3 tips to significantly increase range in winter and message for Tesla

[Snowstorm]

Numbers: a 1200 lbs battery needs 19 kWh to go from -15C to 15C (1200lbs*54(temp delta)/3412(BTUs per kWh) and 25 kWh to go from -25C to 15C

Great post and informative. The only thing I would question is the energy required to warm the battery. I have a 6kw charger at home and can say that after 30 minutes, I can get the cabin to 18c and battery to at least 8c with some regen from both cold soaked at 0c. Where do you get the heat capacity of the battery from?

Also, it isn’t necessary to heat the battery to 15c, we get around 30kw of regen at 8c and further hearing can be done with just internal resistance on driving.

I would preheat cabin and battery, but only about 30 min for 3-4kwh worth.

 

[Allanf]

Actually when you charge overnight you can lower the number of amps used, unfortunately this settings can only be done within the car, if you lower it to 8 amps for example your charge will take much longer but the battery will be on the desired temperature.

If Elon is listening enable the charge option within the app, for example a fast option use max power of the charger or low option if you have the time during the night. Other option give me the option to open en close the windows via the app.

Regarding the App, a little work on it would go a long ways. We are told Range Mode must be turned off to preheat the battery when you are preheating the cabin. There should be at least a separate option to preheat the battery that, if selected, automatically turns off Range Mode. When you start your trip a pop-up message could inform you that Range Mode is off. As suggested in this thread a further refinement would ask for estimated departure time and have the battery temp optimal and cabin at desired temp at departure time. There is terrific information in this thread but engineering at Tesla has a lot more information than we would have on things like optimum battery temp at departure and the other variables affecting range.

It looks like there are two concerns expresses in this thread - one being saving on energy usage as a cost and environmental concern and the other is increasing range. Mine is getting maximum range to avoid stopping at superchargers when i have colleagues from work in the car who want to get home. lol.

 

[CHGolferJim]

Another: Turn car heater on 80*F continuously when supercharging, then turn it off and use seat warmers as long as you can stand it.

 

[Joel 3]

If you have the ability to put your car in a warmed garage, do it for the battery. Will help on daily range a ton.

 

[sule]

I'm a long time Model S owner but...

Great analysis. Drag is proportional to the square of velocity.

Drag (force) is. But power to fight it is not - it is proportional to the cube of the velocity. However, because at that power you're traveling faster, when you divide that by velocity to figure out how much energy you need per distance you get back to the square.

After essentially five winters (March 2014 delivery but in COLD Canada) and 115,000 km and a lot of science... yes, the OP suggestions are correct but not all need to be taken entirely, such as hours of preheating. I am not saying OP is wrong. Not at all, but you reach the point of diminishing returns and really need to do this only in extreme cases. Specifically on the point of (pre)heating, it is not just about lowering the internal battery resistance but also about storing heat inside the body of the car so that less heating of the cabin is needed during the drive. If you just prewarm the air of the cabin but panels remain cold, for example, some of that air heat will dissipate more quickly than if the panels were warm too.

So, if you want to maximize the range:

• As the OP says, do preheat the cabin and the car so that less heating is needed during the drive. Energy efficiency aside, you may want to warm the cabin to a higher temperature than you normally would like, such as the maximum comfortable one, as that will heat the rest of the car quicker too. This will cool quickly during the drive. Do note that the remote heating may stop when it reaches the desired temperature.
  
• Preheat the battery. This used to be done best by charging at maximum rate possible just before the drive and/or doing what Bjorn did. If you charge just before you leave make sure it isn't for a few seconds - it needs to last enough to warm the battery - so leave enough room in the battery to do so. You may do what Bjorn did then come back to recharge as well. Now, I haven't followed the forums in a LONG while, but recently the Tesla mobile app was updated to include something re battery heating and there was a note on heating the battery specifically while on shore power.
  
  
• Note on the two above - cabin heating at max power can take 30A by itself (with no charging going on). 80A HPWC really helps here.
  
  
• Drive slower. Aside from elevation (gravitational potential energy) differences, energy needed for the trip is there ONLY to fight various forms of resistance and drag. Energy needed just to fight air drag is proportional to the square of the velocity. Half the speed means quarter the energy needed (or twice the speed = four times the energy). Rolling resistance is also non-linear and worse at higher speeds. Additionally, even though the difference will be small at significant speed, slower driving will preserve more of a surface layer/effect so your car will be less cooled by the outer air than at higher speeds.
  
  
• Do not drive too slowly. At some point the benefits of less drag will be overcome by the need to keep you and the battery warm longer. I cannot give you the exact best speed as it depends on many factors.
  
  
• Reduce the cabin temperature - but not immediately, as you don't want the car to bring cold air to intentionally cool the cabin. This will reduce the temperature difference between the inside and outside air and, thus, reduce the heat loss.
  
  
• Keep your climate system on full auto. Do not set custom fan speeds or otherwise. It seems to be optimized for this case. Whenever I tried to mess with it I got worse efficiency. I do NOT have a good/better explanation.
  
  
• If you can use seat heaters instead of the cabin heat, use that. This does not work well for me, comfort wise so I don't do this ... and I haven't had success using both (with lower cabin heat - I really need my cabin heat). If you don't need cabin heat at all (snow pants?), turn it off
  
  
• Drive gently. Accelerating fast will cause more slipping which wastes energy. Decelerate slower as well - avoid using breaks (complete waste of energy) and know that regen is not 100% efficient, you lose some energy. Try to remain at one speed for as long as possible. Letting the velocity reduce as you climb uphill or go up a bit as you go down may help as well - less slipping both ways.
  
  
• Drive with traffic, especially on roads not cleared from snow/ice. Do not try to cut your own tracks in snow - use those made before you came. Additionally, air drag will be reduced for a closely spaced group of vehicles traveling at the same speed. While the closer you are the more energy efficient you will be I do NOT advise this as you risk accidents and damage from debris.
  
  
• Use winter tires. Less slipping even though the rolling resistance may be worse. They are also incomparably safer and they do not cost extra (you're saving the other set while using winters, you're saving energy and you're reducing risks of trouble)
  
  
• If you have a glass roof (I have the original pano roof) you may consider insulating/padding it from the inside. Bjorn did this. I did not find it necessary.
  
  
• Attachments, such as roof racks (and whatever goes on them) or those rear racks on X increase air drag. If you don't need them, take them off.
  
  
• Model X / wing doors special: don't use your wing doors. They let the hot cabin air out very quickly and they are slow so they do it well. Get into the car quickly to preserve as much heat as possible.
  
  
• Fun one - have live passengers instead of the luggage . Passengers replace air that needs to be heated with their bodies that act as heaters.

 

[sule]

Oh ... and range mode is useless from my experience. Accomplishes nothing but a colder cabin, which I can better achieve otherwise.

 

[incrediwoah]

I figured I would share some of my tips for increasing range in winter (for longer trips). We have an MX 60D, best car ever, do a ton of driving, and live in a very cold place (Montreal). We rarely have range concerns and more importantly, the more we drive our car in the winter, the better we understand how to affect range. So here goes. Don't be shy to correct any of my math/assumptions. Because folks on this forum tend to be

First of, here is my understanding of why range can be an issue in the winter time:

1. Cold air is denser, so drag is greater, 15C vs -15C translates to roughly 12% more drag. This is then multiplied by the cube of speed!
2. Heating the cabin is expensive (2-6 kWh)
3. Rolling resistance is usually higher in the winter time due to snow/ice/rain on roads and ice buildup on cars makes them less aerodynamic
4. Finally cold batteries have higher internal resistance and this is elephant in the room! When I start my drive on a cold day (-15C to -20C). My battery will likely be the same as outdoor temperature (slightly higher). At some point this winter we stayed a full week at our cottage at -25C to -35C!. After about 1-2 hours of driving, the battery usually warms up (can be seen by the regen limitation disappearing) and within two hours you have full regen (battery is now >15C). If you have observed this in your car, you probably also noticed that your consumption was at least 2X rated. The heating of the battery comes from the onboard heater (if you have range mode off) but also comes from the battery's internal resistance. Numbers: a 1200 lbs battery needs 19 kWh to go from -15C to 15C (1200lbs*54(temp delta)/3412(BTUs per kWh) and 25 kWh to go from -25C to 15C. So in my MX 60, about half of the capacity can be lost to waste heat. This is far more significant than the 3 other factors listed above.


3 tips for getting near rated range in the winter time (sorted by most impactful):
1. Preheat. A lot. I will preheat (with range mode off) for up to 4-5 hours If I know that I need the range. Ex for a 250 KM drive (My rated is 310KM). If you have a 6 KW charger, you will need 4 hours to to generate 24 kWh or enough to bring your battery to ideal temp. I like to keep my climate setting at 18C when preheating so that the bulk of the power comes from shore and not from my battery. Preheating like this has a night and day effect on range. If you can park indoors, even better. Preheating gives you a thermal storage equivalent of 25+kWh. Try it.
2. Try to not exceed 20-30 KW of power. Specially with a cold battery. So don't accelerate hard, don't regen hard (coast vs regen). This will again limit the power losses in the battery. Bjorn has a great video on Youtube showing how to very quickly heat up your battery by accelerating and decelerating like crazy. Yes, do the EXACT opposite of what he is doing What is incredible in his video is seeing how quickly you can heat up a battery by having a heavy foot. That's 10s of kWh lost in minutes ... So go easy. This has also made me a much better/zen driver. My Bernese Mountain dog in the back really likes my driving
3. Drive slower. Because of drag being much greater in winter and because of v cubed. CUBED!!!!

If you are still reading, here are some more tips:
1. Use seat heaters. It's by far the most efficient way to heat humans in a Tesla
2. The "% Battery left" in the navigation system needs about 10 minutes of driving to show an accurate estimate, but it works very very well and I use it as my "budget" for fun things like speed and heat
3. Pick your charging stops in a way that your battery is warm upon arrival. This will speed up charging. Ex, I charge at a stop just before arriving to my ski location (fast warm charging) VS charging apres ski (cold battery slow charging).

Elon/Tesla if you are reading, here is my wish list for some software:

1. Conditioning feature: I want to be able to set my departure time at, say 7 AM, hit "yes" on the popup warning me that this will result in more electricity cost, and have the car (using only available shore power) preheat the battery, then the cabin, then top off the battery so that by 7 AM, I have the optimal conditions and the best best range ever. Heck, I would like the battery heated to 35C-40C, so that this extra heat can be used as cabin heat for the next 1-2 hours. Can you imagine getting better than rated range in -20C!!! Come on Elon.
2. Make chill mode more chill and make chill mode chill Autopilot. I avoid using excessive acceleration and deceleration to improve range. It would be great if Autopilot didn't take my speed setting as a do or die challenge. Allowing +-3 KM from set point would improve range drastically by eliminating needless (60%-efficient-at-best-regen AKA regen) and high KW bursts on small hill climbs. We love Autopilot. I think it's incredible that Tesla was able to develop it so quickly and it's amazing how much safer and easier it makes our drives but my wife and I now do this voiceover/if Autopilot could talk thing and it goes something like this: *deep 8 year old eager boy voice* "You want me to follow that car.... Yah Yah, i can do that i can i can. Go go go... Oh no, oh no, regen regen regen. No wait, wait, i got this, i got this, go go go...." And we're like, Chill dude... Driving under an overhead sign (circa Q1 2017, he doesn't do it anymore): *the same 8 year old with the deep voice* "My mom always said life was like a box of ch... AHHHHH THING!!! THING THING, break break br... oh oh oh wait, where did it go?" And we're like, no Boo (car's name) it was just an overhead sign. It's okay, we still love you.

Hope that was helpful...

Elon is you are still reading:

1. This one is more complicated but can be very impactful for range. I have arrived to destination with 0%-1% left on my battery on MANY occasions with no worries about running out. I use my speed and zen driving as my variables to manage my "budget". It would be great if my Tesla can automatically reduce max power to help automate what I do manually. Guaranteeing arrival time and using the full capacity of the battery. Right now, power limitations only kick in when the battery is very low (too late). Having such a feature would allow users to use up the 10%-20% of the battery that they usually put aside as buffer. To cancel this feature, the user can simply kick down on the accelerator and the limitations would be reset...
2. Unlock Boo and all other 60Ds or just Boo
3. Platoon feature: All the hardware and most of the software is already in place to do this.
4. Also Good job, you are killing it.

Excellent post! I have a 70 and do 350mi trips every weekend. With the cold weather and increase in elevation to the mountains range becomes a huge factor!

 

[Graffi]

Fortunately living in San Diego this is not needed, but I was thinking that in very cold areas someone could just build a 2 X 2 frame and cover with a very thick plastic sheeting to build a tent that could be lowered to cover your Tesla in your garage. This way you only need to heat the volume inside the tent, not your whole garage. Almost like a double insulation. This may even work for those without a garage if you have room to build it. Just a thought ....

If you have the ability to put your car in a warmed garage, do it for the battery. Will help on daily range a ton.

 

[DataMN]

Jesus, 4-5 hours of preconditioning? That's surely a waste. I find 30 minutes is more than enough to get the battery (and cabin) up to temperature, and that's having just done it in a Wisconsin winter (we recently had a cold snap where it was about -20°C for a few weeks).

He's using 6 K W charger which takes much longer. Much less time with higher powered charging. Can't give exact numbers. Just know it does.
Definitely need option in phone app to turn Range Mode on and off. Automatically even. Also need timer option to turn cabin heater on (and off) at preset time.
Elon / Tesla?

 

[thefortunes]

He's using 6 K W charger which takes much longer. Much less time with higher powered charging. Can't give exact numbers. Just know it does.
Definitely need option in phone app to turn Range Mode on and off. Automatically even. Also need timer option to turn cabin heater on (and off) at preset time.
Elon / Tesla?

Actually the 6kW is referring to the max usage by the battery heater, not what charger he is using.

I agree it would be nice to turn range mode on/off in the app, although I personally do not see a need to turn it off unless I am in the car and want to improve HVAC performance. I'm not even sure when I last had it off, to be honest, and we've had temps down to -20F recently.

There already are options for cabin preheat timing - the built-in "smart" pre-conditioning (lol), a choice of 3rd party apps (I use TeslaFI) or your Echo or Home programming.

 

[DataMN]

Hmmm, guess his "If you have a 6 KW charger, you will need 4 hours to to generate 24 kWh..." has some other meaning. "Smart" preconditioning doesn't do any good when your are retired, have no routine and take long cold trips 'every-now-and-then'. And much prefer smart functionality over yet another app.
Thanks for the input.

 

[hacer]

I'm a long time Model S owner but...


Drag (force) is. But power to fight it is not - it is proportional to the cube of the velocity. However, because at that power you're traveling faster, when you divide that by velocity to figure out how much energy you need per distance you get back to the square.
...
Drive slower. Aside from elevation (gravitational potential energy) differences, energy needed for the trip is there ONLY to fight various forms of resistance and drag. Energy needed just to fight air drag is proportional to the square of the velocity. Half the speed means quarter the energy needed (or twice the speed = four times the energy). Rolling resistance is also non-linear and worse at higher speeds. Additionally, even though the difference will be small at significant speed, slower driving will preserve more of a surface layer/effect so your car will be less cooled by the outer air than at higher speeds.

Considering the effects of air-drag (the most significant loss absent elevation change at highway speeds): The second point quoted above neglects the inefficiency of converting energy stored in the battery into power to drive the wheels. As you acknowledge in the first point, power is proportional to velocity cubed. Energy lost in electrical resistance is proportional to power squared at constant voltage which is true for the battery and approximately true for the DC/AC converter system. So power lost in the battery/converter system is approximately proportional to velocity to the sixth power. Dividing by the time to get to the destination brings it down to the 5th power for energy consumption. In the motor and connections to it, the electrical power loss is proportional to velocity to the 4th power, so energy loss in that part is proportional to velocity cubed. These resistive system losses are non-trivial and even more sensitive to speed, so slowing down is a really good idea to save energy.

I was surprised that the OP didn't mention drafting behind another vehicle because this can dramatically reduce energy consumption at higher speeds, even with 4 or more car-lengths behind a large vehicle.

 

[thefortunes]

Hmmm, guess his "If you have a 6 KW charger, you will need 4 hours to to generate 24 kWh..." has some other meaning. "Smart" preconditioning doesn't do any good when your are retired, have no routine and take long cold trips 'every-now-and-then'. And much prefer smart functionality over yet another app.
Thanks for the input.

Lol. If you "take long cold trips every-now-and-then" but don't have a routine that smart conditioning or an app can follow, what do you want? Do you want the car to just guess when you will do this?

The native Tesla app (or Echo, or Home) already allows you to preheat/precool upon tap/command. 3rd party apps (for those people reading this who want to know options) can even do this on a schedule.

 

[sule]

Considering the effects of air-drag (the most significant loss absent elevation change at highway speeds): The second point quoted above neglects the inefficiency of converting energy stored in the battery into power to drive the wheels. As you acknowledge in the first point, power is proportional to velocity cubed. Energy lost in electrical resistance is proportional to power squared at constant voltage which is true for the battery and approximately true for the DC/AC converter system. So power lost in the battery/converter system is approximately proportional to velocity to the sixth power. Dividing by the time to get to the destination brings it down to the 5th power for energy consumption. In the motor and connections to it, the electrical power loss is proportional to velocity to the 4th power, so energy loss in that part is proportional to velocity cubed..

All true. But these are internal losses, not about the main power to move the car. If we get to this level of detail we'll never stop. These losses are not only nonlinear but also have a non-zero most efficient speed and other factors - if you go slower they can increase, in fact. So, if you want truly ideal/maximum range you have to account for many factors that should be something we don't think about.

 

[claudelaval]

Jesus, 4-5 hours of preconditioning? That's surely a waste. I find 30 minutes is more than enough to get the battery (and cabin) up to temperature, and that's having just done it in a Wisconsin winter (we recently had a cold snap where it was about -20°C for a few weeks).

Right on. Electricity is not that cheap in some parts of the USA and ''spilled'' 4-5 hours just to warm-up the batteries is a waste and make buying an EV not more affordable than an ICE

 

[claudelaval]

Another: Turn car heater on 80*F continuously when supercharging, then turn it off and use seat warmers as long as you can stand it.[/QUOTE
not my cup of tea...it would be way too hot for me inside

 

[claudelaval]

I'm a long time Model S owner but...


Drag (force) is. But power to fight it is not - it is proportional to the cube of the velocity. However, because at that power you're traveling faster, when you divide that by velocity to figure out how much energy you need per distance you get back to the square.

After essentially five winters (March 2014 delivery but in COLD Canada) and 115,000 km and a lot of science... yes, the OP suggestions are correct but not all need to be taken entirely, such as hours of preheating. I am not saying OP is wrong. Not at all, but you reach the point of diminishing returns and really need to do this only in extreme cases. Specifically on the point of (pre)heating, it is not just about lowering the internal battery resistance but also about storing heat inside the body of the car so that less heating of the cabin is needed during the drive. If you just prewarm the air of the cabin but panels remain cold, for example, some of that air heat will dissipate more quickly than if the panels were warm too.

So, if you want to maximize the range:

• As the OP says, do preheat the cabin and the car so that less heating is needed during the drive. Energy efficiency aside, you may want to warm the cabin to a higher temperature than you normally would like, such as the maximum comfortable one, as that will heat the rest of the car quicker too. This will cool quickly during the drive. Do note that the remote heating may stop when it reaches the desired temperature.
  
• Preheat the battery. This used to be done best by charging at maximum rate possible just before the drive and/or doing what Bjorn did. If you charge just before you leave make sure it isn't for a few seconds - it needs to last enough to warm the battery - so leave enough room in the battery to do so. You may do what Bjorn did then come back to recharge as well. Now, I haven't followed the forums in a LONG while, but recently the Tesla mobile app was updated to include something re battery heating and there was a note on heating the battery specifically while on shore power.
  
  
• Note on the two above - cabin heating at max power can take 30A by itself (with no charging going on). 80A HPWC really helps here.
  
  
• Drive slower. Aside from elevation (gravitational potential energy) differences, energy needed for the trip is there ONLY to fight various forms of resistance and drag. Energy needed just to fight air drag is proportional to the square of the velocity. Half the speed means quarter the energy needed (or twice the speed = four times the energy). Rolling resistance is also non-linear and worse at higher speeds. Additionally, even though the difference will be small at significant speed, slower driving will preserve more of a surface layer/effect so your car will be less cooled by the outer air than at higher speeds.
  
  
• Do not drive too slowly. At some point the benefits of less drag will be overcome by the need to keep you and the battery warm longer. I cannot give you the exact best speed as it depends on many factors.
  
  
• Reduce the cabin temperature - but not immediately, as you don't want the car to bring cold air to intentionally cool the cabin. This will reduce the temperature difference between the inside and outside air and, thus, reduce the heat loss.
  
  
• Keep your climate system on full auto. Do not set custom fan speeds or otherwise. It seems to be optimized for this case. Whenever I tried to mess with it I got worse efficiency. I do NOT have a good/better explanation.
  
  
• If you can use seat heaters instead of the cabin heat, use that. This does not work well for me, comfort wise so I don't do this ... and I haven't had success using both (with lower cabin heat - I really need my cabin heat). If you don't need cabin heat at all (snow pants?), turn it off
  
  
• Drive gently. Accelerating fast will cause more slipping which wastes energy. Decelerate slower as well - avoid using breaks (complete waste of energy) and know that regen is not 100% efficient, you lose some energy. Try to remain at one speed for as long as possible. Letting the velocity reduce as you climb uphill or go up a bit as you go down may help as well - less slipping both ways.
  
  
• Drive with traffic, especially on roads not cleared from snow/ice. Do not try to cut your own tracks in snow - use those made before you came. Additionally, air drag will be reduced for a closely spaced group of vehicles traveling at the same speed. While the closer you are the more energy efficient you will be I do NOT advise this as you risk accidents and damage from debris.
  
  
• Use winter tires. Less slipping even though the rolling resistance may be worse. They are also incomparably safer and they do not cost extra (you're saving the other set while using winters, you're saving energy and you're reducing risks of trouble)
  
  
• If you have a glass roof (I have the original pano roof) you may consider insulating/padding it from the inside. Bjorn did this. I did not find it necessary.
  
  
• Attachments, such as roof racks (and whatever goes on them) or those rear racks on X increase air drag. If you don't need them, take them off.
  
  
• Model X / wing doors special: don't use your wing doors. They let the hot cabin air out very quickly and they are slow so they do it well. Get into the car quickly to preserve as much heat as possible.
  
  
• Fun one - have live passengers instead of the luggage . Passengers replace air that needs to be heated with their bodies that act as heaters.

I don't see anything on the Tesla App concerning heating the batteries only...

 

[sule]

All true.

Actually, that was wine talking. It isn't all true. You say "Energy lost in electrical resistance is proportional to power squared at constant voltage". There are multiple ways and places you can approach this. In a DC world the voltage would NOT remain constant. It would change and would be proportional to the current (Uloss=Rloss*I) needed to yield actual useful power (Puse=Uuse*I) where Uuse, if simplified to a resistance would be Uuse=Ruse*I. Total power would be Ptot=(Uloss+Uuse)*I=(Rloss+Ruse)*I*I=Rtot*I².

Thus, Ploss (which is Uloss*I = Rloss*I²) is lost, which is (Rloss/Rtot)*Ptot. In other words, Ploss is a linear fraction of the total power - and also a linear fraction of the useful power.

Now, in an AC world things get a lot more complicated to describe here. Also, (electrical) resistive losses aren't the only losses. So no point in debating that.

Finally, energy lost in electrical resistance is not proportional to power ever or any exponent of that because the unit is very different. You need to multiply the power with time to get the energy.

 

[SageBrush]

Numbers: a 1200 lbs battery needs 19 kWh to go from -15C to 15C (1200lbs*54(temp delta)/3412(BTUs per kWh) and 25 kWh to go from -25C to 15C.

This says that the heat capacity of a Li-x battery is 0.83 J / g*Kelvin

For a 500 Kg battery it works out to 3.45 kWh to increase temperature 30 C
--

Power increases with the cube of velocity, but you are interested in the energy/mile change. The Aero resistance (force) increases quadratically (to the second degree) with speed. At the same speed, the change in energy/mile is simply the fractional change in air density. So a 10% increase in air density will lead (all else being equal) to a 10% increase in energy/mile

 

[sule]

I don't see anything on the Tesla App concerning heating the batteries only...

Well, look at the screenshot below. Now there is that battery icon in there that wasn't there for years - it is relatively new (I've seen if at least a few weeks now, maybe longer).

*EDIT*: Note - the icon appears a little while after the heating is turned on, not immediately. Almost enough to give up waiting and miss it - i.e. red arrows showing hot air appear first without the battery icon. [end edit]

There was an announcement I heard or read somewhere (forgot)... but I was able to uncover the following:

Tesla is working on a battery pre-heating feature to maximize efficiency in cold climates

Screenshot_20180129-074203

• sule
• Jan 29, 2018

Tesla app showing heating