Webasto Gas Heater Install

[danfromsyr]

Soo if you have to change your PS rear tire you have to crawl/reach under and undo the exhaust from the muffler? that seems like it would be mighty inconvenient in a roadside emergency in the rain or such..

you could just wire tie it beside the jack port.

[owokie]

Good catch. I don't have or use the stock jack and can still use that stock jack point from below. Also, this location is slightly more to the rear than where most people put it (wired just in front) thus nearly eliminating exhaust entry into the open sliding door.

[davevickery]

This seems like a pretty ideal location for the controller. You have to trim just the smallest amount off the ashtray opening to fit the controller.

This is what I did with the fuel pump this time. I would like to find a full box cover for it

The exhaust routes nicely through the frame and out the back.

OK this foam enclosure was stupid. If you don't do something to block the noise at both ends of the heater, all the noise just goes out the open end. This does quiet the output end but the overall noise level isn't much lower until I do something on the intake side. I'll have to redo this whole thing. The foam seems to handle the heat o.k. but the hard plastic grill is deforming so it will probably get replaced by a metal grill.

[davevickery]

So, I put this Webasto 3900 gas heater in 2 years ago and tweaked several things to make it quieter. It has been good and hasn't caused any major issues, but this year I started getting low battery faults where the heater won't restart. If I start the engine, it fires right up.

I am going to upgrade the wiring and redoi the connections and maybe repace the battery. I think I originally used 10 guage wire which is supposed to handle 22 amps but maybe I am getting some voltage drop anyway. I ordered 6 guage wire and will make sure the connections are super solid.

I have watched when I get the fault. I have a voltmeter plugged into a socket near the battery and it reads about 11.4 volts when the heater stops and gives a low voltage fault. The heater fault is triggered when the voltage drops below 10.5 volts at the ECU for more than 20 seconds. So unless the heater is misreading the voltage, I am getting a pretty big voltage drop from the battery. The wiring runs from under the driver seat to the heater under the rear bench.

11.4 sounds like a really low battery but voltage drops significantly at the battery during the glow plug heating/startup process And the heater is so powerful that it shuts down and needs to restart a fair amount in fall weather. In hindsight, this is the wrong model for a vanagon. After the heater has been running for 8 hours the battery reads 11.4 but will come back up to 12.2 volts or so after it sits for a bit. So basically the heater currently shuts off at 12.2 volts which I think is kind of crappy. But keep in mind this is just using the house battery. I can connect them both together to get a longer run than 8 hours. But hopefully the rewiring helps a bunch. That is one complaint a lot of people have about these heaters with the glow plug.

Another thing that may be in play here. I am just using a group 41 battery for my aux battery. I don't know if it has been depleted too much too often and is not doing as well as it did 2 years ago when it was new. It still seems to charge up to 12.65 volts. I may get a group 65 AGM battery for the house battery now but then they won't be matched batteries so I would not run them combined. 2 AGM batteries might be a solution to that, but then we're talking 300-400 bucks.

I would be interested if anyone else has had similar issues, or has comments about the wiring or the battery(ies).

[jordauto]

You should easily be able to run 30+ amps through your 10ga wire to your heater. The glow phase at start up of my Espar B1LC is only about 20 amps for 15 seconds and I assume a Webasto is about the same. . If it were mine I would use a multi meter and check voltage drop on both your power feed and ground, from the heater to the battery terminals. Basically connect one lead of your multi meter to the positive post, and the other end to the connector at the heater. Check for voltage drop with the furnace starting up. I would hope to see no more than .1 voltage drop. Then repeat the process on the negative side of your circuit. It sounds like your battery has enough power but you’re losing some to high resistance somewhere in your circuit. Also some of those plug in battery meters are pretty inaccurate. Check your actual battery voltage at start up with a multi meter as well. I love my Espar, having it draw fuel from the tank means almost unlimited heat. My unit is smalller in btu than yours so it gets up to the target temperature and then slows right down to an idle. Which makes it very quiet and uses little power.

[davevickery]

That is a good suggestion before I just throw parts at it. I'll have to strip off some of the insulation at the wire near the heater so I can read the voltage closer to the ECU but I might as well do that before I rewire it with the heavier gauge. It should tell me something.

[edit] I'll have to spend some more time on this. The 6 gauge wire I ordered is way overkill, but I am seeing a voltage drop with the 10 gauge but it could be a connection rather than the wiring. I'll redo it and see how it goes.

[davevickery]

I am beginning to think that there is nothing wrong with the heater or the install except my expectations. I did rewire it adding 8 gauge wire (and kept the existing 10 gauge) and I made sure the connections were good. There is now no detectable voltage drop now from the battery to the heater but it still shuts down with a low voltage fault using my partially flattened house to test with. It is just a Autocraft grp 41 starting battery that I am using as the house battery, which I had hoped would be sufficient but may not be.

I watched the voltage at the battery drop from 12.3 to 10 volts before the heater faulted. So I think the battery is just not as strong as it was when new. Fully charged it will run the heater for 8 hours but when it was new it seemed to do better. Bringing it down to 50% each time I use the heater may have damaged it. Even though I haven't really used the heater that much.

These heaters just uses a lot of power at start up and trip the low voltage fault. I don't think there is any internal crude causing resistance because the heater is still pretty new with low hours. And many posts online complain that these heaters just need a very good battery supply. Webasto changed the low voltage shutoff from 10.5 to 9.5 volts on the new model, so they must have recognized the heaters are temperamental.

I am doing some more testing with a spare battery, but I will probably have to buy an AGM Battery and Yandina Combiner so that I can run it down wiithout damaging it.

[owokie]

[davevickery]

[HoustonPhotog]

[HoustonPhotog]