Hello guys,

I’m a bit ahead of myself, I’ve just brought a 24v Webasto air / air heater, I don’t yet know the model number. I’m wondering is there anything I should consider with its installation / positioning ? I plan on installing it under the rear bed area, where I have easy access to the rear body air vent.

Now I can convert it to 12v but been told this is expensive, as I have 2 batteries I presume I can use the 24v or should I look to use a step up from 12v to 24v….

Any advise on the subject very welcome, needless to say its second hand and cheap… the car is a HJ75

Cheers
Matt

OK, your vehicle has 2 batteries. Are they in series or parallel? IOW, is it 12V or 24V? It is unclear from your post. If you don't know, you should have found out before deciding what kind of Webasto to buy.
Assuming the car is 12V, use a 12V-24V convertor on a switch so it isn't constantly working. Make sure it has lots of surplus capacity.
You may not have gotten much of a bargain buying an electrical device of incorrect voltage.

Charlie

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Unimog U500 w/Unicat

You've got the exhaust and air intake to worry about too, otherwise they sound like a 747 engine i

And make sure the 12 - 24v converter has a high enough rating

Toyota has a habit of putting 2 batteries in a 12 volt truck (caused no end of probs with my folks hiace camper) , you cannot take 24 volts off those batteries

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Rich

Iveco Turbo Daily 4x4 40-10
Ex Owner LR101 300Tdi Ambi 'Tiggurr'

Using the vehicle cranking batteries for running heaters/fridges is a recipe for stuck in the middle of nowhere without a crank in sight.

Ideally you should have 24V (2 x 12V) leisure batteries with sufficient capacity to run the heater for however long you think you'll need it to run. Size your leisure batteries to suit the Amp Hours being drawn by the heater (and lights/fridge/etc). realistically you need to start at batteries with a minimum rating of 80Amp Hours - that gives you about 40AH to use before damaging the batteries. There is a simple way to recharge the 2 x12V batteries but requires two or maybe three relays - a weblookup might be better for diagrams - I think the SBMCC website has some schematics.

I'd put the heater as far away from the sleeping area as possible, the exhaust and intake as well, run the heater flex hoses to the places you want the outlets at floor level and near to bed and shower cubicle (see I'm a sook) are a good start. You can wrap insulation around the flex hoses if they have to be run under the floor for any length. I'd put the controller at hand or foot reach to turn on/off. Use the timer as much as possible.

Cab footwells are good spots for the air intake, if you are taking warmish air into the heater it takes less to heat it up and the heater will cycle on/off using less battery power. You should have a permanently open bottom vent to allow fresh air to circulate.

Exhaust has to be away from intake, windows or vents - if you must put the exhaust under a window make sure you fit an interlock switch so that the heater turns off the moment the window opens. You can buy smallish diameter steel flex hose joined to steel pipe and run the exhaust well away.

You need a permanently open roof vent (for gas cookers and fridges as well) in case the heater leaks CO into the flex hoses.

He Matt,

Your quite busy A google search gives this Webasto installation manual. Your type may be in the list but the principles are all the same. I have one installed in my LC on 24 V but mine is 24V. your HJ is 12V so you need a step up converter but that is indeed a big one as the start-up power of the unit is considerable.

Download

cheers,
Noel

Matt

In addition to what the others have said (your installation is 12V, only the starter motor is 24V; using starter batteries for running camping equipment is asking for trouble), please mind that by using a step-up converter you only increase the load on these batteries (converters are NOT 100% efficient).

While an extra deep cyle battery (or two) is always a good idea, the rest of your project looks like a non-starter, because 12V and 24V loads do not mix well on one bank of 12V batteries. Even if you fitted two extra batteries, you still should not not use just one to power 12V loads while both are connected in series to produce 24V.

IMHO, the only way to save your heater project is by adding a large capacity deep cycle battery (wired through a split charger) and a properly rated, high efficiency step-up converter.

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Roman (UK)

Well, goodwoodweirdo, roman seems to know more about your vehicle than you do; you haven't answered my question as to the voltage of your vehicle.
Actually, HJ75s come in different battery/voltage configurations for different markets.
IF your vehicle is as described by him, I agree 100% with his suggestion: get a deep cycle leisure battery and a HD 12V-24V convertor.
Additionally: the electronic installation of a Webasto is not trivial. Likewise, the proper installation of air intake and exhaust is critical. Do you have the necessary technical skills?

Charlie

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Unimog U500 w/Unicat

I would not think it is worth the trouble of a converter as others have said it needs to be massive they draw at least 20 amps at start up. I would sell it and buy a 12v one. probably cheaper in the long run.

Graeme

Hi Guys,

Thanks for the feedback and sorry for the late reply, yep got side tracked with work.... Indeed I should have been clearer in my initial post.

So it’s a 1988 HJ75 12v electrics...(not a 24v starter) there is a second 12v Deep Cycle battery for the accessories…it was all converted when new by Trakka back in the 80’s. I will need to further research the split charging system that’s installed.

I’ll take on board your comments and let you know of the outcome. Don’t hold your breath though… could take some time.

Cheers
Matt

I second the selling and buying a 12v version.

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- On the road since 2003 in a vintage Land Cruiser

I put a Airtop2000ST 12V in my defender. Easy to fit and wire up. IF you do decide to sell it and get another i'd consider one that makes hot water so you can use it for a shower.

BTW the support from Webasto is crap. I hope you got it from a dealer who can help or is it from Turkey?

its second hand, but to be honest... fitting it is rather low on the list of " todo's "

I'll get back to it, later in the year...

First I need Brussels to give me a number plate ..

Cheers
Matt

Funny you say so, but the Webasto guys in Turkey fixed our diesel heater temporarily but made a lot of shortcuts, no way to figure out the color coded wires anymore....

Adventurous greetings,
Coen

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- On the road since 2003 in a vintage Land Cruiser