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Replace a 55 year old furnace?


ladhunt
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I'm not sure what information you need to give me an informed answer so feel free to ask. We live in a 55 yr old house, hence the 55 yr old furnace. We've heard differing information on whether to replace it or not. One guy says that this "iron horse" will still outlive any new system we put in and another one says it's a carbon monoxide hazard and it should be replaced.

Right now, we're having some issues with the coils freezing up. We turn off the AC and let it thaw and then turn it back on again to cool for awhile. We've got someone coming out to take a look at it and to clean the coils. Other than that, it works well.

Also, we are thinking of turning our oversized garage into three separate areas all with HVAC, of course. It's about 660 sq. ft. This being the case, would you recommend replacing the existing system to cool the entire house (1479 sq ft) and remodeled area (660 sq ft) or keeping the old "iron horse" and adding on a separate AC for the new area?

P.S. I tried to call my husband to get better information for you and couldn't get in touch with him. He'll probably laugh at the sketchy information I gave you. Sorry!

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Hi,

Well, you didn't tell us whether it's a gas-burning furnace or an oil-burning furnace - although I suspect, being in Texax, it's probably gas-burning.

The description of an 'iron horse' is interesting. I have seen a few old gas furnaces from the 1950's that were built far heavier than the typical gas furnaces are today; these were essentially furnaces that were designed to burn either gas or oil. They were fabricated with heavy cast iron faceplates and heavy welded steel heat exchangers with ceramic fire pots. From the outside, except for the burner, they look exactly like an oil-burning furnace but they aren't conversions and they have factory-built-installed gas burners. Even after more than half a century, those were still in pretty good condition and that's sort of a puzzle when one realizes that the typical gas furnace today is built so light that it's only expected to last about 20 years. I wonder if this is what you've got.

Can you take some digital photos of the furnace, including the type of burner array and the exhaust pipes and upload them here? If you can, take a couple wide establishing shots showing the whole setup before you take any closeups.

Even if you can post photos here, there isn't going to be a whole lot that we can tell you from here; you'll ultimately need to decide which one of the experts that's already looked at it that you want to trust.

I can't comment on that type of AC system; we don't see a whole lot of them here in the Seattle area. Wait a minute while I reach over here and open my own air conditioner up and allow some fresh air into the office. Jeez, it's time to clean the glass.

ONE TEAM - ONE FIGHT!!!

Mike

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The 55 year old furnace is probably about 55% efficient, meaning 45% of your gas bill is going up the chimney.

Furnace guys still routinely dismiss this stuff. They may be entirely correct in telling you the furnace works fine, but they are remiss in their responsibility for educating you about all the things that matter.

The AC freezing up probably means you don't have enough refrigerant in the system. It's counterintuitive, but an undercharged system will ice up.

If you remodel, change out the equipment. Engineer something that's efficient with the appropriate supply and return layout to provide even heating and cooling.

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Winging it here with the limited info, but a few things to consider...

Efficiency: Your old dinosaur furnace has a very simple heat exchanger and wastes a lot of energy up the flue. A new, high effeciency furnace would probably reduce your fuel bills by 25% or more. Stay there long enough and it would likely pay for itself.

Sizing: Your old furnace could probably handle an extra 600sf. But that's only "probably" and a new one would be sized to fit. As for seperate AC for the new "wing", I guess that could depend on whether it's going to be everday space or a guest suite only used a couple of time a year.

Selling your house (say in 10 years): With a furnace as old as yours, it is very likely that a buyer would want to "negotiate" a new furnace. You could spend that money now and enjoy the benefits and savings while you are still living there.

Safety: Hard to say from a distance if your old furnace is a hazard or not, but a new one definitely would not be. Meanwhile, I recommend you invest in a CO monitor if you don't already have one. They are not that expensive and would add a margin of safety while you decide on the rest of the stuff.

Convenience and space: I don't know where you Texans typically have your furnaces, but I'm going to assume it's in the garage you want to remodel. A new furnace would have a much smaller footprint and, typically, only require service access from the front. Your old furnace probably has the filters at the rear panel requiring space to walk around the beast? And then there's combustion air supply which gets a little more complex but, basically, needs to be adequate and cannot be drawn from a bedroom. A 90+ furnace can use a pair of 3 or 4" plastic pipes to easily draw and vent air directly from and to the exterior. The end result is that you could have a 90+ furnace in a small closet but you may need a small room for the old one. The gained space alone might be worth the expense of upgrading. (Note that a gas water heater also requires adequate combustion air but there are also "direct vent" solutions for those.)

Even with photos I doubt we could give you a definitive answer. Your best bet would be to ask your neighbors and friends (Angie's list?) for an honest HVAC company and have them give you some options and estimates. You would, of course, want to decide about the garage conversion before doing that.

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OK...

Since no one else took the bait, I will. I see that you posted your question with the user name of "ladhunt." I know what a foxhunt is. Can I infer that you hunt small boys?

(You are, after all, in Texas. Wasn't that where Dick Cheney successfully shot an attorney a little while back during what I can only presume must have been a lawyerhunt?)[;)]

As for your question, I agree with the other guys. Might as well bite the bullet (surely you have one) and enjoy not only the safety but the increased efficiency of the new system.

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