resize with haier furnace for whole house or ...

[llouk]

I live in Georgia.
I purchased a 45,000 BTU furnace with a 3 ton coil and 2 ton blower, which is okay to be paired up this way. It is an Amana/Goodman unit, 90% efficiency, 2 stage complete HVAC system.

My problem is that I purchased this off Craigs list, was assured still under warranty, but isn't. And I have found out that the unit is too large for my studio basement apt. of about 600 sq feet or so. It was a really good deal, but not if can't use.

My main furnace for the house is a 1968 Coleman with cast iron heat exchanger, 115 BTU, works well but not efficient. The furnace does buzz a good while before kicking on, so needs a new igniter.

What is best to do, resell the craigslist furnace and purchase a new Haier 90,000 BTU and zone the basement to the main furnace?
or
keep the Craigs list furnace system and install, and maybe later install a smaller system for the main floor of my home?

My home is the typical 3 bedroom, 2 bath on the main on a (half) partial walkout basement. I do have a large family room that is a bit atypical. But not more than about 2200 sq feet; maybe slightly less.

Does anyone have any experience with the Haier furnaces and AC units? I know their appliances do not rate very well, but not sure about the HVAC systems.

Also the product I'm looking at is an R22, and so costs much less, but the installer says that it is warranted; and that in the event it fails the compressor can be converted to 410A since the motor, compressor and etc are all pretty much made my the same manufacturers; and the refrigerants can be used in either type of system.

Thoughts, comments, recommendations???
Thanks for any helpful comments.

[jadnashua]

For a/c, the absolute worst thing you want is a unit that is oversized. Before you do anything, you should have a heat load analysis done to see what size unit you really need for both heat and cooling. Then, using that, determine what you want to do. It may be that the smaller unit would work for the whole house and the one you have now is oversized. Running it at or near its maximum output constantly on the coldest (or hottest) day it's designed for is the most efficient and comfortable.

I think R22 won't be available for sale (new anyway) shortly. recyclers will likely still have it, but at potentially very high prices in the future. Now, the system should not need any, but if it ever does (say you decide to replace the compressor rather than replace the system), it will start to become a very expensive proposition.

[llouk]

Okay,
So if I keep the AC unit 3 ton 410A compressor it might work for my whole house with a new furnace and larger blower? The 45K BTU is too small for my whole house.
Is there a way to up the fan speed on the 2 ton blower to make it match the 3 ton compressor?
And which furnace should I purchase to match up to all this; I need at least a 90K BTU to serve both the main floor and basement, with zoning?

Thanks for all your help.

[jadnashua]

And I repeat my question...how do you know you need at least 90K BTU? Just replacing what you have may be a lousy decision as often they put in oversized units because it is easier than doing the calcs. If it doesn't run nearly constantly on a worst case cold day or can't keep up and the house gets gradually colder, then it's not sized properly. If it doesn't run constantly, it may be oversized. For maximum comfort, it should run all the time. On/off cycles decrease efficiency. Obviously, not all days are equal, so it won't run constantly on a mild day, but it should run almost constantly on the coldest day it was designed for in your house.

Many furnaces can adjust the fan speed, some by flipping some switches, some by changing the motor taps, some by changing the pulleys. If the ductwork isn't sized properly or the air flow isn't matched to the BTU's you are trying to move, running it too fast will not work well, nor if the coil is sized for a smaller a/c, work well for cooling. running a large a/c unit into a mismatched evaporator coil is not a good practice nor very efficient (from what little I know). Might work, but probably lousy performance and efficiency.

[Runs with bison]

I wouldn't dream of buying a new R22 unit. I'm looking at replacing mine soon.

Having lived in Georgia, I too wonder about the 90,000 Btu/hr sizing (would that be a 90-95% efficiency?) I suspect your HDD/yr are 3,000 or less.

I'm in a much colder winter climate now (5200 HDD/yr, with subzero annual lows) and my 110k input/ 89k Btu/hr output is likely oversized for my 2800 sq. ft. (includes walk out and sub basement, 3/2 split.) At -3F at night the furnace was running roughly half the time and holding set point.

[burleymike]

First thing is you need to get a manual J calculation done so you know how much heating and cooling you need. An oversized system is as bad as an undersized system.

Second, a 3 ton coil with a 2 ton blower is asking for trouble. You will not be moving enough air over the evaporator to keep it from icing up. Most Goodman evaporators come from the factory with a piston metering device not a TXV. If you insist on using this setup you better replace the piston with a TXV it will help reduce the chances of your coil turning into a block of ice.

How big is the condenser? If it is a 2 ton you might be ok with an oversized evaporator as long as you have a TXV on it. It really is best to have a matched system. Evaporators are not that expensive you can swap out the 3 ton for a 2 ton.

R22 will be around for service for a long time and it will still be a few years before the price starts getting high. They will stop manufacturing it all together in 2020. You already have an R22 system so stick with it. IF you system is properly sized, installed, and has no leaks you won't need to replace the refrigerant until you replace the system.

You absolutely cannot use r410a in a system designed for R22. The pressures are so much higher it will destroy the compressor not to mention the incompatibility of the oils. Your metering device would also have to be replaced switching to R410a.

[llouk]

I sincerely appreciate the education I'm getting here.
Thank you sincerely for helping me stay out of future trouble.