I did my own heat calculation, I DO need a 5 ton

[sb023]

49140 heat loss, 53974 heat gain

[DGIO-Not]

Like I said to your previous post, I am late to the party.

I have to ask you based on what???

So you used the availabe heat/load calc online? You plugged in numbers you know, guessed at others (climate, codes and construction.) You are close. Your ductwork maybe still undersized for construcion, period. Sorry, we see it on daily basis.

So now look at proposals closely. Construction, and use, can make huge difference. What I did not say in my last post (although I seemed to be leaning towards your "computer guy") computer programs,just as hand sheets, excel sheets, are prone to errors. You have to undersand heat/load in the first place to use any of these tools effectively. And most (available as free to homeowner online) will not even address your available ductwork volume that has already been mentioned to you. It is a "Big Picture" versus the "Little Picture" (in this case, unit size.)

You have gotten solid advice, you cannot oversize a system to the ductwork, regarless of house size. You will only make things worse if you try, you can only suck so much air through a straw. Go ahead and try it for an hour, tell me how effictive and efficent you were able to work at it. That is your unit, period. Another analogy, heart disese. Your duct system is your arteries and ventricles to your home. Constrict it, you are probably on meds.

[egads]

And please post follow ups in the existing thread.

[amd]

49140 heat loss, 53974 heat gain

Does that heat gain figure include the latent load? What is the design temperature?

If this is for an existing house, can the existing ductwork even handle the 2000 cfm required for 5 tons of cooling?

If applicable, how does the existing system perform? What size is it?

Reducing heat gain is preferable to installing a large unit. A high cooling load means high energy bills.

[beenthere]

You still didn't answer, if your old 5 ton ran continuous or cycled on and off on the design days.

[Airmechanical]

see;

now you can be cool on the hottest days of summer



.

[sb023]

I used this tool: http://www.heatload.com/unico/heatloadpreform.htm

I got very detailed and measured every room and did closets separately as well. I did not round any measurements. It should be very accurate.

I also built the home so I know the ceiling and wall insulation, no guessing was done.

I am in the Central Florida area so I used the Orlando guide for temperature which is 95 for high temp, 34 for low temp, and 37 grains of water.

The existing unit is a 5 ton and performed well the first few years, then I had a couple freeze issues, coil was cleaned and it worked again for a while and now I have had some more freeze issues. I have had a few people lately who have given me estimates and said that the weld job is terrible and that I am probably losing freon.

Is the ductwork designed for a 5 ton, I have no clue. Is the return sized for a 5 ton, most say NO.

Did it cycle during hot summer days, I would say yes. It does get the house to desired temperature and turn off, it does not run continuously. But to be honest I haven't paid alot of attention to this but I do know even lately in the hottest part of summer I can set it at 78 during the day and it will satisfy and turn off. I also ALWAYS keep it at 72 in the summer at night and it can accomplish this setting also, even 70.

Thx !

[snupytcb]

are you having a unico system installed?

[sb023]

no, just using a measurement tool to figure btu's, there are a bunch out there.
i can then pick any brand that satisfies that requirement.

[heaterman]

I ran through that "tool" quickly and it's real generic. I don't have time right now but I will try to run one of my known Js against this one later. It's missing several key components for doing a truely comprehensive heat loss / gain calc.

[snupytcb]

no, just using a measurement tool to figure btu's, there are a bunch out there.
i can then pick any brand that satisfies that requirement.

why are you doing all this work and not your contractor? are you telling what size unit to install? if so he's crazy.:det:

[beenthere]

Considering that a Unico would loose ½ a ton or more of capacity. I think that program has lots of padding in it.

[heaterman]

Considering that a Unico would loose ½ a ton or more of capacity. I think that program has lots of padding in it.

Kind of what I was thinking.......................................... .......

[VetNutJim]

I used this tool: http://www.heatload.com/unico/heatloadpreform.htm


Ever heard that guy on John Boy & Billy that says; "That's a LOT better'n the one I had" ?

That's a LOT easier than HVAC-Calc.

HVAC-Calc has a lot more detail pertaining to the construction, insulation, window area, sun loads, room area, wall/ceiling heights, ect.
Since you have detailed information on hand about the construction of your home, maybe you could try HVAC-Calc and see if it jibes with the Unico calculator.

If it does, I want to know 'cause the Unico load calculator is so easy to use.:det: