View Full Version : New system purchase
05-20-2007, 11:12 AM
I am in need of an opinion with respect to purchasing a new furnace and ac unit
I live in northern indiana
I have a small 2 story house 1600 sq feet
I have been battling with substantial differntial between first and second floor temps
House is 18 years old with lennox 80,000 btu furnace and lennox 2.0 ton ac
I am looking at Trane and now American Standard Systems
I am looking at an aircleaner and humidfier and a programmable stat
I am debating 80% efficient vs 90% +
variable speed blower and two stage burner
I am also looking at trane 16I ac unit
Help with suggestions / opinion
I need to do this reasonably soon as my AC unit has failed
05-20-2007, 11:28 AM
Brand is less important than installation.
Your contractor should do a Manual J load calculation to determine proper size of equipment. Do NOT size by square feet of floor space. If you have issues between up & down, you may want to consider a zoning system. You should also get someone certified at air balance. Duct modifications may be in order.
Trane makes really good equipment but it must be properly designed and installed to improve your comfort. If you go back with the same size of equipment you had before, you will likely have the same comfort.
I lean heavily toward Variable Speed blowers to overcome MINOR duct problems and balance problems.
05-20-2007, 11:49 AM
Regardless what you may or may not have been told, new HVAC equipment will not solve the temperature differential between floors that you describe. You like many people who have two story homes have poor ductwork design usually too little air flow to the top floor. I suggest you discuss this with your dealer on what can and can not be done to correct this problem and at what cost. Zoning might help but really noone on this forum can offer any practical solutions. You should also evaluate your home's insulation properties for the second floor.
As far as equipment, you should insist upon a heat/cool load calculation for correctly sizing new HVAC-both heating and cooling. I would not even consider an 80% AFUE gas furnace unless there are installation issues or if it was paired with a heat pump and that would depend upon your utilty's electric rate.
05-20-2007, 01:17 PM
First, in this area you do not need a 16i 2 stage unit. If you want the lowest possible heating costs without spending an absolute fortune on equipment, a 90% furnace and 13 SEER heat pump is best compromise between initial cost and utility savings. If you want to spend the extra for the variable speed 90, that will turn most models of A-S/Trane 13 SEER heat pumps into a 14 SEER rating. Put a Honeywell Vision Pro IAQ on to control this and add summer dehumdification to the mix with a good air cleaner and you'll have one humdinger of a system.
05-20-2007, 02:05 PM
Thanks for the prompt posts :)
I could have included more detail in the original post
I have a small 2 story on a slab with the ductwork all running in between the first and second story
The vents are in the floor on the second story and in the ceiling on the first floor
I have a lot of glass doors and oversize windows on the south facing side of the house
The furnace is located in the garage and the lines currently run thru the slab in a conduit pipe
With a 90+ furnace the vent would be pvc vs 4 inch as it is now and they are talking about running the lines up and out vs using the conduit in the slab as originally done
Of the two who have come out to provide an estimate, they both have looked at the exisitng equipment and worked of that.
Both have indicated that a variable speed furnace will somewhat compensate for the poor ductwork design...
When you are spending this much I dont care to be the high gross deal of the year and buy way more than I needin equipment But I have always had issues in the summer with cooling the second floor..
Thanks again for your insight and time
05-20-2007, 04:15 PM
I too stay near this area far soth suburb and have a 1880 sq. ft house 3 ton a/c 100,000 btu input furnace lots of windows and doors both grossly oversized per my calculations and having done better windows,doors, insulation 60,000 two stage 80% with two stage 3 ton for extra cap when we entertain plus out here nothing to shade or protect from wind without improments 80,000 two stage so make sure ductwork and manual j as well as energy audit done or you'll be wasting money.I'm an Hvac Installer and tech and i personally think sizing correctly the furn. and a/c is more important than a 90% i think payback is too long and a two stage 80 var. speed payback is quicker.Don't get me wrong a properly sized 90 will pay back if installed properly
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