New house. No clue what to pick

[kellarm]

Help if you could
My house is located in South Carolina and is roughly 2300sqft--one floor\brick. I upgraded the windows to a Low-e\argon\1" glass that according to the "specs" perform very well. The exterior walls will have regular fiberglass (R13) batt insulation. I am condsidering foam in the exterior walls with fiberglass\cellous in the rest.

I had a Manual J study done and it only recommened a 3.5 ton unit. Does this seem correct? I realize some people do it by sqft, but shouldnt the study be somewhat helpful?

What should I look for in a unit?
The builder is only going to put in a seer13. Is that a waste considering the upgrade to the windows?
Should I increase the seer rating versus "foaming" the walls?

any ideas?

[ga-hvac-tech]

Do you live in a humid climate close to the ocean?

The reason I ask is that humidity control is part of what A/C does.

Over here in Atlanta, we do not have the humidity the folks on the coast have. But humidity is an issue.

You will accomplish more in the way of humidity control with a 2 stage variable speed blower furnace than with a special A/C unit.

Your house will be tight enough already, I doubt a 14 SEER would help that much. And 16 SEER or higher equipment requires lots of maintenance... it is really better suited for really HOT climates like Az.

[larobj63]

Way too many topics to cover in one post. :eek:

Here is my tid-bit of info:

Spray foam the entire house. The reduction in infitration is significant, R-value is only a part of the picture. In practice, spray foam insulation out-performs fiberglass by a large margin.

Let your HVAC contractor know your insulation intentions. A spray foam house will have significantly smaller heating and cooling loads. And a mechanical fresh air system of some sort will be necessary. But the savings will be there year after year....

Others will chime in all sorts of info... :cool:

Welcome...

[dash]

kellarm,

Foam the walls ,you'll nevr get another chance to do so,the A/C system will be replaced in 10 to 15 years.

Load calc. results sound oversized have them double check,did they know about the window upgrade?Tell them about the foamed walls too.

I'd go with a variable speed indoor unit 14SEER ,or more if you can swing it.Ask to talk directly with the HVAC sub..

[ga-hvac-tech]

Things are different with each contractor;

RNC residential new construction is a different market and business than replacement systems in an existing home.

New construction is sometimes less technical and less feature rich... Be sure your HVAC contractor understands both markets. And be sure your contractor understands load calculations. The advise given to tell your HVAC contractor about the foam and the windows is good advise. The more he knows, the better he can do your load calc. Also the advise about some form of fresh air; you probably will need an ERV unit (energy recovery ventilator) is worth it.

Also be sure you have a Manual D duct design. You can have the right sized equipment; but if the air is not moved around the house properly, there will be warm and cool spots.

The more information the HVAC guy gets, the better he can design and install your system.

[beenthere]

Foam those walls, you won't regret it. It will save you money in both heating and cooling season. And pay for its self quicker then the highest efficiency furnace or A/C can.

[teddy bear]

Most heat and air goes up through the ceiling. Foam roof deck is the best. Someone mentioned fresh air and humidity control. Both are important. You should have an air change every 4-5 hours when the home is occupied. This is about 75-100 cfm of fresh air which purges indoor pollutants and renew oxygen. <50% RH is ideal for comfort and indoor air quality. A good air tight home saves energy. During wet cool weather with sufficient fresh air and occupants, 40-70 lbs. per day of moisture (no cooling load) must be removed to maintain <50%RH. A whole house venitilating dehumidifier is an ideal device to add to an a/c system. I am involved with Ultra-Aire VDH for 15 years. This is highest efficiency dehu in the world. Fresh air and dry even when the a/c is not operating. Check thermastor.com Regards TB

[larobj63]

Most heat and air goes up through the ceiling. Foam roof deck is the best.

Yes - I agree. It's worth saying agin - foam the whole house. Money well spent. Rediculously fast payback.

[energy_rater_La]

foam the roof line. ductwork will benefit, unit's life will be longer in semiconditioned attic.
air seal walls with conventional insulation and air tight drywall approach.
the study you had done is helpful, but with foam insulation and the window
upgrade the size required will be less.
are you installing a heat pump?

best of luck.

[super_tech_1]

Your house will be tight enough already, I doubt a 14 SEER would help that much. And 16 SEER or higher equipment requires lots of maintenance... it is really better suited for really HOT climates like Az.



What more maintenance does a 16 seer require. I've never had any more maintenance to do on 16 seer's.

I would strongly recommend a higher seer system I'm not sure where in sc you are but here in the hilton head island area it's well worth it. As far as brand if your near the water i would say stick to carrier/bryant or lennox they stand up better then others to salt air

[ga-hvac-tech]

It has been my experience that higher SEER equipment does not work at its rated SEER unless it is cleaned every year. All equipment does better when it is maintained properly. But high SEER equipment is more sensitive than basic 13 SEER.

One might remember that with many brands, IF the installation is done properly, and a VS furnace or AH is installed, one generally gets 14 SEER. Not all equipment is this good, but many are.

We can add to this in a humid climate if one sets up a dehumidification cycle with the VS blower, the RH inside can be held down to a level where it feels comfortable with the T-stat set a few D higher. This means energy savings.

Now tell me: What percentage of your customers do a full service including cleaning the condenser and coil EVERY year?

[beenthere]

It has been my experience that higher SEER equipment does not work at its rated SEER unless it is cleaned every year. All equipment does better when it is maintained properly. But high SEER equipment is more sensitive than basic 13 SEER.



Are you sure your getting 13 SEER from a 13 SEER unit?

[ga-hvac-tech]

Are you sure your getting 13 SEER from a 13 SEER unit?

OK Been, tell me which hairs you want to split, and we can get out the razor knife and attempt to split them... :rolleyes:

If an installation done by ABC contracting of a 13 SEER system does not do 13 SEER, would an installation of a 14 or 16 SEER system by the same ABC contractor do 14 or 16 SEER?

[super_tech_1]

So how often are you cleaning your equipment? Over here where doing it twice a year. 13 seer 16 seer 19seer. And seer is only under certain circumstances. sometimes it's higher sometimes it's lower just depends on temps.

[ga-hvac-tech]

So how often are you cleaning your equipment? Over here where doing it twice a year. 13 seer 16 seer 19seer. And seer is only under certain circumstances. sometimes it's higher sometimes it's lower just depends on temps.

Seems to me that is the customer's choice.

My question was how many of your customers have you clean their equipment yearly? And BTW: I agree that if it were a high SEER HP, twice a year would be a good idea IMO.

[beenthere]

OK Been, tell me which hairs you want to split, and we can get out the razor knife and attempt to split them... :rolleyes:

If an installation done by ABC contracting of a 13 SEER system does not do 13 SEER, would an installation of a 14 or 16 SEER system by the same ABC contractor do 14 or 16 SEER?

A new 13 SEER might get them 10 or 11, a new 14 SEER might get them 12, and a New 16 SEER might get them 13, or 14 in second stage.
My point is. Few customers will get the units SEER rating no matter which they choose.

So using they won't get the rating as a reason not to sell or install a 16 SEER is a misnomer.

There is a good chance they will get 14 SEER from first stage of a 2 stage 16 SEER before they get 14 SEER from a single stage 14 SEER of the same size.

Low air flow is the number one reason that most people don't get the full SEER of their unit.
Unsealed ducts next.

Most duct systems don't need major alterations to improve them enough to make a 16 SEER a viable option for the customer.

There are a lot of 3 ton units with duct systems that are only allowing it to move 800 to 1000 CFM.
A 3 ton 2 stage 16 SEER operates in first stage most of the time. Which would be about 960 CFMs. Meaning the customer would get higher SEER from the 16, most of the cooling season then they would get from a 13 or 14.

[super_tech_1]

all of them have me clean it twice per year. What are you doing when you do a maintenance if your not cleaning it. Isn't that the purpose.

[ga-hvac-tech]

Been I totally agree with you on the issue of inadequate ductwork. We could spend lots of time telling stories of duct systems each of us have seen that were un-believable.

Just a side note: Most installations down here are flex duct, it is generally easy to seal them up during a replacement.

My apologies for making an aggressive comment when we were debating on different details.

I might mention that many of my installations include duct modifications to allow the air to flow as it needs to. I stress this during the first visit of the sales process (yes, I always make two visits for a sale). On the second visit, I have a package ready for the customer that gives them solutions and options. Few folks go with the other guy, and most buy the whole package. They end up with comfortable homes and a good experience with an HVAC replacement.

[ronnrs]

A Carrier Tech told me that a 16 or 18 seer is only a 16 or 18 seer in optimum conditions, like foam insulation and good windows. So if you have a tight house you need to put in a fresh air or static pressure will not be right. If not a 16 seer is just a 14 seer with a higher price. What do you think?

[beenthere]

He's slinging BS.

[beenthere]

Few places are optimum. But many get the benefits of the higher SEER units.

Improving the homes envolope is always a good idea.

Sounds like he just doesn't like working on higher SEER equipment. Or doesn't have the training on it.

[Kevin O'Neill]

Where in SC are you? Santee Cooper and all of the co-ops have a program called Good Cents. They will do the load calc for the builder. If you install a 14 SEER or higher heat pump, they will give you a rebate of $12.00 per month. This is on top of the savings you get from a properly sized high efficiency heat pump.

I live in Myrtle Beach, SC. I have a 2000 sq ft house with (1) 2-ton heat pump. But it all depends on how much glass you have. Even with low e, large amounts of glass can increase your load. But still your load calc sounds awfully high.

[ronnrs]

Few places are optimum. But many get the benefits of the higher SEER units.

Improving the homes envolope is always a good idea.

Sounds like he just doesn't like working on higher SEER equipment. Or doesn't have the training on it.

He worked for Carrier and gave classes on high seer equipment, pretty scary. We have a lot of shot gun houses in new orleans that are drafty and a don't think there is a lot of benefit to a high seer unit in that type of house. I think that is what he was explaining.

[beenthere]

We have a lot of shot gun houses in new orleans that are drafty and a don't think there is a lot of benefit to a high seer unit in that type of house. I think that is what he was explaining.

Hmmm.
So he/you are saying.
Why use a unit that uses less electricity in a house thats an energy hog.

True, the homes envolope should be improvend before any system goes in.
But, even a drafty house can see reduced cooling bills from a higher efficiency house.

Over the years, I have found that many instructors/trainers for manufacturers, express their personal feelings.

He would probably be one of the guys that says, don't install a 90% furnace in a drafty house, use an 80%.

[larobj63]

Hmmm.
So he/you are saying.
Why use a unit that uses less electricity in a house thats an energy hog.

True, the homes envolope should be improvend before any system goes in.
But, even a drafty house can see reduced cooling bills from a higher efficiency house.

Over the years, I have found that many instructors/trainers for manufacturers, express their personal feelings.

He would probably be one of the guys that says, don't install a 90% furnace in a drafty house, use an 80%.

Exactly.

The irony is, the bigger the energy hog the house structure is, the faster the higher efficiency equipment will pay back. Think about it. :)

[ronnrs]

Hmmm.
So he/you are saying.
Why use a unit that uses less electricity in a house thats an energy hog.

True, the homes envolope should be improvend before any system goes in.
But, even a drafty house can see reduced cooling bills from a higher efficiency house.

Over the years, I have found that many instructors/trainers for manufacturers, express their personal feelings.

He would probably be one of the guys that says, don't install a 90% furnace in a drafty house, use an 80%.

Good points,that why I like to ask the pros, I asked my boss and we can't get 16 seer r-22 units anymore only r-410a which we push the 410a sales.

[beachtech]

He worked for Carrier and gave classes on high seer equipment, pretty scary. We have a lot of shot gun houses in new orleans that are drafty and a don't think there is a lot of benefit to a high seer unit in that type of house. I think that is what he was explaining.

shot gun brains :)

these carrier guys are really starting to scare me with thier ignorance!!!

[beachtech]

Where in SC are you? Santee Cooper and all of the co-ops have a program called Good Cents. They will do the load calc for the builder. If you install a 14 SEER or higher heat pump, they will give you a rebate of $12.00 per month. This is on top of the savings you get from a properly sized high efficiency heat pump.

I live in Myrtle Beach, SC. I have a 2000 sq ft house with (1) 2-ton heat pump. But it all depends on how much glass you have. Even with low e, large amounts of glass can increase your load. But still your load calc sounds awfully high.

if i where in SC i would pay this guy whatevver he wanted to charge me to put in my equipment! well, i am not a ibg fan of lennox :D but even knowing what i know about HVAC i would give my money for his time :p

if it where my home, and since you climate isn't far off from mine, i would install Trane XL16i equipment :) and with the right indoor unit you will get 17seer out of that 2 stage outdoor unit that is going to give you better indoor humidity control on night's like the last 2-3 weeks :)

is this home going to be built on a crawl space? go ahead and leave the crawl space vents out during construction!!!