Author Topic: Diesel Heaters  (Read 367 times)

glort

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Diesel Heaters
« on: July 07, 2019, 11:38:30 AM »

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

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Re: Diesel Heaters
« Reply #1 on: July 07, 2019, 11:21:22 PM »
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

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Re: Diesel Heaters
« Reply #2 on: July 07, 2019, 11:42:56 PM »
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. 




glort

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Re: Diesel Heaters
« Reply #3 on: July 08, 2019, 03:54:31 AM »

From the various Vids I have seen I don't think combustion gasses would be a problem.
The combustion chamber seems to be on the inside of a casting and the airflow over the outside.  Pretty confident  with the amount of these thing in use in Trucks and mobile small spaces, the issue would have been picked up by now.

The Vid bronco linked to the guy had a CO meter and didn't report anything.  In any case they still sell unflued gas heaters here.
In any case I'll guarantee I have already inhaled enough exhaust from running engines in sheds and being around them than I could in the rest of my days inhaling from one of these things even if the exhaust was inside!  :0)

I'll look up how much a CO meter can be had for anyway. I think such a precaution in the advent of anything going wrong would only be wise.

ajaffa1

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Re: Diesel Heaters
« Reply #4 on: July 16, 2019, 10:13:22 AM »
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

glort

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Re: Diesel Heaters
« Reply #5 on: July 16, 2019, 12:05:26 PM »

Hi Bob,

Looking into these things some more, I am sure they will NOT run on anything but a substantial Diesel/ Bio Blend.
They work by feeding the fuel over a glow plug which vaporises it so it can burn. As far as I can tell, the GP must be on all the time because I can't see any other way for it to self sustain sufficient heat.

Any waste oil will carbonise on the plug and cause the heater to stop working. They are a ceramic type plug which is said to be brittle and expensive ( $30+ in a $150 heater.
A low conversion Biodiesel should work OK but I have my reservations about blends although the guy I communicated with reckons he was doing OK with 50%  Diesel / Veg oil. I suspect he is using new oil  That's not economical but he seemed environmentally conscious so that may be his motivation if that is what he is using. If Bio could be made for what I think presently, around .50C a litre or less, it would be well worth the Minimal effort required.
A processor could be set up that required nothing more than mix the meth-oxide, throw it in the reactor and let it mix  a while.
When I used to do the 1000L batches with a mate we used to mix for an hour ( with a geared down Motor driving a 25HP outboard propeller in the tank)
Then let it rest an hour, Drain the Glyc, Remix a while then let sit and drain the final Glyc.
I'd set it up with a DC fan motor running off a panel and let it mix a day or 2 settle a day or week then pump off the top of the drum.  For a burner I wouldn't even take the Meth out, it would help with ignition and any soap which the meth usually holds wouldn't matter anyway.

If one were using engine oil it could be Cracked to remove a lot of the ash producing impurities which would make it much cleaner burning that way.

I have been doing a bit behind the scenes with control system for burners.  Using pumps and PWM controllers for the fans allows much more stable output at low outputs.  I have also done a bit of tinkering with some glow plugs left over from my Lovely but completely unreliable Peugeot and dribbling oil onto those.  I believe they have the grunt to burn off any deposits from used oil and am doing the mental arithmetic how to best utilise them in a DIY burner.

I am thinking of them as a pre ignition/ heater for the oil which may be employed as either a way to get faster and possibly even push button starts of a burner or just good stability at lower outputs. Using waste oil is a bit of a trick over Diesel / kero/ turps/Bio etc because it burns with a lot of residual crap unlike the refined fuels that burn clean. 

I believe the heaters are safe, they have over temp sensors and it they had caught fire, pretty sure it would be all over the net by now.  Everything I can find rather than complaining typically about " Chinese Rubbish" seems to suggest these are better than the webastos and Esbarchers they copy.
I have read a good number of comments from people that have had those which cost many hundreds of pounds/ Dollars and tried the Chinese heaters and said they are vastly more reliable and trouble free.

This place has I think more windows than walls so I was thinking to  make an insert for the heater to sit in one of the windows in the middle of the house.
The whole thing could be outside and set back a bit from the window so if it did go up, it would be pretty free and clear of anything combustible.
I have a few 40oC temp switches left over from attaching to Solar GTI's to kick in external cooling fans so one of these mounted on the unit to a Buzzer ( car horn) would add a degree of comfort to my paranoia.

I was thinking of RUG in the mix and as cautious as I am with that, I can't see a problem with it here.  There is really no opportunity for a deflagration of any consequence as long as the ratio is kept low. I don't use it above 10% in engines and if its going to vaporise at any time and cause a build up of flammable gasses in the unit, it might be better to light them off earlier with the RUG than allow them to build more as they will anyway with diesel. The combustion chamber has an always open path in and out so no opportunity for pressure build up anyway. Might get an amusing pop  but that would be about it.

The other thing I was thinking about was my beloved water injection. If there were a way to get a very slow drip into the intake of the burner it may help with keeping the combustion chamber clean  and deposits at bay. There is a bit that needs to be thought through with it however.

You don't need one of these for shed heater, I already have designs for those that will heat a warehouse! these diesel heaters do 5 KW output. If you were careful you could  keep one of my heaters down to  50 Kw..... Maybe....
The things I have been playing round with would definitely allow control and workable output for a shed heater and you could burn any waste oil you could get hold of with no worries.
Gravity feed is OK for shipfluckery in the back yard but for any serious heating where you don't want to have to stand over the burner or never be more than 6 Ft away, Pumping is the way to go.

That said, I'm also working one an old batch burner design I never actualy made a vid of but used it a lot at home myself.  Mrs and I would often go and sit  round the thing in the yard in the middle of winter listening to it quietly roar away and the only time we got cold was when we came inside.
This is a batch burner setup so depending on the size of the thing and how hard you run it, You only have to top it up every so often. Mine used to throw out a lot of heat ( about 50 Kw) and I only had to top it up every hour.

Spsoe I should get into the vids like I have been saying I will... forever, before winter is over again.

old seagull man

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Re: Diesel Heaters
« Reply #6 on: July 16, 2019, 12:47:30 PM »
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.

ajaffa1

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Re: Diesel Heaters
« Reply #7 on: July 16, 2019, 01:47:19 PM »
Hi Glort, it`s nice to have an internet connection again, ours failed about ten days ago. When we reported the problem to our telco, by landline telephone, they diagnosed that we needed to buy a new telephone despite the fact that I was talking to them on our existing phone! F*cking morons finally realized that it wasn`t just our property that had no internet, the whole district was disconnected. Eventually they sent out an engineer to reboot the ADSL router at the local exchange. Guess what, all the locals now have internet again, next time it goes out I`ll just go to the local exchange and kick the door in, turn the router off and restart it, problem solved! It`s not quite that simple, this problem occurs every six months, I suspect the router has a memory cache and error file that builds up until it is full at which point it falls on it`s face. A little routine maintenance and remote supervision would cure the problem but I`d bet my house it will fail again in December or  January. The real killer with these outages is that the local Canoe Center is unable to take bookings or deal with necessary bank transactions, I would estimate the financial loss at between $5,000 and $10,000, none of which the telco is responsible for unless we can prove negligence!

Enough of my problems, back to your project. I have never seen a glow plug that would heat diesel/kero/veg to the point of ignition. Much more likely it heats it to increase volatility before passing it through an atomizer nozzle with a spark igniter. Once alight the fuel burn should be self sustaining. I think I suggested before that a gas pilot light could easily replace the spark igniter and would be better suited to igniting veg oil.

Your concerns about the dangers of mixing diesel/RUG are unfounded. I recently wanted to quench some red hot steel parts in oil, the only oil I had available was a 5% RUG/diesel mix left over from fighting the forest fires earlier this year. I filled a container with the mixture, dropped the red hot steel into it and ran like f*ck. I was expecting it to ignite or worse but nothing happened, it did boil rather harder than neat diesel but left a very nice blued finish on the steel. I continued with this process for over an hour with no ill effects until I managed to boil the Diesel/RUG mix at which point it spilled out of it`s container and all over the shed floor! So much for health and safety.

I like your idea of feeding the hot/return air through a window, I have no idea about which way your windows open but a sliding window could easily be modified with a small strip of plywood to allow for the inlet and outlet pipes, without effecting the window.

With respect to your idea of water injection, I doubt that this will do anything. In an ICE the water droplets work under high pressure on each compression stroke, this has a hydraulic/steam cleaning effect that you will not find in an low pressure burner system but I might be wrong and look forward to hearing what you discover.

Generally you need to adjust the fuel air mixture in any burner until you have no signs of yellow flames; blue is good, yellow/orange produces soot and blocked chimneys and all the associated dangers, carbon monoxide and etc.

Let us all know what you find out.

Bob


EdDee

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Re: Diesel Heaters
« Reply #8 on: July 16, 2019, 03:24:39 PM »
I jump in to add my not even 1c worth....

<Quote:>
With respect to your idea of water injection, I doubt that this will do anything. In an ICE the water droplets work under high pressure on each compression stroke, this has a hydraulic/steam cleaning effect that you will not find in an low pressure burner system but I might be wrong and look forward to hearing what you discover.
<Unquote>

I have been playing around a little with this lately and found one interesting thing, haven't verified or documented it properly yet, but when I took the water from the over pressure bleed off/expansion valve of my boiler to the path of the flame, the stack cooled slightly overall, but I found the heat transfer to the heatex coil a little better... Could have been atmospherics, dumb luck, or error... As I say, I need to look into this a bit more, it could prove interesting....

Cheers
Ed
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glort

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Re: Diesel Heaters
« Reply #9 on: July 16, 2019, 04:01:45 PM »

Bob,

Optus have a wireless Internet service that I have read many good things about. You can connect you home computer, laptop, tablet and phone all through the one connection and it's available everywhere you go..... more or less.  I think it's about $70 a month.  I have been meaning to look more into it myself.  The NBN that was supposed to be here 2 years ago has made it to the street. They were digging and making a mess down the end a fortnight ago and were supposed to be finished 2 Fridays back.  I am sure like the endless broken promises it will be another 2 months of fridays before it's all connected and then will be garbage when you do get it.

My windows there are the normal up down type although there are sliders elsewhere.
I was thinking to just get a Piece of suitable gauge Tin used for ductwork and the like and cut that to the window width and let the window sit down on it.
If I fold a lip in it, I can mount the heater to that and just have the hot air ducted in.  I was thinking to pull the air from the outside so as to give the house a touch of pressurisation so all the cold air in the gaps of the many doors is pushed out if anything.  I was also thinking to compensate the colder air intake by making a heat exchanger of a tube in tube design of solid pipes with teh exhaust running down the middle of the intake then exiting  well up and away from said intake.  I was thinking to put some twisted thin sheet metal down the centre of the exhaust tube to create some turbulence and break up the cold boundary layer gasses to give the best heat transfer.

I have tested the glow plugs I have and they glow quite a bright red at their rated Voltage of 11V and definitely ignite the oil I have dropped on them.
The question is how much oil can they ignite on a continual basis.  I haven't managed the current yet but I expect it to be about 5A.
I remember the Peugeot's were a real pains with teh glow plugs and had a propensity to go though them.  Not a matter of the glow time but I think the way they were located in the Cylinder.  Never changed the Plugs in my patrol in 4 years.  The ones in the Merc were average.  Lasted a good while before falling over.  The ones in the pug almost needed to be on a belt feed damn things.

I don't know about the WI, as I said, needed more thought.... and probably some testing.  I can see things for and against. First thing is IF a problem occurs for it to fix.  May not need it in the first place but then again, If I put on a system and the burner stayed clean, even if it would have anyway,  I could claim the WI was a success!    :laugh:

I'm not sure if the heater has any mixture adjustment. I have not seen mention of it.
In my burners it's more about keeping the heat in the burner and the fuel levels stable.  My bigh burners all run very air rich to make a clean burn.  With low output burners, it's real easy to over cool them. By reducing the airflow to what you need, one reduces the excess and the cooling allowing the burn chamber to remain hot enough to vaporise the oil.

I built a new burner a few weeks ago on a design I have had in mind for years specifically  for low output and complete combustion.  Must get round to firing it up and seeing how it goes. I already have another more compact and efficient design in my head that is based on another desighn I did years ago.  That one worked on the heat travelling back on itself  as well and was very effective. The outside of the burner was almost cool enough to touch while the inside was really hot and the output of the thing reflected how well the oil was phase changed to a gas and well mixed with the air.  It was an absoloute mongeral to light though  so I'm hoping this new idea over comes that.

I'll have to put some effort into the Draft burner as well. I always did like the way that one worked.  No external power or fuelling needed. Light and walk away for an hour then top up again and another hour of impressive heat with nothing to set flow rates on or anything else.

veggie

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Re: Diesel Heaters
« Reply #10 on: August 14, 2019, 05:26:37 PM »

Very interesting little heaters.
So many uses.
Small shop, Greenhouse, Camping vehicle, Generator shed.
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