Electric heating conversion

[Ian b]

Hello everyone

I am in the midst of a 1976 2L Westafalia full restore that i am doing in large part by my self. The engine and tranny are fully rebuilt now and I want to get rid of the old heating system and replace with fully electric heating instead.
I will walk you threw my calculations for what I will need.

Rule of thumb for electric heating is 1.25W per cubic foot is needed for electric heating. With the top down I have 240 cubic feet of space, so that translates to 300W of electric heating needed.
The stock Alternator would be too weak to power all that so I am going to upgrade to a high output 160Amp alternator. Rule of thumb for alternator drag is 1HP/25 amps, so I will be loosing around 4Hp with the larger alternator(I can live with that I suppose).
The extra amperage that is left over from the alternator will be used to recharge my battery array that I'm going to have onboard if needed.
I am also replacing the gas cooktop with a small induction unit instead, and putting some flexible high output solar panels on the top.

I believe I should keep the heat exchangers on with maybe a fan to circulate air inside them to simulate the original setup.

So my big question was, if anyone out there has already done this, and how it turned out?

[Wildthings]

Some people report luck with using an electric heater but your 300 watts isn't much heat in a poorly insulated space. Maybe camp out in your van either at home or somewhere else you have shore power and see what wattage gives you a comfortable inside temperature at whatever outside temps you are thinking of driving.

The BN4 heater is rated at 4000 to 16000 BTU which is about 4 to 16 times the 300 watts you are talking about:

https://www.esparofmichigan.com/manuals/Archive%20Models/Air%20heaters/BN4/BN4%20TD.pdf

[SGKent]

300 watts \ 12V = 25 amps. While 300 watts might work to keep you from freezing, with the loss thru the metal, and windows my guess is that it will not nearly be enough. A stock heating system in a bus puts out a lot of heat but that heat gets lost pretty quickly in really cold weather.
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[Angus II]

Hello, ^^^^ Wildthings comment.
Why, try reinventing the wheel... A VW Bus, isn't a Tesla....

[busdaddy]

300W?, that's 5 x less than the average hair dryer, it might help a little on a cool summer evening, but if it's cold out it'll barely defrost part of the windshield. Like a fart in a windstorm.
Unless you plan on strapping a generator to the roof you'll be better off going diesel: https://www.thesamba.com/vw/forum/search.php?searc..._chars=200
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[airschooled]

I can’t wait to see this alternator!
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[SGKent]

[Mberglo]

For all things heat (heater, coffee maker, cooktop), I'm planning on propane. It just takes too much electricity. For heat, it's easy

https://www.amazon.com/Mr-Heater-F232000-Indoor-Sa...amp;sr=8-1

[airschooled]

[Ian b]

I forgot to mention this Westfalia wont be used in the winter and it will have new insulation and seals everywhere, that will help with the heat loss. The maximum temperature raise needed will be around 15 deg C.
True there will be wind chill while driving , theoretically I could go up to 600W in front and another 600W for the back or something like that, so to spread out the heating.
I never said anything about converting the van to electric, looks like there are some Tesla haters around lollll. Just trying to find a simpler way of heating the vehicle without sending engine fumes into the cabin when the original heating system is no longer there.

[danfromsyr]

Ohh boy here we go again..

the one thing to do when contemplating electric is to just do the math..
math will show you the answer.

just a fun fact. in my 1980 westfalia with the same engine as a 79bay.
I could noticeably feel the loss in acceleration when I had the 12v fridge on vs when it was off.. the extra time it took to get up to 55mph on my normal route on the highway.
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[airschooled]

Ian, I don’t mean to assume that you’ve never driven a bay bus before, but if those are your lowest ambient temperatures, I urge you to go drive a well-sorted bus. Hit up Facebook, samba, etc. and go drive a bus where someone has actually spent the 20+ hours to restore the stock heating system.

I hate solutions to nonexistent problems.
Robbie
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[alman72]

be aware that some insulation will hold moisture, rusting you from the inside out.

[Wildthings]

[busdaddy]

[ivwshane]

As someone who refurbished their heat exchangers and other components including seals and insulation on the accordion tubes, I do not get any engine smells in my bus. My heat works quite well in terms of keeping me warm and the Windows clear. However if I had to make one complaint about the heating system it would be the lack of direct heat. Not having heat come out of side dash vents sucks for really cold days when you want to have your hands warmed via the vents.

Granted I don’t live in a super cold environment so I’m sure those that do will need more heat.
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[Abscate]

[raygreenwood]

So...some thoughts on this....

It takes 0.24 Btu to heat one pound of air by 1 degree (yes there is a 1.08 conversion buried in there going from one pound of water to one pound of air)
0.075 lbs of air per foot (average)

So…. 13.3333 cubic feet per 1 lb. of air.

So 0.24 BTU to raise 13 cubic feet by 1 degree

So….240 cubic feet divided by 13.33 = 18 (18 x 0.24 =4.32 BTU to raise that volume by 1°)

BUT…..its not an exactly enclosed space. You have leakage. Figure about 15% just generously guessing unless you are sealed air tight…call it 275 cubic feet (275/13.33 = 20.6) (20.6 x 0.24 = 4.944 BTU to raise that volume by 1°)

So, lets say…fairly…you have been running the heat for a while and the basic metal, upholstery, dash etc…are warm already. You are just looking for the heat volume required to keep up and heat constant.

But....your main heat sinks are the glass. That’s huge loss.

Typically single pane glass in houses with windows at about 5% of a rooms walls area are a constant 10% loss rate (can be huge depending on how much wall area they are).
I would say in a bus…you are looking at about 15-20% window area. This will be …. let’s just guesstimate…..a constant 15% loss rate and go from there.

Sorry…I have not had to actually calculate heat loss in decades and never on a vehicle.

So, if you have 15% constant loss…meaning outside air temp is constantly trying to cool your inside air temp through thermal conduction….we can generalize and say your 275 cubic feet can act like you are trying to heat a 15% larger space…..so….275 x 15% = 316.25 cubic feet of space to heat.

(316.25/13.33= 23.724) (23.724 0.24 = 5.69 BTU to raise the air volume by 1°F)

So….lets say its 30°F outside and you want to raise the temp to 60°F:

(30° X 5.69 = 170.7 BTU)……BUT….that is CONSTANT USE.

The cooling effect…heat loss…is constant. You could express that as constant per second….or be less discerning and call it by the minute.

Either way…BTU load is BTU/hour. So is you say you need 171 BTU per minute: (171BTU X 60 = 10,260 BTU per hour).

BTU per second would be a shitload of heat example ( 171BTU x 3600 = 615,600 BTU per hour)….damn.

But…because heat loss through crack leaks , vents, gasket leaks and glass can be huge…..lets call it 171 BTU of “load” every 30 seconds……that’s 20,520 BTU……and…..

For reference…if memory serves….the BA4 heater in my VW 412 puts out about 18,000 BTU.
I think the BA6 in the bay window is virtually identical in mechanical and electronic componentry…just a larger chamber….so I am betting that 20,000 BTU output is a good guess.
I think these are fair heat load requirements as they both do just a bit better than keeping up in their respective applications. So….20,000 BTU requirement for a bus is good in my guesstimation.

So….how much electrical power does it require to deliver 20,000 BTU per hour?

Well….1 BTU = 1055.056 watt-seconds. A watt-second is one watt of power production or consumption sustained for one second.

So let’s go back….you need 171BTU of constant load heat (171 BTU X 1055 WS = 180,405 watt seconds)

So, divide by 60 seconds to get kind of a real-time load per second…and you need about 3006 watts of heat power output. 100 watts at 12 volts is 8.33 amps.

3006 watts at 12 volts = 250.5 amps
That’s a BIG alternator. And....this assumes what....a radiant coil type or ceramic block heater? There will be a lot of conversion/efficiency loss to that possibly.

You can get killer "SPOT" heat out of a nice little 12 volt ceramic parabolic heater of say 500 watts...but that pulls 41 amps....and it will work well point right on you from a foot away...but the big issue here is that the metal walls and all that glass and moving air will remove more BTU's of heat than that heater will put out. So you can heat yourself with 41 amps....but not the whole bus
Ray

[tootype2crazy]

The heat output of the BA6 with the engine at highway speed is 49,000 BTU/hr. Running independent of the engine its at 23,000 BTU/hr. https://www.thesamba.com/vw/archives/manuals/1977eberspacher_ba6_repair_manual/1.jpg
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1978 Sunroof Deluxe Bus (daily driver)
1978 Transporter (mom's, making into a camper)
1970 Single Cab 2.1 turbo/EFI 6 Rib, 78 front beam, vanagon backing plates on rear (project)
2001 GTI VR6 (wife's)

[CanStan]

Ray, I immediately went into cold sweats reading the math. I'm not going to be double checking your work on that.