Gas and Oil Home Heating Furnaces - question

we currently have a three and a half ton unit for our 1646 sq.ft. home. we are in the process of adding about 425 sq.ft. will the unit handle it? if not, what are some options. oh yes, we only have one air return and a local guy who seemed knowlegable said that was not right. i am trying to keep the add-on costs down and would like to hear that the current unit will work. if not, we will take any advise we can get.

thanks

is this an a/c or a heatpump and how do you like to keep the house ?

its a pane a/c and we keep the thermostate set about 70 degrees. there is usually someone home at all times so it does not change much. we are in north texas. the home is about three years old. we currently have issues like in the winter it will be hot in the master and cool in the other end of the home. opposite in the summer. i understand there are alot of factors to consider, but i was just told over the phone by an a/c guy that three and a half was too small for the origional 1640 sq.ft. home. isnt there a rule-of-thumb like 500 sq.ft. per ton or something like that?

There is no rule of thumb. Every home is diffrent one way or another.

If the guys tells you over the phone, is not good enough in my opinon.

You want a good guy who WILL come out and messure your home, windows, doors, # of people, R-Value of your walls, ect ect.. Then the guy puts all info into a program and it will tell what you need for system. Also a good dealer will look at the duct work to see if it will be able to handle the addtion onto the house. It won't hurt to get more retuns in your home for better comfort.

So when you talk to a dealer, ask them if they do a heat lost/gain program, and shows a print out of the report to the owner.. If they don't, keep on looking.

You keep your A/C at 70?? that's cold! lol I keep ours at 76

Rule of thumb 500 sq feet per ton is a ballpark guess. Since your house is new I would assume it is energy efficient, so 3.5 tons is a lot of cooling for 1640 sq ft. As far as cold and warm areas, you need to make sure you are getting airflow into and out of the other parts of the house. This would require your duct work to be checked to see if it’s sized and installed correctly. I assume you adjusted the registers.
Here we are required to do an energy package when the home addition is done. You can go to
hvac-talk.com and for 49.95 purchase the software to do a load check. Or you can go to http://www.wrightsoft.com/ and use there software for free, but the temp values can’t be changed, but it might be close for north Texas. Fight figures with facts.
good luck

1646 sq ft home 3 1/2 ton of AC we keep it at 70o WHY?

Going to add 425sq ft tot 2071 sq ft when done.

With that 3 1/2 ton in that 1646sq ft home. The poor unit never did get a chance to get the humidity out of the home . Thats why you had it down to 70o. It would pull down the temp and shut off before it got the humidity out.When you have a AC that runs right and get the moisture out of the home you are going to be cool at 76o and 78o.

Id think this way . For sure have them run a AC load on the home. But the main thing here is go over the duct work. so it can get the new part of the home and get that hot and cold room you have now fixed. You could look into down there in TX. a company makes a split coil there . This way the AC can run and pull more water out of the home before it has to drop the temp. This can be put on the unit you have.

Thats like in the winter we have to put the humidity in to feel warm and in the summer we have to take it out to feel cool.

Get 3 bids for sure

;) ED

thanks for the advise all. i need to decide this week on how to go about this. my builder needs an answer so he can continue. do most all a/c guys have the ability to do the load tests etc? most of the local boys are pretty small. what is involved in the test and how do i read it? i dont have a reference. im reaching for info. i want to get the best bang for the buck.

Get 3 bid now for it . Yes any good AC guy can run a load ED;)

You can download a program for $49 from http://www.hvaccomputer.com/main.asp The program is pretty easy to do once you get a hang of it!

If you feel that the dealers are not doing the figures, go ahead and do it.. It will be well worth the money for your comfort.

Ed made a point of why you would run your A/C at 70*


Most dealer should be able to do such thing. If they say the do an avg home, don't waste your money on it.

jay is right...use that program, best 40 bucks you ever spent.

Kerry don't forget to answer the question, do you like it 70 degrees or does it does not feel cool until you reach 70 degrees.
The new variable speed furnaces, allow you to blow less air over your A/C coils there by removing more water from the air. Get 3 bids, even if you don't buy anything, you will learn details, by asking questions when they come out. Don't forget to explain any current problems, like one room to cool/hot.