Hapy Heat Repeat (Part 2)

Continuing the efforts on creating some cabin heat in the old microbus, today's post covers sourcing the air for the heater from inside the bus.

Grounding

air sourcing from inside

In the last post on this topic, I mentioned that the prior attempts, and the original heat, for that matter, all pulled in air from the outside. The original heat pulled from the engine bay, sent it through heater-boxes (insulated boxes around the exhaust manifolds) and then up to the front of the bus. There was even a booster fan to push air when the engine speed was too low to push air. Years ago, I added a bilge-blower fan mid-stream to help get the air forward, and replaced large sections of pipe with insulated hose. In the end, the original system at-best, delivered warm moist air when it was raining (again, it's Oregon so that's 8 months of the year). When not-best, we got cold moist air that smelled like oil or exhaust.

When I did the ALH-TDI engine swap, I removed the original system rear of the front frame, setting a Vanagon rear-seat heater against that frame crossmember. While it didn't leak for a while, it started leaking again this past year. The unit was really never up to the task, and since it was only designed to heat the rear of a Vanagon cabin, I was probably asking too much of it. Still, it was a significant improvement over the original and bilge-blower-enhanced systems. The air was warmer more often, and exhaust-smelled less often. Overall, though, it was not "warm" in Hapy from the use of the heater, and the issue with moist air remained.

Fast forward to the Maradyne heater I just installed. Unlike the Vanagon rear-seat heater, the Maradyne is a 3-row heater core and it is almost twice the width. The core alone could provide considerably more heat. The fan is way more powerful too, so moving that heat into the cabin will be that much more  effective. What remained, however, is the air is still sourced from below the bus, so the wet roads will provide an endless supply of moist air to fling onto the inside of the windscreen. I hope I resolved that with the changes below.

Maradyne Heater Prep

purists love this

In the last post on this topic, I described how the heater was installed on an angle to minimize the ground clearance impact and so the outlets point more directly at the original air pipe. This orientation, however, meant that the brackets were hanging into the space where air intake hoses would go. So, first order of business was cutting those brackets down with the death-wheel (angle grinder). Once cleared, I could easily see that the coolant outlet jutted too far into the same air-hose space so I cut it down as well. Last, I changed the hose from the outlet from a straight hose to a 45* angled hose, routing the coolant above and away from the air inlet. While the inlet is not completely exposed now, it is considerably better. The inlets are 3" diameter and have a lip that's maybe 3/8" for a hose to fit onto. I had intended to add something more substantial for the hose to attach to, but once I got into it, I concluded that the original fan housing could hold a hose and clamp. Time will tell, and I am retaining the extensions I bought for this purpose in case I need to add them in later.

Holy Bus

Well, more like holey bus. In order to send air from inside the bus to the air intake on a fan system that is outside the bus, I need to add a hole or 2 for the air to pass through. I did not want to put air intakes in places where I would accidentally spill water (or other beverages), or get dirt and the like into it. I also did not want the air intakes to be so close to the front that the fan was effectively pulling the warm air right out of the outlet vents. I applied some cold-air-return thinking and chose to put one intake inside the rock-n-roll bed base cabinet. This cabinet is probably the coldest space in the bus (second only to my feet) and the vacuum created by the fan will draw air from the front to the back, creating room for the warmer air to enter the bus more freely. Of course, it's not like a 50+ year old microbus is sealed, but my 70+ year old house isn't either and once I tied the cold air intake into the house system, the house grew measurably warmer.

From underneath, I considered where there was a space without structure nor pipes to interfere with the air intake plumbing. With the radiator, wiring, original stuff and everything else, it is quite busy under there, but there is a space just behind the rear cross-frame (think: rear jack-point) but in front of the rear wheel well that is inside the cabinet, nearest the front outer edge. I tested a few spots with a drill to make sure that I could fit a 3-1/2" circle without hitting something neither underneath nor inside the cabinet and found a good spot. I cored a 3-1/2" hole with a hole saw. Why 3-1/2"? The inner diameter of these hoses is 3", and I felt that leaving a little extra room for wiggling was better than having it tight as would have been with a 3-1/4" hole. This turned out to be a wise decision. Once the hole was cut, I shot it and the support brackets with paint to delay (can it really be stopped when it rains 9 months of the year?) rust.

Fitting

cabin air intake

Once the hole was cut, I was on the home stretch. I found what look like air outlets with metal grills that fit a 3" hose to act as an air intake screen. I a-fixed one end of the hose to the grill, cable-tied it to be double-sure and passed the hose through the hole from above. The hose barely fit. It was so tight, I had to cut off the cable-tie because the cable tie end prevented the grill from sitting flat on the floor. Anyway, I chose an orientation that pointed the grill away from the center of the cabinet so things don't accidentally fall in or over it and then screwed it down to the wood floor of the cabinet. From underneath, I stretched out the compressed hose, stretching it along the side of the radiator, and turning it towards the fan.

I had initially planned to have 2 air intakes, one per fan intake, but after cutting the passenger-side hole, decided that I had 3" of outlet, so having only 3" of inlet was actually a fair balance. So, rather than run 2, I added a 3" wye along the passenger-side frame rail. I sent the stretched and then cut hose into the base of the wye and shifted to the fan inlet on the driver side, knowing it would be the harder of the two. I can always choose to add a driver-side inlet, but with the furnace on that side, there will be additional complexities.

The driver-side was definitely harder, but simply because the coolant outlet hose still ran across the air flow path. I twisted and bent the air hose and jammed it onto the inlet lip. I added a hose clamp while pressing the hose onto the lip, threading the clamp until it was quite secure. Content, I stretched out the hose, threading it behind the fan housing, but in front of the radiator intake to the passenger side. I added a cable-tie on the driver-side to hold the air hose in place. I cut and then sent the other end of the hose into the wye. It got another cable-tie up to the underside of the bus before it entered the wye.

The section from the passenger side air intake to the wye was a little over a foot, and was the easiest part of the install. I attached to the fan intake first, adding a hose clamp, of course. Once stretched and cut into the wye, I cable-tied the wye up near the floor of the bus, mostly out of sight. I cable-tied the passenger-side hose as well so there would be minimal pressure on the hose clamp. At this point, the air intake for the cabin "climate control" sourced from the inside of the bus.

Testing

ground clearance mostly unchanged

All that remained was testing the system, both for air flow as well as coolant. I started with the air flow, accepting that I could confirm that without running the engine. As expected, the fan blows hard, and draws through the inlet. Because the inlet is inside cabinet, it make less noise than it might have had it been placed elsewhere. Still, I will need to be aware of it when we pack things so it is not even remotely blocked.

Satisfied, I exposed the top of the engine and started it up. I had expected to simply add coolant/water while air bubbles appeared but 2 things interrupted that plan. First and worst, the injector pump started leaking all over the place. Now, to be fair, I had smelled diesel on my last couple of drives, so this was not 100% a surprise, but it still was a little bit. Second, air bubbles did not really appear. I will need to bleed the heater core segment, once I replace a seal or two in the injector pump. A seal set has been ordered, so until the kit arrives and is installed, Hapy will sit.

That's where we are at this point. I may try to bleed the heater while I wait for the seal kit, but it will depend on the weather and my workweek. Thanks, as always, for following along. More next time-

Hapy Heat Repeat (Part 1)

Ask anyone who has owned or simply driven an old air-cooled Volkswagen in not-Summer and 9 times out of 10 they will regale you with tales of being cold. These awesome vehicles were designed to have heat, its just that they were also designed to be owner-maintained, and maintaining the cabin climate control is not easy. With aftermarket replacements of J-tubes for heater boxes, cardboard pieces eventually failing over time and long channels under the car (where road salt, etc gets in), it's no wonder heat doesn't make it. Anyway, today's post documents another attempt to get some warmth into Hapy, specifically onto my feet and maybe even onto the windscreen.

Why the Obsession

By now, you must wonder why am I so focused on getting heat into the bus. And I get it. Put on a coat or something, right? Besides, it's not like we really get snow in the Northwestern Willamette Valley. This is all true. For folks who own these cars and busses in genuine snow country, I suspect either they are summer-only vehicles or you are far more brave than I, driving in moon boots or something. Around here, we really only have about 10 weeks of warm-to-hot weather out of the 52 in a year. For the rest of the year it is either cold or cold and raining. Driving around in the cold is not as fun when you're bundled up (ski-gear head to toe) and still cold. Regardless, the temperature is hovering around the dew point during those 42 weeks, and overnight for most of the 10 weeks of warm-to-hot season. In the mountains, it approaches the dew point earlier in the evening and remains later into the morning. So, having a means of getting the fog off the windscreen, and not adding to it, is super important.

The Plan

so it begins

Last November, I posted an update (see: Hapy Update) where I replaced Hapy's crappy glow plugs with a new set. I did not circle-back on that since, but he has started without a hitch all winter. Those plugs are fantastic. The real test will be how well they behave next winter. Anyway, in that post, I mentioned that I had acquired a Maradyne Fans heater unit and shut off the Vanagon rear-seat-heat unit because I believed it had started leaking again. We had a "break" in the weather (almost 10*C / 50*F and only occasional rain), so I took the unit out to Hapy. The think was to remove the old, and swap in the new. Ain't nuttin ever that easy, but it's in now.

Old Heat Exit

The Vanagon rear-seat-heat was suspended from beneath the belly of the bus just forward off the radiator. I had fab'd a custom plenum from the heater unit into the original 3" diameter air channel, run coolant lines along the driver side to feed it and run electrical from the dash to control the fan. I hadn't tried to control the valve, choosing to leave it on or off by setting the valve before a drive instead. I unplugged the electrical first, then the flashing/plenum that routed the air into the 3" channel. Then I set to removing the heater from the underside of the bus. Both of the nuts at the bottom of the threaded bolt supporting the unit had rusted so I had to encourage them with a hammer.

Last, the coolant lines needed to be removed. I held the lines closed with vice grips so I did not lose a bunch of coolant and then set a dishpan underneath so I didn't spread coolant all over the ground when I disconnected things. The lines removed easily enough and a small amount of coolant dribbled into the pan. From this I concluded that the unit had been the source of the leak in the cooling system or there would have been more than the few ounces that appeared. I set the unit aside and shifted to the new heater.

New Heater Hung

mounting angle

For installing the new unit, I started with placement thinks. I wanted it in essentially the same place, running air into the same 3" diameter hole. The force and size of this new unit dwarfs the Vanagon rear-seat-heat unit, however. The Vanagon unit is 6" tall and about 9" wide. The Maradyne unit is also 6" tall, but it is almost 18" wide. The Maradyne unit arrived with a cover that had 3 3" vent protrusions. The outer edges of those protrusions are 13" apart, so I decided I would retain the cover and enclose the vent protrusions inside my new plenum. I was unable to reuse any of the old piece.

After some failed attempts to place the heater straight/level with the ground, I shifted the mounting hardware so the new heater was at approximate 45* angle with the bus, pointing upwards. One would reasonably assume this would cause the unit to hang considerably lower, but because of the placement of the fans, the unit is only about an inch lower. How? Well, in this configuration, the top edge of the heater unit nearly touches the floor of the bus. Neither the Vanagon rear-seat-heat nor this unit could do that in the horizontal position because of all the various pipes running under the floor. In the picture on the right, here, the heater looks much lower than the radiator; that is probably caused by the angle I held the phone. In reality, the radiator is a hair lower. The mounting brackets have 2 holes, designed to be used with the enclosed screws. Yes, that's right, screws, and short ones at that. With this install design weakness in mind, I suspended the heater from a pair of metal tubes under the bus floor with.. wait for it... cable ties. Yeah, that is so RoadKill; I am not a fan of using cable ties this way. Having said that, I have not ever experienced a failure with cable ties, and if my 20-year history with Hapy is any guide I will be up under this bus fairly frequently. So, I will be able to monitor the health of these ties and resolve before any real issue arises.

Plumb It

With the heater relatively stable, I flipped to the driver side of the bus and started working on the coolant lines. As I mentioned in the referenced post from November, I picked up an old-skool control valve. Prior to installing, I noticed that the valve seemed to operate more like a shut-off valve than a gradual taper. When "closed", it was definitely closed, but it remained mostly shut through about half of it's travel, then opened up very quickly through the next 1/4 of it's travel and then that last 1/4 its no more open, in fact it almost seems to close a little bit. So, from closed to open the valve really only had to move a little over 1/4 of it's overall travel. I chose to drill out a little bit of material at the barely open part of the valve so that the first 1/2 of travel now actually opens a little bit near the end of that movement. Overall, I think the open-to-closed is closer to 1/2 the overall travel now.

Once modified, installing the coolant lines part was fairly easy. I cut a short stretch off of the return line, and added that to the return off the heater. To that I attached the valve, minding the indicated direction of coolant flow marked on the side. Last, I connected the supply and return lines and then removed the vice grips. I am not 100% thrilled with the routing of the hoses and will incorporate a 45* angle so they are not forced so route to low. After this picture was taken, I shortened the return line another inch or so to reduce the droop a little bit. I poured a bunch of water into the coolant bottle and called it a day as it was starting to get dark.

Plenum

I returned the following morning to complete the job. In a typical install of one of these Maradyne heaters, either the purchaser connects 3" hoses to the outlets or maybe some directional vents (neither are included). Remaining a-typical, I assembled a 4 sided plenum, like the one before it, held together with the higher-end flashy ducting tape.. The top is a 13" by 5" rectangle with 1" long drop-down sides, with a 45* angled rear tail and an up-turned front (image on the right). The bottom is 13" long by 4" (with 1" drop-sides along the shorter edge) and the plenum sides are right triangles with 4" long sides. Remaining ever cost-conscious, I cut material from the old furnace intake. Recall, it was 15" square, so I cut up one side and got 13" length with 1" for the drop-sides with one cut. I taped on the top and bottom first, then the sides, and closed up all the gaps. I get this is not exactly contours-quality... this is far from that. This is all about getting on the road with whatever heat I can extract from a TDI engine. Besides, the last taped-together plenum lasted a few years and would have continued had I not torn it apart for this install.

Electrical

Before I got started on the electrical, I looked back on the post I wrote about the Vanagon rear-seat-heat fans (See Defrosting - Part 4). I discovered that the fan switch that I bought for that install was the exact same as the one that delivered with the Maradyne fans, just with a different knob. So, while I could run new wires and replace the switch, I didn't need to. So, I didn't. Instead, I cut the 3-wire plug off the fan power wires and the ring terminal, leaving enough material so I could reuse it somewhere later. I added female spade connectors to the four wires. I could easily identify the ground wire and low-fan wire so I connected those and tested the fan. Success! And even on low, this fan is more powerful than the Vanagon rear-seat-heat unit on medium. It probably rivals that unit on high, in terms of airflow, but not fan noise. This is super quiet: no fan noise, only the sounds of the rush of air.

With a multi-meter, I confirmed which of the remaining 2 disconnected wires was the wire for medium. I decided that since I had a strong 12V signal, I would reuse the relays and simply wire up the fan. This was also much easier and it insurers that the wires won't melt when I turn the fan on one of the higher settings. The air flow on the "medium" setting is considerable. Boo and I have noticed that the heat in ToyoTruck is most effective on the not-highest setting, concluding that the air speed is so high on the highest setting, it is unable to pull heat out of the heater core as it passes through. As I wired up the high fan, I considered that we could have a similar issue in Hapy now, and may really only use the lower 2 speeds. Time will tell.

Any time the coolant system is open, there are a series of engine runs or test drives followed by adding water and coolant until it levels off. Since I did not need to drive Hapy during the week following this work, I didn't run the engine. Instead, I prepared for "part 2".

The inlets for the fans are drawing outside air and the control valve is still managed by rolling under the bus. I'll get to the valve eventually, but I don't want to wait too long. The drawing outside air, however, needs to be considered right away. As it is, a drive through one of our seemingly ever-present puddles and I've got warm fog blowing up on the windscreen. At least until I route the fan inlets to the bus interior. Since wet season will persist for another few months, I got after changing the air source shortly after I completed this post. I added the image on the right here to illustrate the first problem I encountered: the return coolant line runs straight through where an air inlet would go. Of course, the support bracket isn't helping either.

Thanks, as always, for following along-