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JonC 02-26-2009 05:54 PM

HVAC Upgrade Questions
Hi folks, I'm planning to upgrade my forced-air HVAC system in mid to end of summer with a full Heating and A/C system. The current system is an old oil fired Magic Chef unit with no AC on a basement tank. The current heating company (at time of purchase) came out and performed some maintenance on it before I purchased the house about 4 months ago. The home is appx 1800 Sq Ft 2 story ollld construction. I've been going through about 400-500USD a month worth of oil which isn't killing me considering the NE winters, but I would like to reduce that through more efficient equipment and better insulation.

I'm looking to do a few things as follows and I'm just hoping someone can provide some input on what I want to do and any pitfalls/gotchas about doing them.

1) I want to switch to natural gas, the local energy company will pipe in the gas line for free if it's for 2 or more appliances so I am considering a gas water heater / on demand water heater as well. I'm fairly experienced mechanically and electrically and very experienced with electronics and control systems in general. I do realize I'll need to contact the building/permitting dept in my town to see what work requires a permit, and also what work requires a licensed tech.

2) The chase for the second floor air intake and hot air feed goes right through the living room and master bedroom closet into the attic, it looks terrible and eats up a lot of space, so I want to relocate it or eliminate it (possible with a split system?) The current space occupied by these ducts is approx. 4' x 2'. Are newer HVAC units capable of higher flow and pressure / reduced duct sizes to second floors, which is then diffused when it reaches the second floor or are these large ducts pretty much a requirement with one HVAC unit servicing both floors?

3) How much, on average/guestimates, does the addition of AC to a new system add to the total (non-installed) cost of an HVAC system?

4) Any guestimates on tank decommision and removal costs (from a basement, easy access)?

Thanks to anyone who responds for their time and interest.


handyman78 02-26-2009 06:44 PM

I am a homeowner handyman who has installed 3 of my own hot air systems over the years.
My 2 cents for your questions-
1) I like natural gas and have it now. You are replacing forced air with forced air so no major change in delivery should be needed i.e. ductwork unless it is severely undersized, rusted out or leaking. You might want to insulate it as well. It depends on the type of replacement system you use to determine the exhaust. 10 years ago I replaced a 1970 hot air system with a hi-efficiency 92% system. This changed from a galvanized 6" exhaust to a 2" PVC exhaust thru the roof. Major effort was manipulating sheet metal ductwork. Gas pipe was already in place where I needed it.

2) Unless you are referring to a new exotic type of system like high velocity, most standard forced air systems require large ductwork to flow thru the house air in = air out. A central system must provide for the entire house and duct installations usually decrease in size as you get further from the unit. Hard to say without seeing it though.

3) In my experience it doubled the price of the heater alone. Also be advised- as far as I know you cannot install your own AC due to EPA regulations for Freon- you must be licensed. I was fortunate to find a licensed guy to work with me- I did much of the mechanical & electrical install, he loaded the freon. For AC you'll need 240v to the compressor, and an external disconnect. Split systems have the coils in the heater plenum duct, the compressor outside. they are "connected" by copper tubing for the freon supply & return which is brazed to fittings at both ends.

4) No but I would guess it is strictly by local costs. I'd get at least 3 estimates.

Plumber101 02-26-2009 07:15 PM

On an older house depending on how tight she is you will probable be putting in a 3 1/2 or 4 ton A/C and a 75k but more likely a 100k BTU furnace. Now, what I would advise you to do is have a couple of companies come out and size up your house and get their imput.

One question I have for you is does your 2nd level stay colder in the winter or hotter in the summer as compared to the main floor. If it does I wolud put in two systems one on the main floor and one for the second floor. Other here will say that this is a waste but you will have two thermostats so when the upstairs is not used you can dial it down. In the long run your house will better conditioned.

Also, many name brand like Trane, Carrier and Lennox will offer less warranty like 1 yr Pts and labor, 5 yr parts, 5 yr compressor and 20 yr heat exchanger.

I am a dealer for Trane and Arcoair. Arcoair and Comfortmaker are made by Carrier or ICP (Internation Cooling Products) and automatically you can get 10 yr parts 10 yr compressor and depending on the furnace limited lifetime for the heat exchanger. Limited means only lifetime applies to the original owner.

It may cost alittle more but really look at the option of two units.

Also ask about two stage furnaces and go with atleast a 92%

Most energy companies will do an energy audit free of charge..DO IT
This will also help you to see if the installer is over or under sizing.

Hope this helps

Lic Master Plumber
Lic Master Mechanical

beenthere 02-26-2009 07:33 PM

Find out all the areas you can improve on your house for infiltration, and insulation.
Then improve them first before you think about putting in a new system.

New systems, need to move more air per BTU of heat then older systems.
So you want to decrease the size furnace you need before you get a new furnace.

Home Air Direct 02-26-2009 07:55 PM

You are probably looking at 3 tons of air and about 80,000 (output) or 90,000 (input) btu for heat, but get a load calc if you can to be sure.

1) Switching to natural gas is great idea in your case. The next time oil prices lose their minds you are covered. A 93% efficient furnace will certainly help you with your $ issue, though there is no substitute for good insulation, but it sounds like that is a big issue in your case. As far as the mechanical portions of this job, you should be fine to remove the old, set the new. If you are comfortable with wiring and controls, even better, but I do think that every DIY homeowner should always call in a pro for start up.

2) If you have the financial where-with-all to have two separate systems, that is great, but I really don't think it is necessary on 1800 squares. If you ductwork was originally sized correct, you should not have a problem. If you will be taking out the chase, two systems may be your only answer. A couple advantage of two systems, is that if one should go down, you are not completely without, and smaller equipment seems to last longer than larger motors and burners (that may be just me?)

3) This is the one question that I can answer. If you are buying on the direct level, as a DIY, you can expect to pay a little more then double after lineset, pad, whip, disconnect to add AC, using a 93% gas furnace as your price standard. And, as I said above, I really do think that there is lots that you can do on the DIY level. Set the unit, run the lineset, stat wires and electrical, but again, hire a pro for the final phase of connecting and start-up

4) I have no idea about decommissioning a fuel tank, but I am interested in the answer to this. I got a call last week with the same question and I have yet to find out. Looking forward to finding out myself.

Good Luck on your project.

JonC 02-26-2009 08:10 PM

Thanks for the information so far, calling in someone who does it for a living before final startup is certainly a good idea as I know with each trade as in mine there is the huge benefit of years of experience for hammering out the details before they become 'issues' :)

I am going to be working on the insulation this spring and summer, which is why I'm planning the furnace upgrade towards the end of the summer season. I don't want to be sucking plaster and drywall dust/etc through any new equipment.

I guess once I improve the insulation and air leaks more I will get someone in to do a door suction leak test to see what I missed and get a better idea on the requirements for a furnace. This oil furnace does pretty good at maintaining heat throughout the house once I sealed up a lot of air leaks in the place, the upstairs is normally warmer. I've kept it down at 55(first floor thermostat) all winter to reduce the costs, I can't imagine what it'd be like at 70-75 and 55 is fairly comfortable for me as I spend a lot of work-time outdoors in the winter.

I did have one other question I forgot to add, I really want to get rid of the brick chimney, is PVC type exhaust common to all newer furnaces, or just the super efficient types? We put a couple of propane fired units in our warehouse and they just have a PVC pipe to the outside.

tk03 02-26-2009 08:14 PM

Always tighten up the home before replacing the hvac equipment. Than and only than have properly sized hvac equipment installed.
Get a good heat loss done. After the heat loss is done and the equipment is sized can you tell what size the ducts need to be.
For more info on heat loss and the importants see this link to FAQ Heatloss

Plumber101 02-26-2009 08:19 PM

Any 90% or higher furnace is a condensation furnace where as a 80% and lower are not.

Hi-eff furnaces accomplish by having a longer or bigger heat exchanger which will allow more heat BTU's into your house.

Also, all climates where freezing is a concern no condensating furnace should be installed in attic spaces.

JonC 02-27-2009 05:04 PM

Looks like I have some things to think about and look into. Thanks for the information!:thumbsup:

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