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newowner 11-11-2005 03:39 AM

Hvac Diy?
Is it possible to put central air in yourself or should you leave it up to the professional?

Seems pretty straight forward but I could be missing a lot.

rabadger 11-11-2005 08:54 AM

No, you need special tools, and have to be EPA certified to deal with a installation and start up.

TxBuilder 12-01-2005 04:08 PM

Has anyone gotten a HVAC guy to plan the vents and then you do all the manual labor of install routing the vents and lines and he does the final install of the unit? It seems like a way to save some cash and not deal with the technical aspects of it.

rabadger 12-03-2005 09:45 AM

Thats what I do. Load calculations, duct sizing, and layout for homeowners.

TxBuilder 12-04-2005 08:54 PM

I know little about HVAC. What are load caluclations?

rabadger 12-05-2005 07:25 PM

Load calculations are the correct industry accepted way of sizing equipment according to the temperature ranges in your area. The building volume, areas of floors, walls, windows, doors, aux heat sources, number of people, direction of exposure are figured. When your done they give requirements in BTU/HR, CFM in heating and cooling for the structure.

If you do a whole house load calculation it will tell you the equipment requirement and CFM for the whole house. If you do a full blown calculation listing each room it will give you the BTU/HR and CFM requirements for each room. You use the full blown room-by-room calculations to size the air distrubition system.

No matter what others say or believe, guessing by some BTU per square foot to come up with a size is not accepted by true industry professionals.

mattman 01-13-2006 07:42 AM


Originally Posted by newowner
Is it possible to put central air in yourself or should you leave it up to the professional?

Seems pretty straight forward but I could be missing a lot.

Are you talking about new construction or retro-fit. New construction wouldn't be all that bad but there are a lot of things that are climate specific. If you did all the let work you might be able to pay a company to come out and braze the lines and charge the system with dry nitrogen (I am talking about in the rough phase.) As far as trim you could do your own grills but I would pay someone to set the outdoor unit and do the start up (if you even put gauges on the system the EPA can fine you. Another thing you need to keep in mind is that 9.9 out of 10 supply houses will not sell to the public and Home Depot adds TONS of markup and won't even carry all of what you need.

Now if you are talking about retro-fit my answer is no. Doing your own change out would be like removing your own spleen. There are just to many things that you can run up against that the average Joe with no HVAC experience will not know how to do. Also there are a whole lot of industry specific tools and knowledge that even going to trade schools can not teach.

Also keep in mind that you are paying for a quality install when you use a professional. If the system is not installed right you will lose heat and cooling out your ducts and you can easily restrict airflow if you don't know what you are doing.

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