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-   -   Anyone integrate central air into forced hot air system? (http://www.diychatroom.com/f17/anyone-integrate-central-air-into-forced-hot-air-system-169340/)

lewisthepilgrim 01-16-2013 10:17 PM

Anyone integrate central air into forced hot air system?
 
I have forced hot air. I want to integrate a Central air system into my house. What exactly is involved in integrating the Air conditioning unit INTO the existing ducting/blower system ???

HVAC1000 01-17-2013 12:33 AM

depending on the house and existing ducts its usually pretty easy. first you must make sure you have enough wires between your thermostat and the furnace, a Y is what you need, may need to run new wire but maybe not. next a section of duct needs to be cut out above the furnace then the evap coil will be installed in that spot and sealed into the ducts. next we place the condenser somewhere around the house this is pretty simple most of the time. then comes the hard part. we need the run the line set (two copper tubes plus a two wire) from the evap coil to the condenser, if you have a crawlspace, unfinished basement, or a drop ceiling this goes very quickly and easily. the last part is to have the electrical ran from your breaker box the the outside of your house at the condenser then the electric is hooked up to the unit. depending on your local codes you can use the same hole the lineset comes through. then once the lineset is sweated in at both ends a vacuum is pulled on the system and checked for leaks. then the system is charged with the refrigerant (either shipped in the condenser or must be filled from tanks). its not too hard but it is law to have a EPA certification to handle refrigerant or charge the system. if you DIY this call out a pro to do the charging of the system

lewisthepilgrim 01-18-2013 08:19 AM

Quote:

Originally Posted by HVAC1000 (Post 1095432)
depending on the house and existing ducts its usually pretty easy. first you must make sure you have enough wires between your thermostat and the furnace, a Y is what you need, may need to run new wire but maybe not. next a section of duct needs to be cut out above the furnace then the evap coil will be installed in that spot and sealed into the ducts. next we place the condenser somewhere around the house this is pretty simple most of the time. then comes the hard part. we need the run the line set (two copper tubes plus a two wire) from the evap coil to the condenser, if you have a crawlspace, unfinished basement, or a drop ceiling this goes very quickly and easily. the last part is to have the electrical ran from your breaker box the the outside of your house at the condenser then the electric is hooked up to the unit. depending on your local codes you can use the same hole the lineset comes through. then once the lineset is sweated in at both ends a vacuum is pulled on the system and checked for leaks. then the system is charged with the refrigerant (either shipped in the condenser or must be filled from tanks). its not too hard but it is law to have a EPA certification to handle refrigerant or charge the system. if you DIY this call out a pro to do the charging of the system

How exactly is integrating the evaporator into the ducting/blower unit done?

Im universal refrigerant certified. But I only work on fridges and window units :wink: I have replaced a few central air compressors though...

av-geek 01-18-2013 09:39 AM

The following image shows a gas furnace, the green part, equipped with a central air conditioning system added to it. The silvery part of the ductwork on top of the furnace is where the evaporator coil is. The black hose coming out of the duct is the gas, suction line, while the tiny copper line is the liquid line. The expansion valve, or capillary tubes (depending on which design is used) is within the coil assembly sitting on top of the furnace too. At the top of the photo, you can see where the duct takes a left turn and heads towards the regesters within the house. The large duct to the left of the furnace is the return air line. The white PVC lines coming out of the furnace are combustion air intake and exhaust. The gas line is the yellow line between the return air duct and the furnace.

http://www.bullmarketrealty.net/_acc...ting/26-16.jpg

HVAC1000 01-18-2013 10:20 AM

Quote:

Originally Posted by lewisthepilgrim

How exactly is integrating the evaporator into the ducting/blower unit done?

Im universal refrigerant certified. But I only work on fridges and window units :wink: I have replaced a few central air compressors though...

The way I like to explain it to people is that the conventional (at least around here) HVAC system is made up of three modules. First you have your fan module which is in the bottom of your furnace and is used by both the heating and cooling. Next you have your heating module which contains the burners heat exchanger(s) and so on. Last is the cooling module which is the A coil on top of the furnace. Basically to integrate you are just adding a new module on top of the furnace. The only other integration part is wiring it in and making sure your tstat can do cooling.

And if you have the universal license you are good the handle the refrigerant. Just make sure you sweat the line set in well enough

JScotty 01-18-2013 11:38 AM

Quote:

Originally Posted by av-geek (Post 1096314)
The following image shows a gas furnace, the green part, equipped with a central air conditioning system added to it. The silvery part of the ductwork on top of the furnace is where the evaporator coil is. The black hose coming out of the duct is the gas, suction line, while the tiny copper line is the liquid line. The expansion valve, or capillary tubes (depending on which design is used) is within the coil assembly sitting on top of the furnace too. At the top of the photo, you can see where the duct takes a left turn and heads towards the regesters within the house. The large duct to the left of the furnace is the return air line. The white PVC lines coming out of the furnace are combustion air intake and exhaust. The gas line is the yellow line between the return air duct and the furnace.

http://www.bullmarketrealty.net/_acc...ting/26-16.jpg

You'll want to measure your existing duct on top of your furnace. Make sure you get a coil that is pretty close to your existing duct size or you'll have to make transition pieces to make it fit in your duct. The easiest way is to get a cased coil. Which is what is shown on the above picture. Assuming you can get a cased coil you just cut the duct at about 1/4" shorter than the size of the coil case bend that extra 1/4" 90 degrees out on all 4 sides, slide coil in, screw down through the 1/4" flaps you made above the coil (be careful not to screw into the coil), screw the bottom of the case into the top of the furnace.

Another way is to find a coil smaller than your duct, cut out the front of the duct, set the coil inside (you may have to make something to set the coil on) Then have a patch made to cover the hole you cut, cut out holes where the linesets & drain will come out, screw patch onto duct again being careful not to hit the coil. It won't be as pretty as the cased coil, but it'll get the job done.


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