BN4 Eberspacher Restoration and installation - 72-78

[pittwagen]

With respect to the heat, which way do you have the heater thermostat (hot air regulating switch) set. Lever arm to the rear (toward the heater) or forward (away from the heater and toward the front of the bus when installed). If it is toward the heater that is the low position and the output would be 120 degrees or so and warm to the touch. The other way would be about 180 degrees (where you want it) and you would not be able to hold your hand there for long. The hot side will be the Bowden cable pulled out when connected. If you are set to hot and only getting warm air, you need to sort that out before you install the unit.

Now for the switch. Any on/off switch will do as you are simply transferring power to the grey wire coming from the heater. A lighted toggle switch will do to get things running. In my installation I am using a BN2 switch. Three wires - ground, power in and power out and lighted switch when on. Interestingly the rear window defogger switch is the same but for the different plastic lens. Again, in a pinch that will work. I believe there is an original T2 switch for sale in the classifieds by the way.

I am in a similar stage to you but my heater is in the final installation stages. I am using a dual control. On/off switch at the front. Full heat, no low/high so now Bowden cable. When I want heat, I want heat. At the rear I have an RV thermostat that has a full off position. So when I am in the rear I set the thermostat and the heater does its thing as and when required. The hot air regulating switch cycles the heater off and on to maintain the temperature. I can heat it cut in and out and see the results with my HVAC thermometer at the hot air discharge duct which I have mounted in the center of the bed unit near the floor. When I move to the front for driving I shut the thermostat off and control the heater with the on/off switch. Hot air blows forward right between the cabinets to the front.

Oh and I have a nice big AGM series 31 hattery under the back seat for power.

My thoughts.

[notchboy]

[pittwagen]

Well the BN4 install in my 79 bus with the Westfalia Helsinki interior is nearing completion. The most difficult part of the installation was attaching the metal air return shroud to the inside left corner and then sealing it by reaching through the left rear tail light opening. It would have gone faster with a helper.

I ran the heater for about 20 minutes today and here are some preliminary numbers:

- ambient air temperature was about 43 degrees
- inside the bus the temperature was 45 degrees
- the heater started right up and was powered by my AGM auxiliary battery under the rear seat. The engine was not running.
- the heater seemed to be providing maximum heat in about 5 minutes cycling between 145 and 170 degrees at the heater air outlet which is in the center lower floor area of the bed cabinet face. I do not have the Bowden cable connected. The thermostat regulating lever is set to the maximum position. The output temps did not vary much during the test. I can hear the thermostat cut out at 170 and back on at 145. The pump as well.
- the rear cabin temperature reached 72 degrees in about 10 minutes as measured by my HVAC thermometer sitting on the top of the fridge/stove cabinet by the sliding door.
- temperature in the front seat area was 69 degrees indicating some heat loss from the front window glass. I have some heavy curtains in the rear that help with the heat loss. The front curtains were not in place for test. It would be interesting to see how much the heater would need to run (and how may amps would be pulled from the battery) to maintain 60 degrees inside the bus overnight with outside temps around freezing. Oh and the beer in the fridge needs to stay cold too.

I still have some wiring to finish for the dual controls - front on/off switch and rear thermostat. As well I need to insulate the heater pipe and plumbing under the rear seat to prevent heat loss as well as protect any items that come in contact with the pipes etc. Why didn't I do this in the summer?? The journey continues.

[notchboy]

Excellent! You weren't in the bus during this were you? Aiding with body heat? Just curious.

Ive been restoring the spare stuff I have so I can sell it on as working. Got two done. I think Ill stop - list them then put the heater in the 74.

Good work brother ! Got pics?
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[pittwagen]

Yes I was in the back, in the warm, fudging the numbers. The rear engine compartment install is the same as any of the others but the under seat plumbing is somewhat different from stock.

So on the left you see the fuse panel, the battery box and the genuine Espar 90mm hose, flange mounted to the bus discharge and the rotatable air vent. Still need to do some wiring cleanup, some hose insulation and devise some protection for the hose.

This morning I did another test to see what temps I could get with the engine running. It was a few degrees below freezing so it took a little longer to warm up. Slightly below freezing in the van as well. I started the engine and let it idle, turned on the BN4 and put the dash heat lever fully down to activate the rear fan. Front fan was on low speed. At 17 minutes I saw 78 degrees at the rear top of the fridge cabinet and 75 degrees in the cab. Front heat and dash outlets were putting out about 135 degree. The rear BN4 at about 170, same as yesterday.

So today it took longer to heat up likely as the result of the colder outside temps and likely the initial rush of cold air from the engine heater. It might have warmed up faster if I had just driven off but the windows were really iced up. Or I could have left the engine heat fully off so that when turned on I was getting 100+ degrees of heat from the front.

Not bad and shirtsleeve temps in under 20 minutes. Now I need to think about some added insulation. Thermostat installation to come.

[notchboy]

I was thinking not bad as well especially for 70s tech!
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[pittwagen]

So I'm out driving around for about a half hour. Never got over 45mph. Engine heater and rear fan on, front booster on 1st speed. Turned on the gas heater as well. Pulled into the driveway and grabbed the thermometer. Outside temps are a degree or two above freezing. Both systems had been running together for no more than 15 minutes - 90.2 degrees in the cab.

I still think there are more efficiencies in the system, particularly the engine heater and the insulation that I mentioned before. The only downside with an air heater system is the rush of cold air until the system is fully functioning.

In comparison the current crop of 8000 btu bunk heaters put out half the heat but only draw about 40% less power. Gas consumption for the BN4 is double that of the smaller heater but almost the same as the Espar D4. Power consumption for the BN4 is about 25% more than the D4 on high. So not bad for 40 year old technology.

[notchboy]

Ive wanted to pull up to my friends that are outside in the freezing snow while wearing shorts and a T shirt Sounds like that dream will come true!
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[pittwagen]

Friends will love the heat. My friend Les came by to enjoy the tropics and help with the pipe insulation.

You will enjoy this notchboy. His T34. First one in western Canada. A Feb/62 production. At a commercial shoot last year.

[notchboy]

Nice. Cheers to that
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[notchboy]

So with Pitwagen getting on his BN4 - his progress kicked me in the but as its high time I put the BN4 in the 74. Its fitment has been holding up inal engine bay resto and putting the engine back in. So I slowly worked on putting the Eberspacher in.

I took it slow because I was cutting holes, and fitting ducting to the fire wall. I wanted it to be right and as the dealer/factory would of done when Heintz or Deiter put one in. Call me Claus because I think it looks good

As some of you may have seen in my 74 thread - I started by cutting the return air stamp in the back, fitting the snorkel receiver, painting it all up with the protective grill on it.

After that I cut the fire wall to accept the ducting - I did it while I had a og one to copy - so I made a duct tape template, traced it and cut it out of the 74's fire wall. I took it then and put it into place, fitting the duct in - drilling a couple new hoels for it as well. Using the duct and and old unrestored unit - I put them in and used them as a template. It helped me find the spot where the stand holes need to be. I took it all out and re painted the firewall a better gray, put new gasket all around and put it in.

When I was painting the firewall, I also painted a duct piece and the paint lid cover on the other side of the engine bay - it was white from the painting of the bus.

I then went to home depot and bought a couple of metal hole bits. A 51mm and a 29mm, closest I could get. Next I used busdaddys super pic of where the holes go and measurements - hence the bits. I did a quick measure - checked it once or twice then drilled some holes! After that I cleaned it up and put the exhaust silicone gaske in - fit perfect

I pretty much stopped there. I still need to put the insulation and board back in the ceiling of the engine bay, I need to put the thermostat duct section & cable in as well as cut the hole in the cab. After that I can fit the heaters exhaust and fresh air intake. Most of that's ready to go, just need to do it. I am also going to peroxide/UV light the snorkel to see if I can whiten it up - looking forward to that one

But the bulk section of the project is done. For now.

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[pittwagen]

That busdaddy diagram was spot on. I used it too. My combustion air pipe was pooched. A fellow gave me a piece of 1" stainless tubing already bent. Should outlast everything else.

[samwise]

So, as the new guru , do I take it that a BN4 sends the heated air directly into the cabin area, but a BA6 uses the bus' own heater tube set up?

Could a BN4 send the heated air into the central tube instead of/in conjunction with the heat exchangers?

My 79 7-seater has neither Eberspaecher fitted (San Francisco car originally, not much call for it.. ), but I'm trying to decide which way to go. As a 7-seater with an original z-bed setup, the Westy look with the heated air being vented through the front panel of the rock'n'roll bed set up wouldn't work quite as well for me.

Full BA6 setups don't come up very often, from what I can see, though.
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Ben
1979 7-passenger bus
Harvee the Wonder Bus' pics

[notchboy]

Yes, the BN4 blows directly into the cabinet through the rear bulkhead - that will be the cut I make next and hook up the rest of the ducting showing this.

The BA6 is by far a better overall unit - and with that comes the complexities. Switch controlled temp, utilizes the heater booster fan a swell as its own fan, replaces the central toob under the floor so that now all hot air from the motor as well as BA6 heat comes out at the dash - giving you all those benefits of window defrost and toasty toes.

Downfall - its spread all over the place. Components under the dash, under the bus and all separate from each other. You need a belly pan as well to protect it all.

I love the BN4 because its simple in that its all in one place. For the most part the BA6 is the same as far as basic function - its just all spread out.

When I get to the part of my 77 westfalia retrofit with the motor and "planned" BN4 installation - im going to seriously consider putting in the BA6 instead. Its just better to heat the cabin whereas the BN4 is alot more plug and play. The BA6 requires lots more work to install, but benefits you 10 fold if done right. Hell Stewy took a couple hours and was able to half ass his BA6 in and have it running. He was running off pure excitement, just think if he would of took the time in a nice work space on a lift - it would of been done in 2 days

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Diesel
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[pittwagen]

My bus is a 79 as well and was originally a 7 seater. Actually it was one of the last ones delivered into the port of San Francisco and spent most of its life in San Jose.

My stock air heater system works very well, probably as good as when it was new. I also have a second 3 speed booster fan under the front floor to pull the air. Defrosting is never an issue. The advantage of this arrangement is at low speeds around town. I never use the high speed.

For the 7 seater the BN4 discharge would have been under the rear seat by the left wheel well. It works very well and at near freezing temps outside I can have the whole of my bus up to the mid 70's in about 15 minutes. The other day with the engine heater and the BN4 running I saw 90 degrees in under 20 minutes in the cab. The BN4 can be run on a thermostat as well.

As far as I know, the BN4 was not available for North American vehicles in 1979, only the BA6.

I had a BA6 from a 77 bus that I had though about installing. To do it right it is complicated especially the fresh air return. At the time I had some parts of the BA6 that were questionable and were not available at the time.

Parts for these units are becoming more scarce as well and most of the ones you find for sale haven't run in decades so it is a crap shoot. You can find reconditioned ones too and for my money that would be a better bet if there was a guarantee.

Oh and another point the fuel line install is a little more complicated with fuel injection. Just not a lot of room underneath.

If your goal is to augment the stock heater for driving the BA6 may be better. For camping the BN4 is better and draws a less electricity, uses less gas and it provides heat in the rear where you need it, especially at night.

[pittwagen]

Just a separate post to identify a couple of issues I found with the BN4 install into my fuel injected bus. Didn't want this to get lost.

The hole that must be cut under the back seat next to the left wheel well is much larger that any of the diagrams show due to a raised panel piece that is not present on the earlier non fuel injected units. That extra metal must be removed in order for the discharge pipe that goes into the cabin to sit flat. It is quite obvious and the rubber seal still works well.

With respect to splicing into the fuel feed line, the best place is about 4 inches from the tank feed outlet (right side) if you have the stock steel line that goes from the outlet to the fuel filter over on the left side. There is not enough room on the left side between the steel line and fuel filter. It is much easier to cut and shorten the steel line on the right side. I then ran the line over the top of the trans and secured it. Routing a steel line on the left side is fun with the discharge coming in the engine compartment. Just make sure that any place where the pipe can come in contact with metal that the steel line has a rubber jacket around it. I just used rubber hose. You will likely land up with 2 pipes as it is virtually impossible to bend and fit the pipe in one go.

I also have a fuel shut off to the gas heater in the engine compartment and a steel fuel filter. With this relative long fuel line you may need to bleed the air from the line before the heater will fire.

FYI. Sorry no pics.

[notchboy]

[pittwagen]

Yup. That looks like the bigger cut out. I will try for some underside pics but it will be a few days until the rain stops. Can't get under this beast without jacking it up quite a bit. Everything is done outside. More precious toys in the garage!!

[pittwagen]

I'll get a pic of the shut off too.

[samwise]