Window AC + furnace mod = Cheap central air?

[Red Squirrel]

As a cheaper alternative to a proper central air system, I was thinking if I was to rig up either a window AC or one of those portable ones to feed the cold air to the furnace intake, and duct the heat outside, then run just the furnace blower, would that work as a cheap "central air" solution? Obviously it would take much longer to cool the house, but would it work?

Or would doing furnace modding like this be against code? Or I suppose another option is just use a portable one as it is meant but put it near the intake vent.

Just thinking of various AC solutions I could rig up for my house once I move in. Not that it really matters as I'm only moving in in August and by that time summer weather will be long gone.

 

[Iron Woode]

I doubt it will have enough capacity to cool much of anything.

this is why central air units are rated in 22,000 BTU range as opposed to 8,000 BTU for window mounts.

 

[Rastus]

Ducts for heaters and ducts for heaters+a/c are not the same. Heater ducts will corrode and leak due to condensation if A/C is blown through them. Also a window A/C isn't powerful enough to cool down an entire house.

 

[Red Squirrel]

Originally posted by: Rastus
Ducts for heaters and ducts for heaters+a/c are not the same. Heater ducts will corrode and leak due to condensation if A/C is blown through them. Also a window A/C isn't powerful enough to cool down an entire house.

Hmm never thought of this. The real central air units have a condenser unit that goes in the furnace which catches all the moisture before it hits the ducts.

Probably better off to just save up and do it the real way. I have all winter to save up anyway.

 

[Iron Woode]

Originally posted by: RedSquirrel

Originally posted by: Rastus
Ducts for heaters and ducts for heaters+a/c are not the same. Heater ducts will corrode and leak due to condensation if A/C is blown through them. Also a window A/C isn't powerful enough to cool down an entire house.

Hmm never thought of this. The real central air units have a condenser unit that goes in the furnace which catches all the moisture before it hits the ducts.

Probably better off to just save up and do it the real way. I have all winter to save up anyway.

yup, high efficiency central air is the way to go.

 

[zerocool84]

Never Mickey Mouse stuff in a house you want to live in.

 

[Sea Moose]

Originally posted by: Iron Woode
I doubt it will have enough capacity to cool much of anything.

this is why central air units are rated in 22,000 BTU range as opposed to 8,000 BTU for window mounts.

This. Those window units are very crap, and will not cool your entire house. They will struggle to cool a room.

 

[rhino56]

i was thinking maybe a water cooled suit you could wear?

 

[EricMartello]

Central Air units are rated in "tons", and the rule of thumb is 1 ton of cooling capacity per 500 sq ft. 1 ton is about 12,000 btu...but there is more to it than that. There are in fact A/C units that have that kind of cooling capacity, but they are not "window mount". They are designed to be mounted permanently in a cutout within the wall.

As long as you can isolate the compressor portion of the A/C outside of your building, it is feasible for this to work. You could buy the foam laminated with foil ducting material to make a ghetto duct which goes into the return side of your furnace. The fan would then circulate the cool air through your house...the condenser is part of the A/C unit that will be outside. On central AC units, the condenser/compressor is a separate, self-contained unit which is installed outside.

 

[Sea Moose]

Originally posted by: EricMartello
Central Air units are rated in "tons", and the rule of thumb is 1 ton of cooling capacity per 500 sq ft. 1 ton is about 12,000 btu...but there is more to it than that. There are in fact A/C units that have that kind of cooling capacity, but they are not "window mount". They are designed to be mounted permanently in a cutout within the wall. <-- Window unit are the nick name for what your talking about.

As long as you can isolate the compressor portion of the A/C outside of your building, it is feasible for this to work.<---Nope, not enough capacity You could buy the foam laminated with foil ducting material to make a ghetto duct <--- WTF is ghetto duct, is that a nickname for somthing? which goes into the return side of your furnace. The fan would then circulate the cool air through your house...the condenser is part of the A/C unit that will be outside. On central AC units, the condenser/compressor is a separate, self-contained unit which is installed outside. <-- This last sentence is true, this is the equipment you require to cool your house.

I am a HVAC mechanic, so i kinda know what im talking about.

 

[EricMartello]

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit...but it would probably make a house more comfortable than on a hot, humid day.

 

[Sea Moose]

Originally posted by: EricMartello

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit<-- A waste of money and effort...but it would probably make a house more comfortable than on a hot, humid day.

First of all, the fan in those window units would not overcome the static pressure of the ductwork, so simply you will not get enough airflow.
Secondly, 8kw is enough to do a large living area, not an entire house
Thirdly, those window units are rubbish and are not very efficient (which is why they are being phased out)

To the op,

You could get a high wall split system, to cool your living area or a bedroom. (these are reverse cycle and are the most efficient way to heat or cool if you get an inverter)
You can get "multihead" unit that have one outdoor and up to four indoor units. <-- Expensive


You could get a central air unit to do your whole house, i am not sure if you could integrate this with your furnace. (dont need a furnace where im from)

 

[Sea Moose]

Originally posted by: RedSquirrel
As a cheaper alternative to a proper central air system, I was thinking if I was to rig up either a window AC or one of those portable ones to feed the cold air to the furnace intake, and duct the heat outside, then run just the furnace blower, would that work as a cheap "central air" solution? Obviously it would take much longer to cool the house, but would it work? <--- NO IT WOULDNT

Or would doing furnace modding like this be against code? Or I suppose another option is just use a portable one as it is meant but put it near the intake vent.

Just thinking of various AC solutions I could rig up for my house once I move in. Not that it really matters as I'm only moving in in August and by that time summer weather will be long gone.

 

[EricMartello]

Originally posted by: Sea Moose

Originally posted by: EricMartello

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit<-- A waste of money and effort...but it would probably make a house more comfortable than on a hot, humid day.

First of all, the fan in those window units would not overcome the static pressure of the ductwork, so simply you will not get enough airflow.
Secondly, 8kw is enough to do a large living area, not an entire house
Thirdly, those window units are rubbish and are not very efficient (which is why they are being phased out)

Right, which is why the OP was going to route the cool air from the window unit to the blower fan of his furnace which would distribute throughout the house. The window unit would not need to overcome the static pressure of the entire ducting system. Hey if he's game let him try. The worse that could happen is it doesn't work.

 

[Sea Moose]

Originally posted by: EricMartello

Originally posted by: Sea Moose

Originally posted by: EricMartello

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit<-- A waste of money and effort...but it would probably make a house more comfortable than on a hot, humid day.

First of all, the fan in those window units would not overcome the static pressure of the ductwork, so simply you will not get enough airflow.
Secondly, 8kw is enough to do a large living area, not an entire house
Thirdly, those window units are rubbish and are not very efficient (which is why they are being phased out)

Right, which is why the OP was going to route the cool air from the window unit to the blower fan of his furnace which would distribute throughout the house. The window unit would not need to overcome the static pressure of the entire ducting system. Hey if he's game let him try. The worse that could happen is it doesn't work.

Yes he could try, or he could save his money and not buy a window unit.
Best thing for you to do op is get your local HVAC professional in to give you a quote

 

[Iron Woode]

Originally posted by: EricMartello

Originally posted by: Sea Moose

Originally posted by: EricMartello

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit<-- A waste of money and effort...but it would probably make a house more comfortable than on a hot, humid day.

First of all, the fan in those window units would not overcome the static pressure of the ductwork, so simply you will not get enough airflow.
Secondly, 8kw is enough to do a large living area, not an entire house
Thirdly, those window units are rubbish and are not very efficient (which is why they are being phased out)

Right, which is why the OP was going to route the cool air from the window unit to the blower fan of his furnace which would distribute throughout the house. The window unit would not need to overcome the static pressure of the entire ducting system. Hey if he's game let him try. The worse that could happen is it doesn't work.

it still is a waste of time.

1. the unit will be constantly stressed

2. the cooler air will warm in the duct work and will cause condensation and mold.

3. there is not enough capacity to cool a multi-level house.

4. it would be more effective to install some ceiling fans and open the windows.

just save for a high efficiency central air.

 

[Sea Moose]

Originally posted by: Iron Woode

Originally posted by: EricMartello

Originally posted by: Sea Moose

Originally posted by: EricMartello

Originally posted by: Sea Moose
I am a HVAC mechanic, so i kinda know what im talking about.

http://www.walmart.com/catalog....do?product_id=8798103

A 29K BTU "window" unit with enough cooling capacity for about 1,500 sq ft - i.e. a modest-size house.

This whole rig qualifies as "ghetto", so naturally the ducting would be as well. A window unit piped into the blower fan of a furnace? Ghetto indeed, but if set up correctly it would work. It would not be as efficient as a true central air unit, and it would probably not cool as effectively as a central air unit<-- A waste of money and effort...but it would probably make a house more comfortable than on a hot, humid day.

First of all, the fan in those window units would not overcome the static pressure of the ductwork, so simply you will not get enough airflow.
Secondly, 8kw is enough to do a large living area, not an entire house
Thirdly, those window units are rubbish and are not very efficient (which is why they are being phased out)

Right, which is why the OP was going to route the cool air from the window unit to the blower fan of his furnace which would distribute throughout the house. The window unit would not need to overcome the static pressure of the entire ducting system. Hey if he's game let him try. The worse that could happen is it doesn't work.

it still is a waste of time.

1. the unit will be constantly stressed

2. the cooler air will warm in the duct work and will cause condensation and mold.

3. there is not enough capacity to cool a multi-level house.

4. it would be more effective to install some ceiling fans and open the windows.

just save for a high efficiency central air.

This

 

[MikeyIs4Dcats]

Originally posted by: Rastus
Ducts for heaters and ducts for heaters+a/c are not the same. Heater ducts will corrode and leak due to condensation if A/C is blown through them.

you're an idiot. ductwork is all sheet metal. The only difference may be if the duct is insulated or not, but in many many homes duct doesn't get insulated.

 

[feralkid]

Originally posted by: MikeyIs4Dcats

Originally posted by: Rastus
Ducts for heaters and ducts for heaters+a/c are not the same. Heater ducts will corrode and leak due to condensation if A/C is blown through them.

you're an idiot. ductwork is all sheet metal. The only difference may be if the duct is insulated or not, but in many many homes duct doesn't get insulated.

I got a good laugh trying to imagine a house with separate ducts for heat and A.C.

 

[Capt Caveman]

Being up north, I don't know if the cost of a central a/c system will be worth the investment. I believe your house is fairly small too. A couple of window ac with the assistance of fans to help circulate the air should suffice at a low cost.

 

[PowerEngineer]

If you are seriously thinking about adding a central air conditioning unit, you should consider going with a heat pump. Being essentially a reversable air conditioning unit, it might save you enough on heating costs to offset its slightly(?) higher cost.

 

[Red Squirrel]

Originally posted by: PowerEngineer

If you are seriously thinking about adding a central air conditioning unit, you should consider going with a heat pump. Being essentially a reversable air conditioning unit, it might save you enough on heating costs to offset its slightly(?) higher cost.

I've thought of this actually, and the goverment will give a tax break on stuff like that too.

But yeah I'll probably just save up for real AC. Just an idea I had

And yeah Central air is hooked up the the furnace, that's how it gets distributed throughout the whole house. They basically cut some holes in the main duct to add the condenser unit which is also where the cold freon lines coil up, and the compressor / hot side is outside. So I figured, could rig up something using a smaller AC unit. But guess it would probably end up using more electricity as it would be constantly running. I'm probably better off getting real central air just for the fact that in the end it will be more efficient.

 

[Uhtrinity]

Originally posted by: Sea Moose

Originally posted by: Iron Woode
I doubt it will have enough capacity to cool much of anything.

this is why central air units are rated in 22,000 BTU range as opposed to 8,000 BTU for window mounts.

This. Those window units are very crap, and will not cool your entire house. They will struggle to cool a room.

I have a large window unit rated at 22,000 btu. Been running it for almost 5 years and works great. Only paid ~$250 for it at Sears on clearance.

 

[zerocool84]

Originally posted by: Uhtrinity

Originally posted by: Sea Moose

Originally posted by: Iron Woode
I doubt it will have enough capacity to cool much of anything.

this is why central air units are rated in 22,000 BTU range as opposed to 8,000 BTU for window mounts.

This. Those window units are very crap, and will not cool your entire house. They will struggle to cool a room.

I have a large window unit rated at 22,000 btu. Been running it for almost 5 years and works great. Only paid ~$250 for it at Sears on clearance.

I have one too. Loud, takes forever to cool, and doesn't pump enough air. They are good for rooms but that's about it.

 

[DrPizza]

Actually, something that I think Sea Moose is overlooking - OP lives much closer to the North Pole than Sea Moose thinks. The air conditioning demands in a climate 100 miles north of the US border are far less than the air conditioning demands where seamoose lives (doesn't have a central furnace.) The worst the OP will probably experience is a couple of days in the high 80's. And, living on the frozen tundra called Canada, I'm going to guess that his house is very well insulated. I've been in very well insulated houses in this area (western NY) in the summer when it's 85 outside. The owners typically brag about how their house AC only cycles on about once per hour. And, I've been in upstairs apartments of houses that have virtually no insulation - those window AC units work their asses off.


In my opinion, OP, go for it - what have you got to lose? Spend a couple hundred on a new window air conditioner at wallyworld. If it doesn't work, you're only out $100 (sell it used on craigslist for $100 less than you bought it during the first "heat wave" you experience up in the Great White North.