Window Unit AC modification into Split System? Possible?

[bwpatton1]

Hello, This is my first post on the board! I have tossed an idea around in my head for a while now and before I tried anything, I wanted to confirm the idea was solid. Is it possible to extend the refrigeration lines in a standard window unit to turn it into a split system? Now I'm not talking about 10-20 foot of extra lines here. Just a few feet (3-5) To put the condenser on the outside of the building an the evap. inside or to have the two separated for whatever reason. Is this even possible? I read somewhere that compressors on window unit AC's are sized exactly for their application, no deviation. I have no idea if that is true or not but that's what someone else posted. Thanks for your time!

[texas64]

You would need another fan motor for starters..

[Tesla]

Hi bwpatton1 and welcome to our forum

Yes you can split the system and adjust the charge to suit. Adding another fan motor as one does both heat exchangers with a double shaft. Considering condensate which is used in some units to assist cooling of the condenser of outdoor coil on cooling mode. I have a window rattler which is undersized for my bed room and on really hot days (+40degC) it makes a groaning noise so I have to switch it off for an hour to cool down before starting it again, this happens when the sun hits it which is only for 5 hours max in the peak of summer. Another feature is allowance for fresh air to be drawn into the room.

[mad fridgie]

It is good to see young fellow thinking! There are no technical reasons why it could not be done, how ever the practical issues well that another matter, as state above.

[Gary]

I see no reason the window unit couldn't become a window-sill-saddle type unit with the primary noise makers outside. Something would have to be done about the condensate drainage and there would need to be two separate fans. Definitely could be done.

[bwpatton1]

Awsome! I had figured on having to redo the fan setup on the unit, since there is only one fan motor on any window Ac's I have encountered. I think this could have practical uses, like in a room that large holes in the wall are not obtainable or for interior rooms. Maybe even for aesthetic appeal, the condenser could be hidden somewhere...Definitely cheaper than a mini split system.
Oh, I almost forgot, Does anyone know of a place where I can obtain a formula or something of the like to calculate heat load. One of my possible future projects (if parents allow!) would be to modify a window unit to build a type of package unit for an outbuilding that we have on our property. This would mainly be to decrease noise inside the building and to add a heat strip/burner assembly for in the winter. The reason I have an interest in window units is that they all I can legally touch...I am about to become certified with a Type 1 608 EPA license and that license is limited to small appliances. :( Well That and they are relatively cheap and easy to come by. Thanks for everyone's time and the fast responses!

[Gary]

Window shakers are my favorite experimental platform.

I once modified one to chill denatured alcohol for cooling a computer CPU. I got it down to -30F in my basement. The guy I sold it to said he stuck it in a window in mid-winter and hit -76F.

More recently, I (heavily) modified one to heat domestic hot water and hung it in the attic. It's running way outside the envelope... so I'm thinking the warranty is void.

It's a great starting point for all sorts of experimentation... and best of all, cheap.

Keep us posted on your progress. Should be interesting. :)

[bwpatton1]

Sorry for such the late reply but school has been so busy here recently. Since my last post I have come into several components of interest, the main being a possible reversing valve in a 3/8in size. At one of my dads jobs he had to replace a small special purpose packaged AC unit used to keep electrical control panels cool. Since it was a total replacement he gave the old unit to me, the unit is only 1200BTU but the reversing valve is the same size as a window unit piping. My question is if implemented in a standard window unit, could I create a heat pump? Heat pumps work the same as normal ac's just with the reversing valve and different controls (I'm completely replacing the controls). If I could turn the window unit into the split system and add this reversing valve in, that would just be amazing.

[bwpatton1]

Oh I forgot, the packaged unit (Could it be a PTAC since it has separate fans and its very packaged?, Industrial Cooling Systems Model IQ1200VS) has a bad compressor. If I were to change out the compressor and expansion valve (and flush the system) could I use a compressor from a small dehumidifier unit (provided the same hp) as I read somewhere that those compressors are only rated to about 1200BTU. I would like to use a proper replacement but Im only a student with no access to spare parts of fairly cheap nature, that is what all of this rigging is about oh and its also kinda fun to see how much of this rigging can work out in the end. Thanks alot, You guys are the best!

[Gary]

If the component ratings are not matched, that doesn't necessarily mean it isn't going to work... but it may not work at it's best or most efficient. Since you are experimenting, just go for it and see what happens. :)

If the compressor is undersized, it may be overloaded. You can guard against this by installing a crankcase pressure regulating (CPR) valve. This may or may not be needed.

[Gary]

A heat pump gets a little more complicated than just installing a reversing valve. The flow in the liquid line is reversed, so you will need a check valve bypassing around each TXV. In addition, both coils must be bottom fed so the liquid can be fed into the liquid line when that coil becomes the condenser.

[Gary]

You may want to start here:

http://www.refrigeration-engineer.com/forums/showthread.php?19701-Refrigeration-101

[Gary]

I would recommend taking this a step at a time.

First step would be to replace the compressor and get the unit working properly.

Second step would be transforming it into a heat pump and getting that working properly.

Third step would be removing and separating the evaporating (indoor) section and getting it working properly.

[bwpatton1]

Ok, I see what you mean about the heat pumps, I never knew that the coils had to be bottom feed. I really meant to phrase my sentence in my last post about the workings of heat pumps as a question but instead it looked like a statement. Its amazing what a little lack of punctuation can do, oh well...:o
I figured the compressor idea would not work but I just had to throw that out there. I will probablyend up salvaging the parts from the little 1200BTU ac for later projects and continue on with the single window unit seperation. I think I'm going to try and build a tiny air handler cabinet for the window unit. Basically I figure that I can enclose the evaporator coil within a fabricated box along with a new blower assembly and add ducting on either end of that as a return/refrigerated air config. The condenser portion will be just a few feet away in another housing in the attic(would it be better to go the extra few feet to just outside the gable of my house and build it a platform to sit on?) and reuse the condenser fan from the original window unit(maybe). This idea has changed somewhat since I posted originally as my parents have said cutting into the floor for the registers in the game room will not fly, so the default is cutting into the ceiling in my room. :D

[mad fridgie]

Parents who would have them!!!
Remember that ducting has resistance, and this resistance has to be overcome by your fan, if it does not then the airflow is reduced, lower the refrigerant temperatures in the evap "reducing capacity and efficiency" Cooling only.
I have to agree with Gary master the basic firsts, then make one change at time. If you do to many at once you may not know if you have a problem or not and if so where the problem lies