, but only one 1" diameter opening so the route to the inside of the heater would require some form of intelligence to get there.

Testing

motorbike muffler added

With the exhaust completed enough for testing, I fired up the heater and let it run. I checked dB levels (reads as "quiet house" within a few feet of the exhaust, bouncing around 55dB) and wandered around for a sense of sound impact. I am unable to hear the fuel pump at all outside of 15 feet (5 meters) away. The sound of the heater running disappears into outside noise after another few feet. Within the bus, the pump cannot be heard over the sound of the fan except at the lowest setting. I let it run for about an hour and the temperature inside the bus climbed from 12C (about 54*F) to 20C (68*F), while at the 3 pulse-per-second setting, around the mid-point. I kept getting in and getting out, leaving the slider open sometimes, etc, so this is not scientific. Still, since the bus had not been over 60*F since last Summer, I consider a nearly 15*F increase a fairly significant feat. It will be interesting to see how effective it is when I really just let it be. One thing worth noting: the exhaust has no smell. None, and no smoke either. I cupped my hands at the exhaust outlet and breathed it in just to see if I could get any smell. Nope. That's efficient.

My last test was to fire up the engine of the bus to confirm that I did not interrupt the fuel supply to the engine. Obviously, that's kind of important and arguably could have been done sooner. Honestly, I wasn't sure he would fire up, but he did on the first try. Good boy, Hapy. I drove around the cul-de-sac but he dropped into that 1200RPM can't-read-the-throttle mode, so I parked him again. Looks like he's trying to tell me that the next thing needs to be resolving his electrical.

Well, I think that's enough talk of the Parking Heater. It really isn't completely done. I did the install of the motorbike muffler with exhaust hangers to help make the exhaust look nicer. It does end up a little quieter, now in the low 50's at the boost or high-power setting rather than low 50's at mid-power, so that's good. You can see how it appears in the picture to the side here. Not sure it actually looks that much better, but the cut off pipe looked pretty janky. I will be installing a false-floor in the cabinet so it can be used as a cabinet again. I will be attaching the power selector switch to the bus as well as running a power line from the luxury battery. I intend to put some kind of heat insulation on the register to retain heat, and might add some air baffles to direct the air flow a little. I don't think any of those warrant a 6th post, though. Then again, one or more might appear on their own if I have nothing else going on, or they become more involved than I thought. Oh, one last thing: I found a guy who makes an after-market thermostat/controller for these things, called Afterburner. I intend to experiment with one of those, if I can get my hands on one.

Thanks, as always, for following along. If you have more questions about these heaters, I fully endorse JohnMcK's videos. They are incredibly informative.