1950's house, original furnace

[kjones]

Hey folks, got a situation to ponder on...

I've been considering replacing my classic Premier 120000 BTU gas forced-air furnace with something a bit more modern. Haven't got any bids yet, but did do an on-line energy use review with the local gas company (Consumer's Power). At first I was amazed that it indicated that my usage was average, but then I figured out it was average for a 40+ year old home - $1715 - 5 year old homes averaged less than half that (same square footage and other variables). My electric was way over average, possibly due to the existance of a massive window A/C unit (biggest 110V they had) and the fact that the original 1/4HP blower motor got swapped with a 1/3HP unit when it died some years ago. BTW I am in southeast Michigan (Pontiac).

So, I don't know what the efficiency of this furnace is, although it states that the input BTU is 150000 - could it really be 80%?!?. Way overkill for an 1100 square foot house over a full basement, anyway.

Looks like most of the output ducts are 4" round, although the house was expanded (almost doubled) at some point and those ducts may be different. Return air ducts are the width of the joists (16x6").

Chimney is brick, in the center of the house, with the water heater (and an old Calcinator incinerator!) sharing it.

So I guess I am looking for justifications for swapping this antique out, primarily cost (although the floor space could be put to better use, too). There are no known service problems outstanding. If I go and get a few quotes, given what I have told yall what kinds of things should I look for?

Probably will be looking at A/C with this too, so I can retire that monster window unit (12000 BTUs, I think).

Thanks,
KJ

[coolwhip]

No priceing questions allowed. The furnace is probably about 60% efficient. Go with a 92% furnace,and a chimney liner for the orphaned water heater. Have the incinerator removed as well. Have your contractor do a load calc. to determine the size of the equipment, also you may need some of that ductwork replaced. Good luck!

[Black Adder]

Why would you need "justification" to replace this big pig. I would think simple common sense dictates furnace way oversize and inefficient for high efficient correctly sized unit = more comfort less cost per month.

[Edmund Forsthe]

hes nostalgic

[kjones]

Yup, nostalgic, that's me!

60% efficient to 90+% should save me more than the 10-15% that the utility's calculator states, wouldn't you think?

Guess I'll have to get a few bids and see if they are consistant in any way, shape, or form. I guess that I was hoping for some indication of what work would probably be needed in this type of scenario (old house, ducts, etc), but I wasn't expecting any pricing info (I did read the rules, folks).

Frankly, I am a complete neophyte, ignoramus even, at getting bids for home repair. I don't have any idea what to expect as far as level of detail OR types of activities that would be required.

So I will learn by doing, eh? Wonder if AAA heating is any good - must be a reason they are first in the directory! Seriously though, any guidlines for selecting an installer?

KJ

[dro1984]

I live in your area. Similar situation as yourself as I am/was proud owner of a 1957 LuxAire! Served a faithful 48 years! I called about 5 different Heating and Cooling companies in the area. The one I was happiest with and also had the most recommendations was Family Heating Cooling. Try the Madison Heights number.

[Mr HVAC41]

i worked on a 'johnson' furnace or something. serial number was j7. big old green thing with one burner 120kbtuh

[zzyzzx]

For one thing, it may be oversized like mine because my house had no insulation in it when I bought it (2 years ago!). Add insulation, and now furnace is oversized. Same thing might have happened at your place. Speaking of which, if your going to add insulation do it before replacing the furnace so you get the right size.

[kjones]

Can't say there is NO insulation - the ceiling had loose insulation between the rafters and I added 6' batting on top of that. Also, the original half of the house has a flat roof which is now covered by an attic roof (added batting on that flat roof, too). I think you are partly correct, though they just plain oversized furnaces 50 years ago.

BUT, the outside walls are 8x16 concrete blocks with face brick (1/2" thick brick on a 1/2" thick fiberboard panel). Not much insulation there, and I don't think there are easy ways to add any. Windows are old aluminum storms.

I played around with a couple different heat loss calculators, and it looks like my 1100 sq foot house with a full basement needs at least a 50KBTU furnace, but those calculations can change a LOT with a few variables I'm not sure about (basement floor construction, air changes/hour). Also, the listed R values for various materials vary from source to source. Bottom line, it is an old concrete block house, with old storm windows, and a basememt that is only 3/4 underground and has an outside entrance.

Bottom line will be to have a few HVAC experts look it over and give me their recommendations. Hopefully there will be some consistancy in their bids. Should have changed out the furnace when I had to put in a new water heater a few years ago.

KJ