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Question on Portable Heat Pump

Posted by BillyBobJo (My Page) on
Sat, Nov 5, 11 at 0:40

Y'all I've got me a little question on a new portable AC unit. I will add more details tommorw but I just want to ask a small question here.

So I recently bought me a big ol' 14,000 BTU Portable Air Conditioner with a Heat Pump. I got a KILLER deal on this bad boy at the flea market, its a De longhi probably worth $600-$900 its brand new in box and the Sharp one it had owners manuel everything there. It wasn't used or used very little as far as I know. I stole it for $90! They had no idea what it was worth! And I got another Sharp 10,000 BTU Portable unit for $50 discounted from $80 that they wanted for it! They had a bunch of them for these prices, damn I shoulda bought all of em and sold the rest!

Anyways, its a Dual Hose model. It has one intake hose for outside air and one for output of cold/hot air from the condenser/compressor so it don't create negative pressure and lose lots of efficiency. Great design!

However, summer is over and its getting into winter now, so I am now using it as a Heater for my room, it has a heat function as well so it blows out cold air through the hose.

My question is that I heard Y'all can't run ACs at temps below 50 Degrees or the compressor may be damaged. So is it ok to run this thing with both hoses in the window when its real cold out[Below 35 Degrees]? This means its intaking super cold air from the outside and blowing it over the compressor and at the time evaporator coil and blowing it out even colder. I would imagine these compressors are designed to take it, I mean some houses have Central Heat Pumps and People run those at freezing temps and the compressors outside. So I just wanted to make sure I ain't supposed to take the intake hose outside or anything. Thanks to anyone who responds in advance.


Follow-Up Postings:

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RE: Question on Portable Heat Pump

A true heat pump is designed to run at cold outdoor temperatures, however, as outdoor temperature drops, so does the temperature of the 'hot' air delivered.

The two hoses are for taking in outside air and exhausting air which has passed through the condensing coil. So the 'intake' should be drawing in outside air.

A traditional HP system includes some type of backup heat for when the unit can't keep up. Does yours? Does the manual mention defrosting? Would be interested in knowing how melt water is handled.

V


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RE: Question on Portable Heat Pump

Highly unlikely that portable units such as the one being discussed have electric heat strips for a backup heat function.

BillyBobJo doesn't cite the unit's model number. A particular one-hose unit I found online with heat mode, the instruction manual does not have any warnings against operating in low-temp conditions but does advise that the unit may go into defrost mode (operating sound changes and Lt (Low temperature - frost prevention) appears on the display for the duration until defrosting is finished. Defrost condensate is collected in the internal bucket same as condensate during air conditioning mode. Ft (Full Tank) appears on the display if it needs emptying.


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RE: Question on Portable Heat Pump

Hey guys thanks for the replies, sorry about the late follow up I's just been real busy.

veesubotee yea I know them Central Heat Pumps is designed to work in mighty cold temps, but I wasn't 100 Percent about this here one.

But the thing is I just wanted aint oe this cold outto make sure I wasn't supposed to remove the intake hose when its extremely cold. Cause if I did it'd get warmer but I guess it'd be like my AC and not work without both hoses real well?

dadoes yea I don't think its got a heat strip, however I haven't seen it go into defrost mode either. I haven't used it A LOT I'm using a quarts heater now cause I still gotta get wood or a window kit for it I's just usin cardboard boxes now but they had to come down it won't cut it when its real cold or raining and have poor insulation. So it looks to me like its ok to run both hoses in the winter? I don't know just wanted to check I've heard people sayin operating an AC below 50 Degrees is real bad on the compressor, I don't know if I believe that now! Why would cold hurt a compressor? Its just an electric motor with a pump!

Anyways, any other ideas? I appreciate all comments.


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RE: Question on Portable Heat Pump

The compressor on your portable unit won't be located outside, it's in the room being heated so it's not directly exposed to cold temps. The evaporator coil in heating mode (which is the condensor in cooling mode) is exposed to the outside intake air and may frost-over, thus triggering defrost.

The danger of low ambient temps is that the refrigerant will migrate into the compressor and mix with the crankcase oil, creating a thin fluid that may boil/foam and not properly lubricate the bearings. Central units with the compressor outside typically have a crankcase heater that keeps the lower section of the compressor warm enough so the refrigerant doesn't condense into the oil when the unit is off. Homeowners who shut off the breaker on their a/c unit during winter non-use are advised to turn it on at least 24 hrs before starting the next cooling season so the crankcase heater can get warmed.


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RE: Question on Portable Heat Pump

dadoes thats pretty much exactly what I was wandering.

First off the Compressor is located inside, HOWEVER I was looking in the intake vent where outside air goes into from the hose with a bright light today to see whats in there and I can see the compressor in this area. Basically there is a chamber with the compressor and lines and such, I believe it is insulated in and contained away from the rest of the unit, and on the right of the compressor in this chamber is the condenser coil radiator, and behind it is a big fan and the output hole for the exhaust hose. Basically as far as I know the temp in here wouldn't be THAT much different than if the unit were outside, say during winter cold air from the outside is constantly blowin on the compressor and that chamber is always full of outside air being sucked through over the condenser and blown out the exhaust hose. There is likely little to no inside air in the compressor area. So I'd recon if its 30 Degrees the Compressor wouldn't be at much higher temps, although it is working which produces some heat and when it shuts off so does the fan, so maybe it doesn't get super chilled because of this?

My real question is maybe I'm supposed to take the intake hose for outside air off and just let it suck in warm air from the room and leave the exhaust hose in?

I also looked online at instruction manuals on portable ACs with a heat pump function, however the only manuels I could find were on models with single hoses that use air in the room to exhaust outside. I thought about just doing this, but this is highly inefficient. I learned about this on this forum actually last summer when I had that big ol' Window AC unit mounted on the inside with just the condenser coil on the outside but the rest sitting inside with the intake vents on the inside, and it was almost ineffective at temps over 76 Degrees. However when I installed it correctly in the door with the unit all the way out like it was made to it worked like a champ, kept my room at 68-69 Degrees the remainder of the Summer even in nasty humid 95 degree days.

I don't REALLY need this portable AC, but I saw the thing for 90 Bucks and said how could I go wrong? Works great. Didn't use the AC a whole lot cause I haven't set it up properly yet just cardboard boxes which is hard with the unequally sized hoses. I still have the Sharp Window Unit, and will still use it to cool the room, but I took it out last month cause its winter now and I no longer need AC. So I've got the DeLonghi sitting here and I'm gonna set it up and use it for heat. Reason is I really like the heat function on it, uses less electricity than a space heater yet still pumps out 14K BTUs of heat vs 5K for the space heaters. Yes its not efficient when it gets REAL cold, but around here it really doesn't get much below 36 Degrees most nights, maybe 20-25 but thats only once in a while, and most days are in the 50s so it'll be fine.

But yea less efficient at lower temps, means less warm air. What I'm trying to figure though is one night I ran it with just the exhaust hose and the intake hose removed so it used hot room air to exhaust over the condenser, and it worked just fine and the air coming out was far warmer.

So the summery I guess of that long writin is:

1. I want to find out if its ok for the compressor to operate at them temps, SHOULD be right? I mean it SHOULD be designed for it, right? Or should I remove the outdoor air intake hose?

2. Would it run more efficiently with the intake hose off or on? With the hose off the coil condenser runs warmer which means outdoor temp is irrelevant [a plus!]. BUT on the downside negative pressure it created and cooler air seemingly would be sucked into the room. BUT if the furnace in the rest of the house keeps it not too chilly in the rest of the house and I leave my door propped an inch I don't know if it'd be the end of the world.

So what do Y'all think? I very much appreciate your responses.


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RE: Question on Portable Heat Pump

The danger with the negative air pressure is you may draw combustion products back inside if you have gas hot water or a gas stove or a fireplace.

You really should be able to download a proper handbook for your model which ought to specify the operating temperatures. As for the window insert, it should be easy to cut a close-fitting piece of plywood (actually two matching pieces) and sandwich some insulation styrofoam inbetween, and stick some weatherstripping around the edges to create a seal.

Most heatpumps start to cost more to run closer to freezing (some newer ones are much more efficient) but if your temps remain in the higher thirties it may be an option, provided the electricity price is comparable or better than gas. As you say, less power than a space heater, but more heat output.


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RE: Question on Portable Heat Pump

pjb999 I didn't think of the issue with the gas appliances, I do indeed have a gas furnace in a utility closet right outside of my room, as well as a gas water heater and drier.

So i GUESS it SHOULD be fine to run with both hoses in super low temps. BUT damn it I REALLY doubt this thing has a crankcase heater so seems like that might cause problems.

I just REALLY don't want to do the compressor any damage, I love this unit and I'll NEVER find one like this again for $90, and I'll probably not have $600 to spend on one anytime soon. So I just want to be sure.

Yea MOST of the days its in the 40s to low 50s in the winter at night here. Just once in a while 30s that why I want to be sure its compressor can handle those temps.

And I can NOT find a manuel for it! I's searched high and low all day yestarday, I found a different company that had a heat pump and Dual hoses and it didn't meantion anything about super low temps.

Also I doubt a lot of PTAC units and window units with heat pumps have crankcase heaters, but maybe they do? I doubt it though.

HOWEVER, my only thought is this. The Compressor does generate a considerable amount of heat while running, right? The fan is only on when the compressors on to take in cold outside air and exhaust. This means cold air only circulates with the compressor on which may keep itself from getting to SUPER low temps in mildly cold envirements, and then when the compressor shuts off thus seizing to create heat from running, the fan stops brining in cold air. The compressor is inside the unit indoors, so maybe it then retains some heat and doesn't get too cold?

This is the only thing I can think of. Sound reasonable? Cause I just don't want it havin that there problem with oil getting mixed with the refrigerant and ruining it.


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RE: Question on Portable Heat Pump

Anybody got ainy ideas?


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RE: Question on Portable Heat Pump

Still no ideas? Tough one huh! I am really starting to think its got to be designed to run 2 hoses in heat mode. Seems like if it was a real danger theird be all kinds of warnings or at least a sticker or something.

I mean a lot of Window Air Conditioning units come with a Heat Pump mode, and I'd kind of doubt they'd have a Crankcase heater, well maybe but if they do seems like this could too. But it doesn't say anything about plugging it in for 12-24 hours like you'd think of it did. I ran it on a cold night without problems so far with both hoses. It works great too! Can heat my whole house to a reasonable temp and keeps the whole area wherever it is very comfortable. Most nights aren't actually below 40F here many in the mid 40s so it works very well for the climate here.

And for Y'all that were wondering about defrosting yes it does defrost and the tank fills up a lot maybe every 6-8 hours. Maybe it does have some sort of warmer or something when it goes into defrost cycle if it gets to cold? I don't know sure beats me but I think its ok.


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RE: Question on Portable Heat Pump

My suggestion is use the unit in heat mode with the two hoses as intended and assume the mechanism will take care of itself.


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RE: Question on Portable Heat Pump

dadoes I think thats what I'll do, maybe just incase for now on REALLY cold nights I'll just use space heaters [I have 5 all different types that work fine], plus heat pumps REALLY don't work all that well in environments below like 20F-30F anyways, but I'll tell you anything above that it works great.

I also have Central Natural Gas Heating however gas is a bit pricey not that bad but I mean in the winter it may cost nearly $100 for gas, so I figure setting the Central Heat for like 65 or something so it don't get to cold and then using the heat pump or space heater to keep it comfy [I know if I use more than 1 space heater at a time it'll run the bill up more than gas for the whole house so I only run 1 at a time]. And this heat pump if its say 45 Degrees will work real well and quick.

So I think I'll just take your suggestion and run it with 2 hoses I doubt it will fail.


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RE: Question on Portable Heat Pump

Hey just wanted to let Y'all know I just read the owner's manuel of a similar Portable AC with Heat Pump and Dual Hoses. Its a Soleus LX 140. I read the whole Manuel, its a full manuel too, not a partial one.

I didn't find anything or any warnings against using both hoses in low temps in heat mode, it just says in heat mode unit needs to be properly ventilated with the hoses. Only thing I did find is it does have an operating range temp chart for both AC and Heating. It says 21 Degrees F as the minimum in Heat mode. This may just mean in it will be very inefficient at these temps or ineffective, or just don't use it below that? Well whatever I have no intention on using it at temps below 30 Degrees and mostly 40s anyways.

So I guess thats pretty much my answer? I'm not gonna worry about it and I'll let Y'all know how it works out.


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RE: Question on Portable Heat Pump

billybobjo you got it all wrong.


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RE: Question on Portable Heat Pump

heatseeker what do you mean? What do I have wrong? I shouldn't have the intake hose intaking from the outside when its cold?


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RE: Question on Portable Heat Pump

I'd really like to know what you think is the problem? I want to use it but know I want to take it out if you have a good reason so please let me know ASAP.

But I did use it all last night and it was 38 degrees out, and it doesn't have any signs of problems. I mean what the hell? Do you think them Window ACs with a Heat Pump mode have a crankcase heater? I really doubt that.

And I have another idea since nobody really seems to sure. There is a 120 Volt Crankcase heater I could buy that is made for small hermetic Compressors, but its a bit expensive like $100 and if anybody else thinks its necessary its better than a $600 unit right?


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RE: Question on Portable Heat Pump

Still NO ideas? Its ok if nobody don't know I mean if Y'all don't know you don't know right?

But heatseeker you shouldn't go tellin me I's got it all wrong but with no reason, you kind of stirred it up cause we'd just about pretty much solved it then you come in sayin I got it all wrong.

Now thats fine and I very much appreciate it if you actually think I'm wrong, if I am I'd like to know why though. Maybe you just ain't been on for forgot, but I'd really appreciate it if you could get back to me soon.

Anyways have a good thanksgiving tommorw Y'all and I'll research more next weekend.


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RE: Question on Portable Heat Pump

WELL I'm REALLY starting to think its FINE.

When I look in there the compressor looks to be wrapped in some sort of insulation cup or something. Maybe it does have some sort of crankcase heater or something? Come on a unit this big CAN'T use one hose, I've tried it with one hose before and its just dangerous with the amount of negative pressure it creates with the furnace and water heater in closets right out in the hall next to my bedroom. It creates SO much negative pressure too my door will fly open when you open it with the attachement opening in the window before you seal it without the intake hose you can feel A LOT of air sucked through the hole into the outdoor intake hole. SO I think its fine.


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hell yes!

HELL YEA! Found the answer Y'all! After ALL this damn time!

Guess what it is? Well, I recently found out that this here unit uses a Rotary Compressor. Yep, theres your answer.

WELL from my research Rotary Compressors do NOT require a Crankcase heater or Oil Separator or nothin like that.

Well I wish someone'd known, but lets all remember this one. Thank you to those who tried to help, I preciate it it was a hard one huh? Even scroll compresors require Crank Heaters, but not Rotary!


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