Waste Oil Heater Forum - Your definitive source for burning waste oil for heat.

I have wondered about the purpose of that pipe myself.
I cannot figure out what it is suppose to do.

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.

Must have been quite a bit of vapor in there to get that much energy out of the light off.

Vaporised Oil  which can be smoke, is not much different to gas or petrol fumes in that state.
Good job you were standing where you were when it Blew.

It pays to make sure any enclosed space is ventilated or cooled down before trying a relight.
Look on the bright side, You'll never be unawares of the problem again!  :0)

One other thing to add to the already long and boring rant is something I'd probably do thats a little out the box but could be a LOT better way to go.

Co-gen.

Don't burn the fuel in a burner just for heat, Burn it in an engine driving a Generator.
You pull the waste heat out the cooling and exhaust system and get the power as a bonus. You can feed that back to offset your power usage or divert it to resistance heating where you could say heat water to circulate back around at night to eliminate running the engine unattended.

This is a very efficient way of going about things and has the potential to be cheaper than a commercial burner if you can source an engine or 2 at the right price.  All you really want is something that will meet your heating needs which can easily be worked out and is mechanically instead of electronically injected.  Most diesels pre 2000 are like this and a lot of newer ones still are as well although less now due to emissions. May also be possible to fit an old pump on a new core.

The only drawback to this idea is your fuel needs to be filtered  better.   Burners don't need much more than straining though a couple of layers of cloth to get the chunky bits out, engines need much cleaner fuel.  That's not at all a problem is you set up right.  I can process 200L of oil in as little as 30 Min for veg, a LOT quicker for engine oil. Instead of a 200L drum I use for processing which meets my needs, would be no problem to upsize to a 1000L IBC and scaled up wouldn't take much longer to process that with bigger pumps and more filtering.

My costs to filter about 2500L of oil are around $10. $8 for a filter I change pre emptively anyway and I over allow a couple of bucks for power. That's cheap fuel and well worth my time.  Just built a processor for my mate whom has a tree felling business to run all his machinery in the yard on.  He's very happy with how it's going and the savings he's making.  His mechanic spends about 10 min in the morning loading the processor and switches it off at whatever point later on.  If he has time he will spend another 10 min pumping the finished oil out and reloading the processor and  setting it going again. It does not need a minutes hands on time in between.
If he has the time He may reload several times and if hes busy he doesn't touch it.  They have a reserve now so works real nice.

You could make a LOT of power with the amount of heat I envision you will need so it may be possible to sell any excess back to your utility and make a second income stream there.  Other way is use the power for heating and you could downsize the setup accordingly.
Crunch the numbers, find out the info and see which works best for you.

The only other thing I would strongly suggest with doing this is run a very basic water injection system.  I was banging on about this 20 years ago and basically being called an idiot.  Now I look on the veg fuel forums and everyone recommends it as a basic part of of veg fuelling.
Water injection keeps any residues and build-ups at bay and keeps the engine clean. The biggest danger with waste oil is incomplete combustion that causes the rings over time to coke up and stick which results in the engine loosing compression and needing  to be torn down.

Water injection prevents this 110% guaranteed. Many ignorants scoff at the idea of putting water down the intake of an engine but it was done on loads of high performance piston aircraft, ships and many other applications. BWM even put it on their cars for a while about 10 years ago.  It has a lot of benefits but the one thing often touted that it will not do is better fuel consumption.  It will keep engines clean, stop detonation, stop pistons melting in high load situations, add power ( that and the meltdown prevention was the main thing it was used for in aircraft )  and is a great all rounder preventative of problems.

You do NOT need some expensive 500PSI commercial system that sprays a micro mist fog as touted by the guys making systems for go fast vehicles, just a constant metered drip into the intake is all that is needed for cleaning purposes.  In my vehicle I do all sorts of things that should have killed the engine years ago from high boost and fuelling to running straight oil all year round and NEVER had a problem.  If that was just luck I would have won the lottery 10 times by now but seeing I haven't, must be the WI working. I also add alcohol to the water to give the thing a big power boost but you would of course not need that although it is effective for Cleaning out used engines that haven't had the WI treatment before a lot faster.

If done right, you don't NEED WI with waste oil fueling but  given you can set it up for literally $20-30 and the safety net and benefits it provides with virtually zero running cost, I think a person would be mad not to put it on an oil burning engine. More people use it just for diesel fueled anyway. All the high performance truck and tractor pullers out there use them and Banks performance parts have a heap of systems and I think Holley does too. 

Anyway, something else You might like to look into that's a bit left of centre but entirely doable. There are commercial co gen systems out there so you could compare the features and benefits and costs of these to a commercial heater system or  DIY it would would be not much more than moving the radiator  of the engine to inside the green house and tieing in the electrical side wherever you wanted to use that.

I guess what I am asking is there anything I should try before I rip this POS out and go back to burning wood?

Oil has a learning curve.  It requires heat to work.  Most people get the burners started then freak out the flames are too big and shut it down when they sould keep it going, let it heat up and settle and go from there.

Getting oil to burn is not the trick, controlling it is.  If you are not getting enough heat, it comes down to two things and 2 things only:
 1. You have too much air for the amount of oil you are burning.
2. You don't have enough oil flow.

The 3rd is a combination of both.

If you have control of the air and the oil flow then you can do anything basically. You can have a small gentle fire or you can have a clean burning raging inferno.  It's just a matter of balancing the two.  You have to learn how to read the fire.  Having too much oil will also make a fire burn cold. You want the oil to change from a liquid to a gas. It's gas that burns not wet stuff. For that to happen you want the burn chamber to be at very least 350oC for engine oil.

Hard to say without seeing any pics of your setup but Rather than force the air down onto the opil pool which largely cools it, I like to have the air spin around the  bowl it's burning in unless one has a very tall vessel that the fire will heat as it escapes and transfers the heat back to the oil pool. Having a tall vessel also allowed the pipe with the incoming air to be preheated which helps a lot. I also feed the oil into the air pipe so it also has a chance to preheat to a gas at least boiling off the more volatile components in it which means it is burning as soon as it exits the pipe and imparts more heat to the burn vessel.  Spinning the fire also sends it outwards to the heater in this case to warm it up

One thing i see a LOT of people do which puzzles me is they duct the flue out of the building as soon as possible.  In a shed the best thing to do is run that flue from one end to the other inside the space you want to heat. There is a lot of energy and a lot of surface area to transfer the heat to the air in there and it increases efficiency dramatically. Throwing all the heat straight out to atmosphere is stupid really. The longer you can keep it in the building to radiate the warmth you are doing the whole exercise for, the better.

If you are not getting enough heat, simply turn up the burn. You may have to increase your air and oil rate but that should be no big deal.
If you can see in your burn chamber and there is very little oil or the fire goes out or drops within 10 seconds of shutting the oil off, you are probably running lean or too much air.  If you shut the oil off and the thing continues to burn pretty much the same for the best part of a minute or more, you are too rich.  Smoke can indicate this but I can also have a litre of oil sitting in a burner and the fire will burn perfectly clean because all the vapors are being mixed with enough air at the top.

Don't ever doubt oil doesen't have enough power. I'm building a waste oil powered spa heater to heat the home with and my biggest trouble is keeping the output down to 20KW ore less.  If I wanted to do 200KW which is what most Olympic size pool heaters are here, I could do that with great ease and ramp it up to 500KW VERY easily.  5-10 Kw is going to keep most homes hot let alone cosy once the place is up to speed so it just comes down to burning enough oil to provide the heat you need.

Seems like you got it running nicely.
I have always preferred forced air ( blown) type setups over draft for the reasons of cleaning and flexibility in the power you can get out of them. Draft is always limited in that you have to have a certain size fore to create enough draft and heat or that you max it out. Not saying it doesn't work, clearly it does but forced air works so much better.

You are averaging roughly about 20 Kwh out of the heater at the fueling rate you are giving it which is the same as a mid size wood stove will produce. The nice part is you can easily quadruple that at start up to get the chill off and then back it way down to sustain the Heat.
Being a heavy set up it will radiate the heat gently and not be too temperamental. I'll bet you are able to shut it down some time before you are finished in your shed and the stored heat keeps the place warm for a good while.

What size tank are you using and do you have to adjust your flow much as the fuel is used?  This is one reason I like a dosing type pump arrangement. The fueling is the same wether the tank is near full or empty. If you are working around it and giving it a tweak every so often insn't a problem, so much the better.

I am wanting to get started on the oil heater for my house but I'm a bit premature.
40O C here today and the 737, DC10 and other jet water bombers were flying over every 10 Min  for the fires burning not 20 KM away. Between the smoke that looked like thunder clouds only far more sinister and the Jets running low level steep turning passes overhead, place looked like the set of a doomsday Movie here today. Saturday is supposed to be worse with temps of 45oC plus.
 In American Terms that's ummm, Forking  damn hot!

With a bit of Luck the smoke won't be as bad tomorrow and I'll be able to see the back fence again.
Not really weather to be constructing oil burning heaters and firing one up would rightly have one shot by the Neighbours long before the police arrived to take me away.

Nice setup and I'm glad it worked out for you and hope the suggestions were of some help.

There is a big difference between waste vegetable oil and waste petroleum based oil.

No, sorry, when burnt properly and completely in burners there is no difference except WMO produces a bit more Ash than WVO but essentialy there is no difference at all.... IF burned properly and completely.

With petroleum based oils you will have ash. The ash will be very fine powder like drywall dust and should be white to tan in color.

The ash, If burned completely, is no different with mineral oil or with Veg oil. I can't actually thing of ash from anything not being grey-white  Wood, coal, Plastic....

If you do not burn something completely you can get residues but both Veg and mineral oil produce black carbonaceous material in the mid phase before it is burned completely and turned to ash.
This is a problem with draft type burners as they only get the oil hot enough to burn off the surface vapors and once the lighter fractions have been consumed there is insufficient heat to burn off the left over carbon. this is why those burners need cleaning where the forced air type with an oxygen rich atmosphere and much turbulence of the flame front resulting in the burn chamber running at hotter temps burn off all the residuals.

When commenting people need to clarify between the type oil and if they are using it for heat or fuel for your vehicle.

Given i'm the only one I can see mentioned a Vehicle, I take it that comment was directed at yours Truly.
Seemed clear enough to me I was talking about burners and only made a comparison to vehicles.
In any case, there is NO difference.

Have poor combustion in a burner, you'll soot it up. Run it clean, no deposits and maybe minimal ash if you have poor drafting in the flue or minimal turbulence in the burn chamber. From what I have seen of commercial gun type burners they run minimal excess air for efficiency ( not heating excess air) but this does not bode well for removing deposts.

If you have poor combustion in an engine on WVO or WMO or even Diesel, you will get buildup and deposits which will build up on the ring lands, stop the rings expanding and it's a fast demise from there.
With clean combustion there is no problem. The fuel is burnt in suspension as it should be completely and the ash is exhausted.  Over fueling, ( rolling coal/ Smoking) is incomplete combustion. On diesel which has virtually zero ash production, it's not so much of a problem unless the engine is driven for long periods over fueled. With WVO or WMO, it's a BIG problem.

There is a way around it though in a vehicle at least, Water injection.
Have been using this over 10 years and put many others onto it and there is no question of it's effectiveness.  It basically steam cleans the engine internals and dislodges any buildup and prevents any happening.  Any deposits are exhausted out the tail pipe and it is my belief that even the tail pipe itself is cleaned out due to performance increases remaining even after WI is no longer being used ( dry water tank) .

 It does not need to be sprayed into a Diesel in Micro fine droplets, even a rough stream up the inlet tract a ways will disperse itself Sufficiently and flash to steam in the combustion chambers. This is actually a form of cavitation and is useful in the cleaning process. I believe droplets for CLEANING purposes are more effective than vapor like mists.
In a vehicle Methanol not only adds significantly to the power output but the cleaning effect of WI.

There is no reason why WI would not work in some Burners depending on the setup.  Given the " Tuneability" of a burner and the fact it is usually running at one output, the better solution would be to correct the incomplete burning in the first place. Any deposits are a sign of inefficiency and wasted fuel.
Depending on the burner, an injection of water into the combustion chamber will have the same steam cleaning effect.  This is/was used in ships that burned bunker oil to fire steam boilers and it is used in piston engines to keep them clean.
In steam boilers the water is injected to keep deposits off the steam tubes and the internal passages clear. The oil they burn has a LOAD of ash content so is far more prone to leaving deposits as it is harder to get perfect combustion and good efficiency at the firing rates they use. 

While I have not tried WI in burners/ boilers, my thoughts are that any deposits removed will not be burnt ( NO, water does not separate into oxygen and hydrogen and burn unless it is introduced to the sort of heat found in a Nuclear Fuel fire) but merely dislodged or suspended and WILL end up somewhere.  Wether that is out of the burn chamber but somewhere in the flue or wether it is ejected from the flue completely would be the question and again depend greatly on the turbulence and speed of the exhaust gas stream from the burner/ boiler and it's stack temperature. Certainly if the temp in any part of the Flue, particularly the boundary layer was below about `120oC, I would expect to see deposits of material.
That in itself may not be a big concern as nearly all Chimneys need cleaning and if the interval is infrequent enough and the cleaning quick and easy enough, why worry?

The only thing coming out of a Burner should be the white/ grey ash no matter what fuel it is burning.
if there is any black/ soot, the thing is not running properly.

A " Hybrid" wood burner would work.
You could NOT just dump an amount of oil every so often. The oil would want to flash to vapor and there would not be enough air and the thing would smoke like a bitch and then probably over heat the boiler before dying down to nothing again.

The way to do it would be to Pump the fuel in a controlled and relatively constant manner. If the thing has a thermostat, then trigger  an amount of oil when heat is required and shut off when not.

You do not need ( or probably want) some superfine mist, anything that is better than a direct stream would be fine. A bit of flattened copper tube would be fine.  Spraying the oil on the coals/ wood will do the rest.

I would use either a Diaphragm pump like the little 4l/hr caravan type water pumps or the larger fuel pumps.  A gear pump would be good but I have not yet seen one capable of handling oil with any longevity. I make my own pumps using engine oil pumps and scooter motors and I literally pump 10's of thousands of liters with them over years without problem.

You could have 2 or more squirters on the pump to spread the oil around on the fire and just " tune" the output to the firing rate you wanted.

If you wanted to do away with the wood all together, just build a forced air type burner and it it in the fire box of the boiler.  I'm doing one for a spa heater and it will simply be a 2 Step. Idle when heat is not requires and ramp up to full power ( whatever I set that up at) and then back to idle.