Rear heater heat output/BTU (Thinking of swapping for Espar)

[vwwestyman]

Hello All-

I've actually got a '78 Bay Westy, but it's got a TDI motor and a pair of Vanagon rear heaters. One under the rear seat, of course, and one under the front splash pan piped into the old heat tree.

I'd like to at some point get an Espar Airtronic heater for camping. What I'm wondering is if it could effectively replace the rear heater? The current rear heater does a pretty nice job of helping warming things up. In fact, the rear one probably does at least 2/3 of the overall heating in the Bus (due to losses in the ducting for the front, and the fact that the front can't recirculate). So I certainly don't want to reduce it.

Replacing the rear heater core would have the big benefit of space savings.

So the question is: What is the heat output of the Vanagon rear heater? The Airtronic D2 is rated at 7500 BTUs on "Boost" mode. The D4 is at 13650.

Many thanks!
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Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[danfromsyr]

for your question, I don't know..

but as an FYI there is a whole new batch of chinese knock off Espar diesel heaters in the $200~ range.

https://www.ebay.com/sch/i.html?_from=R40&_trk...p;_sacat=0

8k watts is approx 27kbtu.
5k watts is 17k btu
2k watts is ~7k btu

I'd go 5kw or 8kw
https://www.ebay.com/itm/12V-8000W-Car-Air-diesel-...mp;vxp=mtr
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[IdahoDoug]

I don't think you are gaining anything here by comparing an engine water heat powered heater to an Espar or another heater designed for engine-off use. Right? What if the engine heater is crazy high? Who cares? You are looking for a camping heater.

Just pointing that out to make things meaningful unless you have something else going on.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[djkeev]

Doug, I think he is trying to figure out if the diesel heater will be larger enough to heat the Bus while underway, replacing the rear under seat water heater completely.
As a bonus, he now has stationary camping heat.

Many, probably most, Vanagon owners keep the rear water heater and add a diesel, or Propane heater. This eliminates the need to burn fuel for warmth while underway instead of using the "free" hot water heat that combustion provides.

Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[vwwestyman]

[vwwestyman]

I guess I'll add that I got this idea from someone here who had done a similar swap. At least I'm really sure there was someone who did it! Though I don't know if they wanted to still use the diesel fired heater while underway.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[WestyWanter]

I'm not knowledgeable on their comparable BTU output but I have a little buddy heater that puts out 4000-9000BTU and it warms the van up quickly and is more than enough, I'd say you wouldn't need anything more than 9000BTU.

[danfromsyr]

I have a 6k btu Espar diesel in mom's camper and a 9k btu propex in mine.
I'd vote for more than 6k also.
it also depends on just how cold it is that you intend to drive in.

20-30f no problem
0-10f might want more
neg10-0f you want a woodstove.
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[vwwestyman]

Thanks Dan.

I would say it would be pretty rare that I'd be camping in temps lower than 20-30 in most cases. If I get a D2, and happened to be in those low temps, I'd certainly just bring some extra blankets. The Great Dane is also a pretty good warmer!

For purposes of support or finding parts in the future, it makes sense to me to buy one of the name brands (Espar/Eberspacher or Webasto) than one of the Chinese knock-offs. Also seems like the odds of needing a spare part are lower with a German-built unit.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[djkeev]

They've changed things now but the old BTU was bringing one pound of water from 32°F to Boiling 212°F ?

A whole lot of math and ambient temperature adjustment, yada Yada Yada...... all of which far exceeds my math abilitues or interest.


Dave
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Ghia
http://www.thesamba.com/vw/forum/viewtopic.php?t=392473

Vanagon
http://www.thesamba.com/vw/forum/viewtopic.php?p=6315537#6315537

Beetle
https://www.thesamba.com/vw/forum/viewtopic.php?t=482968&highlight=74+super+vert

[vwwestyman]

I wish I could remember where I saw the person replacing the rear Vanagon heater with the Espar or whatever, to see how they ended up liking the mod and all that.

Or if there is anyone here who has both and could comment on a comparison that would be great to hear!
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[MarkWard]

Here are a couple pictures of my D2 install. Our 82 did not have a rear heater core. It takes up about the same amount of space as the WBX rear heater core assembly. That storage is rarely accessed, so I installed our auxiliary battery and inverter next to the espar. The aluminum cover is to protect the unit as well as the other things that get stored in their.

Unit:

Cover:

For camping, you can't beat it if you have diesel fuel available.
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[WestyWanter]

Maybe a dumb question but do you experience any type of smells?

[MarkWard]

Me? Nope, intake and exhaust are outside the van's passenger compartment. A blower circulates air over the "hot" part of the unit and that is what heats the compartment. After a few camping trips I did add a muffler. I have a couple other photos of the install.


My nose may not be that sensitive. I hear folks complain that cooking in the van stinks it up. We cook all our meals and have a 80 pound dog and everything smells normal to me. So, I may not be the best person to ask.
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[WestyWanter]

[Abscate]

[dobryan]

[?Waldo?]

[Abscate]

Ill swag the output of a generic hot water core heater at 3000 Watts.

When I started needing depends, I stopped doing Imperial units to real units conversions. If you give people crack they stay addicted.

MelB is a British Thermal Unit, all the rest are obsolete
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.ssS!

[davevickery]

I have a Webasto 3900 gas heater in my current van. It is a bit overkill.

The D4 would be a decent choice though, it's heat output range is wider. My Webasto 3900 is a little too powerful for camping in the spring and fall but is great for quick warms up and does fine in the dead of winter with the top up. These heaters with the glow plug are desgined to run continuously and just lower the fan speed automatically as the demand decreases. When they are too big, in moderate temperatures they will cycle on and off because they can't rev down enough. That causes extra camping noise because the fan comes on at about 70% during startup and wakes me up. Insulated ducting can help a lot with that. So anything bigger than the D4 wouild be a mistake I think.

I think the D2 would be fine too. It would help regardless of the outside temps as an aux driving heater. If you had little kids in the back, possibly you would need the D4 but I think 6-7K it is plenty for winter camping and you can add insulation to the windows worst case. The 2K Watt (6-7K BTU) heaters are generally the best size for a vanagon, enough heat, more efficient, smaller, less expensive, and you can do other things to minimize heat loss.

The issues I have with mine being too powerful is not as much a problem with the D4. It can cycle down more than mine. My lowest BTU setting on mine is about 5500 but the Espars can cycle down to something like 3000 BTUs which is preferable. The D2 cycles down to about 2100 IIRC so there isn't too much difference and both of those heaters will be able to keep running in moderate temps while mine has to shut down and then restart which is annoying. The D4 would work faster as warm up heater which is nice. I don't sleep with my heater on all the time and waiting for the smaller heater to warm the van up is not that practical. You will want to get up and moving before it has really warmed the van up a lot. Also as a preheater when sitting in the driveway, bigger is nice on those 10 degree mornings.

The stated output of the rear stock heater must be pretty high. Similar sized coolant heaters look like they are rated to 20K BTUs or so. But in practice I think my 13K BTU gas heater is as strong as the rear heater. I had a 17K BTU Eberspacher gas heater that for sure seemed more powerful than the rear heater. But that could be just because the output air temperature burning gas is way higher than the air temp from the coolant heater.

So I think you could go with either the D2 or D4 and be happy. More isn't always better but if there was no cost difference I'd go with the D4. Since they cost quite a bit more, I'd probably go with the D2. If you didn't have any sort of front heater, I would say the D2 wouldn't be enough as your only heat source, but as a helper heater I think it would be fine. VW put the optional 2K Watt heaters in the aircooled bugs and the 4K Watt heaters in the air cooled vans. But those were designed for only intermittent use and ran off a timer and they had no other source of heat.

I don't drive with my gas heater on typically. You should be careful with the intake location and maybe add some sort of intake filter if you are going to do that I think. I get a lot of dust and dirt in my intake hose and I don't even run it while driving. It is like a little vacuum when it is running and if you are kicking up dust while driving, it is getting sucked right into the heater. They can be temperamental too if not keep in perfect working order and clean and used regularly.

Hope that helps.