Unimogadventures - Our build and travel thread

[Iain_U1250]

I looked at them and was really tempted as they were cheaper than the whole kit I ended up with, and whole lot simpler to install. It is a really nice compact solution for providing hot water and warming the camper.

What swayed me to the 90ST is that I wanted something that would be able to heat the engine block as well, as we plan on traveling to northern Europe ( Norway/Sweden) in winter to see the northern lights. I did some heat calculations a while back, and needed around 4-5kw to keep us warm when it is -20C outside. The "spare" 4-5kw should be enough to stop the engine from freezing we hope. I know that Charlie has a 90ST just to heat his engine for his Unimog U500 and another 5kw unit for the camper, but his truck is a lot bigger than mine and he travels in really cold places.

The other advantage of what we ended up with is that the engine heat is used to heat up the hot water system. That is the main advantage of what I have, I don't have to fire up the 90ST for hot water at all if we are moving regularly as the calorifier would retain enough heat to let us have a shower the next morning, and according to a few people, sometimes two days. We can also use the residual engine heat to warm the truck in the evenings, even after stopping thanks to the EBP.

I was also considering having the 90ST closer to the middle of the truck, under the floor, rather than where we have it. After hearing one start up, I decided to put it as far away from the bed area as possible, so moved it. It is not that loud, but does sound like a mini jet engine on start up, once it is going, it get quieter. I'm not sure how quiet the DuoTop is, have not heard one run.

When we camp, it is unbelievable how quiet things are out in the bush, so I am doing my best to keep all the stuff in the truck as quiet as possible, I'm even replacing all the fans on the fridge and freezer with more silent magnetic bearing fans, and sealing the front of the fridge cabinet, adding sound insulation. Adding all this sound insulation then requires ventilation fans around the fridge cabinet to get the hot air outside, so everything is a compromise.

 

[mrFelix]

Cheers for that, I hadn't even considered the noise factor but as all our travel is in oz, the Duo will be all we'll need, hope it isn't too loud
The duo is designed to be mounted outside the camper, wonder how they would take to being dunked in a river crossing ?

 

[Iain_U1250]

I'm not sure about the DuoTop, but the 90ST is supposed to be able to survive river crossings, but it will need to dry out before starting if water gets up the exhaust for a prolonged period of time, like getting stuck in a river. I mounted mine as high up as possible, around 5ft off the ground, which is pretty easy in the Unimog

 

[LoRoad]

What about AquaHot?

The internals are Webasto with a multitude of controllers.

 

[Iain_U1250]

Never heard of them, not sure if they are available in Australia.

 

[whatcharterboat]

I'm not sure about the DuoTop, but the 90ST is supposed to be able to survive river crossings, but it will need to dry out before starting if water gets up the exhaust for a prolonged period of time, like getting stuck in a river. I mounted mine as high up as possible, around 5ft off the ground, which is pretty easy in the Unimog

Hi Iain,

Long time....how are you?

Love dropping in on this thread to see your progress.

Re: Duo Top. Have done a couple ...... I much prefer the Webasto hydronic furnaces for anything travelling offroad. Duo Tops are perfect for Winnebagos type campers though. Have only done one 90ST but plenty of the smallest ThermoTops. If you ever have a problem with it, garaunteed it's something you've done yourself. These things are such good quality.

Re: the comment back a couple of pages about always heating the engine block every time you to hot water.

The posters comment is valid . Not good to waste heat out through the engine block. ......but you can still isolate the engine form the ST90 circuit an easy way. As you stated, You do need enough volume (when engine is isolated) in your hoses though or else the system cycles too often. You may need an accumulator possibly if the hose runs are real short. Also you can't isolate the engine completely cause you need to allow for expansion in the lines. The way I've done this before is using one NO and one NC solenoid valve. Basically you make a "H" shaped manifold with Tees . The NC valve goes on the leg of the "H" from the engine (and the leg opposite back to the engine) and the NO valve goes on the crossbar of the "H". I hope you get the explanation but what happens is when the engine is running the coolant is heated in ... Lets call it the long circuit. Then when you switch the engine off and de-energise the valves the Webasto system swaps to a short circuit but one leg is still open to the engine. So while you won't get flow through the engine you have allowed for expansion and also you only have one fill point through the radiator which makes it much easier to bleed, less potential problems, etc. than adding in a header tank into the Webasto circuit.

Then the next step is to wire up an over-ride switch so that you can manually switch to the long circuit to incorporate an engine pre-heat function. Give me call if it isn't clear as mud cause my drawings really suck.

Owen (Skifreak) is pretty switched on with this gear too by the way.

Take care mate. I am long over due for that visit to your shed. One day.

Kind regards
john.

 

[Iain_U1250]

Thanks John, next time you are coming down the M1, give me a ring ( still got my number?) Mog will still be there for a while

I understand what you mean, basically creating a short circuit, but I'd be lucky to have about 3.5 litres of water in the system if I bypass the engine, even with 10m of 3/4" hose. I'd rather not have another tank in the system, mainly because I don't have one lying around and I'm running out of space believe it or not. I need to get it on the road so I can measure the flex in the frame and clearance to the camper box and see if there is any more space left.

The U1250 Mog is actually quite small compared to the Fuso/Mitsubishi, the cab is set back, 3.2m wheelbase and 44" tyres, torque tubes, transmission, air tanks ( all four of them) the overdrive, two fuel tanks and an battery box and all the pivots for the four point mounting means there is not that much space available under the frame, and getting the hoses from the engine compartment back to the camper was a pretty tight fit.

 

[LukeH]

OK I understand your point about the low volume increasing start stop cycles. However, none of the Webasto schematics are designed for the supplementary heating of the camper box, and forcing coolant through the Webasto at engine pupm rates is not ideal.
So how about this:
You set up your 3.5 litre loop with the webasto as it should be, and the engine in parallel as previously described. This means the coolant in the small circuit will heat quickly, which is what you want when you get back from a walk or whatever. However before the coolant in the small circuit gets hot enough to shut down the Webasto a thermally controlled valve opens the circulation to the engine, giving you the increased volume required, "dumping" excess heat and avoiding a shut down.
So it's exactly what John is describing only with a thermal switch to engine preheat instead of a manual override.
No extra tanks, no extra lines, just a different routing to save your Webasto from being directly subjected to forced engine coolant flow.

 

[Iain_U1250]

Thanks for all the comments, I will have to look into how I plumb it, maybe with a bypass for the 90ST. I'll have to work on how that works. Any idea where I can get a thermatic valve from, they are not so common over here in Australia, no central heating shops around. It might be a good thing to add to the rear compartment as well.

On another subject my induction cooker arrive, so I had to repeat the same test as before, how long to boil up a litre of water. After figuring out how it worked, I pushed the power button at 10.45 with 1 litre of water in the same pot as before.



I set it to 1600W as that's the maximum my inverter can handle, and 240 degrees C, maximum temperature to boil fastest. At 10:51 it was simmering, and it had just turned to 10:52 when it was boiling. That's pretty good going, 1 litre of water in 7 minutes, half the time of the diesel stove.



The only bad side is the amount of current draw, it was pulling 185A out of my battery bank (300AH) at the 1600W setting. This took the battery from 100% charge (battery charger on float charge of 13.5V) to 80% charge to boil the water.



It would be no problem with the engine running, but not something I could say would be practical as a replacement with my battery set-up. I have a power meter at home, so will measure how much the actual 1600W setting draws. i must say I'm pretty impressed by the cooker so far, for the $56 including shipping, it is worth having just to use in hotels/motels.

The next thing to test would be a kettle, but I would need to find a 1600W or smaller kettle, which is not easy over here.


Finally, I'll test my little two burner gas stove ( as soon as I replace the hose that the dingo ate ) and see what that does.

 

[whatcharterboat]

On another subject my induction cooker arrive, so I had to repeat the same test as before, how long to boil up a litre of water. After figuring out how it worked, I pushed the power button at 10.45 with 1 litre of water in the same pot as before.

I set it to 1600W as that's the maximum my inverter can handle, and 240 degrees C, maximum temperature to boil fastest. At 10:51 it was simmering, and it had just turned to 10:52 when it was boiling. That's pretty good going, 1 litre of water in 7 minutes, half the time of the diesel stove.

The only bad side is the amount of current draw, it was pulling 185A out of my battery bank (300AH) at the 1600W setting. This took the battery from 100% charge (battery charger on float charge of 13.5V) to 80% charge to boil the water.

It would be no problem with the engine running, but not something I could say would be practical as a replacement with my battery set-up. I have a power meter at home, so will measure how much the actual 1600W setting draws. i must say I'm pretty impressed by the cooker so far, for the $56 including shipping, it is worth having just to use in hotels/motels.

The next thing to test would be a kettle, but I would need to find a 1600W or smaller kettle, which is not easy over here.


Finally, I'll test my little two burner gas stove ( as soon as I replace the hose that the dingo ate ) and see what that does.

Hey again Iain....speaking of dingoes , a funny thing happened to me on Fraser a couple of weeks agao. Had a dingo come and lick my head while I was sleeping in my swag!!

Mate, that looks like a stainless pot on the induction cooker. It probably has a plate of steel in the base covered by stainless or else it wouldn't work at all but try a cast iron pot with the same volume of water and see the difference.

Regards John.

 

[whatcharterboat]

OK I understand your point about the low volume increasing start stop cycles. However, none of the Webasto schematics are designed for the supplementary heating of the camper box, and forcing coolant through the Webasto at engine pupm rates is not ideal.
So how about this:
You set up your 3.5 litre loop with the webasto as it should be, and the engine in parallel as previously described. This means the coolant in the small circuit will heat quickly, which is what you want when you get back from a walk or whatever. However before the coolant in the small circuit gets hot enough to shut down the Webasto a thermally controlled valve opens the circulation to the engine, giving you the increased volume required, "dumping" excess heat and avoiding a shut down.
So it's exactly what John is describing only with a thermal switch to engine preheat instead of a manual override.
No extra tanks, no extra lines, just a different routing to save your Webasto from being directly subjected to forced engine coolant flow.

Hi Luke, Not sure I understand this. The problem isn't engine flow through the Webasto. It's that when you don't have enough capacity in the lines, the coolant cools too quickly and the cycle is therefore too short. Is that the way you see it.

Obviously this won't be possible for Iain but if anyone is doing research here in Oz, Webasto in Sydney also do an alternative to the Sigmar tank. They build this themselves. Doubt it is available elsewhere. The Sigmar tank as you know is a WATER tank with a single or dual heat exchange coil running through it. The alternative was developed for compact caravans and camper trailers....basically it is a larger header COOLANT tank with enough volume for the Webasto system that has a plate heat exchanger built inside. So water goes in to the plate exchanger cold and instantly comes out out. I guess this would be another way to short circuit the Webasto system successfully.


Regards John

 

[Iain_U1250]

Dingoes are getting a bit too friendly on Fraser. We were doing a photoshoot at the wreck of the Maheno early one morning, and I noticed two dingoes heading towards us on the beach, then I realised they were heading straight for my wife's bikini she had left further up the beach :Wow1: - I sprinted toward her costume, and so did the dingoes, but I just managed to get there first and grabbed it, the just looked at me, then took off, could have been interesting walking the 2km back to the campground when all the backpackers woke up if they had gotten away with it.

We think it was the same two dingoes that chewed through the gas bottle hose. The only think we left out was on our table was the stove and gas bottle, once they bit it, they didn't like the taste of the gas coming out, but they emptied the gas bottle as the missus had not turned it off on the bottle properly.

The post is stainless, with a steel base. I'll see if we have a cast iron one, don't think we do, missus likes shiny things

Hey again Iain....speaking of dingoes , a funny thing happened to me on Fraser a couple of weeks agao. Had a dingo come and lick my head while I was sleeping in my swag!!

Mate, that looks like a stainless pot on the induction cooker. It probably has a plate of steel in the base covered by stainless or else it wouldn't work at all but try a cast iron pot with the same volume of water and see the difference.

Regards John.

 

[whatcharterboat]

Dingoes are getting a bit too friendly on Fraser. We were doing a photoshoot at the wreck of the Maheno early one morning, and I noticed two dingoes heading towards us on the beach, then I realised they were heading straight for my wife's bikini she had left further up the beach :Wow1: - I sprinted toward her costume, and so did the dingoes, but I just managed to get there first and grabbed it, the just looked at me, then took off, could have been interesting walking the 2km back to the campground when all the backpackers woke up if they had gotten away with it.

We think it was the same two dingoes that chewed through the gas bottle hose. The only think we left out was on our table was the stove and gas bottle, once they bit it, they didn't like the taste of the gas coming out, but they emptied the gas bottle as the missus had not turned it off on the bottle properly.

The post is stainless, with a steel base. I'll see if we have a cast iron one, don't think we do, missus likes shiny things

Hi Iain,

Well actually I was camped only 300 metres north of the Maheno when I had the encounter!!! Probably one of the same pair.

Yeah...definitely try a cast saucepan. Otherwise you can buy proper induction cookware but I've cooked with an old cast iron frypan like they sell in camping stores and they work great. Basically if a magnet won't stick to the pot it won't work on an induction cooktop.

 

[mrFelix]

I reckon that pot would boil a bit quicker if it had a lid on it :coffeedrink:

 

[PeteFox]

Iain
A quick bit of maths. Your meter with the induction cooker set at 1600W shows 185A at 12.1V, this is 2238W, so either a dodgy meter or a lot of losses in the conversion to AC, in the order of an extra 40% power to drive it.
Is the cooker rated at the watts used in cooking or the power used to drive it? If it's 1600w of cooking power then it's similar to a microwave in the power lost/consumed in operating
Pete