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HVAC DIY #4564854
11/05/17 12:44 PM
11/05/17 12:44 PM
Joined: May 2011
Posts: 1,055
Greenville, SC via Chicago, IL
dja4260 Offline OP
dja4260  Offline OP
Joined: May 2011
Posts: 1,055
Greenville, SC via Chicago, IL
My home has two HVAC systems, one per floor. My second-floor system is 22 years old. It's located in a spacious area of the attic. The returns and runs to vents are all flex duct. The current system still works. I feel that it's oversized as it cycles on for 5 minutes, then off for 20 during the summer months. I know AC compressor is 3-ton. The second floor is ~1250 sq ft. All brick home with quality thermal windows and R-19 insulation. Home is in Upstate South Carolina.

Armstrong Furance-G8A75DC10-18
Carrier coil-CE3AXA036000ABAA
Payne unit outside- PA12NA036-A

I've called a few contractors for quotes and they both have just sized the new replacement system based on the old set up. I KNOW this isn't correct, they're being lazy and not doing a manual S, and J. They will not get my money.

My thought:

Have someone help me properly size what I need. Purchase a simple Goodman single stage 80% furnace, 16+ seer setup based on my needs and assemble it next to existing. Remove existing and hire someone to do the sheet-metal work and connect line-set/compressor etc. Because everything is flex-duct, it's not challenging complete.

Whoever installed my current furnace takes zero pride in their work.

Anyone else tackle HVAC on their own?


2013 Hyundai Elantra Gt Hatch 6 spd
2005 Toyota Highlander V6
1997 HD Sportster
Re: HVAC DIY [Re: dja4260] #4564896
11/05/17 01:17 PM
11/05/17 01:17 PM
Joined: Oct 2004
Posts: 8,300
Cincinnati, OH, USA
bullwinkle Offline
bullwinkle  Offline
Joined: Oct 2004
Posts: 8,300
Cincinnati, OH, USA
If the unit doesn't run very long, downsizing the condensing unit for a smaller one, possibly 1 1/2-2 ton, while keeping all your existing furnace, coil, plenum, ductwork, etc. might be a less expensive alternative to replacing everything. I'm guessing you probably don't need the furnace in winter (since heat rises & you obviously have good insulation), so basically using your existing attic system as an air handler should get it done. A good friend of mine did this with his whole house system years ago-the A/C ran a lot, but it did an excellent job at dehumidifying the air & was less expensive to run than his old bigger condensing unit.


06 Ram 3500 CTD 4X4(FG Venturi), 93 GMC C3500 6.2, 89 F-450 7.3, 98 XJ 4.0(XG8A), 05 xB(XG3600), 18 Transit 3.7, 03 Merc Grand Marquis 4.6 2V(XG2)
Re: HVAC DIY [Re: dja4260] #4564954
11/05/17 02:06 PM
11/05/17 02:06 PM
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
Definitely over sized. My whole house is 1200sqft and it has a 2 tonne unit that comes on for about 20 minutes and shuts off for an hour. In the summer when it's really hot 100F or more it will run for an hour and shut off for about 20 minutes.

The guy told me I could be fine with a 1 tonne but I insisted on a 2 tonne because we have no insulation in the walls of our 1940's house.

Get the contractor to do the actual J-Manual calculation and not just guess. Most are lazy and go by... "Well I just did a house this size" and the J-Manual calculation takes into account insulation, windows, levels, square footage etc.

Last edited by StevieC; 11/05/17 02:07 PM.

'18 Dodge Grand Caravan GT - AMSOIL SS 5w20
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF
Re: HVAC DIY [Re: dja4260] #4564966
11/05/17 02:19 PM
11/05/17 02:19 PM
Joined: Aug 2015
Posts: 310
TX
KJSmith Offline
KJSmith  Offline
Joined: Aug 2015
Posts: 310
TX
You can probably get the furnace and coil.
It is not legal for you to buy a condensing unit with the Freon in it, unless you are EPA certified.

At one time you could buy "dry" units. Not sure they are available anymore.

FYI, Goodman is now Chinese owned, if that matters to you.

Re: HVAC DIY [Re: dja4260] #4565104
11/05/17 04:54 PM
11/05/17 04:54 PM
Joined: Dec 2006
Posts: 370
Tampa, Florida
flanso Offline
flanso  Offline
Joined: Dec 2006
Posts: 370
Tampa, Florida
The Braeburn 2200NC thermostat in my HVAC system can be adjusted to change the temperature increment from turning off to turning back on. Changing the increment from 0.5 to 2, made the system run longer each time it turned on but it ran less frequently.

Re: HVAC DIY [Re: dja4260] #4565150
11/05/17 05:41 PM
11/05/17 05:41 PM
Joined: Apr 2004
Posts: 5,242
Texas
JustinH Offline
JustinH  Offline
Joined: Apr 2004
Posts: 5,242
Texas
Put the job out for bid on service pro or thumbtack.

I used thumbtack for my ac/furnace replacement and found a very reasonable rate for a well installed American Standard system (Trane).

10 year warranty, no problems.

I looked at goodman but they had poor ratings, and I paid the same price for American Standard as someone else had quoted for goodman.

I believe I paid $2600 for a 2.5 Ton 14 seer American Standard unit with a 80 percent gas furnace installed.

Based on price of the materials, I figure the contractor made $800-$900 to install the unit and I was fine with that.


'11 Hyundai Sonata GLS
'11 Scion XB
Re: HVAC DIY [Re: dja4260] #4565217
11/05/17 06:48 PM
11/05/17 06:48 PM
Joined: Feb 2010
Posts: 4,838
Central Texas
sleddriver Offline
sleddriver  Offline
Joined: Feb 2010
Posts: 4,838
Central Texas
I calculated my own Schedule J. It was close tonnage wise to what's installed however, I keep my house at 78F rather than the lower design point. This affects how long and how often the unit runs at. As someone else posted, my t-stat also could be tweaked to reduce the deltaT setting. I'll look into that.

Also designed my own duct system using Manual D and installed it myself. Previous system was restricted on both supply & return.

Still running a 27yr old 13 SEER Janitrol heat-pump. I clean the coils annually and closed up all return plenum leaks. House stays quite dry indoors given humid S. Tx conditions.


1998 Volvo V70 T5 228,880 mi. Original Owner.
M1 10W-30 HM
"It's never a mistake to buy tools, defined broadly. They're not a cost, they're an investment." - J.B. Peterson
Re: HVAC DIY [Re: dja4260] #4565683
11/06/17 08:58 AM
11/06/17 08:58 AM
Joined: May 2003
Posts: 7,389
Oklahoma
Schmoe Offline
Schmoe  Offline
Joined: May 2003
Posts: 7,389
Oklahoma
If it's got R22 in it, that stuff is crazy expensive now. You could get a HVAC company to remove that refrigerant and then sell it to them.


01 Supercrew Lariat 4X4
06 Accord EX-L V6
14 CRV EX-L (RIP) 2018 CRV EX-L
Re: HVAC DIY [Re: KJSmith] #4565697
11/06/17 09:14 AM
11/06/17 09:14 AM
Joined: Sep 2012
Posts: 5,455
DFW
DBMaster Offline
DBMaster  Offline
Joined: Sep 2012
Posts: 5,455
DFW
Originally Posted By: KJSmith
You can probably get the furnace and coil.
It is not legal for you to buy a condensing unit with the Freon in it, unless you are EPA certified.

At one time you could buy "dry" units. Not sure they are available anymore.

FYI, Goodman is now Chinese owned, if that matters to you.


Dry charge units are no longer available. They took advantage of a loophole in the R-22 phase out rules (charged with inert nitrogen at the factory instead of Freon). But they were generally the low end units as manufacturers weren't going to invest in high efficiency dry-charge units with regional standards on their way. The minimum efficiency required for new units in my region is 14 SEER.

Also, you are incorrect about Goodman. Daikin owns Goodman and is a JAPANESE company.

Re: HVAC DIY [Re: Schmoe] #4565698
11/06/17 09:17 AM
11/06/17 09:17 AM
Joined: Sep 2012
Posts: 5,455
DFW
DBMaster Offline
DBMaster  Offline
Joined: Sep 2012
Posts: 5,455
DFW
Originally Posted By: Schmoe
If it's got R22 in it, that stuff is crazy expensive now. You could get a HVAC company to remove that refrigerant and then sell it to them.


R-22 may be expensive, but with the sales dropping like a rock it's readily available and has actually come DOWN in price about 25% in the past six months. It's one of the commodities I manage for my employer. As long as leaks are repaired it's still way cheaper than replacing your system.

Current going rate if you're an OEM, is under $450 for a 30 lb jug. That's $15/lb. Many contractors are gouging.

Re: HVAC DIY [Re: flanso] #4565730
11/06/17 10:08 AM
11/06/17 10:08 AM
Joined: May 2012
Posts: 4,531
Baltimore, Maryland, USA
zzyzzx Offline
zzyzzx  Offline
Joined: May 2012
Posts: 4,531
Baltimore, Maryland, USA
Originally Posted By: flanso
The Braeburn 2200NC thermostat in my HVAC system can be adjusted to change the temperature increment from turning off to turning back on. Changing the increment from 0.5 to 2, made the system run longer each time it turned on but it ran less frequently.


That would be the first thing that I would try. Find a thermostat that allows for greater temperature swings. They do exist. I think Lux makes one.

Re: HVAC DIY [Re: DBMaster] #4566283
11/06/17 08:35 PM
11/06/17 08:35 PM
Joined: Aug 2015
Posts: 310
TX
KJSmith Offline
KJSmith  Offline
Joined: Aug 2015
Posts: 310
TX
Originally Posted By: DBMaster
Also, you are incorrect about Goodman. Daikin owns Goodman and is a JAPANESE company.


OK, Goodman is Japanese owned, if that matters to you.

Re: HVAC DIY [Re: dja4260] #4566287
11/06/17 08:44 PM
11/06/17 08:44 PM
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
StevieC Offline
StevieC  Offline
Joined: Aug 2008
Posts: 21,194
ON, Canada eh?
My Amana (Goodman) is 5 years old and we run the A/C cold like a freezer in the summer and the Furnace runs all the time in the winter because we have no insulation in the house and it's been rock solid reliable. Really happy with it.

I also keep the 24 volt ECM fan motor running 24 hours a day for circulation and to keep dust down. No issues.


'18 Dodge Grand Caravan GT - AMSOIL SS 5w20
'06 Santa Fe - 535,000km AMSOIL SS 0w30 / ATF
Re: HVAC DIY [Re: KJSmith] #4566796
11/07/17 12:21 PM
11/07/17 12:21 PM
Joined: Aug 2002
Posts: 14,556
Silicon Valley
PandaBear Offline
PandaBear  Offline
Joined: Aug 2002
Posts: 14,556
Silicon Valley
Originally Posted By: KJSmith
Originally Posted By: DBMaster
Also, you are incorrect about Goodman. Daikin owns Goodman and is a JAPANESE company.


OK, Goodman is Japanese owned, if that matters to you.



Japanese knows how to make AC, Daikin is a very good brand in the Asian market.


"You keep asking questions PandaBear and you'll end up a vegetarian like my wife" - Camu Mahubah
Re: HVAC DIY [Re: PandaBear] #4567128
11/07/17 06:58 PM
11/07/17 06:58 PM
Joined: Aug 2015
Posts: 310
TX
KJSmith Offline
KJSmith  Offline
Joined: Aug 2015
Posts: 310
TX
Originally Posted By: PandaBear
Originally Posted By: KJSmith
Originally Posted By: DBMaster
Also, you are incorrect about Goodman. Daikin owns Goodman and is a JAPANESE company.


OK, Goodman is Japanese owned, if that matters to you.



Japanese knows how to make AC, Daikin is a very good brand in the Asian market.


I never said anything bad about them.
They are made in what I call far NW Houston.

Daiken moved all its USA manufacturing there earlier this year.... according to the local news.

Pretty sure Americans and Texans know a little about it also.

Last edited by KJSmith; 11/07/17 07:01 PM.

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