I looked at his estimate again. He is recommending a 5-ton A-coil Luxaire AND a 3-ton A-coil Luxaire.

Where are you located? Those furnaces seem large for 1400 sq ft and 1000sq ft. And if the 5 ton and 3 ton "coils" are AC compressors, they are way oversized.

North Missouri, not far from Iowa. So we can get pretty cold for extended periods of time. We are not newbie home owners, though this is the first 2-story home we have ever looked at/considered purchasing.

I thought the equipment sounded excessive - though I know next to nothing about HVAC. His total bid, including the two Luxaires, gas lines, flues and intakes, replacement of flex pipe with new, misc. materials, and labor, is $7,500.

I also think the furnaces sizes are too big. The proper way to size the equipment is with a load calculation. I would think a 60K or 80K BTU for the first floor, and possibly a 40K BTU for the second. The insulation and quality of the windows will determine which size is appropriate.

I recommend you purchase 95%+ efficiency furnaces. In your climate and size house the return on investment for the higher efficiency equipment will not be too long plus you may qualify for a local utility rebate.

Has the contractor given you the model numbers of the furnaces? Luxaire makes contractor grade equipment. He may be quoting a basic single speed 80% efficiency furnaces. Get the details and post them.

Can you explain the coils? Is the plan to reuse existing AC condensers? The contractor may be quoting large furnaces because the house has over sized AC equipment. Over sized equipment is just as bad as under sized.

Are you sure natural gas is available to this area? The reason I ask is if it's not you're then forced to install a propane tank in the yard and convert the furnaces. Propane prices could change the equation, not to mention propane is much more dangerous than natural gas. In a world of unskilled labor passed off as skilled, I would not install propane anything. If you like living on the edge go for it.

As far as sizing goes... the contractor may be sizing the 1st floor system to be able to heat the basement.

Sizing depends greatly on number of windows among other things. Due to age of the home it could be very drafty... this ultimately decides what amount of load the home has. Square footage alone, does not qualify as anything to determine the proper size of HVAC equipment.

Having a 2nd system on a 2nd floor delivers better controllable comfort. If you only had one system and one thermostat --- cool air falls --- hot air rises. In other words the lower level is always too chilly and 2nd floor is always too hot.

Thanks for your comments thus far. Below is the quote we received. You all have eased my mind a bit about the need for a SECOND unit as that is outside our realm of experience and was really worrying me.

Answers to some of your questions: yes, natural gas can be made available at the home. We currently live 3 blocks away and have natural gas in this house. It is produced a large company (Empire Gas) and is priced reasonably, as opposed to electricity which is produced and sold by our city-owned utility company.

We believe the windows are probably original to the house.

I expect the existing AC unit is large-sized as well. The home was built by, and is still owned by, a physician who did many things to excess. So you are saying that the heating system and the existing AC system need to be of similar size?

Edited to add: I should say that we live in Small Town, USA. Just in case these prices don't look correct to you. We have known the fellow who wrote this quote since he was born and, while we expect that he will make money on these installations, we don't think he will scalp us either.

The furnace blower provides the air for both the furnace in the winter, and the AC in the summer. The blower has to sized so it matches the AC condenser capacity. A 5 ton AC needs about 2000 CFM (cubic feet per minute) of air flow. In most cases you will only find that size blower on a 100K BTU furnace. Over sizing the AC causes the furnace to be over sized. Most houses don't have duct work that can support 2000 CFM of air flow. The equipment never performs well and wears out prematurely because it cycles frequently. Over sizing causes a lot of problems and is expensive to operate.

Your friend is giving you a good deal assuming the installation will be done correctly. The price you are getting would only cover one furnace and gas piping where I live in NJ.

I would still ask for model numbers of all equipment. The duct work should be inspected to see it is sufficiently sized to handle this large equipment. Also what are you getting in terms of thermostats and filters? I would want programmable types and 4 inch thick media filters.

Nothing wrong with propane AAC. It burns hotter, and the conversion makes the orifice(s) smaller to compensate, that is it. A lot of people have been using propane for a long time with no ill consequence. Found more often in rural settings, considering natural gas is typically available in cities.

160k BTU for your house is easily oversized. AC coils also are very oversized.

The only thing we don't know about the home is it's insulation value. Built in the 60's with the original single pane windows, R19 walls and R25 attic in northern Missouri and maybe the larger furnace sizes make more sense.

Having two units is not a bad thing. In fact, having two means you have a good one running if the 2nd one fails. It also means you can turn one down when not using that part of the house and save some energy.

If it was one unit and had bad insulation maybe, but two oversized units is too much. The guy is calling for like 8 tons AC.

But yes, two units are not an oddity.

How old are your outside AC condensers? Its possible that they are driving the oversized coils and furnaces. You are getting a great deal on the equipment listed but you might want to consider replacing everything with smaller sized units to better match the heating and cooling needs of your house. See if your contractor can do a rudimentary heating and cooling load calculation to see if you could go this route.

Nothing wrong with propane... sure in a normal well educated world in which pros are pros and DIY's don't exist. While even natural gas can explode given the right quantities it is far more difficult to build up to that because it doesn't have the 'pooling' characteristics that propane has when a leak develops. Natural gas smells like rotten eggs which tends to alert people long before an explosion potential exists.

Typically when there is a propane explosion it levels the home and kills everyone inside.

The original poster stated natural gas is available so need to continue the propane debate.

I think in most parts of the country a heat pump with electric back up is a cheaper heating option than a propane fired furnace. Calculations on this forum have demonstrated several times. The other disadvantages of propane furnaces are delivery schedules and additional maintenance. Propane is good for those, like myself, don't like electric cook tops and want to cook with a gas flame.

You don't have to over size the first floor furnace in order to provide heat to the basement. Basements which are mostly underground have a small heating load. A load calculation would show this.

Yes, AAC, gas can explode. Who knew? Both have smell. Most DIY who dont have a clue about it are too afraid to touch gas lines. Explosions are most likely due to a burner on with it not lit, not DIY activity. That is part of the reason I dont have a gas stove, the other part is I dont like using indoor air for combustion. To each their own.