How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Phil Your Own Question
Phil, Mechanical Engineer
Category: HVAC
Satisfied Customers: 8426
Experience:  Retired HVAC/ Electrical & Boiler contractor. Industrial
Type Your HVAC Question Here...
Phil is online now
A new question is answered every 9 seconds

What size furnace and AC will I need for 3000sft house?

This answer was rated:

What approx size furnace and A/C will I need for a 3000 sq ft ranch home with a full walk out basement in NW Penna?

Let me get back to you, I need to look up the climate zone there, and the ASHRAE guide 2% weather conditions.

For now, as an wild guess, not knowing how much south and west facing glass you have and of what type, insulated glass or not, home construction details etc.

You will end up in the range of 6 to 12 or more tons of cooling required... Lots of variables involved. How much electronics on at one time, and how frugal or not frugal are you?

Would you be willing to have the home get up to 80F on a few hot days a year or not... That can have a huge impact on sizing and operating costs.

Are you interested in an exceptionally green approach or not.

Does the 3000sqft include the basement space or is the total space 6000sqft. What kind of roof does the house have, insulation?

Zoning and back up are issues as well... On a house that size, I would use 2 or 3 totally separate systems.. That gives you back up, and a way to shut down areas of the home not in use during the day or night etc.

Fill me in on some of those details and I will estimate your load a bit closer.

Customer: replied 7 years ago.

This is a new home and I want to make sure that the builder is putting is a sufficent size HVAC system. The house sits E-W, West facing. The 3000 sqft is only for the main level, doesn't include the w/o basement. It will be well insulated R-15 walls, R-42 ceilings, and Anderson energy efficient windows. We will be using ceiling fans to help circulate the air and would like the system to be 90-95% efficient.

How many sq feet of glass facing south and west? Is it solar reflective glass? It probably is.. If not high reflective glass, the best you can get, would be a really good idea on the south and west facing glass, but not the East facing or North facing glass... You want solar heating on the east side.

Efficiency is rated in SEER, (Seasonal Energy Efficiency Rating).. For an AC in your area, if I owned the home, I'd pay 50% more and get SEER 14.

If you have natural gas(not propane), I would go with gas furnaces, 90% efficient max, not 95% etc.. The cost of repairs dwarfs the energy savings in my experience.

From what you have said so far, a total of 6 tons for cooling would be a bare minimum... 7 would be better and I recommend splitting that up to 2 each, 3 or 3.5 ton units (14 SEER) and 2 each 90% efficient gas furnaces, (the cooling coils (A coils) above each furnace located in the basement. Furnaces rated 120,000 BTU's each at least in order to handle the air required for cooling. This estimate is plus or minus 20%.

If I were the home owner, and wanted to keep it below 75F no matter the heat of the day I would be looking, 2ea, 4 ton SEER condensing units with A coils, and 2ea 120,000 bu furnaces (required for air flow during summer).

I'd buy Rheem if I wanted the best for less and ease of maintenance... I don't appreciate the serious complexity the two market leaders provide.. Costs too much to repair, with scant benefits if any... That would be company names beginning with C and T... Those have great promo though.

The contractor may want to provide heat pumps. I don't like them for widely distributed systems. These get double the wear on compressors as compared to what I have recommended above. Package units, heat and cool in the same box, with ducted distribution is not the best in cold east coast climates and puts service men outside in the weather, that is expensive.

Costs in your area will range between $1,500 and $2,500 per ton+. Worthwhile add's are Honeywell automatic wash electronic air filters, if anyone has allergies or smokes. Those are expensive and high quality humidifiers, stainless steel basin type those will improve the family heath in the winter. Buy them over sized, and in stainless steel, don't skim on the east coast, they get a lot of use.

Phil and 2 other HVAC Specialists are ready to help you
Customer: replied 7 years ago.

Thanks!!! This is exactly what I needed, I appreciate the detail!