Ductwork

[remodel80]

In advance thanks for all replies, you knowledge and expertise is greatly appreciated.

I have had 3 different contractors look at my home to update the heating and cooling.

1-100,000 BTU/4 ton HP
1-70,000 BTU/3 Ton HP
1-60,000 BTU/2 Ton HP

Non of them performed a Manaul J, but I did have one performed on my own.

The 60,000 BTU/2 Ton HP came up the closest to the Manual J (1600 sqft 44,000 Heat Loss/14,000 Heat Gain)

The two that oversized stated they did so due to the amount of ductwork, the one that was closest stated it would work fine.

Your Opionions.

[Kevin Weaver]

Heat load and gain has a lot to do with the location you are at. IMO, it sounds like the 14,000 btu. gain is way low. There again, I don't know your location. Here in central Indiana, your home would most likely call for a 2.5 ton- 2 ton. It is a rule of thumb to upsize a heat pump a half a ton so you get more heat in the winter time. Here is a thought, get a 2 speed 3 ton hp, it will run at 2 tons mostly but if you ever need more power, than it boosts itself to 3 ton.

Good luck

[udarrell]

I have had 3 different contractors look at my home to update the heating and cooling.

1-100,000 BTU/4 ton HP
1-70,000 BTU/3 Ton HP
1-60,000 BTU/2 Ton HP

Non of them performed a Manual J, but I did have one performed on my own.

The 60,000 BTU/2 Ton HP came up the closest to the Manual J (1600 sqft 44,000 Heat Loss/14,000 Heat Gain)

The two that oversized stated they did so due to the amount of ductwork, the one that was closest stated it would work fine.
Your Opinions.

Does that 14,000 Heat Gain include the latent heatload Btuh?
If it does, then we're talking about a 1.5-Ton heat pump for the cooling load.

Two of them appear to be way oversizing the equipment; 4-Ton cooling wow.

The duct system will usually work okay, & perhaps more efficiently, because it's usually under-sized for 4-Ton of cooling & 100,000-Btuh for heating.

[tipsrfine]

2 speed is the way to go, even for straight a/c. I'm no heat pump sizing pro, but I believe climate zone plays a part, but a heat pump is usually unable to to be sized to meet your heating needs because it results in an oversized air conditioner in summer. Assuming your ducts are sized correctly, a 2 speed makes good sense, considering all properly sized a/c's are oversized for the majority of the cooling season because single speeds have to be sized to meet the peek load conditions of summer, which is a small percentage of time. A 2 speed heat pump will allow you to meet more of your heating load by running in 2nd stage, and in summer it will likely stay in 1st stage the majority of the cooling season, with 2nd stage as a back-up for a heat wave.

[remodel80]

My main trunk line is 18"x16" for 12' the turns and reduces to 13"x17" for 37', there are 4-6 round and 7-8 round runs off of this.

And all quotes where for 2 stage heatpumps since I knew that they most likely would be oversized for the cooling side.

Also I am in central Illinois

[dan sw fl]

My main trunk line is 18"x16" for 12' the turns and reduces to 13"x17" for 37', there are 4-6 round and 7-8 round runs off of this.

And all quotes where for 2 stage heatpumps since I knew that they most likely would be oversized for the cooling side.

Also I am in central Illinois

Should we guess that it's a 1953 ranch?
and that it's 1,600 square feet without a basement?
and it only has 7.5 windows?

Double Jeopardy game doesn't always work that well here.

[remodel80]

Dan,
It is a 100 year old two story with a addition done last year.
Basically 1600 sqft on the first floor, second story is heated and cooled by seperate system,9' 800 sqft basement, 400 sqft cellar type basement, remainder crawl space. There is 14 windows 10 of them 6'x30" the rest 4'x30", 1-6' Slider and 2-36" Entry doors.

I have completely remodeled the 100 year old (Everything new but the wood in the walls) and added approx 1,000 sqft to the first floor last yeat which is when the basment was installed. The duct work I listed was installed with the new addition, and I continued to use my existing system which is a 90% 100,000 BTU Furnace.

[dan sw fl]

Dan,
It is a 100 year old two story with a addition done last year.
Basically 1600 sqft on the first floor, second story is heated and cooled by seperate system,9' 800 sqft basement, 400 sqft cellar type basement, remainder crawl space.
There is 14 windows 10 of them 6'x30" the rest 4'x30", 1-6' Slider and 2-36" Entry doors.

I have completely remodeled the 100 year old (Everything new but the wood in the walls) and
added approx 1,000 sqft to the first floor last year
which is when the basment was installed.
The duct work I listed was installed with the new addition,
and I continued to use my existing system which is a 90% 100,000 BTU Furnace.

30,220 BTU/HR Heating
20,710 BTU/Hr Cooling for 1,600 Sq. Ft. FIRST Floor

Windows 240 sq feet at U value of 0.3 with 120 Square Feet facing E/W
Walls R15
Average Infiltration yields 7,400 BTU/HR
Manual J abridged 8th edition

Seems a bit low on heating but the differential temperature is 75'F ( 72' - -3')

1000 sq feet ceiling R30 because second story covers about 600 square feet

I'm going to have to reconfirm calc
because 30,200 BTU/HR
just doesn't "feel right/ accurate", but
It Is, What It Is.

[remodel80]

S Wall 36'/Windows 48sqft/R15
N Wall 36'/Windows 66sqft/R22
E Wall 44'/Windows 30sqft/28' R22/16' R15
W Wall 44'/Windows 65sqft/28' R22/16' R15

Window Values
U Value-0.28
SHGC-.18
R Value 3.57
Attic-R60
Ceiling of 1st floor over 2nd Floor R-30

I was in unbelief when I had the load calc performed.

My current AC is 2ton, 27 years old. I made it through this summer comfortable and it actually was leaking refrigerant.

The load calc also included my basement if that makes a difference.

[remodel80]

My bad my walls are 9'

[remodel80]

Load Calc Was based on the following information as well, I should probably just load up a copy but dont know if that is allowed.

Indoor
Summer Temp 72
Winter Temp 73
RH-50

Outdoor
Summer Temp 93
Winter Temp 0
Summer grains of moisture 194
Daily Temperature Range Medium

[dan sw fl]

S Wall 36'/Windows 48sqft/R15
N Wall 36'/Windows 66sqft/R22
E Wall 44'/Windows 30sqft/28' R22/16' R15
W Wall 44'/Windows 65sqft/28' R22/16' R15

Window Values
U Value-0.28
SHGC-.18
R Value 3.57
Attic-R60
Ceiling of 1st floor over 2nd Floor R-30

I was in unbelief when I had the load calc performed.

My current AC is 2ton, 27 years old. I made it through this summer comfortable and it actually was leaking refrigerant.

The load calc also included my basement if that makes a difference.

IF your SHGC is actually 0.18, I'd suspect that you _NOT_ may be able to see through them so-to-speak.
( in other words, darker than h_LL).

Please verify that value with a purchase order, window tag, vendor catalog or correspondence with the window mfg representative.

[dan sw fl]

Those windows have got to be something REALLY SPECIAL.

http://www.efficientwindows.org/glazing_.cfm?id=8

[tedkidd]

S Wall 36'/Windows 48sqft/R15
N Wall 36'/Windows 66sqft/R22
E Wall 44'/Windows 30sqft/28' R22/16' R15
W Wall 44'/Windows 65sqft/28' R22/16' R15

Window Values
U Value-0.28
SHGC-.18
R Value 3.57
Attic-R60
Ceiling of 1st floor over 2nd Floor R-30

I was in unbelief when I had the load calc performed.

My current AC is 2ton, 27 years old. I made it through this summer comfortable and it actually was leaking refrigerant.

The load calc also included my basement if that makes a difference.

Lol. "your 27 year old 2 ton works fine, so you really need a 4 ton because, well, my daughter needs braces"

44/14 split sounds suspicious. Intuition says heat load is high or cooling is low. Even 44/24 seems off, so maybe both are off. If you are getting a heat pump you'll be much happier with 2 stage given your apparent seasonal split.

[remodel80]

IF your SHGC is actually 0.18, I'd suspect that you _NOT_ may be able to see through them so-to-speak.
( in other words, darker than h_LL).

Please verify that value with a purchase order, window tag, vendor catalog or correspondence with the window mfg representative.

Dan,
I can see through them fine! I retrieved the value from the website of the manufacturer which is Integrity. Windows are there wood ultrex casement with LoE366

[remodel80]

Tedkidd,
What would your guess be?
And my plan was to go with a 95% 2 Stage ECM Furnace with 2 Stage 15 seer or better heat pump and use an ecobee thermostat
If i was going to size the unit I am thinking a 60,000-70,000 BTU with 3 Ton HP, but I am not HVAC technican and just a guy trying to educate himself to make sure my money is well spent.

[tedkidd]

Any sense how long your current furnace runs per hour on the coldest days?

Annual gas consumption?

Sounds like your replacement plan is good. Dict diagnostics wb nice, at least external static on current system. Want to be sure 1200 cfm works ok on your duct. (Udarrell can tell if it's definitely not off the top of his head).


Thought about getting ecobee now, replacing equipment in spring?

[remodel80]

No, havent run the furnace through the winter since I have done the addition. But currently with 40f evening temps runs less time than it takes to heat the exchanger up.
Gas usage is typically 500 gallons-Three year base, but this is also during remodel and improving envelope and insulation and windows but 1st year Heating 65F,2nd year 68F, 3rd year 72f. Last winter usage was 200 gallons but had considerably fair weather compared to 3 years before.

Duct is 18x16 for 12' 90's and reduces to 17x13 goes 11' 90's continues 17x13 10' 90's runs 15' end of main.
5-6 round, and 6-8 round off of this. Another line 12x8 10' with 3-6 round

Both main trunk lines come right off the coil box on each side.

Already have Ecobee, was planning to upgrade yet this year, I believe that the unit is not sized correctly and is costing me by not upgrading.

[dan sw fl]

Dan,
I can see through them fine! I retrieved the value from the website of the manufacturer which is Integrity. Windows are there wood ultrex casement with LoE366

I am now updated on Marvin Integrity Low E 366 which has SHGC 0.18 U-Value 0.28 and VT 0.41. [ reviewed Marvin website literature].
That means __ the windows Heat Gain is about 20% of a clear glass __ and saves about 12,000 BTU/hr / 1-ton + of cooling capacity.
+ along with VERY High R-value walls/ celing, the Manual J calculated heating/cooing requirments are MUCH Less than half of what one would normally expect.

[remodel80]

I am now updated on Marvin Integrity Low E 366 which has SHGC 0.18 U-Value 0.28 and VT 0.41. [ reviewed Marvin website literature].
That means __ the windows Heat Gain is about 20% of a clear glass __ and saves about 12,000 BTU/hr / 1-ton + of cooling capacity.
+ along with VERY High R-value walls/ celing, the Manual J calculated heating/cooing requirments are MUCH Less than half of what one would normally expect.

So now my manaul j calculation that seemed out of whack is in line? I appreciate your questioning Dan since it was striving to reveal the truth to the numbers.

I wish I could find a contractor locally that would do the quality job that you guys belief is standard.