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NiHaoMike 09-24-17 05:39 PM

Direct the cold air up towards the ceiling.

ecomodded 09-24-17 05:50 PM

I did read manufactures say these portable AC heaters were to be used for heating between 40 and 50*F

My thinking was they were talking about the dual hose Models well that was my assumption , you know what they say about those ..

the facts are a heat pump moves heat from once place to another

The way its placed it will move cold from the room and expel cold out the back at a Cop of 2.7 bringing in new air to run continuously.

Hopefully it heats for me this winter or its Junk as far Im concerned as Jeff suggests
I feel pretty good about it Im hopeful anyways as that 75 cfm air coming in and out allows 245 cfm of air to be conditioned

ecomodded 09-24-17 06:13 PM


Originally Posted by NiHaoMike (Post 55653)
Direct the cold air up towards the ceiling.

Do mean the cold intake air ( probably just a typo and you mean Hot air) anyways the intake comes in threw cracks and out the back of unit and out the vent.

I will be directing the hot air up to the ceiling so we are thinking similar just different criteria, I want heat upstairs

Thinking I will sit the unit on a table so the vent will go straight out a old pellet stove vent , then tape a cardboard duct to the units cold intake that leads to the exhaust and extend it down low to the floor so it will draw cooler floor air out the back of the unit and out of the rear vent. Then direct the front heat vent upward toward the the rooms roof and out the doorway that leads to the stairway and upper floor.

Might hang a blanket in the rec room doorway with 18 inches of space at the top of the door and 12 inch gap at the bottom so the house will have good convection.

As right out that doorway two flights of stairs are leading to the upstairs where I hang out.

So the downstairs room will be like a breathing and heating room for the house

The house is a open concept so the stairway and front door has no walls upstairs just a iron railing to separate the stairs from the living room etc.

Its good to get input as its a challenging premise using a little unit like this

Ive invested money into this thing so have a little tunnel vision going not too much I hope.

I guess worse case scenario is it can be use in the milder weather if so I'll call it a wash.

I will put it on a power meter and see what kind of economy it provides as it is the house uses $20 to $25 a month in electricity without heat so the bills will be easy to decipher.

NiHaoMike 09-24-17 10:46 PM

The idea is that since heat tends to rise, directing the cold air up in heating mode offsets that and reduces losses through the ceiling. You'll have to experiment to see if it's more efficient than directing it outside after accounting for leakage.

jeff5may 09-24-17 10:55 PM

Ok, here's my take on what you're figuring. The compressor uses maybe 1000 Watts up from the power line. Some of this is radiated from the compressor shell directly and some superheat is added to the cool refrigerant as it passes by the motor coils. The rest is used up as work of compression. As the preheated and compressed refrigerant condenses, all of the added superheat is dissipated before the gas condenses. So there's your standard resistance heating component. The fans don't count, as they are not using lots of power, and are either both adding to indoor heating or subtracting heat from each other.

As the refrigerant condenses, it gives off lots of heat. It is then subcooled a few degrees. Due to the high surface area and high airflow, heat recovery is effective. Lets say that x amount of airflow heats up 9 degrees F in one pass through the condenser. The warm air rises naturally away from the unit. Between the compressor radiation and forced air convection, there's your 14K BTU of raw heat gain.

On the other side, the room air is sucked through the evaporator at a slower rate and is cooled by the evaporating refrigerant. Let's say that x/3 amount of airflow is cooled 30 degrees F. This cold air is exhausted outside. Let's say 12K BTU makes it outside. So you lost 2K BTU in leakage between everything everywhere. That's 12K BTU NET HEAT GAIN.

This arrangement works well because the x/3 amount of infiltration (make-up) air is not always as cold as the exhaust air, especially in spring and fall. When it is warmer outside than your exhaust air, let's say 35-40 degrees F, the system is gaining BTU from your make-up air. With a 1-pipe setup, the delta T is always going to be low, as both heat exchangers are being fed room temperature air. As a result, the evaporator is not going to frost up on you (more latent energy rejection down the drain as condensed humidity), and the unit COP remains high. Even when it is frosty outside, the recirculated BTU (drawn into the refrigerant in the evaporator and rejected into the house) is much more than the power drawn from the power line. The gradients from (the make-up air minus exhaust air) and (outdoor air minus exhaust air) subtract from the overall refrigerant heat transfer.

With a 2-pipe setup, the evaporator is fed cold outdoor air. The delta T works against outdoor temperature, and so does COP and condenser discharge temperature: as outdoor temperature drops, they all get worse. As outdoor temperature approaches freezing, the evaporator can frost up fast, then the unit loses its advantage. Efficiency really depends on lots of stuff that is usually not included in these rigs, like variable expansion valves and hot gas defrost. That's why the makers discourage 2-pipe use below about 40 degrees F: passive defrost using ambient airflow to thaw out the evaporator is slow, plus the compressor is shut off.

ecomodded 09-25-17 12:56 AM

NiHoaMike that would be a easy install plug it and let it run , where do see the heat gains coming from ? is it in the refrigeration cycle ?

I know of heat gain by enthalpy of moisture vapor in the room , not sure where other gains are made , Where or what are you thinking it will make gains in a closed loop system ?
Maybe enthalpy in the cooper tubing ?

Im thinking the trick is to scavenge the heat from the room and blow out condensed cold air to the outside vent leaving the condensed heat in the house.

Like this

70* house air gets cycled and exhausted back to the house at say 110*

With a 2/3 smaller volume of air being chilled down from 70* to say 35* on the cold side and expelled.

The heat gained is scavenged from the outlet air with a bit more from the enthalpy of water vapor to liquid.

I don't know the cycles well at all , can you explain your Theory ?


After reading Jeff5mays post again I see the magic is right there in front of us

Quote Jeff5may

The compressor uses maybe 1000 Watts up from the power line. Some of this is radiated from the compressor shell directly and some superheat is added to the cool refrigerant as it passes by the motor coils. The rest is used up as work of compression. As the preheated and compressed refrigerant condenses, all of the added superheat is dissipated before the gas condenses. So there's your standard resistance heating component.

So its condensation in the unit that makes up the mystery heat , if I understand it correctly

ecomodded 09-25-17 01:14 AM

Jeff5may I am following you on your understanding its the one I guess I need to work with and pretty much convinced that's how it will work for me as a few People have had the same suggestion.

It will be depended on the intake temp vs outlet temp.

Unless part of the refrigeration cycle makes up more heat then air infiltration would cause in losses

I don't know of what cycle that would be if it exists , Maybe NaHoemike has a idea

jeff5may 09-25-17 01:33 AM

The main idea is this: as long as the evaporator doesn't freeze up, the one pipe setup will work as best it can. The reducer coupling on the exhaust pipe may or may not keep the evaporator from freezing. Rig it up and see if the unit short cycles. It might not do it until it gets pretty cold outside. If it does, a bigger exhaust pipe will probably keep the unit going, but by then the make-up air will already be eroding at your net heating factor. Trial and error will figure it out. Compared to a baseboard heater, the little heat pump has a long way to fall before it is less efficient, watt for watt.

Ormston 09-25-17 01:53 AM

We are talking about a heat pump, it doesn,t create, destroy, amplify, magnify, concentrate or otherwise pull heat from the ether.
It's only purpose in life is to move heat from one place to another.

In your case it is pumping heat from inside the house and blowing it back inside the house for a gain of nothing.
Some chilled air gets blown outside, so long as this chilled air is colder than the outside air that infiltrates the house there will be a net heat gain.
Once the outside air temperature drops to equal the temperature of the outlet duct the gain will be nothing.
When the outside temperature is below the outlet duct temperature you will be pumping heat out of the house.

Virtually all of the electric consumed will degrade into heat and end up in the house.

What you need to test is what is the temperature of the outlet hose when the device is sat in a room at the temperature you maintain during the winter.

As the only gain is the temperature difference between the outlet duct air and the external air this is where your answers are.


ecomodded 09-25-17 02:00 AM

The idea is 1200w will make 11,000 BTU of heat at a 2.7 COP gain
In practice this may well not work as its a semi closed loop ?

Part of the heating equation is heat loss by conduction threw walls making the house part of the systems usefulness of it.

So the interior air needs heat added on a regular cycle as the house cools by conduction and air infiltration.

Its sounding like both jeffs are thinking the same as you Ormston thats 3 people so far sounds like we have this dog figured out

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