What should I pay for two 5 tons unit?

[vcc_inc]

Well i'm building a house and am getting ready for the a/c. Just need to know what the going rate is for installation on a new construction. I heard it's $1000 per ton, is that right? Should I be expecting quality units for that kind of price or is that the going price for lower end units? Can anyone confirm or advise? Thanks in advance. Ace

[Zatol]

I have been paying approx. 1300 per ton (split system heat pump, 10 seer, york)...

10 seer is pretty much minimum efficiency. I believe that next year the minimum allowed for new construction will be 13 seer.

Based on my experience, you will be getting a lower quality system at 1000 per ton...

Or.. I have been getting screwed by my HVAC contractor...

Also FYI... Generally speaking, plan for 1 ton per 500sf...

[rabadger]

There is no magic number. It all depends on what you want and what the load calculations come out to be. I must be an large house. 2 5 ton units is a lot of cooling. Where is the construction?

[Sparks]

$1000 per ton was a figure used 10 years ago from my recollection. Everything has went up since then, I think at $1000 per ton you would be getting the bottom end equipment.

[rabadger]

Your right Sparks. Not only the bottom end equipment but also a bottom end duct system also.

[vcc_inc]

The house is just over 4300sf being built in Encino, CA. Actually a buddy of mine is going to do the job for me at $12k. He says he's going to use good units and ducting. I think I can trust him. Thanks for your help fellas. Ace

[rabadger]

4300 sq ft? 2 5 ton units? I would question that. It seams high. Just looked in the manual and Encino CA is not listed.

[vcc_inc]

What manual are you talking about? What would you say is the right system for that size house? Maybe 2 4 tons units? Thanks

[rabadger]

Sorry, I will not guess at heating and cooling sizing. There is no such thing as per square foot sizing for heating and cooling. Every home is different. You can take the same house plan, rotate the direction it faces and come up with different requirements. You can build two identical homes next to one another and end up with different HVAC equipment sizes. By changing windows and doors during construction you also change the required BTUH need. Homes are built to tight to guess and oversize HVAC systems. An oversized system can and will cause all sorts of problems.

When I do the sizing calculations and duct design for my clients I use the Manual J, 2003 International Residential Code Book, 2003 International Code Book, 2003 International Fuel Gas Code Book and the equipment manufacturers installation instructions, performance specifications.

I do not remember the HVAC industry ever recommending square foot per ton guess work. I have been in the industry for over 27 years.

The manual J takes the home volume, square area of walls, windows, doors, ceilings, floors, and insulation r-factors then calculates the correct BTUH required for heating and cooling according to the recommended design temperatures for the location. It not only will give you the load requirements but also required air turnover and recommended register count for each room.

You can get to the ASHRAE and ACCA consumer pages from the links page on my web site. I suggest you spend time surfing them.

[Sparks]

Considering the cost of energy as well as the possibility of creating a mold problem by oversizing an hvac system, I would certainly follow Rabadgers suggestions. Secondary to those, an oversized HVAC system will not keep the humidity at a comfortable level in some climates. An oversized system will quickly lower the sensible heat (temp) and shut down thus not affecting latent heat (humidity), of course a high end variable speed unit with a modulating compressor, etc, etc, will do a better job even being oversized than a low end unit will. The point is, buddies are great when they offer to help, but, for your sake, have a heat loss/ gain calculation performed to determine exactly how many btu's the house loses and size of equipment and ducting needed. If you're going to do it, at least spend the time and effort to make sure it's done right. Also, sq. ft. sizing and rules of thumb are for people who would rather guess than spend the time to calculate the needed size of the system. There are hacks in every field.

[GiantScale]

Just from the hip. Id say one 5 ton would be more than enough. Unless you have allot of glass.

[Sparks]

:? Hence my long winded point. "More than enough" is NOT a good thing when sizing hvac sytems.

[GiantScale]

Totally agree sparks. Big homes like vcc_inc's are harder to size. Have someone calculate the load.

[rabadger]

When I calculated my home it came to 3.5 ton for peak load. I installed the zoning and kept the 3 ton. It works fine.

[Sparks]

Good point, I would rather undersize a unit anyday than oversize.