What's a crancase heater?

[webea/c]

I know "webea/c" sounds like I don't know and although I will not say I know everything I think after 20 years in the biz and countless schools and seminars I've picked up something I can call knowledge. Besides my tech school instructor made us read the Modern Air Conditioning and Refrigeration book cover to cover. (I've forgotten a lot of the theory though.) So I'm looking for you guys to back me up on something so I can prove a point.

The Project Manager of our company is trying to tell me that a crankcase heater keeps the oil from "gelling" up during cold weather and that in Florida we do not need them.

I am trying to convince him that it is to keep the refrigerant from migrating to the compressor and mixing with the oil during the off cycle, thus preventing the refrigerant from carrying the oil away from the compressor during starts.

Please post some threads so I may print this and set him straight. I wonder if I should follow him on some installs to make sure he's not disconnecting them.

By the way, In Florida we run commercial A/C systems all year because even on a 40deg day the buildings here are in the high seventies by 11:00am.

[joeywpittman]

if he won't listen to what you have to say, why do you think he is going to listen to what we have to say. You are the one with " 20 years in the biz and countless schools and seminars" You know your right. Don;t put up with that crap. Your boss has been in the office to long.

[Edited by joeywpittman on 06-11-2005 at 02:12 AM]

[ultratec]

Yes you are correct, also, you dont want the liquid sitting or migrating back to the pump during the off cycle and then starting up w/ a throat full of liquid. Tell him compressors dont like liquid and dont compress it very well, if he asks you why, just walk away.

[echomech]

He knows better let him believe in mickey mouse , already in flordia. guess we don't need a compressor either this is fla damm sun will heat up refrigerant .

[R12rules]

Stupid is as stupid does..... leave him alone.

Otherwise you are trying to teach a pig to sing. You simply CANNOT DO IT!!!

You may prove your point, but end up on his hit list.


It is not about being right! It is about getting the work done and coming home with a weekly check in your pocket.
This will never be accomplished by proving your superiors they are wrong.


If they ask your advice, be kind and patient with them. Show them. But stop there. Let it sink in.

If it does, they will be better for the effort.
However, if it does not sink in ... they will only hate you.

[fick]

I love doing it their way when you told them it was wrong. Then when the crap hits the fan you get to sit back with a grin on your face and say told you so.

Better yet. Call the manufacturer and ask if the warranty will be voided if you don't install the CCH.

[Senior Tech]

This may not be the best advice but here it is anyway...

Find literature that identifies what a crankcase heater does and what it's purpose is...not from a website such as this but perhaps training manuals and such, leave it in very conspicuous places...like on his desk when he's not around. He will eventually begin to "think" the right way and doe's it on his own (or so he thinks)...sometimes things of this nature, when it's a battle of "I'M RIGHT, YOUR WRONG" makes a certain type of person feel insecure and they will battle to the end beacause it gives them a feeling of power or strength...the end result is you want to do it the right way and he will to eventually...(we hope). Okay, so that's it from Senior "freud" Tech.

[greg o]

Originally posted by webea/c

I am trying to convince him that it is to keep the refrigerant from migrating to the compressor and mixing with the oil during the off cycle, thus preventing the refrigerant from carrying the oil away from the compressor during starts.


By the way, In Florida we run commercial A/C systems all year because even on a 40deg day the buildings here are in the high seventies by 11:00am.


You are correct.
As far as running AC in low temps, try here in North Dakota. We have some computer server rooms that the AC runs all winter long. With no possible way to get outside air we can not use economizers so straight AC only. It is real fun trying to set up a unit when it is -20F outside.
We get very familar with crankcase heaters, and low ambiant controls.

[webea/c]

Originally posted by senior tech
This may not be the best advice but here it is anyway...

Find literature that identifies what a crankcase heater does and what it's purpose is...


Thanks Senior. Your right, I’ve been putting literature around the office and struck up conversations with the service techs and he is avoiding me now. Doesn’t want to admit he’s wrong.

[webea/c]

Funny word, superior. Thanks everyone for the answers. I reread my post and realize that it does sound like he is my superior. We are actually equals as far as seniority. I'm in sales and he coordinates the projects us salesman sale.

Salesman! I bet that's why he thinks I don't know what I'm talking about because most salesmen don't.

"If you can't do it, sell it!" right?

Anyway, I thought “superior” was an interesting word since I have a hard time thinking of someone as superior in a situation like this. I read your posts all over this sight, and it seems to be the same group of people, and I can’t help but to feel inferior. Sometimes I wonder if I made the right choice to hang up my tool belt and put on a “shirt and tie”.

Thanks for some fun reading. Keep it up.

[john dalton]

Dear Webea/c,

You could have just shown your co-worker the section on crankcase heaters from “Modern Air Conditioning and Refrigeration” and tell him you obtained your understanding about crankcase heaters from this “text book” and ask him where he obtained his understanding from? Remembering to do so with the utmost respect and humbleness, since most of us here have been on both sides of this fence.

Then laugh it off with the statement that now it’s your co-workers turn to find a problem in your knowledge so you can benefit from “his” HVAC knowledge and experience. And lastly, really mean what you say and remember to always be humble.

Respectfully Submitted,
John J. Dalton

[h2045]

Ask this Engineer what POUR POINT means and where in Fla does it get that cold.....

[Control Man]

Crankcase heaters are used on most units that may be in a region that the AMBIENT TEMPERATURE will or could drop below 50'F to stop oil migration.

Florida always above 50'F ?

[powerhead]

Originally posted by webea/c

The Project Manager of our company is trying to tell me that a crankcase heater keeps the oil from "gelling" up during cold weather and that in Florida we do not need them.

I am trying to convince him that it is to keep the refrigerant from migrating to the compressor and mixing with the oil during the off cycle, thus preventing the refrigerant from carrying the oil away from the compressor during starts


He must be thinking of oil sump heaters that are used in hydraulic systems (lifts, trash compactors, etc) to keep the heavy hydraulic oil from gelling. Quite common up north.

[john dalton]

Dear Control Man,

Regarding your previous post:

“Crankcase heaters are used on most units that may be in a region that the AMBIENT TEMPERATURE will or could drop below 50'F to stop oil migration.”

Not exactly friend. Crankcase heaters are used ANYTIME the temperature of the compressor becomes the coldest part of the refrigeration system, regardless of the ambient temperature.

Respectfully Submitted,
John J. Dalton

[webea/c]

h2o45 & Control Man,

It gets below 50 deg every year here. We’ve even seen frigid temperatures in the thirties. Damn that’s cold!

LOL

Last winter I even had to turn the pool heater on so we could continue swimming in Jan & Feb. Oh. And it has a crankcase heater.

John is correct. Even in the Arizona summers there is crankcase heaters although I think it’s unlikely refrigerant would migrate to the compressor there.

By the way. The customer has now asked for his maintenance fee back for this month because he’s convinced that since we didn’t catch the bad crank case heater on the PM service it cost him a compressor. Does everyone check the heater on every maintenance service? I used to turn units off and see if it would warm up but I guess a lot of guys don’t do that.

[cxagent]

There is a really good explaination in the Tecumseh Hermetic Compressor Services Data book. In my August 1991 version page 29 describes the refrigerant migration to the compressor and has pictures of the compressor running without oil.

For any refrigerant system there will be liquid some where in the system during shut down. Generally the liquid refrigerant will be at the lowest and coolest place in the system. On a residential system with the evaporator in the attic, this will be in the condenser & compressor. Liquid refrigerant is more dense than oil so it will sit under the oil in the compressor. When the compressor starts, the refrigerant boils off and pushes the oil out of the compressor (see pictures). The oil will return eventually, but the compressor is running with little oil until it makes it all the way through the system and back.

Just my opinion, but I think the crankcase heater should be checked on all PMs. It doesn't take much to touch the heater and see if it is warm and/or check the current through the circuit.

[john dalton]

Dear Webea/c,

Regarding your previous post:

“…Even in the Arizona summers there is crankcase heaters although I think it’s unlikely refrigerant would migrate to the compressor there….”

Please read my previous post:

“Crankcase heaters are used ANYTIME the temperature of the compressor becomes the coldest part of the refrigeration system, regardless of the ambient temperature.”

The key phrase here is “…regardless of the ambient temperature.” Liquid migration can and does occur in Arizona as well friend.


”By the way. The customer has now asked for his maintenance fee back for this month because he’s convinced that since we didn’t catch the bad crank case heater on the PM service it cost him a compressor. Does everyone check the heater on every maintenance service?”

Almost no company checks crankcase heater operation on ever P/M, at best the majority of companies only check their operation annually, even though their operation can be verified by either simply touching the crankcase heater, checking the amp draw of the heater, or by checking the surface temperature of the heater with a non-contact infrared thermometer.


“I used to turn units off and see if it would warm up but I guess a lot of guys don’t do that.”

There are easier and faster ways to verify the crankcase heater operation than this, please see above.

Respectfully Submitted,
John J. Dalton

[webea/c]

John,

Thanks for correcting me. You are right that the ambient outdoor temperature is cooler than an air handler above a ceiling or in a crawl space. Our company tends to deal mainly with air handlers that are mounted in the conditioned space or in an open plenum ceiling as opposed to not and therefore the air handler is the cooler section. As for checking the crankcase heater when the unit is off is due to some crankcase heaters energizing only during the “off cycle” and can only be checked when then system satisfies.

As for the statement of ” Liquid migration can and does occur in Arizona as well friend” prompts me to say that since I don’t know you, never have meet you, and have not been on HVAC Talk long enough to call anyone my friend leads me to since sarcasm and that “my friend” is not appreciated. I am simply asking for opinions on a subject. Isn’t that what this sight is all about? If we all have to watch EVERYTHING we post in fear of making a small mistake then that is a sham.
******************************************
The project manager approached me yesterday with the copy of a page out of the Modern Air Conditioning and Refrigeration textbook I left on his desk and said. “I get it, you can stop now”. Thanks for the suggestion John and thanks again, everyone, for your support.

[acjourneyman]

Just to throw another wrench into the mix, in some climates the factory crankcase heaters maynot be sized properly to prevent migration as they maynot be large enough.When ambient temps reach 140+ you can still get migration to the compressor crankcase.

[Control Man]

John Dalton

Gee "FRIEND" you are not TOTALLY CORRECT , seeing I am in a region that drops into the -40'F range and I have numerous units that do not have crankcase heaters.

LIEBERT only suggests a crankcase heater if there is a chance of the ambient dropping below 50'F, hardly ever called for in the specs.

Anyway just posted my opinon no need to constantly correct things to suit yours

[john dalton]

Dear Webea/c,

Regarding your previous post:

“As for checking the crankcase heater when the unit is off is due to some crankcase heaters energizing only during the “off cycle” and can only be checked when then system satisfies.”

The control circuit that energizes the crankcase heater when the compressor is on it’s “off cycle” is superior in operation to the much more common “on all the time” system. A service technician can wait until the compressor cycles off and then warms up the surface of the crankcase heater itself to check it’s operation, but this safety device can also be checked faster by jumping the relay or contacts that are controlling it and then check it’s amp draw. Just one of many ways to check it’s operation friend.


”As for the statement of ” Liquid migration can and does occur in Arizona as well friend” prompts me to say that since I don’t know you, never have meet you, and have not been on HVAC Talk long enough to call anyone my friend leads me to since sarcasm and that “my friend” is not appreciated.”

Although it’s true that we do not know one another, that we have never met, and that you have not been on HVAC Talk long, we are colleagues my friend. And after reading that you have worked twenty years in the business, have taken countless school, seminars, that you were once in the field, but are now in the sales area, tells me that we have shared very similar life experiences. More people than you think here on this forum have lived similar experiences in our craft my friend. You, like most of us here, have worked in this field and found ourselves working in attics that are so hot that any normal person would have quite half way through, but we complete the job. We have worked seventy, eighty, ninety hours a week, or have even lived on the jobsite for a month, just to get the project (s) done. Have worked in extreme heat, with extremely cold refrigerant; with high power everywhere, with moving components that can remove body parts, up high on top of the ladders or on top of buildings, under both office and Client pressures to get the job done quickly, cheaply, and with no call backs. Your right, we have never met, but we have walked the same paths over the last twenty years haven’t we friend. You have more friends here than you know, and like me, you have never met any of them……..friend.


“I am simply asking for opinions on a subject.”

And you have come to the right place for that.


“Isn’t that what this sight is all about?”

This site , this forum, this coming together of the minds, personal experiences, knowledge, and schooling, is what this place is all about.


“If we all have to watch EVERYTHING we post in fear of making a small mistake then that is a sham.”

What we post here, is always open for discussion, which is what this forum is all about. If we make a mistake in our post, we should expect a fellow colleague, a friend, to gently correct us, least we look ignorant in front of our Clients at a later time. We all here have make mistakes in the past, have holes in our knowledge even now, have been instructed or taught, incorrectly by someone else, have steered ourselves wrong, and will continue to do so in the future. But we also have a great resource….this forum, our fellow colleagues……. our friends. You want to see my mistakes, my misconceptions, my holes in my knowledge, just look at my previous posts, they are all here on display, searchable, like everyone else’s, to remind us all, we are not infallible, that we are not perfect, that we are but human.

And when people are passionate about something, like their jobs, our profession, our craft, they will tend to be emotional at times, for without emotion, there is no passion. There will be times when you will see arguments, sarcasm, defiance, ill fated humor, people making fun of one another, people talking down to each other, and people poking fun at your posts, these are all wrong and should not be displayed, but like our own problems, and ignorances, are only part of the sharing process when passionate subjects are discussed between family, colleagues, or even……….. friends.

I too have fallen short at times to the trappings of what I write. But in the end, we should be fellow colleagues, or even………….friends.

This is only my option regarding this forum and my friends on it.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Control Man,

Regarding your previous post:

“Gee "FRIEND" you are not TOTALLY CORRECT , seeing I am in a region that drops into the -40'F range and I have numerous units that do not have crankcase heaters.”

Just because a unit, or units, do not have crankcase heaters does not negate the fact that liquid migration occurs, and that crankcase heaters or some other form of compressor refrigeration oil warming should be installed in all units. Just like combination high/low pressure switches should be installed in all refrigeration units to protect the compressor from a multitude of different field scenarios, but because of marketing cost limitations, most smaller systems do not.


”LIEBERT only suggests a crankcase heater if there is a chance of the ambient dropping below 50'F, hardly ever called for in the specs.”

Here again, Liebert is but one manufacturer, who base their standard, options, and specs on marketable costs of their equipment.


”Anyway just posted my opinon no need to constantly correct things to suit yours”

I too post my options, and facts, and try to identify each for what they are. If I correct, as you say, a fellow colleague’s post, I do so based on facts or basic refrigeration and physics principles, not my options.

Lastly, the only thing that’s “suits me” is the facts as they are, and the options, as they are experienced by others.

And if you read my above post, you’ll see why I use the term….friend…so much on this forum. It’s not for sarcastic reasons, but rather one of camaraderie……...friend.

Respectfully Submitted,
John J. Dalton

[webea/c]

Ok, I accept that “friend” is sincere I’m just not used to it. Sorry for being so sensitive. I shouldn’t be so thin skinned.

I have read that some manufacturers will keep one winding of a compressor energized to create heat in the crankcase but I have not been able to find a lot of literature on this. Some single-phase condensing units use a single pole contactor, which leaves one winding energized. A Goggle search brings up some information but I don’t seem to find it in any of my textbooks (not that I have many).

Can any one tell me where I might find more information on this?

[cxagent]

Most of the Trane single phase residential units used to use the start winding as a crankcase heater. I don't know for certain if they still do. Look at the wiring diagram to see if there is circuit through the start winding when the contactor is open.

[john dalton]

Dear Webea/c,

Thanks for taking the time to read my previous post…..friend.

Respectfully Submitted,
John J. Dalton

[john dalton]

Dear Webea/c,

Regarding your request for information on off cycle single pole contactor/start winding crankcase heater operation, try the following site:

http://www.achrnews.com/CDA/ArticleInformation/features/BNP__Features__Item/0%2C1338%2C104625%2C00.html

You might also recognize the author of this article as well.

Hope this helps, and let me know what you think of it……..friend.

Respectfully Submitted,
John J. Dalton



[Edited by john dalton on 06-15-2005 at 09:03 PM]

[robnjr]

I have two identical 3 ton systems, 15 years old and working fine. While changing a condenser motor last year (Being an EE, I do my own PM work, like cleaning coils, electrical problems, etc.) I noticed that one of my systems had the crankcase heater (CCH) disconnected. It didn't come loose, both of the CCHs were wired to the same pole of the contactor, thus it was never energized! Of course I reconnected it, but have always wondered WHY it was wired like that. I assume it has been wired like that since day-1, since I had one HVAC person out only once before then, to inspect the system when we first moved in 12 years ago (this house was built in 1990). Also, my second system had the CCH connected correctly, and always energized. I confirmed both were drawing current and warm. Anyway, the bottom line is that both systems ran, and still do run fine, one without a CCH, for 15 years, and one with one. I had a HVAC person out after I discovered this, to confirm the system was in good order (you know the guy must have been honest after that call: "Mr Service Man, did a lack of a CCH ruin my compressor?"). I live in the Dallas area.

Each CCH uses 100 watts, 24/7....doing some math, and that's 15 bucks a month, $180 a year in electricity. Over twelve years that's $2160, more than enough to pay for new compressors (that still are good anyway!!)......so what am I really gaining with the CCH in my climate?? It doesn't seem very economical, at least in my case, to use more money in power than the cost of replacing the equipment....you would at least think these things had a thermostat or something, but I do understand that it would have to be a compressor-internal thermostat. I've also played around with the idea of connecting a relay, so the CCH is off when the system is running, but that would cut the CCH bill down by less than a third, probably less...any thoughts on how to reduce this energy-wasting CCH setup (yes, I know, I could replace my entire system!!!). Thanks.

[webea/c]

Rob,

I admit that the lack of a CCH in your/my climate on a residential application is not going to hurt anything in most cases, as the air conditioning does not run when the outside ambient temperatures drop below 50’. There is still a concern with heat pumps and to say that you haven’t had any failures is a “roll of the dice”.

My concern would be that in a commercial application a compressor could and does operate 12 months a year and in low ambient conditions. A commercial compressor is not a $2,000.00 repair and in some cases can reach $10,000.00 or more, not to mention that in restaurants and manufacturing facilities you could be talking hundreds of thousands of dollars of lost revenue, product or production.

So you see, in a residential application it is not so critical as in a commercial application. To answer your question about reducing the operating cost of the CCH I would not worry about it. $15 per month is cheep insurance. As far as the relay idea, there are systems out there now that only operate CCH when the system shuts down. I wouldn’t recommend you doing this unless you really knew what you are doing. Electricity is not something to play with.

Be Safe.

Webe

[robnjr]

Webe:

I posted on the "commercial" forum after doing a search for crank case heaters, and reading this several page thread. It seemed relevant to something I had experienced, so I added my 2-cents concerning my residential system.....yes, not the same, but I though it would add to the discussion.

Remember, those pennies add up over the years......but you're right, the 15 bucks a month is good insurance, especially on an older system...I was just wondering how **necessary** the CCH was for my climate....not very from my experience, or else I have just been lucky...

I would assume a larger commercial system would draw more power for its CCH, but the economics that you mentioned of commercial systems makes sense....

I'm an Electrical Engineer with lots of field work under my belt (industrial controls, PLCs and the like), so hooking up a relay isn't really a big deal for me....I know the safety procedures, but thanks for your concern...

LOL....AC never runs if its below 50 outside??? That's funny......Do you have a wife and kids who play with things, or forget to turn things off???

[webea/c]

Originally posted by robnjr
Webe:
LOL....AC never runs if its below 50 outside??? That's funny......Do you have a wife and kids who play with things, or forget to turn things off???


Yes. You are right. I wish I could just get them to stop standing in front of the refrig with the door open staring at the shelves or leaving the back door wide open letting the cold out.

OOPS, letting the heat and humidty in!! LOL

[john dalton]

Dear Robnjr,

Regarding your previous post:

Mt father-in-law is 84 years old and thinks smoking DOES NOT cause lung cancer, and that all these commercials on TV are just politics generated by people that want to tax the honest, sincere, and misunderstood tobacco companies. The reason he thinks this is because he has smoked for the last 71 years of his life, and does not have lung cancer.

Webea/c was correct in his analogy that this is merely a lucky roll of the dice, and should not be used as a litmus paper test as to wither a crankcase heater should be used for residential applications, or not.

The fact that you live, and work in the Dallas area is also not an indication of wither you should use a crankcase heater or not…..you should, period.

As for the energy the crankcase heater consumes, Webea/c was also correct in his statement that this is just cheap insurance to prevent a compressor failure, or system contamination with excessive refrigeration oil, at a filter/drier, at the metering device, or even in the evaporative section reducing the overall cooling capacity of the system.

Your concern of “lifetime energy consumption” of these safety devices is a very valid one, and can be addressed if you so choose.

First and foremost, a 100 watt crankcase heater, for a 3 ton compressor, in your area is too large. The unit, or compressor manufacturer installs these “generic sized” heaters for installation across the country, and therefore builds in some degree of safety, in your case, a lot of safety. Next, your post states you are an electrical engineer with lots of field experience, so installing a crankcase heater relay would be a relatively easy task for you, as you stated. Third, there are crankcase heaters that actually vary in their energy consumption based on the amount of heat the compressor actually needs, they’re called “self-regulating PTC heaters”

Based on the above information, I would recommend that you do the following:

Remove the existing manufacture’s crankcase heaters; install new 45 watt self regulating PTC crankcase heaters, and connect them to a relay so as to only operate when the compressor is off, this should conservably saves you at least 80 to 85% of your current energy consumption regarding these necessary safety devices.

Respectfully Submitted,
John J. Dalton

PS: I know what you mean, I have a wife, and six children that play with our house thermostats all the time, regardless of how many times I tell them.

[john dalton]

Dear Webea/c ,

Regarding your previous post:

“I admit that the lack of a CCH in your/my climate on a residential application is not going to hurt anything in most cases…”

The key word….”most…”, and in those “other” situations, when a crankcase heater is needed, your gambling with your company’s dollars. You be the judge, are you are gambling man, or not?


“So you see, in a residential application it is not so critical as in a commercial application.”

Your statement here is not all together correct, in as much as the statement more accurately should be stated:

Although the use of a crankcase heater is more critical in commercial applications for several reasons, the use of a crankcase heater is just as important in residential applications in respect to what they protect, and the potential of the damage that can occur without them.

Respectfully Submitted,
John J. Dalton

[robnjr]

Thanks John Dalton, that's exactly what I was looking for....where can I find these "self-regulating PTC heaters"??? It always thought 100 watts was a little excessive!!!

Again, thanks for the valuable info....

[john dalton]

Dear Robnjr,

Any major local refrigeration/air conditioning supply house should either have these in stock or at least we able to order you these. If you have any problem obtaining these, post here again, and I’ll get you an actual part number, and supplier. The please was mine friend.

Respectfully Submitted,
John J. Dalton

[webea/c]

Thanks John,

You are absolutely right. I should have worded that differently. I think a CCH should always be used.

Thanks for your input. After reading your previous, numerous, posts on other threads it took me a little time to "get" where you are coming from and admit to some misunderstanding. You have earned my respect and attention.

May others enjoying this forum see past there own "head trash" that keeps them from learning.

Respectfully listening,

Steve

[d big 1]

I wish I could find that picture of the service tech who used heat tape around the belly of a hermetic. At least his heart was in the right place.

[john dalton]

Dear D big 1,

Although that sounds ridiculous, if one was to use self-regulating tape, and used enough of it, and position it correctly, it would functionally work as a crankcase heater in an emergency situation. But then again, that’s a lot of “what ifs”…….lol.

Respectfully Submitted,
John J. Dalton

[d big 1]

Wonder what that would do for the SEER? (just kidding folks)

[john dalton]

Dear UD big 1,

If a service technician used the self regulating tape and experimented on how much of the tape to use, and then connected the tape to a small relay with inverse properties to the main compressor contactor, he would most certainly INCREASE his SEER rating “slightly”.

Of course, that would be in relationship to a stock, and generic crankcase heater supplied by the factory.

Respectfully Submitted,
John J. Dalton