another estimate, more confusion

[tipsrfine]

When we bought this house, I did a lot to it. it had real lousy single pane basement windows, now they are glass block. I added insulation where the foundation meets the walls, adjusted doors and added seals, better bathroom exhaust fans that closed when not running, replaced seals on the windows and now I put plastic on the windows for the winter. I love that stuff, can't even tell it is there. Added insulation to the attic. Installed seals on all outside-walled switches and outlets, sealed my air ducts in the basement. This was after the first winter, dropped my propane consumption by 20%.

What kind of insulation did you use "where the foundation meets the walls"? Stuffing fiberglass in there doesn't do the job. The air leakage at that area will just blow through it. If you didn't air seal attic penetrations before insulating it, you should check to make sure you're not getting moisture damage up there, especially if you live in an area with long & cold winters.

[troyport]

All this sizing talk on this thread, had another guy here today, said I'm borderline with the smaller furnace... but probably okay.. But I will be using propane, if the GMVC furnace I thinking about is a 70Kbtu input... should I be concerned since the output of 65K will actually be less because of the propane?

[second opinion]

All this sizing talk on this thread, had another guy here today, said I'm borderline with the smaller furnace... but probably okay.. But I will be using propane, if the GMVC furnace I thinking about is a 70Kbtu input... should I be concerned since the output of 65K will actually be less because of the propane?

How does propane affect your output?

[JonesHVAC-R]

How does propane affect your output?

I have that same question as I saw someone else say they had it in some downloaded specs from a manufacturer... it is known to us in the HVAC field that propane delivers more btu/hr than NG. Example: at 60 °F a flow of 1 cubic foot/hr of natural gas will deliver 1030 btu/hr but 1 cubic foot/hr of propane will deliver 2488 btu/hr...about 2.5 times more heat!

[beenthere]

How does propane affect your output?

Often manufacturers derate their furnaces when converted to propane because it requires more combustion air per BTU for a clean burn.

[Kevin Weaver]

Get an actual load calc done and find out exactly what you need for our design temps 0 to 5 degrees is a good way to go. 70K to 80K at 95% would be my sight unseen guess. Dont guess, have a load calc done. I also like the 2 stage furnace. They are really paying off this m ild winter so far. Good luck

if you e-mail me your address, i have a cyber space program that will do the calculations for me/you. Any additional information like attic insulation, 2 story or ranch... as much info as you can.

[George2]

I found a fill-in-the-blanks chart load calculator on line, where I input details on wall size and r value, ceiling, windows, design temp, etc.. Took a few hours to fill out. funny thing, the initial answer was 68K, then I adjusted the design temp a few degrees either way and got 63K and 85K, then I played with the R value of my attic, jumped the load again back and forth. Makes it sound like if there is a wall someplace in this house that the builder got lazy on and missed a few bats of insulation, I'm screwed... Or if my daughter leaves the bathroom fan on I'm screwed... My Dad says I am WAY overthinking it, and I am starting to agree with him... If I undersize, one day out of every year I can plug in the electric heater and call it a day...

Good for you "for over thinking" ur HVAC purchace. If more people were like you, our business would have a better name.

Not so many disappointed customers! I used to get calls all the time to "fix" other contractor problems.

When we did homeshows, people would come to our booth and tell us, "Geothermal doesn't work, it won't keep my house warm."

[beenthere]

Homeowner314, this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

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[jpsmith1cm]

CAVALIER MECHANICAL GROUP

this is the Ask Our Pro's forum, and only Pro members that have been vetted by the AOPC may post advise here. Please apply to the AOPC today, thank you.

You can find the rules for posting and qualifications here.




Further infractions may result in loss of posting privileges.

You post in this thread and the other have been deleted.

[JonesHVAC-R]

Often manufacturers derate their furnaces when converted to propane because it requires more combustion air per BTU for a clean burn.

I buy that. I guess I haven't really paid much attention to them derating for LP. Kind of odd though considering you change out not only the orifices but also the regulator spring... The spring obviously having the biggest factor.

[beenthere]

Propane has a much high SG then nat gas. So more pressure is needed to move it through the smaller orifices.

Carrier has some furnaces out that only run 3.5" on propane.

[catmanacman]

Once you decide on a contractor and a size i would also look at adding a heat pump and going dual fuel ,depending on your electric rate there can be a big savings on utility's , here in virgina a dual fuel system can lower propane usage by 40 to 60 percent and at 3.25 a gal it can add up

[George2]

Once you decide on a contractor and a size i would also look at adding a heat pump and going dual fuel ,depending on your electric rate there can be a big savings on utility's , here in virgina a dual fuel system can lower propane usage by 40 to 60 percent and at 3.25 a gal it can add up

Cat beat me to it. Also here in the midwest, propane is expensive to operate verse a duel fuel or also known as a "hybrid" system. The payback is very fast.

Carrier/Bryant have a variable-speed HP that is amazing (and expensive).

Those dealers can give you a operational cost comparision in minutes on 4 differant system combinations.