Replace 105,000 btu with 60,000 btu ?

I had an estimate today from a local hvac company, and they figured that a 60,000 btu furnace should replace my 105,000 btu furnace. it is in a double family, brick constructed home that was built in 1949. The furnace is working fine, I just thought i might get a replacement estimate before it breaks down.
Does this sound reasonable? he took measurements of all the windows, and walls, and got a reading for what walls/ceilings were insulated and came up with this estimate. it does seem like he did a good job, but i am wondering if i am being bamboozled, or if long ago they just slammed too many btu's into housing units.
Thanks for the comments. Let me know if you need more information for this to make sense.
Fish
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fish wrote:

It sounds like he did a Manual J which is what he should have done. Sounds good. You should find the new solution both more comfortable and more efficient.
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Joseph Meehan

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Yes, i think he did the J. He quoted a good price too, it included a/c and the estimate was under 4k. Its something to think about.
On Wed, 01 Feb 2006 02:17:17 GMT, "Joseph Meehan"

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Ask the guy if he'll replace it if it isn't big enough. If he says yes, that's good enough. If he has a good reputation, he'll stand behind his word. Remember, the next 6 contractors you get to look at it will tell you to get a 105MBH heater because most consumers are scared of going lower.
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I come up with numbers like that all the time, especially when new windows and insulation was added since the old furnace was installed. With a smaller furnace, your heat is going to be more even as long as there's enough CFM, but newer blowers are usually more powerful. Consumers almost always think "bigger is better". I just tell the people that if it isn't big enough, I'll pull it out and put in a bigger one at no charge. Haven't had to do that yet.

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Very good point, yes he gave a 100% warranty/guarantee. If i dont like it for any reason he said he would replace it or give the money back. You are right about the cfm, but funny thing is the fan looks just about identical to the fan i have in my primary residence, and that furnace was installed in 1981.
Thanks... Fish

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You are lucky , it looks like you got someone honest that knows his trade the first time, 99% of what I see here is no load calc questions. I had 110000 btu and super insulated on 1800 sq ft in zone 5, to -15f, and my last load calc was 50000 btu. Insulate to optimal, not just code and you will require even less. With your smaller unit you will now heat more evenly and short cycle less.
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You have actually found a well qualified, honest HVAC guy. Tie him up and don't let him out of your house.
wrote:

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efficiency unit (and I assume you are) the BTU capacity should be lower. Should it be 1/3 lower? Probably not, but it is possible that the builder just put the same unit in every house and yours was smaller than most.
Or maybe you insulated or improved the windows since 1949?
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Since 1949 there probably had been added insulation, new windows, storm doors, etc.; and new more efficient furnace designs. Yes, it was quite common to go bigger as it was cheap back then. If your furnace cycles frequently, that is a sign of over capacity.
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Everyone here is wrong, dead wrong so far. Make sure you get a dual stage furnace which measures 80% of the existing BTU output. Most of the hvacs are crooks and will promiss the sun and stars and leave you stranded. It is far better to overproportion the heater than under. Conventional furnaces deliver a burst of cold rushing air when they turn on, a dual stage applies even, consistant heat. The house will be warmer, tennants content and the fuel bill will be far lower due to the absense of cold rushes.

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I agree on the increased comfort, but how does the asbense of a cold rush lower the fuel bill?
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Edwin Pawlowski wrote:

I am guessing he is assuming that the owners will lower the temperature setting since they are not cooled by the "cold rush"
As for:

It appears to make no sense at all. although I do like the "dual stage" part, everyone else are right. Also the suggestion to use 80% of existing BTU it totally insane.
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Slim Bastard wrote:

A dual capacity unit is a good idea, but will still not compensate for oversizing . Have the contractor do the job. It was not uncommon in 1949 to oversize by a factor of 2 or 3. Fish, it sounds like you found a gem of a contractor. Don't let him get away.
Stretch
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Slim Bastard is wrong, I never could get the house within 5 degrees in several rooms with a 110000 btu unit , going to a 47000 low fire on a 2 stage got me temps to within 2 degrees. I atribute this to longer running. Also Slimy, It is even heat, no hot blasts and less short cycling. Short cycling doesnt allow rated efficiency to be realised since warm up periods dont give full efficiency, it is also harder on the equipment. This of course is for a furnace, Boilers are another story, slimmy.
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Fish,
how long does the furnace you have now run on the coldest days to wamr the house...
if it has to run only about 50% of the time on the coldest days then you are probably ok getting a smaller one...
if your present furnace has to run 100% of the time on the coldest days to keep the house warm, then a smaller unit may not deliver enough heat on the coldest days...
just figure a furnace with 1/2 the output will run about twice as long as your present unit...
Mark
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Alright, i will find this out. i dont know how long it runs during the day. Fish

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You can figure it out, but you'd be wasting your time. Just go with the furnace the HVAC guy recommended.
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I read you. and agree.
Fish

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