Carb heat - can it cause ice?
Thread Starter
Join Date: Nov 2002
Location: Pennsylvania
Age: 48
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Carb heat - can it cause ice?
Hi all
I hope this isn't a stupid question, but I've always had the use of carb heat drummed into me throughout my training when power below a certain RPM, etc. However, I'm currently doing my FAA IR, and my very experienced instructor does not like to use carb heat. For example, he says that in the really cold weather, the induction of warmer air can actually warm the carb intake and surrounding air, causing moisture and possible ice! I'm not doubting him at all, but I'd appreciate other peoples' comments on this. Many thanks.
EiNY
I hope this isn't a stupid question, but I've always had the use of carb heat drummed into me throughout my training when power below a certain RPM, etc. However, I'm currently doing my FAA IR, and my very experienced instructor does not like to use carb heat. For example, he says that in the really cold weather, the induction of warmer air can actually warm the carb intake and surrounding air, causing moisture and possible ice! I'm not doubting him at all, but I'd appreciate other peoples' comments on this. Many thanks.
EiNY
EnglsihmaninNY..
Not an expert on this by any means, and as I'm in a public libary I don't have access to any literature, but it does make sense.
You've probaly seen those graphs (CAA Saftey Sense leaflet on Carb Ice, FAA must have them too) which shows that Carb Ice can accure up to 25C. Obviously very cold air has less moisture so is less able to form ice, therefor it does stand to reason that introducing warm air could bring it into the risk area.
Incidently, back in 1998, when I had around 60 hours TT, I was hours building out in Southern California when I suffered Carb Icing. I had been taught to apply carb heat every 10 mins or so for around 10 seconds. No-one had told me what the symtons of carb icing actually were. I knew that with carb icing when one applied heat the engine got worse as the ice turned to water...When the engine started to run rough (I was over the Pacific at the time, planning to fly around an island 10nm out from the mainland) I applied carb heat for what seemed like a long time, but in my, er elevated state of awareness it was probably only 2-3 seconds. Nothing happened. Not better, not worse. As my Dad had taught me about the process of elimination, I assumed it wasn't carb ice..
Anyway, I did get back safely, a somewhat older and more experienced pilot than the 21 year 60 hour PPL who had taken off. My point is, those standard, robotic applications of carb-heat might not be enough (and I had just leveled off at TOC) and when Carb Ice does appear, it might take a long application of heat to clear it.
I've only once since then (now got over 1000 hours, all piston) had carb ice worse than that, in a Pawnee when it was getting icing even at full power!
Not an expert on this by any means, and as I'm in a public libary I don't have access to any literature, but it does make sense.
You've probaly seen those graphs (CAA Saftey Sense leaflet on Carb Ice, FAA must have them too) which shows that Carb Ice can accure up to 25C. Obviously very cold air has less moisture so is less able to form ice, therefor it does stand to reason that introducing warm air could bring it into the risk area.
Incidently, back in 1998, when I had around 60 hours TT, I was hours building out in Southern California when I suffered Carb Icing. I had been taught to apply carb heat every 10 mins or so for around 10 seconds. No-one had told me what the symtons of carb icing actually were. I knew that with carb icing when one applied heat the engine got worse as the ice turned to water...When the engine started to run rough (I was over the Pacific at the time, planning to fly around an island 10nm out from the mainland) I applied carb heat for what seemed like a long time, but in my, er elevated state of awareness it was probably only 2-3 seconds. Nothing happened. Not better, not worse. As my Dad had taught me about the process of elimination, I assumed it wasn't carb ice..
Anyway, I did get back safely, a somewhat older and more experienced pilot than the 21 year 60 hour PPL who had taken off. My point is, those standard, robotic applications of carb-heat might not be enough (and I had just leveled off at TOC) and when Carb Ice does appear, it might take a long application of heat to clear it.
I've only once since then (now got over 1000 hours, all piston) had carb ice worse than that, in a Pawnee when it was getting icing even at full power!
Last edited by Jump Complete; 13th Dec 2002 at 18:31.
Thread Starter
Join Date: Nov 2002
Location: Pennsylvania
Age: 48
Posts: 41
Likes: 0
Received 0 Likes
on
0 Posts
Jump Complete
Thanks for your comments. I agree it seems to make complete sense that if the air is warmed to the dewpoint, moisture will form, and hence ice could be prevelant. I just couldn't believe that I hadn't contemplated it!
Safe ice free flying...
Thanks for your comments. I agree it seems to make complete sense that if the air is warmed to the dewpoint, moisture will form, and hence ice could be prevelant. I just couldn't believe that I hadn't contemplated it!
Safe ice free flying...
I agree it seems to make complete sense that if the air is warmed to the dewpoint, moisture will form, and hence ice could be prevelant.
I've come across the claim of carb heat having the potential to cause icing in cold temperatures, but I've never seen a convincing mechnism proposed for such icing except where the aircraft is in visible, glaciated moisture (e.g. cirrus).
To understand why, look at the reasons for the bounds on conditions that cause carb icing. Take a look at the susceptibility chart in the AIC.
For saturated or almost saturated air, it is indicated that carb icing is possible from -13 degC to +30 degC and the highest risk is between -2 degC to +17 degC.
First the upper limit. How can it be too warm for carb ice? Because the temperature is suffciently high that the drop caused by the induction constrictions (of 20 to 30 degC) doesn't cool it below 0 degC.
Now the more interesting lower limit. How can it be too cold for carb ice? Because the amount of moisture that the induction air can hold varies strongly with temperature. At -2 degC the water vapour content is less than 25% of the content at 20 degC. At lower temperatures, there's simple not enough water vapour in the air to be likely cause a problem.
It makes no difference if we subsequently heat the air before it is cooled in the rest of the induction system. The only way of causing icing at lower temperatures is to add more moisture. I can see only one mechanism for adding moisture by applying carb heat, and that is by melting ice that would otherwise have been prefrozen and therefore not have iced up in an inconvenient place like the venturi or throttle butterfly. That means snow, or ice crystals such as in glaciated cloud.
If you're flying along in cold (and therefore dry) unsaturated air, carb heat will not cause induction icing.
Join Date: Nov 2002
Location: uk
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
Bookworm wrong...........wrong ..........wrong
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi (remeber the theory :- increase velocity and temperature decreases ) when it freezes the moisture will then adhere to the inside of that carb.... guarenteed.
basically it the oat is below -5 degrees putting carb heat will probably not hurt, but above that to about +5 degrees, wow you could be in trouble, Honest, dont try this in the air folks........
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi (remeber the theory :- increase velocity and temperature decreases ) when it freezes the moisture will then adhere to the inside of that carb.... guarenteed.
basically it the oat is below -5 degrees putting carb heat will probably not hurt, but above that to about +5 degrees, wow you could be in trouble, Honest, dont try this in the air folks........
Faultygoods -
Are you suggesting that if the OAT is above -5 degrees then carb heat should never be applied. If so you seem to know a lot more about the subject than the CAA amongst other authorities.
I may be wrong with the next bit, but In a dim recess of my brain lurks a piece of information that for (UK) certification purposes the carb heat must be sufficient that when max heat is applied there will always be a rise in temperature great enough to ensure that the temperature in the venturi is above freezing. (this is as opposed to a warm air system which I seem to recall being fitted to some British engines and could cause the problem you mention at temperatures close to freezing).
Hence unless you have carb heat guages the rule is either all or nothing, don't try and guess what is happening temperature wise.
Incidentally - why does it now seem to be the norm to turn off the carb heat at 300 feet prior to landing, in case of a go around. I was taught (and have taught for the last 17 years) that it should stay on to the ground (this is in Cessnas where it can easily be selected off with your thumb as you open the throttle), but I was pulled up for this on my last Instructor rating renewal.
Surely there is just as much danger of carb ice forming in the last 300 feet of an approach at a low power setting.
Are you suggesting that if the OAT is above -5 degrees then carb heat should never be applied. If so you seem to know a lot more about the subject than the CAA amongst other authorities.
I may be wrong with the next bit, but In a dim recess of my brain lurks a piece of information that for (UK) certification purposes the carb heat must be sufficient that when max heat is applied there will always be a rise in temperature great enough to ensure that the temperature in the venturi is above freezing. (this is as opposed to a warm air system which I seem to recall being fitted to some British engines and could cause the problem you mention at temperatures close to freezing).
Hence unless you have carb heat guages the rule is either all or nothing, don't try and guess what is happening temperature wise.
Incidentally - why does it now seem to be the norm to turn off the carb heat at 300 feet prior to landing, in case of a go around. I was taught (and have taught for the last 17 years) that it should stay on to the ground (this is in Cessnas where it can easily be selected off with your thumb as you open the throttle), but I was pulled up for this on my last Instructor rating renewal.
Surely there is just as much danger of carb ice forming in the last 300 feet of an approach at a low power setting.
Join Date: Jul 2002
Location: too near London
Posts: 214
Likes: 0
Received 0 Likes
on
0 Posts
I forget the exact figure but I believe that a certified CH system must be able to raise the temp by 70 + (?) degrees (F). This should allow for the removal of ice and preclude the formation of ice under any conditions. The danger is that CH may raise the temp in the venturi to within the icing range relates to the use of PART heat not full heat , hence the usual all or nothing advice (if no reliable CAT is available). In any event colder air holds less moisture so the risk will be reduced..
Bookworm wrong...........wrong ..........wrong
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi (remeber the theory :- increase velocity and temperature decreases ) when it freezes the moisture will then adhere to the inside of that carb.... guarenteed.
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi (remeber the theory :- increase velocity and temperature decreases ) when it freezes the moisture will then adhere to the inside of that carb.... guarenteed.
Are you suggesting that the moisture content of unsaturated air is somehow "frozen"? That's interesting physics. I've come across gases, liquids and solids, but my states-of-matter text for some reason omits the "frozen gas" state.
If you have solid ice suspended in the air, i.e. you are flying in glaciated visible moisture, then your mechanism makes sense, as I mentioned at the start of my first post. But if the air is unsaturated, the moisture is gas -- it's not "frozen". And if you cool the air to below its dewpoint, it will freeze where you cool it -- in the induction system constrictions. It doesn't "bounce through" anywhere just because the temperature of the water vapour started out below zero.
Last edited by bookworm; 15th Dec 2002 at 19:42.
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
If you'll excuse the pun folks - chill out a little please?
My understanding, for what it's worth is that application of carb heat cannot cause carburettor icing. Do be able to do so, you would need to have moisture content already in the air. If it's there in moisture form then you are already in danger of carb icing and it's not the application of carb heat that causes it.
If it is too cold for moisture in the atmosphere, and it ain't too cold for you to be there in the first place without freezing your hands to the control column, then application of carb ice will raise the carburettor temperature well above about 10 degC.
My understanding, for what it's worth is that application of carb heat cannot cause carburettor icing. Do be able to do so, you would need to have moisture content already in the air. If it's there in moisture form then you are already in danger of carb icing and it's not the application of carb heat that causes it.
If it is too cold for moisture in the atmosphere, and it ain't too cold for you to be there in the first place without freezing your hands to the control column, then application of carb ice will raise the carburettor temperature well above about 10 degC.
Join Date: Sep 2000
Location: Oz
Posts: 149
Likes: 0
Received 0 Likes
on
0 Posts
As far as I am aware nonradio is correct - the carby heat system when used on "full" is designed to ensure that the temperature is raised to a point well beyond that at which ice will form. I have had it drummed into my head to never, ever, use partial carby heat as, depending on how much or little you use, this may actually raise the temperature from well below to smack bang into the middle of the range where ice will most definitely form.
Faultygoods quote:
Bookworm wrong...........wrong ..........wrong
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi.
Agree that air at temps below 0 degrees celcius does still support moisture, however this moisture can present itself as ice crystals or as super cooled water droplets - therefore suggesting that it will 'bounce straight through' is wrong. Super cooled water droplets would more likely cause impact icing e.g. around air intake, wing leading edges etc. ie you'd be in cloud below 0 degrees.
Foyl
Agree ref use of carb heat - should be all or nothing!
Incidently if I remember correctly from my PPL days risk of carb icing is at its greatest in air temps of -15 to +25 degrees celcius.
Bookworm wrong...........wrong ..........wrong
carb heat CAN cause icing in the venturi of the carb and starve the engine of fuel. air below 0 degrees still has a moisture content. However its frozen and will not adhere to the carb venturi, fuel jet etc but bounce straight through, but..... heat that air to just above freezing and the moisture will then freeze as it goes through the venturi.
Agree that air at temps below 0 degrees celcius does still support moisture, however this moisture can present itself as ice crystals or as super cooled water droplets - therefore suggesting that it will 'bounce straight through' is wrong. Super cooled water droplets would more likely cause impact icing e.g. around air intake, wing leading edges etc. ie you'd be in cloud below 0 degrees.
Foyl
Agree ref use of carb heat - should be all or nothing!
Incidently if I remember correctly from my PPL days risk of carb icing is at its greatest in air temps of -15 to +25 degrees celcius.
Join Date: Dec 1999
Location: In the wilds of the midlands
Posts: 31
Likes: 0
Received 0 Likes
on
0 Posts
excrab i agree with you that carb heat should be kept on till landing. In the event of a go-around it is very easy to go to cold at the same time opening the throttle. Twice in my early years i applied carb heat down wind as i had been taught & put it away on the approach & to my horror when i closed the throttle the engine stopped!! fortunatly i was in gliding range of the field.
The best way to tell if you have carb ice is with the manifold pressure gauge. If you find that you have been slowly been adjusting the power to keep the same pressure you have got carb ice.
A warning when using carb heat at full power & the carb temp goes above 38 degrees you will get dettination & damage the engine.
Going back to the original question yes you can give yourself carb icing when applied in very cold air. The colder the air the less moisture it can hold. Therefore appling carb heat in tempetures below - 10 no visable moisture you are increasing the temp where it can hold more moisture compounded with the venturie effect you now have carb ice with the heater on!
The best way to tell if you have carb ice is with the manifold pressure gauge. If you find that you have been slowly been adjusting the power to keep the same pressure you have got carb ice.
A warning when using carb heat at full power & the carb temp goes above 38 degrees you will get dettination & damage the engine.
Going back to the original question yes you can give yourself carb icing when applied in very cold air. The colder the air the less moisture it can hold. Therefore appling carb heat in tempetures below - 10 no visable moisture you are increasing the temp where it can hold more moisture compounded with the venturie effect you now have carb ice with the heater on!
Join Date: Nov 2000
Location: St Albans, herts, UK
Posts: 120
Likes: 0
Received 0 Likes
on
0 Posts
The colder the air the less moisture it can hold. Therefore appling carb heat in tempetures below - 10 no visable moisture you are increasing the temp where it can hold more moisture compounded with the venturie effect you now have carb ice with the heater on!
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
Kegbuster, there are rather a lot of errors in your post.
1) No - under no circumstances whatsoever should you keep carb heat on, and particularly not if you might need to go around. Apply it, rid yourself of ice, then cancel it again.
2) You cannot tell from the MP gauge if you have carb icing. Indications are ambiguous. Operate the aircraft in accordance with the POH. Further, there are a lot of light aircraft out there that do not have MP gauges at all.
3) No, applying carb heat CANNOT cause carb icing.
1) No - under no circumstances whatsoever should you keep carb heat on, and particularly not if you might need to go around. Apply it, rid yourself of ice, then cancel it again.
2) You cannot tell from the MP gauge if you have carb icing. Indications are ambiguous. Operate the aircraft in accordance with the POH. Further, there are a lot of light aircraft out there that do not have MP gauges at all.
3) No, applying carb heat CANNOT cause carb icing.
Join Date: Oct 2000
Location: Bristol
Posts: 461
Likes: 0
Received 0 Likes
on
0 Posts
The build up of ice in the intake system works on exactly the same rules as on the airframe outside. Solid ice does not stick to aeroplanes. To get ice to adhere you have to have supercooled water present. Supercooled water can be present from just below zero to about minus 45deg, but is only present in effective quantities from zero down to about minus 20deg. Therefore you will get your most serious carb icing at intake throat temperatures of zero down to about minus 20deg. Your average carb, throttle closed, will reduce the air temp by about 25deg, and throttle open – less Bernoulli – by about 10deg.
Thus, with high humidity air at about 20deg throttle closed is your danger zone, the final intake temp coming down to minus 5deg, right in the serious icing zone. Likewise, in plus 5deg air throttle open is your danger area.
Carb heat should take the intake temp back up to above zero, out of the icing zone. Let’s guess that it raises intake temp by 20deg.
If the outside air temp is minus 20deg then you would not normally get carb icing. First, the temperature in the intake will be too low. Second, even if the air at minus 20deg is saturated it will still hold very little water vapour so the rate of build up of any ice will be small. If you now heat the air you will reduce its relative humidity, and no free water of any kind will form, not liquid, not ice and not supercooled water. You will get relatively warm dry air in the intake. The total water content is still the low value that it was for saturated air at minus 20deg. These conditions do not give icing.
You all know there are maximum ambient temperature operating limits. If the outside air is 20deg and you add 20deg of carb heat and open up to full throttle you will almost certainly exceed the temperature in the intake that the engine will take without detonation and loss of power. Believe me! I tried to open up a Pratt and Whitney with full carb heat still on and an OAT of 35deg and it hardly worked at all.
Best answer is if you have a cylinder head temp gauge. Then, if you suspect carb icing you select carb heat and wait for a rise in cylinder head temp and switch off the carb heat for 5 minutes and check again.
Dick W
Thus, with high humidity air at about 20deg throttle closed is your danger zone, the final intake temp coming down to minus 5deg, right in the serious icing zone. Likewise, in plus 5deg air throttle open is your danger area.
Carb heat should take the intake temp back up to above zero, out of the icing zone. Let’s guess that it raises intake temp by 20deg.
If the outside air temp is minus 20deg then you would not normally get carb icing. First, the temperature in the intake will be too low. Second, even if the air at minus 20deg is saturated it will still hold very little water vapour so the rate of build up of any ice will be small. If you now heat the air you will reduce its relative humidity, and no free water of any kind will form, not liquid, not ice and not supercooled water. You will get relatively warm dry air in the intake. The total water content is still the low value that it was for saturated air at minus 20deg. These conditions do not give icing.
You all know there are maximum ambient temperature operating limits. If the outside air is 20deg and you add 20deg of carb heat and open up to full throttle you will almost certainly exceed the temperature in the intake that the engine will take without detonation and loss of power. Believe me! I tried to open up a Pratt and Whitney with full carb heat still on and an OAT of 35deg and it hardly worked at all.
Best answer is if you have a cylinder head temp gauge. Then, if you suspect carb icing you select carb heat and wait for a rise in cylinder head temp and switch off the carb heat for 5 minutes and check again.
Dick W
Join Date: Nov 2002
Location: uk
Posts: 53
Likes: 0
Received 0 Likes
on
0 Posts
corrs carb heat can cause icing Edited. Also cant remeber who said ice crystals would not bounce through the carb, but....... think about the method that turbo props use to DEFLECT ice out of the intake. They have an ice deflector, ho ho., and it is designed to make the ice bounce out of the way. ok guys.
If you dont know turbo props then......well!!!!!
If you dont know turbo props then......well!!!!!
Last edited by Captain Stable; 6th Jan 2003 at 07:12.
Join Date: Feb 2001
Location: Hants, UK
Posts: 1,064
Likes: 0
Received 0 Likes
on
0 Posts
OK, now I'm confused! I had always thought when it was very cold then to use carb heat could help form rather than remove carb ice.
Here's a scenario I had yesterday:
Crusing at 3500ft about 1000ft above a layer of building cumulus (plenty of moisture in the air), OAT of -6 deg C. Carb temp gauge with cruise power shows -15deg C (seems to tally with the +/- 20 deg drop in the venturi). This is just in the yellow 'avoid' zone from +5 to -20 on the gauge. Upon applying carb heat, the carb temp rose to approx +8 deg C, with the occasional indication of some ice having been present (slight splutter and a subsequent rise in MAP to above previous levels once carb heat deselected).
So far so good, but if you extrapolate the line you can see where if the OAT had been -9 deg C then the carb heat would have been insufficient to raise the temp out of the yellow zone, and if the OAT had been -14 deg C it would not have raised it above 0 deg C. Meanwhile the no carb heat temperature would have been -23 deg C and out of the icing zone. To apply it would seem to encourage the formation not removal of ice.
Or are you saying that at -14 or -9 deg C there is insufficient moisture to form ice once inside a venturi warmed by carb heat to around freezing? How come that yesterday there was a layer of cloud at 4300 ft from which snow was falling? Lapse rates would give an estimated temperature up there of +/- -9 deg C.
Any further elucidation much appreciated.
Here's a scenario I had yesterday:
Crusing at 3500ft about 1000ft above a layer of building cumulus (plenty of moisture in the air), OAT of -6 deg C. Carb temp gauge with cruise power shows -15deg C (seems to tally with the +/- 20 deg drop in the venturi). This is just in the yellow 'avoid' zone from +5 to -20 on the gauge. Upon applying carb heat, the carb temp rose to approx +8 deg C, with the occasional indication of some ice having been present (slight splutter and a subsequent rise in MAP to above previous levels once carb heat deselected).
So far so good, but if you extrapolate the line you can see where if the OAT had been -9 deg C then the carb heat would have been insufficient to raise the temp out of the yellow zone, and if the OAT had been -14 deg C it would not have raised it above 0 deg C. Meanwhile the no carb heat temperature would have been -23 deg C and out of the icing zone. To apply it would seem to encourage the formation not removal of ice.
Or are you saying that at -14 or -9 deg C there is insufficient moisture to form ice once inside a venturi warmed by carb heat to around freezing? How come that yesterday there was a layer of cloud at 4300 ft from which snow was falling? Lapse rates would give an estimated temperature up there of +/- -9 deg C.
Any further elucidation much appreciated.
Join Date: Dec 2001
Location: europe
Posts: 546
Likes: 0
Received 0 Likes
on
0 Posts
Is there a confusion by considering the temperature/dewpoint charts of atmospheric conditions used to illustrate the range and severity of potential carb icing which can occour within the carburettor, and applying the same chart indications to the temperature/dewpoint of the air once it is within the carburettor venturi?
If air of a given RH is heated, the RH reduces.
This means the air can hold more water as vapour and is less likely to contain water in the liquid form, consequently less likely to be able to deposit ice particles.
This means that if air was low enough RH not to form water droplets when its temperature is lowered in the venturi, then applying carb heat will only ensure the RH is even lower.
If the RH was such that the lower temperature in the carburettor could result in formation of water droplets and ice particles, adding heat will lessen the possibility.
If ice has already formed, carb heat should be sufficient to melt the ice assuming the engine power is set at a level to produce the carb heat.
If air of a given RH is heated, the RH reduces.
This means the air can hold more water as vapour and is less likely to contain water in the liquid form, consequently less likely to be able to deposit ice particles.
This means that if air was low enough RH not to form water droplets when its temperature is lowered in the venturi, then applying carb heat will only ensure the RH is even lower.
If the RH was such that the lower temperature in the carburettor could result in formation of water droplets and ice particles, adding heat will lessen the possibility.
If ice has already formed, carb heat should be sufficient to melt the ice assuming the engine power is set at a level to produce the carb heat.
Join Date: May 2002
Location: Who can say?
Posts: 1,700
Likes: 0
Received 0 Likes
on
0 Posts
It is possible for the carb heat to raise the temperature of the carburettor to the point at which ice in other situations would have formed.
However, if the temperature of the incoming air is low enough for this to be possible, it is extremely unlikely that it will contain moisture in any form other than as ice. No, not even as supercooled droplets.
Therefore the use of carb heat cannot cause formation of ice in the carburettor.
faultygoods, I have edited your post. I think you know why. Please do not repeat the offence.
However, if the temperature of the incoming air is low enough for this to be possible, it is extremely unlikely that it will contain moisture in any form other than as ice. No, not even as supercooled droplets.
Therefore the use of carb heat cannot cause formation of ice in the carburettor.
faultygoods, I have edited your post. I think you know why. Please do not repeat the offence.