Carrier infinity expert advice: proper blower size?

[ron3637]

Based on the following would you recommend the 2000 cfm blower for the Carrier infinity gas furnace that is speced?

My current system is an 19 year old 4 ton Lennox A/C and a 24-25 year old 120,000 BTU York gas furnace in a house built in the early 1930 with two returns in the larger rooms and one in the smaller bedrooms. The house is located in washington dc and is pretty poorly insulated --blown in insulation in the attic and storm windows is about it. Plaster outer walls get pretty cold in winter. The house has about 2700 square feet of living space over two upper levels and a finished basement. Thanks for all the help and input. Any comments or suggestions appreciated.


Here is what the contractor has recommended for the retrofit:

Carrier infinity Furnace: 58MVB 100-20
Carrier infinity Condensing unit: 24ana748--four ton
Carrier COIL: CNPVP48
Carrier INFINITY CONTROL: SYSTXCCUIDO1-A

[dash]

If that's the correct size furnace ,I don't see any other fan size available,except the -20 .

Chances are at 350 per ton cooling and 1525 cfms needed on high stage heat,it will be able to move as much or more air then your old one did.Really depends on your duct system,which we can't see or test from here.

[clisky]

I live in the dc area and know the load calculations your goin with a 90% have them bring you down to a 80,000 btu you will be much happier trust me bigger is not better and in dc those ducts are little on the small side but see if they can add a return somwhere other than your furnace room. do the mvb080-16. they do a load calculation

[RyanHughes]

I live in the dc area and know the load calculations your goin with a 90% have them bring you down to a 80,000 btu you will be much happier trust me bigger is not better and in dc those ducts are little on the small side but see if they can add a return somwhere other than your furnace room. do the mvb080-16. they do a load calculation

Each home has different load calculations/needs.

[ron3637]

I understand the size issue but I expect the dual speed fan would mitigate a some what larger furnace in milder weather, Is this accurate?

[clisky]

The furnace is a great furnace is costly and labor rates in northern va and dc are not exactly cheap either so your probally paying in 5 digits for that system, but let me explain the infinity and why it should not be oversized this is my problem with contractors in this area. There all scared of puting the right size in a home and fear of complaints they rather take years off of the life span and blame it on the makers of equipment. So let say this the longer the run time of a furnace the more comfortable it makes it in the home and help equal temperatures. So if your home need a 80000btu furnace and someone adds a 100000 btus. Your low stage is 60000btu, instead of having a low stage of 40,000btus. I would rather be smaller on my heat side due to gas prices and comforability. That is me I have sold thousands of these furnaces and go to a smallers size always and never have had a complaint. Look into changing to hybird heat or duel fuel same thing carrier calls it hybird but it really is duel fuel. This can reduce gas prices in this area by almost 50% and plus your saving on your gas furnace. Please listen to me on this, please make sure they measure your duct and home. This system is amazing when design correctly, so please make sure you pick the right contractor.

[ron3637]

Thank you for your response. My current furnace that is being replaced is a 120,000 BTU model--so on low speed the new proposed unit will be 60,000 BTUs at best--- or one half the size of the current unit which I hope Will be effective. so i am going from 120,000 btus to 60,000 btus most of the time .also as described, the house is old and leaky with one unit for three floors. contractor is concerned about going any lower in this situation. sounds reasonable i think, thanks

[RyanHughes]

Same contractor from the beginning?

[ron3637]

yes

[clisky]

did he measure your complete home and do a manual j and do a duct calculation to ensure you will have a perfect system or did he just write you an estimate after lookin over the system.

[ron3637]

yes