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Diesel Heaters

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guest22972:

I have seen these small Chinese Diesel heaters available for Caravans and the like and did a bit of a search on them.

https://www.ebay.com.au/itm/Diesel-Air-Heater-12V-8KW-Remote-Control-Convenient-Durable-Adjustable-RV/113743502806?hash=item1a7ba41dd6:g:ILcAAOSwWiJc1OdO

I was wondering about them for running on veg oil and that would be a cheap and safe way to heat the house. With an output of 5 ( or 8 ) Kw, they would put out enough to make a difference.  Looking on the world encyclopedia, Youtoobe, I found a guy that had done some tests on this.  The thing failed to run on 100% New oil but was happy enough on 50%.

I have conversed with him a bit after seeing he had the idea also of heating his home with the thing and asked how it was going longer term and if he was using any veg oil in the thing?  He said he had and it was happy up to 70%. Of course this got the rusty wheels upstairs Grinding.......

Much as I am obsessed with covering the place in solar panels, they have been coming up a LONG way short of late and heating with the Ducted air is costing a fortune in the generation shortfall.  It's pretty clear that no amount of panels is going to be able to keep up with my electrical needs due to heating in winter. Today was pretty clear and even after adding yet more panels to my systems through the week, I made 30 Kwh and used 55 so still a shortfall and I didn't even kick in the hot water in that period.

 Here a Kwh of electricity is .30c.  Diesel Fluctuates but if you call it  $1.40L, that would probably average out.  Diesel has about 10Kw of energy per Litre so that would make 1 Kw about  .14C, Half the cost of electricity.  The heaters have a specified fuel consumption of about 600Ml an hour or I think, about 80% efficiency.... but could be improved.  If we say 8Kwh of DELIVERED heat, that makes it about 17,5 C per KWH.  Still very worth while.

Of course if we can add 50% Free Veg oil, that would make it half so about .9C kwh delivered.  1/3rd the cost of power here which in winter I am paying for.....  Horriffic as that is!
I know prices for fuel and power will vary around the world and we have high power prices so this may not work out economical everywhere.  For us in oz, it looks pretty good though.

These heaters have a room air inlet and outlet and an intake and exhaust for the burner. Obviously the majority of the heat loss is going out the exhaust.  Just like an engine, seems to me that if we can capture this lost heat to whatever degree our efficiency goes up. If a simple Tube in tube heat exchanger was fabricated, the inlet air could be preheated before it went through the heater and a lot of the heat recovered. Should be very easy in a stationary  setup. Another use could be water preheating. Gas heaters just have a flue up the middle so if the heater were suitable located, the exhaust could be directed up the middle of a water heater and the energy recovered that way.  From what I can tell the exhaust is quite hot if not in great volume.
Might be OK to Duct into my greenhouse as well. Co2 and heat. Perfect!  :0)

In any case, with a little DIY ingenuity, Shouldn't be hard to increase efficiency of these things and drop running costs significantly as well.

I have looked at a number of vids on these things and although most tend to be install vids, I haven't found one where anyone is having problems with them as yet which is encouraging.  The longevity does concern me though.
If I am saving 30C ( power) minus 9C (Heater running cost 50% Veg) that's 21C Kwh Saving.  The best price I can find on the units is a tad over $150 which would make the break even ( less stuffing around) cost about 167 KW Hours of run time.  We are heating about 7 hours a day and for the past few days have been running at about 3 Kwh which is a bare minimum in not too cold weather.  Call that 27Kwh day and we get 6  days to break even.

Someone please check my maths. This is sounding one of those too good to be true deals. Must have stuffed up somewhere but I can't find it.

Thinking some more, I can't see there is a lot to go wrong with these things. There is a fan for the room air to be moved through the heater, there may be  a small fan for the burner as well. Neither of these I can see being costly to replace with off the shelf or bodge able components. Fans last forever in computers and cars anyway so probably Low failure risk there.
The only other thing is a solenoid fuel pump which may be a little more tricky as from what I can tell, it is pulsed by the heater controller to meter the fuel. Where a normal solenoid pump oscillates to move the fuel with what is probably an internal make and break, I saw on one vid connecting the power to the pump pulls it in and it stays there until the power is released again.  this may make it a bit specialist ( Re, exy) or it might be possible to hack a regular fuel pump.  On the 3rd hand, even if it is a specific pump, it's Chinese. If it cost $20  delivered, I'd be surprised. 

The rest are electronics which would be subject to infinitely less vibration and physical load than in a Vehicle so again I'd have to put that at low risk.
IF my figures are correct, at $150, one would still be making a good saving even if the thing had to be replaced every winter!

And there is yet another possibility......

Haven't made any in years but when I was, we were knocking out Biodiesel for about .27 C litre.  I have no idea what the cost of meth is these days and I know KOH hasn't gone down but, even if it cost .50C/L now, that would still be cheap AND...... given this is for a burner, no need to do 100% conversion so it would be possible to cut back on the Catalysts and make low conversion Bio and drop the cost yet again.
I was looking at a Bio forum the other day and one of the all time Gurus has shown you don't even need to heat the oil to get a reaction, it just speeds it up.  I could hook a fan motor to a home made stirrer, sit that in the top of the drum with everything it in and let that run a day  in summer where it would be about 50% Plus of temp anyhow, let it settle and then Pull the Bio off the top.  Wouldn't even need to wash it, dry or otherwise.

@ 600Ml Hr@ 5KW output ( can't see the need to turn it down in this place) A drum of a 200L batch would yield  around 170L of low conversion Bio which would equate to 283 Running hours or over a month at 8 hours heating time. At 5kw, might be able to decrease that run time a bit.

This is definitely sounding too good to be true!

Time I got to low conversion bio, would be virtually free to run one of these little diesel heaters.
Any costs and time involved, like before, I'll write off to savings on Gym membership which is a sound investment for me.  ;D

As reluctant as I am to buy anything off the shelf especially when it comes to burners, time I get pumps and hose and other things aside from the freebies I have for the project, buying one of these heaters is not going to cost any more that to build something bigger, uglier and with less safety built in.

Someone shoot some holes in this for me. It's looking far too good to be this easy and worthwhile.  :-\

broncodriver99:
Here is a review done by a fella I follow on youtube. He is pretty entertaining and  a pretty good machinist for being self taught. May give you an idea of what to expect from it.

https://www.youtube.com/watch?v=SsHiX-y9RrI

BruceM:
Something to look into if you get one of these is: how well sealed is the sealed combustion. Often, the "sealed" combustion is a farce and you get some combustion gasses in the heated air. 

ajaffa1:
Very interesting concept, when I was a much younger man every car service place had an oil burning heater that they used in the winter to keep warm. These all ran on waste sump oil that they collected during the summer months.

I`m not sure how well this will work with veg oil, I suspect the unit has some sort of spark igniter which will not work with veg. Perhaps a blend of veg and diesel/kero/RUG would work or alternatively set it up with twin tanks so you start and stop it on a volatile fuel while burning veg in between.

I have serious concerns about a heater that is largely encased in flammable plastic, I would recommend you mount the test unit outside on something that will not catch fire, then use a non flammable materials for the ducting.

I will be very interested to hear your conclusions about these as it is bloody freezing in my shed at this time of year, minus one this morning!

Bob

old seagull man:
Put me down as interested as well. My container workshop is bloody freezing these mornings. and i do have a bit of fish and chip oil around the place.

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