Replacement furnace size

[Norm Dion]

I'm getting ready to replace my gas furnace with an 80%, two-stage model. How do I determine the size required? TIA

[Tom Pendergast]

Have your contractor do calculations to determine the proper size. Expect to pay for their time involved, it's part of the process for getting a correctly sized unit.

TP

[Joseph Meehan]

There are many answers to that, but only two good ones.

If you are sure the current one is right, then get another with the same OUTPUT. If you are not sure the current one is right, then you need a pro to come in do all the needed measurements, plug in the numbers and come out with an answer.

[thunder]

The internet is full of Manual J calculators, including this one:

[TURTLE]

This is Turtle.

1) if your getting a hvac company or installer to do the work. the installer will furnish to you on demand a complete Manual J as to sizing of the furnace. If he can't furnish a good manual J report. Fire him and get one that can furnish this report before ever starting the work.

2) If your installing it yourself. Look at what thunder had to say.

TURTLE

[Ermalina]

Here's another page with links to several load calculation tools:

[HvacTech2]

Hi Norm, hope you are having a nice day

On 10-Jul-03 At About 23:14:10, Norm Dion wrote to All Subject: Replacement furnace size

ND> From: "Norm Dion"

ND> I'm getting ready to replace my gas furnace with an 80%, two-stage ND> model. How do I determine the size required? TIA

The only proper way is to run a complete manual J calculation for your house.

-=> HvacTech2