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User Projects & Pictures / House heater.
« on: September 29, 2022, 07:18:52 pm »
With my old Ducted AC struggling to heat the house in winter and using a lot of power not to do it, Decided to build another heater for the house.
Being this was DIY and well into the winter time I got round to it, I didn't have time to set up safety features and I wanted it to be safe and Potentially disaster Free.
For this reason I decided to use water as the main heat transfer medium rather than direct air I was going to initially use air but as this would give a direct path for a run away fire to get into the house, I decided to put that idea aside till I thought things though better.
I ended up with 2 Versions of the burner for the heater.
The first was a submerged Burner. Got a piece of 150mm pipe, welded one end shut and got a bit of 50mm for the air tube and bit a bit of 6MM copper down the middle for fuel feed. I wanted maximum heat transfer area of the pipe to the water and my aim was for a max 10 Kw heat output.
I drilled some holes in the down tube and welded on some Tabs to hold the flame and make it turbulent so there would be more contact with the hot gasses and the main burn tube. This is important to break up boundary layer gasses as otherwise the outer coloumn of air gives up it's heat to the pipe which is transferred to the water but the inner gasses go straight up and out ( or along if horizontal) and don't give up their energy when is then vented and wasted.
Because HEAT is the key to oil burning of this type of combustor and The main burn tube would be water cooled in effect, I made a small insert piece for the air fuel tube to sit in which would get red hot to burn off the carbon and act like a big glow plug. In testing the burner in free air, the family ended up coming out and sitting around the thing where I had set it up and was doing a test burn one night and the only complaint was we were all backed up against the walls of the covered verandah and too hot even when the thing was running pretty low.
I thought this would be excellent for keeping frosts away in the garden with a fan blowing across or a great shed heater if a flue was put in the top if it were a small space without a high roof. That said, Checking with my CO meter, the thing runs clean enough to come in under the 8 hour exposure level of breathing the gasses so really not that much of a concern if it wasn't flued in a reasonable are where the gasses could escape and there was some ventilation. The radiant effect would be perfect in that scenario.
I put a small Bilge blower on the down tube for air supply and ran the oil line down the middle to the bottom so the oil would be blown out half way down the tube or carbonise in the air tube and block it.
Sank it all into a drum of water and sat it on some bricks so it wouldn't melt the plastic drum I was using for testing. And NO, It didn't melt as can be seen in the pics and I boiled the hell out of the water which was hot as it would ever get.
For fuel control I used a cheap Fleabay Fuel pump and controlled that with an interval timer. This is really a key part because although so many go on about the simplicity of a drip feed, it is totally useless for unattended running as I wanted this thing to be. I wanted set and forget and with a measured and constant fuel delivery, that's what I got. The only variation was the cold could make the oil thicker and it would slow down but that was acceptable as long as it did not run away. I did have a PWM controller on the blower but that turned out not to be needed and more complication so I ran the fan flat out and to slow it down for lighting or low power running I used a bit of cardboard across the inlet and that worked perfect. In normal operation it runs wide open and creates an oxygen rich fire which makes it burn so clean.
To get the heat into the house, I ended up with an intercooler from a car and put a circulation pump on that. I made up a wooden box as a plenum and put a tube fan on it to suck air through and duct it through a window. This worked but was mostly wrong but was a matter of the materials I had on hand and could put together in a day as it turned out.
Firstly, the Pump should pull from the resivour and push through the Radiator ( intercooler in this case) so any air is expelled. Drawing through although meant the pump got the coldest water ( and the pump is rated above boiling) but was also difficult to get the air out the system. Next time I'll draw from the tank and push through the radiator.
Other mistake was to use an Intercooler. They do not draw enough heat out and the cross flow sections ( whatever they are called) are too widely spaced and too thick with not enough fins to extract all the heat. It worked but the water temp coming out the thing was too high and there was not enough drop. Didn't really matter because little heat was lost as it returned to the " Boiler" but annoyed me as an inefficiency. I later remembered from my go fast days that intercoolers of this type are mainly dependent on their mass to cool the incoming charge air as few turblow cars are on full boost for more than 10 Sec at a time.
I tried a car heater core initially and that was great but the one I had was small and the limitation was the low pressure fan. Cars usually have blowers which do higher static pressure and get the volume through the core.
I have researched online and found that there are car heater cores available in the US that are a universal fit and sold for hotrods etc. They have the core, blower and a speed control all in a nice housing. The largest I found did 12 or 15KW, for get now, but perfect for what I wanted and there were smaller sizes as well. They weren't cheap in our money but typically shipping anything here from the US is total and utter bullshit in how expensive it is, So they were not Viable. Haven't found anyone that has the larger ones here. With free shipping in the US, These would be perfect. Sit the unit in a window, connect up the hoses, a 12V power supply and done and they look decent as well.
The reason I went to the complication of using water as the working HE medium was because again of safety. No way for any fire to get to the house as the burner is situated well away ( slim risk of fire as it is) and the Inter cooler was also outside so if there was a leak, I have 200+L of water on the verandah outside where it don't matter rather than creating a no contest Divorce case if it flooded the house inside. Doing it this way simply avoided as many risks as I could forsee.
So did it all work?
YES!!
And No.
The weak link was the Intercooler and fan. That side could not keep up with the output of the burner. A car or bike radiator would have done the job MUCH better. I have since modified a car radiator and electric fans which will well and truly over cool the incoming water and I can use a PWM controller to get the heat output perfect.
That said, although took a few hours, I could heat my large house to the point of well being too hot. I would fire the burner up about 3 PM and it would keep the house nice till I shut it down about 9 am the next morning. The thing I was not happy with was the heat up wime mainly. I wanted to be able to blow 10 KW into the house and have it hot in 30 Min or less and I think with the right radiator and fan Combo, that's easily Possible.
I made a lot of modifications to the burner tube which were adding a lot more air holes and tabs along the length to swirl the gasses and flame front and also keep the burner insert hot so it burned off all the carbon from the oil. The burner tube would stay nice and clean as well showing complete combustion and of course the thing had ZERO smoke.
The biggest mistake with the whole thing and I still can't fathom how I did it as I still believe my numbers should have been right, is to Miscalculate the heat required. I designed for a max of 10 KW output and that wasn't enough really. The heat up was too slow for what I wanted and I'd have to run the thing flat out on the coldest days for a few hours which indicated my calcs were off. Once up to heat, the thing could be turned down but getting it there was too slow for my liking. I compensated that by starting earlier as here it usually warm enough when the sun is out not to need heating till the afternoon.
Despite being designed for 10 KW, run flat out the burner would do just under 30 Kw by my calculations. The problem there was the efficiency I so carefully calculated with the diameter of the tube with gas flow speeds and surface area went right out the bloody window. As much heat was being blown straight out as was being put to work and free fuel or not, that drove me nuts!
Sure, It will do 30 KW OK but I'm using about 60 Kw worth of oil consumption. Yeah, it's free oil and I have an unlimited supply thanks to a friend but that really Irked my sense of Efficiency OCD. Any idiot can make a big fire, putting the energy to useful work is whole other skill.
At 10 Kwh the thing is great and the efficiency is good but that just wasn't enough for my house in the coldest times which get just below zero.
For what I designed it to do, and I still think that numbers are right and can't work out where I am going wrong, it's not the transfer though the IC, it's good but like anything pushed beyond design limits, it falls over on efficiency about about 15 Kw output.
Now I know, the one thing most people reading are looking for is " How much oil it use an hour?" which is to me sorry, an annoying question because it is totally Irrelevant.
I could dial this thing down to about 300Ml an hour. Way below what I thought it would sustain but it did. That's roughly 3 KW. Flat out it can go through about 6 litres an hour but that's like " emergency power" and is very inefficiency for the heat delivered where you want it.
Fuel consumption is irrelevant because I can easy dial it down to 1L an hour but if that's not enough heat output and my house is still cold, which defeats the purpose of the whole exercise! May as well put a little 1KW bar radiator in the middle of the place and say " Look, only uses 1KW" ignoring the fact it's basically useless because the heat loss in the place is greater than that.
Work out how much output YOU need for YOUR situation and design for that.... Only do it a lot better than I did. The amount of oil it needs is what it needs. If you don't have terrible inefficiency, who cares what the consumption is? the goal is to keep warm and comfortable not save free waste oil!
Now all that said, I was going through about 20 to 25L of oil a day depending mostly on the weather. I did burn Both kinds of oil, Veg and Diesel engine oil. I HATE engine oil. filthy stinking staining black Shit.... but that said I have an endless supply. I still found the Veg to be better. Burned cleaner with less deposits and took a bit of tuning to get the burner to run clean on engine oil when it was perfect on veg.
Veg smells a lot better although that said, once the engine oil is dialed in right it's OK but if it's at all off, it stinks even if there is no viable smoke. We are coming into summer here so I hope to be able to collect and put away at least 2000L of veg and I'd much prefer to get 4000L really. I think our power system is going to be in trouble and I want to be able to fuel the diesel Generators I have Built of veg over WMO as I'm far more familiar with veg and how it burns in engines.
For a lot of houses especially those better insulated than my Glass house, this would be more than enough at 10 KW output. Turning it down is efficient, turning it above the design parameter is not. Running right I was getting an output air temp of about 50-60o C constant running which was OK. With a better heat exchange instead of the intercooler, I'd probably get it more where I'd like it at 80 or so. I could get that when the tank was at heat and the fan turned down.
Anything below 30 feels cold and that's the Min temp output in Air conditioning.
The thing does have a Noticeable rumble that the neighbors Heard when they come out to their back yard but they thought is was the sewer Pump out running or a tap going. I asked if it was annoying and they said they couldn't hear it at all in the House and were only concerned that something was wrong. I can hear it in the house very clearly but I find it very soothing. It did flame out once because the hose came out the fuel drum and I could hear the change in tone and knew something was wrong. i went out and found the simple problem and the thing stuttered for a bit then kept on going as normal.
At night iT seems to put us all to sleep so certainly no problem with the noise of the burner. More an asset than anything. The fan we simply can't hear being outside and very quiet anyway. Cats soon found a chair near the window that caught some of the warm air coming out and would sleep there all the time.
I will add a Thermostat to the setup because when the thing is switched off, there is still over 10KWh of heat in the water drum which I ended up Insulating which was an improvement. This way when I shut down the burner, the pump and fan will keep running till the water gets cold and then shut off.
That said, Shutting off hot wasn't a bad thing. Meant there was heat there ready to go when I fired it back up.
I ended up doing a MK II version that kicked out way more heat ( up to 100Kw!!) and runs beautifully efficient so if there is any interest in that and people are still awake after reading all this, I can do a write up on that setup.
Being this was DIY and well into the winter time I got round to it, I didn't have time to set up safety features and I wanted it to be safe and Potentially disaster Free.
For this reason I decided to use water as the main heat transfer medium rather than direct air I was going to initially use air but as this would give a direct path for a run away fire to get into the house, I decided to put that idea aside till I thought things though better.
I ended up with 2 Versions of the burner for the heater.
The first was a submerged Burner. Got a piece of 150mm pipe, welded one end shut and got a bit of 50mm for the air tube and bit a bit of 6MM copper down the middle for fuel feed. I wanted maximum heat transfer area of the pipe to the water and my aim was for a max 10 Kw heat output.
I drilled some holes in the down tube and welded on some Tabs to hold the flame and make it turbulent so there would be more contact with the hot gasses and the main burn tube. This is important to break up boundary layer gasses as otherwise the outer coloumn of air gives up it's heat to the pipe which is transferred to the water but the inner gasses go straight up and out ( or along if horizontal) and don't give up their energy when is then vented and wasted.
Because HEAT is the key to oil burning of this type of combustor and The main burn tube would be water cooled in effect, I made a small insert piece for the air fuel tube to sit in which would get red hot to burn off the carbon and act like a big glow plug. In testing the burner in free air, the family ended up coming out and sitting around the thing where I had set it up and was doing a test burn one night and the only complaint was we were all backed up against the walls of the covered verandah and too hot even when the thing was running pretty low.
I thought this would be excellent for keeping frosts away in the garden with a fan blowing across or a great shed heater if a flue was put in the top if it were a small space without a high roof. That said, Checking with my CO meter, the thing runs clean enough to come in under the 8 hour exposure level of breathing the gasses so really not that much of a concern if it wasn't flued in a reasonable are where the gasses could escape and there was some ventilation. The radiant effect would be perfect in that scenario.
I put a small Bilge blower on the down tube for air supply and ran the oil line down the middle to the bottom so the oil would be blown out half way down the tube or carbonise in the air tube and block it.
Sank it all into a drum of water and sat it on some bricks so it wouldn't melt the plastic drum I was using for testing. And NO, It didn't melt as can be seen in the pics and I boiled the hell out of the water which was hot as it would ever get.
For fuel control I used a cheap Fleabay Fuel pump and controlled that with an interval timer. This is really a key part because although so many go on about the simplicity of a drip feed, it is totally useless for unattended running as I wanted this thing to be. I wanted set and forget and with a measured and constant fuel delivery, that's what I got. The only variation was the cold could make the oil thicker and it would slow down but that was acceptable as long as it did not run away. I did have a PWM controller on the blower but that turned out not to be needed and more complication so I ran the fan flat out and to slow it down for lighting or low power running I used a bit of cardboard across the inlet and that worked perfect. In normal operation it runs wide open and creates an oxygen rich fire which makes it burn so clean.
To get the heat into the house, I ended up with an intercooler from a car and put a circulation pump on that. I made up a wooden box as a plenum and put a tube fan on it to suck air through and duct it through a window. This worked but was mostly wrong but was a matter of the materials I had on hand and could put together in a day as it turned out.
Firstly, the Pump should pull from the resivour and push through the Radiator ( intercooler in this case) so any air is expelled. Drawing through although meant the pump got the coldest water ( and the pump is rated above boiling) but was also difficult to get the air out the system. Next time I'll draw from the tank and push through the radiator.
Other mistake was to use an Intercooler. They do not draw enough heat out and the cross flow sections ( whatever they are called) are too widely spaced and too thick with not enough fins to extract all the heat. It worked but the water temp coming out the thing was too high and there was not enough drop. Didn't really matter because little heat was lost as it returned to the " Boiler" but annoyed me as an inefficiency. I later remembered from my go fast days that intercoolers of this type are mainly dependent on their mass to cool the incoming charge air as few turblow cars are on full boost for more than 10 Sec at a time.
I tried a car heater core initially and that was great but the one I had was small and the limitation was the low pressure fan. Cars usually have blowers which do higher static pressure and get the volume through the core.
I have researched online and found that there are car heater cores available in the US that are a universal fit and sold for hotrods etc. They have the core, blower and a speed control all in a nice housing. The largest I found did 12 or 15KW, for get now, but perfect for what I wanted and there were smaller sizes as well. They weren't cheap in our money but typically shipping anything here from the US is total and utter bullshit in how expensive it is, So they were not Viable. Haven't found anyone that has the larger ones here. With free shipping in the US, These would be perfect. Sit the unit in a window, connect up the hoses, a 12V power supply and done and they look decent as well.
The reason I went to the complication of using water as the working HE medium was because again of safety. No way for any fire to get to the house as the burner is situated well away ( slim risk of fire as it is) and the Inter cooler was also outside so if there was a leak, I have 200+L of water on the verandah outside where it don't matter rather than creating a no contest Divorce case if it flooded the house inside. Doing it this way simply avoided as many risks as I could forsee.
So did it all work?
YES!!
And No.
The weak link was the Intercooler and fan. That side could not keep up with the output of the burner. A car or bike radiator would have done the job MUCH better. I have since modified a car radiator and electric fans which will well and truly over cool the incoming water and I can use a PWM controller to get the heat output perfect.
That said, although took a few hours, I could heat my large house to the point of well being too hot. I would fire the burner up about 3 PM and it would keep the house nice till I shut it down about 9 am the next morning. The thing I was not happy with was the heat up wime mainly. I wanted to be able to blow 10 KW into the house and have it hot in 30 Min or less and I think with the right radiator and fan Combo, that's easily Possible.
I made a lot of modifications to the burner tube which were adding a lot more air holes and tabs along the length to swirl the gasses and flame front and also keep the burner insert hot so it burned off all the carbon from the oil. The burner tube would stay nice and clean as well showing complete combustion and of course the thing had ZERO smoke.
The biggest mistake with the whole thing and I still can't fathom how I did it as I still believe my numbers should have been right, is to Miscalculate the heat required. I designed for a max of 10 KW output and that wasn't enough really. The heat up was too slow for what I wanted and I'd have to run the thing flat out on the coldest days for a few hours which indicated my calcs were off. Once up to heat, the thing could be turned down but getting it there was too slow for my liking. I compensated that by starting earlier as here it usually warm enough when the sun is out not to need heating till the afternoon.
Despite being designed for 10 KW, run flat out the burner would do just under 30 Kw by my calculations. The problem there was the efficiency I so carefully calculated with the diameter of the tube with gas flow speeds and surface area went right out the bloody window. As much heat was being blown straight out as was being put to work and free fuel or not, that drove me nuts!
Sure, It will do 30 KW OK but I'm using about 60 Kw worth of oil consumption. Yeah, it's free oil and I have an unlimited supply thanks to a friend but that really Irked my sense of Efficiency OCD. Any idiot can make a big fire, putting the energy to useful work is whole other skill.
At 10 Kwh the thing is great and the efficiency is good but that just wasn't enough for my house in the coldest times which get just below zero.
For what I designed it to do, and I still think that numbers are right and can't work out where I am going wrong, it's not the transfer though the IC, it's good but like anything pushed beyond design limits, it falls over on efficiency about about 15 Kw output.
Now I know, the one thing most people reading are looking for is " How much oil it use an hour?" which is to me sorry, an annoying question because it is totally Irrelevant.
I could dial this thing down to about 300Ml an hour. Way below what I thought it would sustain but it did. That's roughly 3 KW. Flat out it can go through about 6 litres an hour but that's like " emergency power" and is very inefficiency for the heat delivered where you want it.
Fuel consumption is irrelevant because I can easy dial it down to 1L an hour but if that's not enough heat output and my house is still cold, which defeats the purpose of the whole exercise! May as well put a little 1KW bar radiator in the middle of the place and say " Look, only uses 1KW" ignoring the fact it's basically useless because the heat loss in the place is greater than that.
Work out how much output YOU need for YOUR situation and design for that.... Only do it a lot better than I did. The amount of oil it needs is what it needs. If you don't have terrible inefficiency, who cares what the consumption is? the goal is to keep warm and comfortable not save free waste oil!
Now all that said, I was going through about 20 to 25L of oil a day depending mostly on the weather. I did burn Both kinds of oil, Veg and Diesel engine oil. I HATE engine oil. filthy stinking staining black Shit.... but that said I have an endless supply. I still found the Veg to be better. Burned cleaner with less deposits and took a bit of tuning to get the burner to run clean on engine oil when it was perfect on veg.
Veg smells a lot better although that said, once the engine oil is dialed in right it's OK but if it's at all off, it stinks even if there is no viable smoke. We are coming into summer here so I hope to be able to collect and put away at least 2000L of veg and I'd much prefer to get 4000L really. I think our power system is going to be in trouble and I want to be able to fuel the diesel Generators I have Built of veg over WMO as I'm far more familiar with veg and how it burns in engines.
For a lot of houses especially those better insulated than my Glass house, this would be more than enough at 10 KW output. Turning it down is efficient, turning it above the design parameter is not. Running right I was getting an output air temp of about 50-60o C constant running which was OK. With a better heat exchange instead of the intercooler, I'd probably get it more where I'd like it at 80 or so. I could get that when the tank was at heat and the fan turned down.
Anything below 30 feels cold and that's the Min temp output in Air conditioning.
The thing does have a Noticeable rumble that the neighbors Heard when they come out to their back yard but they thought is was the sewer Pump out running or a tap going. I asked if it was annoying and they said they couldn't hear it at all in the House and were only concerned that something was wrong. I can hear it in the house very clearly but I find it very soothing. It did flame out once because the hose came out the fuel drum and I could hear the change in tone and knew something was wrong. i went out and found the simple problem and the thing stuttered for a bit then kept on going as normal.
At night iT seems to put us all to sleep so certainly no problem with the noise of the burner. More an asset than anything. The fan we simply can't hear being outside and very quiet anyway. Cats soon found a chair near the window that caught some of the warm air coming out and would sleep there all the time.
I will add a Thermostat to the setup because when the thing is switched off, there is still over 10KWh of heat in the water drum which I ended up Insulating which was an improvement. This way when I shut down the burner, the pump and fan will keep running till the water gets cold and then shut off.
That said, Shutting off hot wasn't a bad thing. Meant there was heat there ready to go when I fired it back up.
I ended up doing a MK II version that kicked out way more heat ( up to 100Kw!!) and runs beautifully efficient so if there is any interest in that and people are still awake after reading all this, I can do a write up on that setup.
