Replace 105,000 btu with 60,000 btu ?

Question

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

Joseph Meehan · Accepted Answer

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.

Bob · Answer

I come up with numbers like that all the time, especially when new windowsand insulation was added since the old furnace was installed. With a smallerfurnace, 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'llpull it out and put in a bigger one at no charge. Haven't had to do thatyet.

fish · Answer

Yes, i think he did the J.  He quoted a good price too, it includeda/c and the estimate was under 4k.  Its something to think about.

Bob · Answer

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 hisword. Remember, the next 6 contractors you get to look at it will tell youto get a 105MBH heater because most consumers are scared of going lower.

fish · Answer

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

Toller · Answer

Well, part of it is that the BTU is input. If you are using a higher 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?

Edwin Pawlowski · Answer

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.

m Ransley · Answer

You are lucky , it looks like you got someone honest that knows histrade 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 codeand you will require even less. With your smaller unit you will now heatmore evenly and short cycle less.

Slim Bastard · Answer

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.

Edwin Pawlowski · Answer

lower the fuel bill?

Bob · Answer

You have actually found a well qualified, honest HVAC guy. Tie him up anddon't let him out of your house.

Replace 105,000 btu with 60,000 btu ?

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