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ecomodded 09-23-17 02:46 PM

Portable Ac with heat single hose for winter heating ?
Edit ~ To get to modifications implemented and required follow the link to post # 91

Going try using a single hose portable 14,000 Btu Honeywell ac with 11,000 Btu heat for the fall and winter heating season.

The usual day and night low winter temperature is between 1*c / 33*f and -5 / 22*f

The unit I picked up has a Cop of 2.75 and has no cold temperature limit mentioned assume because its a single hose unit. It says is good for winter heating and ends there with no temp info.

As it scavenges heat from the warm inside air and exhaust cold air the outside temp can be much lower then a dual hose unit if my understanding is correct

The single hose units are reported to output about 30% of the air it conditions threw the rear vent. The Honeywell unit in question airflow is 245 cfm 30% of that is about 75 cfm so that's its loss threw air infiltration.

I'm thinking the single hose will allow me to run it all winter well that's my expectation.

It will be placed in the basement of a split level home with a open stairway so air natural convection will heat the upper floor or so I'm hoping.

Should mention the basement has its own cracks to feed it with as well as the rest of the house has its little cracks and air infiltration being a mid 70's split level house.

In this case what do you think ? will the single hose Ac/ heater save me money on heating or will draw to much cold air from cracks to make it transfer the heat upstairs ?

I'm thinking the single hose would allow me use it in colder winter weather including at night.

I have not found any info on people using a single hose unit as I described I have read that single hose units are best for one room cooling due to the negative pressure I'm hoping that with it in heat mode its convection will heat the upper floor despite the units negative pressure.

Am I being way too hopeful or what you think offhand ?

Im second guessing myself for buying it and not dual hose i was thinking the dual hose would not work well during the night and on cold days due to its poor cold weather performance. I payed $350 for it delivered or about 1/2 price.

jeff5may 09-23-17 11:11 PM

I ran a few of this type of unit while I was trying out the same concept. There are two ways to approach this concept:

1. put the unit in the cold and blow in warm air
2. put the unit in the warm and blow out cold air

I found that method 2 works very well with the portable aircon units. The things recirculate a lot more warm air than they do cold air. The one I ended up using all winter was a non-reversible, cooling-only model. It was pointed towards a window, and the cold air exhaust was sealed up with xps foam boards against the cracked open window opening. I toyed with trying to recirculate some outdoor air into the evaporator, but found it made the evaporator frost up. The family called it "the wolf" because the squirrel cage condenser blower howled (quietly). It did a good job of keeping the inefficient gas furnace shut off until temperatures dropped below maybe 40 degF.

oil pan 4 09-24-17 11:10 AM

Those things are junk.
But better than nothing, but only by a little.
So glad I replaced mine with a 2 ton inverter split.

ecomodded 09-24-17 12:12 PM

That is reassuring to hear , I should be fine with this units reduced outlet flow

It was a rush purchase they were almost sold out of the single hose units with just 1 left so bought it haphazardly spuriously after quickly deducing it would be better of the two styles for winter heating.

I'm hopeful it will work fine its good to get some input on heating as most people cool with these it seems.

A electric heater down in the rec room heats up the top floor real nice. If I don't heat the basement room the stairway and front door area are chilly all winter long. That air mixes with the living room kitchen and dinning room air.

So with it will be heating 1/3 the basement and the 2/3 of the top floor with 1200w of juice.

That works out to $55 @ 12hrs use or $110 @ 24hrs continuous use.
The coldest months pay as much $300 per month with baseboard heating , $1200 a yr

The owners of the dual hose models defend them strongly for summer cooling I have to agree with those arguments as the temp difference is only 20 to 30 degrees.
Where as winter temps are more like a 60 to 70* difference.

It will be vented from a pellet stove outlet left in place from the previous owners. Currently has a 4 inch vent the AC vent is 5.9 inches.

First thought was to use a 6 to 4 reducer after reading up on it appears it may cause too much of a restriction

In my head I deduced a 4 inch outlet would reduce the airflow by about 1/3 which should reduce the air infiltration by the same amount.
A win win I thought before reading papers on airflow vs pipe diameter.

After checking it looks like a 4 inch vent might reduce the airflow by 50% to 70% if I understand it correctly.

So its looking like I will use the same size vent outlet to keep the units efficiency up.

ecomodded 09-24-17 12:33 PM


Originally Posted by oil pan 4 (Post 55645)
Those things are junk.
But better than nothing, but only by a little.
So glad I replaced mine with a 2 ton inverter split.

Im not staying in my house for much longer 1 yr tops so this is a quick fix for this fall winter heating season and I'll leave in place for the next owners.

If this crappy unit cuts my electric bill in half or there about I will call it a complete success and a worthy purchase.

If it doesn't do that I would have to agree they are junk as I bought it save money not spot heat

I will update the thread as its usefulness or lack thereof unfolds over the upcoming months starting next week.

It will make good use of a vent that's in place if its successful it might pay for itself in the next 3 months, time will tell

ecomodded 09-24-17 01:43 PM

My latest deduction is this

The unit is 275% efficient vs baseboard it draws in 1/3 cold air from air infiltration

So it has a added loss of 1/3 that is re warmed at 275% efficiency rate

So its worse feature is padded by the high efficiency making for a win win no matter how I look at it as compared to baseboard heating.

I could not find one person who thinks along those lines on the internet the HVAC guys know little about these crappy units so their input was always flawed in some way.

A good discussion I found was on "the straight dope" forum - Portable air conditioner - one hose or two?

I learned how not to look at it by reading that forum more so could see the errors in the logic even though it was talking about cooling not heating. I had to reconvert the discussion to my heating needs.

This thread may well gain some attention as there is practically no info on heating with a portable ac with heater on the web not in my search results anyways

A simple query turned into a confusing topic.

Although still not 100% if the negative pressure will or will not hold the warm air in the downstairs room.

That is going need to be tested directly to see if this thing is a win or loss

I'm assuming the first few paragraphs I wrote are correct

Ormston 09-24-17 03:28 PM

1 Attachment(s)
I like the idea but struggle to see it working.
The only way i see it heating the house by more than the power consumption is if the air expelled from the outlet hose is colder than the outside temperature.

Assuming the outlet hose expels air at 0C and the outside temp is 0C, take a look at the attached sketch (I used a cop of 4 to make it easier to see)


Attachment 7907

oil pan 4 09-24-17 04:02 PM

The problem with these units when heating or cooling is the air they draw into the house to move heat.
They work alright cooling since they are drawing in air that is maybe 10 to 30F degrees warmer than what they are trying to cool. The real problem comes when the temperature difference is 50F or more.

ecomodded 09-24-17 04:44 PM

Im not sure you have it correct in the diagram ?

its not what I expect from a heat pump it may well be correct , I don't feel its correct as you left out the input COP which turns that 1kw of cold into heat and the output with its heat stripped out

the unit will turn 2/3 of the interior warmth back on its self at a hotter temperature expelling 1/3 cold and bringing in 1/3 more for a continuous cycle.

The air that comes in allows the cycle to repeat gaining 2/3 the Btu it expels out the back.

As long as the interior is within working temp it will scavenge the heat and reject the 1/3 of colder conditioned air.

So it will heat more then it cools while in heat mode.

1kw in gets turned to 2.7 kw in heat with 1 kw back out for a gain of 1.7 kw

As its a heat pump it must do better then the 1 to 1 performance the diagram has.

Im thinking ( yikes) the chart needs adjusting , the air expelled has 2000w of Cop of heat removed and saved in the house using a 2.7 Cop cycle and a 1200w power draw.

Its the heat concentration that makes the gains or what am I missing ?

ecomodded 09-24-17 05:00 PM


Originally Posted by oil pan 4 (Post 55650)
The problem with these units when heating or cooling is the air they draw into the house to move heat.
They work alright cooling since they are drawing in air that is maybe 10 to 30F degrees warmer than what they are trying to cool. The real problem comes when the temperature difference is 50F or more.

When in cooler mode the manufactures suggest the owners of the two hose models plug the intake outlet and use it as a one hose unit if the temperature difference is high and / or if the humidity is high to get the unit to work more effectively.

Im not sure how that relates to energy savings , it does increase its effectiveness or ability if you exhaust them and let them draw in air from cracks etc

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