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Ask Comfort Specialist Your Own Question
Comfort Specialist
Comfort Specialist, HVAC Technician
Category: HVAC
Satisfied Customers: 1368
Experience:  Master Lic. holder for HVAC & Gas, Contractor, Estimator, Designer, Air Balance Certified, LG Master Commissioner, UNC Cert. holder for Industrial Ventilation
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What size of furnace will I need for an 1800 sq foot house?

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What size furnace am I gonna need for an 1800 sq foot house?

Wvfan79 :

Can you tell me a little about your current furnace. The model number or the btu's

Customer :

not right now i cant. its at the house i am moving into and im at home right now. sorry.

i can make a call over there and see if someone is still there if you can gimme a minute
Wvfan79 :

Ok I understand and that would be great. Before we get started, of course, I have to say that I recommend all work to be performed by a licensed hvac contractor and electrician.

Customer :

my neighbor is licensed but hes out of town for a couple of weeks and i cant get ahold of him. i was hoping to buy the furnace so he's ready to help me when he gets back

Wvfan79 :

great!

Customer :

i was going to get most of the rough stuff done first like removing the old furnace

i just always assumed they went by sqaure footage to determine what size furnace i would need and am basically relying on your professionalism to recommend a good brand name and model
Wvfan79 :

To size heating a heat loss calculation is required. Your neighbor should be able to help you with completing this. I have a heat loss worksheet that will get you started. It is very simple to follow and you only need to use the heating side to size your furnace.

Customer :

sounds great

Wvfan79 :

CLICK HERE for Manual J calcualtor

Well that was a typo, ha ha Calculator.
After running this calculation you will know the rough heating loss of your house. Once that is complete you can compare the existing furnace to the results and select the size based on the two.
Customer :

looks a little confusing but i think i can figure it out. is this all i need to help me decide size of furnace?

Wvfan79 :

Yes, if you neighbor is a contractor he should have the software to run this load himself. He can get better detailed and tell the calculation what area you live in. That will change the results.

Customer :

so any recommendation for brand. i cant remember for sure, but i think the existing is a janitrol

Wvfan79 :

Do yo know if the current furnace has a metal vent or a pvc exhaust vent?

Customer :

metal. but we're going to change that to pvc with the new furnace.

Wvfan79 :

Ok great. That means you can purchase a 90% efficient gas furnace.

Janitrol is made by Goodman. Here is the link to the goodman furnace page - CLICK HERE
You want to look at the 93 or 95% furnaces
A variable speed furnace is nice but can reek havoc on your electric bill if you have holes in your duct work. It gets the air it needs from somewhere regardless of the duct system. It pulls and pulls until it's happy.
Customer :

okalee dokalee. i think i can take it from here. i appreciate everything thanks

Wvfan79 :

I recommend the GMH95 - CLICK HERE at my company.

Its efficient and multi speed
not to mention two stage.
Customer :
thats the one i was just lookin at.
Wvfan79 :

Its more affordable and reliable. We sell a majority of those.

also has the lifetime heat exchanger warranty.
Did you happen to have any further questions for me today?
Customer :

no i think i got it. youve been great thanks. i didnt really expect anyone to answer on a sunday. so double thanks for that. have happy easter and take care

Wvfan79 :

Well have a great day! Remember, you can always contact me with my private messenger even after pressing accept. Also, I love positive feedback. I'm running for customers choice award!

Comfort Specialist and 3 other HVAC Specialists are ready to help you
Customer: replied 4 years ago.
just one last thing. if i decide to pay my neighbor to just do this for me, i know he'll refuse to wanna make any profit. but insist on paying him properly. could you give me a rough idea of what the labor would run for this. the only thins, im thinking, are running the pvc, removing old and puting in new. the plenum will probably be redone also. i know you need more info than that but im just looking for a ruogh idea. worst case senario
Sure give me one second and I'll be glad to tell you
Customer: replied 4 years ago.
take your time
For me that would be about a 2,800 bid, or cost to the customer. We would cover permits and inspections, pvc venting, new drains, plenum replacement or modification, removal and disposal of the old furnace, new electrical whip to the unit. My bid would be +/- 16 hours and around 600-650 of the total cost would be labor. Of course that's my overhead and profit margin.
Customer: replied 4 years ago.
2800 that just labor (and permits) right. cuz i knw my naighbor well enough he'd do it for nuthin. and would never tell me what its worth.but i wanna make sure im giving a decent payment when he;s done. ( with out insulting him)
$2,800 would be total cost to the customer. 600-650 of that would be the labor. The remainder would be materials and markup
Customer: replied 4 years ago.
again. thanks for helpin on easter.
If you paid for all the materials then hand him $250-400 dollars when done...He should be happy.

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