Manual J calculation questions


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Old 12-22-14, 06:12 AM
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Manual J calculation questions

I am doing the Manual J calculation for my house. I use the Hot2000 program (you can download it from the Canada government site HOT2000 | Natural Resources Canada ).

I will post here in this thread all the questions related to this topic, as they come to me while I am progressing through this.

If anyone of you has come across Hot3000 I would like to hear about this (a link to download it). It was available for download while it was in Beta version. I have no idea if the final version is or it ever was available to the public.

This program has no documentation but I came across this set of video tutorial

https://www.youtube.com/playlist?lis...WBxifopoK1oV3V

Have fun watching them if you are interested.
 
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Old 12-22-14, 06:18 AM
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So here is my first question:

When you are using the program they ask you about wall heights and these together with the perimeter of the house will pretty much delimit the volume to be heated or cooled

They don't say anything about the floor for the main level (a bungalow in my case) which in itself is a volume of around 10" height, filled with insulation, wood etc. It is very compact and it is mostly inside excepting for the outside perimeter strip which should be considered with the same R value as the exterior walls above it. Can I ignore the floors in the Manual J calculation? If you watch the tutorials that I linked above you will see that the floor is not mentioned at all
 
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Old 12-22-14, 06:43 AM
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Assume that you have an attached garage.
How is the wall between your house and your garage considered: interior wall or exterior wall?
What R value should be considered for this since this wall is not facing the exterior directly and it has a lower heat transfer to the exterior (garage space which is not heated but it is enclosed)

Answering my own question: Tutorial #2 deals with walls In that one you can see around min 22.37 that the guy ignores the garage and he considers the walls as any other walls around the house
 

Last edited by PF4DIY; 12-22-14 at 07:23 AM.
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Old 12-22-14, 07:26 AM
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Hi PF4,
I tried using HOT2000 years back but on my side of the border there was zero support, no youtube videos back then. I did look at HOT3000 as well, but again no support.

As for the manual J, what is your objective? The M-J approach would be different from the HOT-2000, I'm guessing. If this is a one time application for your own home, there are other options to determine a heat loss other than digging through 2000.

Bud
 
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Old 12-22-14, 07:27 AM
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The terminology used by Hot2000 for walls sucks
They say Wall perimeter...that is actually length . See video #2 for examples.
A perimeter delimits an enclosed area
 
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Old 12-22-14, 04:24 PM
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Very useful link on how to aproximate R values when you do not know the structure of the wall or surface that you need

http://www.ag.ndsu.edu/pubs/ageng/structu/ae1373.pdf

You need an IR thermometer for that (see the PDF)
 
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Old 12-22-14, 04:42 PM
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RE: First question

I have not watched the video(s) regarding the program you are using but the ones I've used, as well as the paper Manual J, asked about the floor of the main level & it's insulation. The programs all wanted to know if the floor was over conditioned area, a vented crawl space, on grade, etc. They also asked about insulation & even floor covering. I don't understand your program seemingly leaving that out. Are you sure it isn't covered somewhere? Maybe later in the program? As for me, I consider the program from HVACcomputer.com to be one of the best. Not sure if it covers Canada or not.
 
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Old 12-22-14, 05:09 PM
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There might be a section where it asks for this but I have not played with that yet

How about this

Floor Header Components
The Floor Header dialogue is used to enter data about the thermal resistance and insulation of floor header components. A floor header component can be added to the house by highlighting a wall or foundation component in the house data editor tree and clicking on the floor header button on the toolbar. To access the floor header dialogues highlight one of the floor header components in the house tree. This will display the Floor Header dialogue (see Figure below) for that floor header component.



In HOT2000, "floor header" refers to the exterior, exposed portion of a horizontal structural element that separates two floors of a house. Floor headers are "attached" to walls rather than the house. Each wall defined may have one or more floor headers attached to it.



HOT2000 allows a maximum of 32 sets of wall - floor header components. Both Walls and Floor Headers share the same set of 32 definitions. If there are already 27 wall components defined, then there can only be a maximum of 5 floor header components.


Is this about the floor ?
 
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Old 12-22-14, 05:11 PM
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You didn't mention what you want this for? If you are going to do multiple homes in Canada, then learning HOT2000 might be worth the effort. For a single home, there are HVAC programs that can be purchased for a one time use. But in most cased you can approximate your losses close enough. Slantfin has or had a free software you could use.

Bud
 
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Old 12-22-14, 05:50 PM
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Thanks Bud, it is just for myself
How can I approximate my losses, what other method is out there?

I can't find the program that you are talking about. Is it much simpler that Hot2000 ?
I am not going to pay any money when Hot2000 is free. That was made with tax payer's money so...why pay twice?

not the best reviews ...see below
https://itunes.apple.com/us/app/slan...552019515?mt=8
 

Last edited by PF4DIY; 12-22-14 at 06:08 PM.
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Old 12-22-14, 06:11 PM
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Here's an older discussion on the slantfin, so not sure if it is still out there.
http://www.doityourself.com/forum/bo...alculator.html

If you are just trying to identify where you are losing heat, then this might help.
Home Heat Loss Calculator

If you are looking to size your equipment room by room, then the HVAC calc would provide a manual J.

There is also the baby sister of HOT2000, called HOT2xp. The nice thing about hot2xp is you can upload that date into 2000. I haven't checked the Canadian web site to be sure it is still available.

Bud
 
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Old 12-22-14, 06:51 PM
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Yes I need to size my equipment

I was under the impression that hot2xp is older so I used hot2000
I will have a look, perhaps that one is simpler

Slantfin is here Contact Us - P.V. Sullivan Supply Co., Inc. I will give it a try

thanks a lot

Update: I could not install slantfin on Windows Vista.
 

Last edited by PF4DIY; 12-22-14 at 07:12 PM.
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Old 12-23-14, 01:34 AM
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I've never used the Slantfin, perhaps others here can help.

2xp is a super simplified version where you pick very rough approximations and it draws from its data base to tell you what other similar looking homes have had for heat loss. You can then open up different sections and add more specific details.

When you say size your equipment, are you referring to just the boiler or the radiators for each room?
The builditsolar spreadsheet uses the basic heat loss equations that can be used manually. It will get you a total number.

Bud
 
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Old 12-23-14, 04:49 AM
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No I don't go room by room. I want the total number of BTUs required to keep the house warm
 
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Old 12-23-14, 05:57 AM
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So after using Heat2000 I got this:

ANNUAL SPACE HEATING SUMMARY

Design Heat Loss at -4.00 F (2.92 BTU/hr / Ft3): 55320.77 BTU/hr
Gross Space Heat Loss: 108.83 Mil.BTU

Gross Space Heating Load: 108.95 Mil.BTU
Usable Internal Gains: 20.30 Mil.BTU
Usable Internal Gains Fraction: 18.65 %
Usable Solar Gains: 11.74 Mil.BTU
Usable Solar Gains Fraction: 10.79 %
Auxilary Energy Required: 76.91 Mil.BTU

Space Heating System Load: 76.91 Mil.BTU
Furnace/Boiler Seasonal efficiency: 88.34 %
Furnace/Boiler Annual Energy Consumption: 85.60 Mil.BTU

I was quoted a 60K BTU Daikin with two stages.
 
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Old 12-23-14, 08:14 AM
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I don't use the results in the form you have, but your end result of a two stage 60K BTU sounds close. What is the sq ft area of your home, didn't see it?

Do you have any previous fuel use numbers, oil or gas?

Bud
 
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Old 12-23-14, 09:11 AM
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Nope I just moved here
~1200 SQF/floor (2400sqft basement+ground floor)
 
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Old 12-23-14, 09:29 AM
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At 1,200 ft your heat loss is on the high side and perhaps there are some easy savings to be had with air sealing and insulation. I'm not sure what is available for a boiler much smaller (the HVAC pros will need to help there).

A couple of details and I'll give you a reality check.
2x4 walls or 2x6?
attic insulation thickness?
age of house?
any insulation in basement?
Heating degree days where you live?

With that I can approximate your heat loss and see if I get close to your numbers.

Bud
 
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Old 12-23-14, 09:58 AM
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Built in 58, location: Toronto
Outside walls 10.5"
Inside walls 5.5"
Basement walls ~16.5" (concrete blocks, batt insulation+blue solid insulation+2x4 I would guess)


Heating Temperatures
Main Floor: 69.8 F
Basement: 69.8 F
TEMP. Rise from 69.8 F: 5.0 F
Cooling Temperature: Main Floor + Basement: 77.00 F

Basement is- Heated: YES Cooled: YES Separate T/S: NO
Fraction of internal gains released in basement : 0.150

Indoor design temperatures for equipment sizing
Heating: 71.6 F
Cooling: 75.2 F

Not sure about the insulation in the first floor walls. Must be none or R14 batt insulation. The calculation was made with batt insulation
The exterior walls on the main floor are brick veneer + 2x4 studs + some sheating+0.5-0.75" drywall.

Attic insulation: lose batt insulation or similar, approximate R vlaue=3
Ceiling Gross area sqft 1130 (less than the floor footprint, obviously)
Exposed areas for: Basement
Exposed Perimeter: 146.00 ft

Basement Configuration: BCIN_1
- concrete walls and floor
- interior surface of wall insulated over full-height
- any first storey construction type









 

Last edited by PF4DIY; 12-23-14 at 10:29 AM.
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Old 12-23-14, 11:17 AM
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PF, great information, but it will take me a while to dig through it, holidays and all. But I will return.

BTW, great job digging through the HOT2000. I may have to have you help me!!! Although I'm pretty much retired now.

Bud
 
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Old 12-23-14, 11:47 AM
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not a big deal, I just followed the tutorials that I posted a link to below
The hardest part was to figure out the R values for different elements
 
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Old 12-23-14, 11:56 AM
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I think weather stations and libraries were an issue when I tried it and without support, doing energy audits for a wide variety of homes meant no place to go for help. I still find it inexcusable for the states to not select one primary software like 2000 and do as Canada has done, make it available to everyone for free. As some have speculated, our current approach of watching the free enterprise market create hundreds of different programs has been a real boon to jobs creation. I guess I was naive thinking we were after energy savings, they just used that as an excuse to spend a lot of money. OOPs, off of my rant box.

Bud
 
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Old 12-23-14, 12:50 PM
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Actually you can edit the libraries and add whatever you want
They have weather, wall codes, windows codes, combustible codes etc etc.
Each one has a dedicated editor and you can add the US data if you want.

There is a more advanced version Hot3000 ..that was available in beta version for a while.
I am not sure what happened with that after it passed the beta stage
 
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Old 12-23-14, 01:46 PM
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If you are going to do a Manual D, you will need to know the load for each room.
 
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Old 12-25-14, 10:53 PM
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I am actually trying to use manual D to calculate the blower capacity.
I already have ducts in place so that is a given
I know that

-CFM=Building Volume/Minutes Air Change

How do I get this Minutes Air change ?

Here is what I know so far:

-Heat loss -55k BTU -> I will need a 60K BTU furnave
-building volume to be heated: 14200cft

AIR LEAKAGE AND VENTILATION

Building Envelope Surface Area: 4545.13 ft2

Air Tightness Level is Average (4.55 ACH @ 50 Pa)

Terrain Description Height ft
@ Weather Station : Suburban, forest Anemometer 32.8
@ Building site : Suburban, forest Bldg. Eaves 11.6

Local Shielding: Walls: Light
Flue : Heavy

Leakage Fractions- Ceiling: 0.300 Walls: 0.500 Floors: 0.200

Estimated Equivalent Leakage Area @ 10 Pa: 137.09 in2
Normalized Leakage Area @ 10 Pa: 0.0302 in2/ft2
Estimated Airflow to cause a 5 Pa Pressure Difference: 120 cfm
Estimated Airflow to cause a 10 Pa Pressure Difference: 187 cfm
ELA used to calculate Estimated Airflows: 54.84 in2
 
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Old 12-26-14, 06:14 AM
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I think what they want is minutes PER air change. If so; in 60 minutes you would get 4.55 air changes. 60/4.55= 13.19 minutes per air change.
 
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Old 12-26-14, 07:20 AM
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That might be the case but then how do I get that 60 minutes number?
 
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Old 12-26-14, 08:08 AM
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I think that the answer is just below ...the ACH number , that is Air Changes per Hour due to air leaking through the walls, ceiling and floors so all the numbers are already calculated by Hot2000 but they are per square inch or foot...
 
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Old 12-26-14, 08:44 AM
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Lacking an actual measure number, 2000 is simply applying a prescriptive number based upon the size and description of your house. If you have done some air sealing or have unusually large leak areas their assumption will be off one way or another.

Your 4.55 air changes per hour is also at 50 pascals depressurization. Dividing that by 20 (or the LBL number for your house) will approximate the natural air leakage, ie 4.55/20 = 0.23 which would indicate a reasonably tight home which may be optimistic.

Still short on time, back later.
Bud
 
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Old 12-26-14, 09:07 AM
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I'm sorry. I'm lost in that I don't understand what you are trying to determine. The blower capacity will be fixed by the furnace manufacturer. They determine what blower is needed to yield a given temperature rise across the heat exchanger at a given (usually 0.5" water column) static pressure.
 
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Old 12-26-14, 10:22 AM
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You are correct.
The problem might be that although the BTU number matches my needs, the CFM number might not be the right one because the ducts are over sized or undersized. I suspect that they might be undersized (I seem to have an overheating problem) and the air path is quite clear IMHO, so it might be the static pressure that my blower is facing.

Here is what I know:

The blower must be powerful enough to overcome:
-external static pressure (that is to move enough air volume to replace or recirculate the air in the rooms)
-internal static pressure (this is due friction with the duct itself)

So the above will size the blower and the ducts

The heat loss of the house is what dictates the BTU size of the furnace

I am not sure where the air leakage (ACH) comes in to play.
This can influence both, the external static pressure and the heat loss.

Great explaination here:

http://www.engineeringtoolbox.com/he...ngs-d_113.html

The overall heat loss from a building can be calculated as

H = Ht + Hv + Hi (1)
where
H = overall heat loss (W)
Ht = heat loss due to transmission through walls, windows, doors, floors and more (W)
Hv = heat loss caused by ventilation (W)
Hi = heat loss caused by infiltration (W)

1. Heat loss through walls, windows, doors, ceilings, floors, etc.>
The heat loss, or norm-heating load, through walls, windows, doors, ceilings, floors etc. can be calculated as

Ht = A U (ti - to) (2)


2. Heat loss by ventilation
The heat loss due to ventilation without heat recovery can be expressed as:
Hv = cp ρ qv (ti - to) (7)


3. Heat loss by infiltration
Due to leakages in the building construction, opening and closing of windows, etc. the air in the building shifts. As a rule of thumb the number of air shifts is often set to 0.5 per hour. The value is hard to predict and depend of several variables - wind speed, difference between outside and inside temperatures, the quality of the building construction etc.

The heat loss caused by infiltration can be calculated as
Hi = cp ρ n V (ti - to) (8)
 

Last edited by PF4DIY; 12-26-14 at 11:12 AM.
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Old 12-26-14, 12:16 PM
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OK so after more digging I came to the conclusion that the air infiltration is consolidated in the total BTU/h heat loss calculated by Heat2000

So if my house loses 60K BTU/h (55K BTU/h rounded up) and it has a volume of 14242 cubic feet then the blower needs to move 14242/60 cfm.
That would be ~ 240 CFM

Also there is this chart from the furnace's manual



So the CFM can be calculated this way as well

something does not match here..back to more reading
 

Last edited by PF4DIY; 12-26-14 at 12:43 PM.
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Old 12-26-14, 01:51 PM
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I wonder if that "temperature rise" axis is in C or F? Big difference!! I have to believe F.
Note: Checked another chart & it is F. CAUTION!!!! RANT AHEAD: I do wish my dear government would get it's head out of it's *&$ & go metric like the rest of the world. This English system of measurements is so hard to use. END OF RANT

According to the chart, a 50* temperature rise on a furnace with an output of 55,000 btu/hr. would be flowing around 1000 cfm. Something IS wrong. I know 240 cfm is no where near enough.
For cooling 400 cfm per ton (12,000 btu/hr) is the typical air flow used.

If the furnace you intend to get has a spec'd temperature rise of 50* you need to flow real close to 1,000 cfm.

If you tell me how many & what size the ducts are (supply & return) I can tell you how much air they will handle.
 
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Old 12-26-14, 02:03 PM
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Here is a close up



and here is a slightly different angle



Genreal view of the basement ducts


The smaller ducts are like 6" diameter (must be standard, I din not get to measure any, they are all covered by drywall

This is an above grade basement, 82.5" is the height
The ground level floor has shorter runs since they see the light just at the floor level, you can count one for each basement run, almost in the same position but of course shorter because they do not run all the way to the foundation slab.

I am not sure about the square pipe on the heated air path (supply) at the left top corner. That might be in fact a 6" tube or so
 

Last edited by PF4DIY; 12-26-14 at 02:23 PM.
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Old 12-26-14, 02:27 PM
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The trunk ducts seem to be unusual measurements ie: 13.56" wide, 8.28" high (supply) & 21" wide (return).
Also need to know trunk duct material as well as branch size(s) & material. Different materials have different friction losses.

Is that duct system just for the basement or does it do the main living area as well?
 
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Old 12-26-14, 02:38 PM
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The material is that common tin that you see, it is not aluminium or anything fancy

the red one are :
11x7 and 8x14
the blue one is 21x8
I just went downstairs and I measured them

Not sure what happened with my 3D model but as you can see the errors are not very big

The duct is common for basement and ground floor
 

Last edited by PF4DIY; 12-26-14 at 03:00 PM.
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Old 12-26-14, 03:11 PM
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11x7 will handle 360 CFM, 14x8=600 CFM, & 21x8=1050 CFM. All flow rates are at 0.1" water column static. If the round branches are 6" metal, they will carry 110 CFM each at 0.1" w.c.

On the left end (last drawing) there is a piece of square(?) supply trunk. Is it connected to a register? If so, what size is that trunk?

Looks like your duct work is marginal but will likely be ok. You don't perchance have any blower specs on the furnace do you?
 
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Old 12-26-14, 08:11 PM
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Not sure what happened, I want to reply right after you asked for more info but the forum was down and I had to leave to visit some friends
Here is the info you wanted

I had a second look at what is there and here is how I believe it is


above the two new ducts are feeding the living which is just above that area where the square duct was on my initial 3D representation.

and here are the specs


this is all that I have about my furnace. It is an Olsen Duomatic

here is the wiring if this helps you in any way

 
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Old 12-26-14, 08:20 PM
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Diameter of those round branch ducts? Also material, please.
 
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Old 12-26-14, 09:02 PM
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Same as the others, 6 in, regular tin
All of my supply registers are 5"x11"
the S like duct feeds a register that is located at the entrance door which is at exterior ground level
The main level (ground floor) is located above the soil level.
 
 

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