New Heat Pump to Replace Old

[rickintampa]

I am replacing an 18 year old Trane heat pump in a house of the same age. I live in very humid Tampa, Florida, where heat is needed at most 10-12 days per year, while the a/c runs day and night for 6-8 months per year. The old Trane is a 2 1/2 ton, and the house was originally 1400 square feet. Since then, a 400 square foot back room has been added, bringing the total to 1800 square feet. The addition is ducted with overhead vents, but the air barely reaches the room. If not for two glass doors, there would be virtually no heating or cooling the addition. I've talked to three contractors so far, but their information seems confusing or contradictory. First, all three recommend a new 12 SEER unit. The say that anything rated higher won't save enough electricity to warrant the additional cost. But 12 SEER seems on the low side, especially considering the new government minimums. Also, they differ on size recommendations: One says stay with 2 1/2 ton. He claims that anything larger would necessitate replacing all the duct work. (However, he said this without ever examining the existing ducts.) Another contractor recommended a 3 ton, and the third said 3 1/2 ton. (These would be the sizes of the outside compressor unit, with the corresponding air handler 1/2-ton bigger in all three cases.) Finally, the three guys all want to sell me different names: Carrier, Bryant, and Payne. I wonder if you could provide some solid info to cut through the confusion. Also, any other considerations or recommendations (i.e. Puron vs. Freon) will be appreciated. By the way, I have lived in this house less than a year, so I have little extensive past history of the existing unit, comfort level, etc. But I do know that the current electric bill runs at least 50% higher than it should.
Thanks for your consideration.
~rick

[travisfl]

Originally posted by rickintampa
I've talked to three contractors so far, but their information seems confusing or contradictory. First, all three recommend a new 12 SEER unit. The say that anything rated higher won't save enough electricity to warrant the additional cost. But 12 SEER seems on the low side, especially considering the new government minimums. Also, they differ on size recommendations: One says stay with 2 1/2 ton. He claims that anything larger would necessitate replacing all the duct work. (However, he said this without ever examining the existing ducts.)

The only way to determine the correct system size (and the duct work needed to handle the air flow) is to do a heat gain / loss calculation (AKA "Manual J"). The duct work is sized by a calculation known as "Manual D". Did any of the contractors offer to perform such calculations? If not, call another contractor or two until you get one that sizes by calculation, not by 'rule of thumb'.

It is true that at TECO's current electric rates, anything more than about 13.0 SEER (a Trane XR12 with VS air handler) won't pay for itself during it's expected lifespan. Energy costs may rise in the future, but those are today's calculations.

The quality of the system design and the installation is more important than the brand name. If you are within 1000' of the coastline be sure to look at examples of the brands that you are considering to see if they are rusting after a few years. Basepan rustout has been a real problem on the coast and that is why Trane (and now others) have started using composite basepans.

Either R-22 or R-410a refrigerants will be available in plentiful quantities for the expected life of your unit.

[dash]

Minimum SEER 13.0 ,next year.

2010,no more R22 systems built for sale in the USA.

Check http://www.410a.com for information.


Just north of you in New Port Richey and Crystal River,so I know the climate,Humid.


I'd go with a Carrier Infinity,two stage ,heat pump,strip heat would be less and if you really only use it 6 days a year,you don't need a heat pump.

Check out a Carrier Factory Authorized Dealer,you can find them on Carriers website,or the yellow Pages,in the column.
100% satisfaction or your money back,garanteed by the Factory!

Whatever you do go with ,get a variable speed air handler ,WIT a good control system to reduce humidity in the summer,Thermidistat Carrier/Bryant is almost as good as the Infinity.

Get a load calculation,and have them test the ESP(static) of the duct system.Consider any upgrades to windows,insulation ,etc.,when doing the calculation,increasing the attic insulation,could save a 1/2 ton .Have it checked out.

The ducts for the addition ,need to come off the trunk or plenum close to the air handler,and be the correct size.They probably "tapped" it in to the closest duct instead.
If attic space allows,not hard to correct,make comfort in the addition part of the "deal"!


[Edited by dash on 02-01-2005 at 10:36 AM]

[rickintampa]

Originally posted by travisfl

Originally posted by rickintampa
I've talked to three contractors so far, but their information seems confusing or contradictory. First, all three recommend a new 12 SEER unit. The say that anything rated higher won't save enough electricity to warrant the additional cost. But 12 SEER seems on the low side, especially considering the new government minimums. Also, they differ on size recommendations: One says stay with 2 1/2 ton. He claims that anything larger would necessitate replacing all the duct work. (However, he said this without ever examining the existing ducts.)

The only way to determine the correct system size (and the duct work needed to handle the air flow) is to do a heat gain / loss calculation (AKA "Manual J"). The duct work is sized by a calculation known as "Manual D". Did any of the contractors offer to perform such calculations? If not, call another contractor or two until you get one that sizes by calculation, not by 'rule of thumb'.

It is true that at TECO's current electric rates, anything more than about 13.0 SEER (a Trane XR12 with VS air handler) won't pay for itself during it's expected lifespan. Energy costs may rise in the future, but those are today's calculations.

The quality of the system design and the installation is more important than the brand name. If you are within 1000' of the coastline be sure to look at examples of the brands that you are considering to see if they are rusting after a few years. Basepan rustout has been a real problem on the coast and that is why Trane (and now others) have started using composite basepans.

Either R-22 or R-410a refrigerants will be available in plentiful quantities for the expected life of your unit.

One of the contractors phoned just as this message came in and I read part of it to him. He said that these calculations (Manual J & D) are complex, costly, and sometimes wind up not proving much. Just his opinion, I realize. I am basically right on the coast (Tampa Bay) and I will keep in mind about rustout. Thanks for your advice. ~rick

[travisfl]

Originally posted by rickintampa
One of the contractors phoned just as this message came in and I read part of it to him. He said that these calculations (Manual J & D) are complex, costly, and sometimes wind up not proving much.

He must not be an ACCA member, and he certainly isn't technically competent to do your job.

http://www.acca.org/tech/manualj/
http://www.contractingbusiness.com/n...sarticleid/616
http://www.acca.org/tech/manualj/art...ane_letter.doc

"Trane / American Standard and ACCA have always agreed on the need to do a load calculation on each installation and are now pleased to announce that we both agree on using ACCA’s Manual J 8th edition."

Run, do not walk away from this contractor.

[Edited by travisfl on 02-01-2005 at 11:35 AM]

[rickintampa]

Originally posted by dash
Minimum SEER 13.0 ,next year.

2010,no more R22 systems built for sale in the USA.

Check http://www.410a.com for information.


Just north of you in New Port Richey and Crystal River,so I know the climate,Humid.


I'd go with a Carrier Infinity,two stage ,heat pump,strip heat would be less and if you really only use it 6 days a year,you don't need a heat pump.

Check out a Carrier Factory Authorized Dealer,you can find them on Carriers website,or the yellow Pages,in the column.
100% satisfaction or your money back,garanteed by the Factory!

Whatever you do go with ,get a variable speed air handler ,WIT a good control system to reduce humidity in the summer,Thermidistat Carrier/Bryant is almost as good as the Infinity.

Get a load calculation,and have them test the ESP(static) of the duct system.Consider any upgrades to windows,insulation ,etc.,when doing the calculation,increasing the attic insulation,could save a 1/2 ton .Have it checked out.

The ducts for the addition ,need to come off the trunk or plenum close to the air handler,and be the correct size.They probably "tapped" it in to the closest duct instead.
If attic space allows,not hard to correct,make comfort in the addition part of the "deal"!


[Edited by dash on 02-01-2005 at 10:36 AM]

You bring up additional interesting points, including the recommendation for a variable speed air handler, which none of the contractors who came by so far seemed to think I needed. You're right that the back room duct work was probably tapped in, but correcting that would probably be a huge job, considering the flat roof on the addition. I'm more concerned with the new recommendation that I'll need to install a second return someplace in the house (I currently have only one return)if I go to a 3 1/2 ton unit. Thanks for your advice. ~rick

[Irishmist]

Well, that's one contractor you can immediately mark off your list! Anyone that chooses to ignore standards of the industry, is probably not someone you want to do business with. Makes you wonder what else he will choose to ignore during the course of the installation. This guy probably doesn't even need to see the home, just hold the phone up in the middle of the room so he can size it.

[rickintampa]

Originally posted by travisfl

Originally posted by rickintampa
One of the contractors phoned just as this message came in and I read part of it to him. He said that these calculations (Manual J & D) are complex, costly, and sometimes wind up not proving much.

He must not be an ACCA member, and he certainly isn't technically competent to do your job.

http://www.acca.org/tech/manualj/
http://www.acca.org/tech/manualj/art...ane_letter.doc
http://www.contractingbusiness.com/n...sarticleid/616

Run, do not walk away from this contractor.

[Edited by travisfl on 02-01-2005 at 11:33 AM]

I see your point; thanks! ~rick

[Swampfox]

I just did a very complex and costly Manual J last night on the computer in about 20 minutes

[travisfl]

Originally posted by rickintampa
I'm more concerned with the new recommendation that I'll need to install a second return someplace in the house (I currently have only one return)if I go to a 3 1/2 ton unit.

You REALLY need a Manual J, but unless there is zero insulation and you have all south facing single pane windows with no roof overhang, 3.5T would likely be oversized for 1800 square feet in Tampa Bay.

Another warning here - regardless of system size for maximum comfort you should have a return in every habitable room of the home except bathrooms. Another option is to undercut the doors or install ventilation ports in them. Regardless, Florida Mechanical Code is as follows:

http://www.iccsafe.org/cs/codes/pdf/...Mechanical.pdf

§M601.4 Balanced Return Air. Restricted return air occurs in buildings when returns are located in central zones and closed interior doors impede air flow to the return grill or when ceiling spaces are used as return plenums and fire walls restrict air movement from one portion of the return plenum to another. Provisions shall be made in both residential and commercial buildings to avoid unbalanced air flows and pressure differentials caused by restricted return air. Pressure differentials across closed doors where returns are centrally located shall be limited to 0.001 inch WC (2.5 pascals) or less.

[Edited by travisfl on 02-01-2005 at 12:30 PM]

[rickintampa]

Originally posted by travisfl

Originally posted by rickintampa
I'm more concerned with the new recommendation that I'll need to install a second return someplace in the house (I currently have only one return)if I go to a 3 1/2 ton unit.

Another warning here - regardless of system size for maximum comfort you should have a return in every habitable room of the home except bathrooms. Another option is to undercut the doors or install ventilation ports in them. Regardless, Florida Mechanical Code is as follows:

http://www.iccsafe.org/cs/codes/pdf/...Mechanical.pdf

§M601.4 Balanced Return Air. Restricted return air occurs in buildings when returns are located in central zones and closed interior doors impede air flow to the return grill or when ceiling spaces are used as return plenums and fire walls restrict air movement from one portion of the return plenum to another. Provisions shall be made in both residential and commercial buildings to avoid unbalanced air flows and pressure differentials caused by restricted return air. Pressure differentials across closed doors where returns are centrally located shall be limited to 0.001 inch WC (2.5 pascals) or less.

I'm sure that a return in every room is good advice for maximum system efficiency, and to be within state guidelines. But can you imagine if everyone who installed a new air conditioner in an older home or condo were to put a return in every room, in cases when only one now exists in the whole house? I just got a price of $300 for installing one return...putting them throughout the house would a prohibitive expense. Let's face it: Few home owners will ever do that, regardless of the codes. ~rick

[travisfl]

Originally posted by rickintampa
Let's face it: Few home owners will ever do that, regardless of the codes

No problem, undercutting the doors will work OK and meets the code requirements. It just isn't the best way in terms of comfort - IMHO.

[rickintampa]

Originally posted by travisfl

Originally posted by rickintampa
Let's face it: Few home owners will ever do that, regardless of the codes

No problem, undercutting the doors will work OK and meets the code requirements. It just isn't the best way in terms of comfort - IMHO.

Thanks for the clarification. So then I'll assume that in a home where doors aside from the bathroom are hardly ever closed, the need for multiple returns and door undercutting is greatly diminished. ~rick

[rickintampa]

Originally posted by swampfox
I just did a very complex and costly Manual J last night on the computer in about 20 minutes

I get your point. But one thing you pros haven't mentioned is who's going to pay for these calculations.... Manual J, D, and anything else that might be recommended? If you guys are willing to do them gratis, along with your free estimates, that's great. You can do all the free calculations you want. But I think that very few home owners--including me--would be willing to pay $ hundreds up front, just to determine A/C unit and duct size. ~rick

[sayco bob]

Rick: you can pay now or pay later. If you don’t have the load calculations done the system will not work properly. Would you rather save a couple dollars now and not be happy with the system you install or spend the money up front for a system that does what it was DESIGNED to do. Find a contractor in your area that is willing to do the job correctly you will be happier in the long run. I agree that a Carrier factory authorized dealer would be a good starting point. This web site if full of people trying to solve problems that they could have avoided.

[travisfl]

Originally posted by rickintampa
You can do all the free calculations you want.

As you know, there is no such thing as a free lunch. The customer pays for everything, one way or the other. The only question is whether you want a quote from a competent, professional HVAC contractor, or not.

[Gunnery Sergeant Hartman]

Originally posted by rickintampa

Originally posted by swampfox
I just did a very complex and costly Manual J last night on the computer in about 20 minutes

I get your point. But one thing you pros haven't mentioned is who's going to pay for these calculations.... Manual J, D, and anything else that might be recommended? If you guys are willing to do them gratis, along with your free estimates, that's great. You can do all the free calculations you want. But I think that very few home owners--including me--would be willing to pay $ hundreds up front, just to determine A/C unit and duct size. ~rick

Why not?
Do you want it done right? You'll already be paying thousands to have it done, why not do it correctly?

[travisfl]

Here are other good reasons to do a formal heat gain / loss calculation:

1) For your personal comfort and to insure that you get good humidity control, thus preventing cold, clammy A/C and the potential for mold growth.

2) Many municipalities in Florida (I don't know about Hillsborough / Tampa) require it for permit issuance. Your contractor IS going to pull a permit, right?

3) The manufacturer of the equipment (well, Trane, anyway) says it is required. If you don't install your system in accordance with the manufacturer's instructions, you may not get the installation approved by the permitting agency.

4) If you are looking for an power company rebate, many utilities require it.

5) The industry association says it is required.
http://www.acca.org/tech/manualj/addenda/addendumA.pdf

Prohibited Practices
Do not use “rules-of-thumb.” The idea that the required equipment capacity equals the floor area divided by some magic number is absurd. Heat loss and heat gain depends on individual circumstances. Floor area to tonnage ratios for the U.S. housing stock can range from less than 500 ft2/ton to more than 1,200 ft2/ton. Efficient single family detached homes with a normal amount of well-distributed glass typically fall in the 700 to 1,200 ft2/ton range. Limited exposure dwellings with concentrated glass (that produces a time-of-day peak) may fall in the 500 to 800 ft2/ton range. Homes with exceptional features can be all over the map in this regard. Just rotating a home and changing its’ orientation exposure on the site can change the ratio by 100 to 400 ft2/ton.

Comfort system performance is only as good as the accuracy of the heat-loss/heat-gain estimate. Efforts to “adjust the load” to provide a “safety factor” or to produce a solution that is compatible with the “I have been doing it this way for 30 years” syndrome are forbidden.

When replacing equipment, do not use the existing equipment size as the criteria for the size of the replacement equipment. (There is a high probability that the existing equipment is oversized.)

6) Professional contractors do it as a standard practice, to mitigate the risk of being sued by homeowners who are unhappy with their HVAC system.

[rickintampa]

Originally posted by sayco bob
Rick: you can pay now or pay later. If you don’t have the load calculations done the system will not work properly. Would you rather save a couple dollars now and not be happy with the system you install or spend the money up front for a system that does what it was DESIGNED to do. Find a contractor in your area that is willing to do the job correctly you will be happier in the long run. I agree that a Carrier factory authorized dealer would be a good starting point. This web site if full of people trying to solve problems that they could have avoided.

Bob,
I understand what you're saying and appreciate the fact that you're kindly spending time and effort offering free advice to help the ignorant. But I doubt that many consumers will ever be willing to pay to do research before buying something; most people probably won't even take the time to thoroughly read a product brochure. It will be left up to those who sell and service goods (in this case, you guys) to tell us exactly what we need at exactly what price, and to give us those professional recommendations free-of-charge. That's why my method is to get many estimates and opinions as possible, then look for the most consistant information. By the way, one of the guys who came out was a Carrier dealer. I didn't care for him much. He came on too much like a salesman, and not surprisingly, his was the highest price by far. ~rick

[jmas65]

Rick,

Finally talked the wife into a new system, eh?

I'm in North Florida and had my heat pump replaced last year. While each of the contractors I called initially offered to replace my pump with a like sized system, I insisted they do a load calc before doing the job. As it turned out, my previous system was a half ton oversized, and my new system keeps the house much more comfortable for less money. Anyway, there's no reason you can't have the contractor do the calc after you make your decision - in other words, the quote should spec a load calc be performed and a system selected accordingly. The difference dollarwise between a 2 ton and 2.5 ton is minimal.

The cheapest time to fix duct and sizing issues is at the time of install. If you're going to do it, do it right.