Heating, Air Conditioning, Fridge, HVAC/Condensing Furnace too Large?


QUESTION: 2600sf SFH in Florida. 2 Original furnaces 2001 were 36K 80% gas split systems, heated home well. Replaced one 2 ton with Amana furnace 95045 unit, works great. 2nd system, a 3 ton, replaced with Amana 95090 recently. Both have matching 18 SEER outside Amana AC condensors.
Having issues with newest furnace. Heats very quickly, cycles off/on, but cold between cycles. Original return and supply vents seem insufficient causing high noise from volume flow.
A good installer, but issues. What are my options to solve these problems short of re-installing a smaller unit?

ANSWER: Joe, I don't or never did do business with Amana because I wouldn't join the good old boys club, needless to say I don't have any references to there equipment.
Don't know how much space the furnace is expected to heat or cool, Your homes ability to hold the conditioned air in and keep the un-wanted out?
Your blower motor most likely has different wire taps for regulating the RPM and changing the CFM?
There should be a schematic pasted on the blower compartment cover?
Your furnace needs to blow 400 CFM per ton of cooling in the cooling mode and less in the heating mode which switches depending on the thermostat setting.
The furnace needs at least 200 square inches of free air area from the intake grill/grills to the blower wheel.
free air means less air filters, grill works, anything in the air stream, check your return from start to blower and calculate the smallest area that the air passes through.
Grills and filters only get 50% of there nominal size.

---------- FOLLOW-UP ----------

QUESTION: FYI, the 95090 translates 95% 90K BTU, likewise the 95045 is 95% 45K BTU ...both multispeed. So my original furnaces had total BTU output at 58K BTU, while my new systems total output is 130K high fire, 91K low fire.
My home is well insulated and sealed. It is all under warranty and I was hoping for a 2nd opinion on the furnace sizing and whether the blower speeds could be lowered enough on the 2nd furnace, while still passing sufficient air over the coils? Both units work great, maybe too great.
Thanks for the quick response, sorry not enough info.

Every thing needs to be sized accordingly,Temperature, CFM, Duct's Registers & Grills, etc. etc.
I don't know what options you have lowering blower speeds or what the taps are set for?
If you can set it lower and your not using that speed try it.

Heating, Air Conditioning, Fridge, HVAC

All Answers

Answers by Expert:

Ask Experts


Jim Barnhart


Fifty + years conditioning the air.


Answer questions about , residential and commercial. Answer questions about sheet metal fabrication. Fifty years plus experience. No answers for oil equipment, No answers for kitchen appliances, No answers for laundry appliances, I don't specialize in one particular area of the HVAC area, I'm more of a General Practitioner, Limited in refrigeration/

Hands on since 1950

©2017 About.com. All rights reserved.