View Full Version : BTU's of Amana's AMV8/ADV8?
04-18-2007, 09:57 AM
What is the lowest BTU model for the Amana AMV8 2 stage var speed 80%
Furance? One contractor tells me 50,000 BTU's would be perfect for my
home, but on their wesbite it show 70,000 BTU's as there lowest option.
Would 75,000 BTU's be way too oversized for my 1100 sq ft condo?
04-18-2007, 12:00 PM
This is Amana's top of line 80% AFUE var speed two stg gas furnace. The smallest size in this model is the 70 KBTU unit which has a 57 KBTU output in high stg and 42 KBTU in low stg. Whether this is a correct size for you depends upon a professionally performed load calculation.
04-18-2007, 12:48 PM
So the overall number of 70,000 BTU is not what I should be looking at, but
rather the 57,000 for high fire and the 42,0000 for low fire?
If thats the case, this furnace may be ideally suited for my home.
04-18-2007, 01:39 PM
You don't give up, do you.
Did you ever get a calc done? You could likely take a window out and heat the house with that furnace :eek:
Guys, he's got units on both sides and above. His only heat loss is front and back.
I did a quick heat loss using a 1100 sq ft space, 40' front, 40' back, no floors or ceiling, 50 sq ft of windows in each wall, R11 wall insulation, 70 inside -10 outside and came up with 11,240 BTUs. You don't need a 57,000 BTU output furnace for that.
04-18-2007, 07:59 PM
I know Bald...I can be a little overboard. Im just a very curious person by
By the way, I dont mean to challenge you here, but I just went to Amana's
web site and downloaded the Owner's Manauls for their two offerings of their
80% 2 stage furnaces. The last section is entitled "thermostats".
Here the text....
"A two stage thermostat should be used with the Amana AMV8. A properly
used two stage thermostat and furnace will maintain a much tigher control
of temperatures than a conventional single stage thermostat and furnace."
They even go further and list 3 2stage stat models that they recommend
for the AMV8!!
Maybe im mistaken, but are you the guy who has stated many times, that
Amana WILL NOT allow you to use a 2 stage stat on their 2 stage furnaces?
04-18-2007, 08:05 PM
By the way Bald, at least in my area, contractors WILL NOT do a load
cal unless you commit to the installation and provide downpayment. One
guy said it takes 2 hours to do...not sure how true that is.
04-18-2007, 09:13 PM
Although I was guessing at window sizes and the sizes of the exposed walls in the calc I did, it took only a few minutes. Let's do this:
You tell me sq ft of the 2 exposed walls, sq ft of windows in each wall, sq ft of doors that open directly outside. If you are on a cold floor, such as slab, let me know. If slab, are ducts in slab or other unconditioned space and finally your city. I'll run the calc and post the pdf.
Your comments from Amana's site are the argument I used with Robo. The top model is what you are quoting from and they recommend the 2 stage stat. The new mid model, 2 stage but standard blower, is the one that can't use the 2 stage stat. I point out to Robo the inconsistency of it all, one model recommends a 2 stage stat while the other can have one.
04-18-2007, 09:26 PM
Sorry, I don't much go to the website. Not being in marketing, I can't much comment on inconsistancies. Is it any worse then Trane's claim to have invented a better filter system or Carrier's old claim that a heat pump is not a reverse cycle air conditioner?
04-18-2007, 09:26 PM
Yes, I see what you are saying Bald...
Is it the AMS8 that you CANNOT use the 2 stage stat?
Thanks....I an on a concrete slab. I will get back to you with the
measurements. Thanks for your patience, as im just trying to educate
myself and make the correct decision.
04-18-2007, 09:28 PM
It's the AMH 2 stage that uses the board only. The AMS is single stage so doesn't apply.
Are your ducts in the slab or overhead?
04-18-2007, 09:49 PM
Here is the information you asked for.....
1100 sqft condo, sitting on a cold concrete slab, new thick top line
wall to wall carpeting and thicker pad covering entire floor.
front wall of condo - 21ft x 8ft ceilings
front window- 4'7" x 7ft
standard size front entrance door, with new storm door with glass, not screen
rear wall of condo - 21ft x 8ft ceilings
rear window - 4'10" x 5'10"
rear sliding patio door- 5ft x 6'7"
Also, both my windows are the low end, original builders grade, 21 years old. I always
feel cold and draft when im close to windows. I dont know if that needs
to be taken into consideration. Im sure right there there is a load of
All ducts are on the ceiling. Large return in second rear bedroom. 2 returns
in master bedroom.
04-19-2007, 08:08 AM
Just two windows? I would consider an upgrade.
Depending upon the area you live,its climate, and your electic utility rate, a good high eff heat pump system might be a better choice for you particularly in the area of closer sizing.
04-19-2007, 10:33 AM
Here's da figgers!
Didn't have your location so I used -10° as the winter design temp. I used what HVAC-Calc calls average infiltration, loose construction. Using better construction (less than 25 years old according to the program) the loss dropped to under 17,000 BTUs due to much lower air change rate.
So even using worst case scenario, you needing less than 24,000 BTUs at -10° outside.
Take it from someone with an oversized 2 stage furnace. Don't do it! The AMV8 is a fine furnace but too big. Find someone with a smaller furnace. Trane has a 2 stage non variable speed at 40K input on high, that's 20K output on low which means you'd rarely hit high except for warming up after a setback. If you really want a variable speed blower, ICP has a model at 50K. While still way oversized, it's far better than 70K.
04-19-2007, 07:34 PM
Thank you for providing me with this information. I really appreciate it!
Now, I have to looking at all the quotes and decide between the York,
Heil or Amana systems for my condo.
I would guess you have the same opinion about Heil's 2 stage 80 furnace....
need to use the 2 stage stat? The Heil contractor told me I would NOT even be
able to use a 2 stage stat because I do not have the wiring . My HVAC system
is located in the back attached shed and my current stat is inside in the
hallway. He tells me it would be VERY tricky to install a 2 stage stat and
would have to run more wire and cut out drywall.
04-19-2007, 08:31 PM
Vision Pro IAQ. Indoor unit connects to control unit via 3 wires. Control unit then handles furnace & A/C, humidifer, etc. If you get the variable speed blower, you can also have the IAQ trigger the dehumidify on demand feature which slows the blower if the indoor humidity rises above what you set it for. Very slick system. Your dealer isn't keeping up with the times :(
04-20-2007, 10:59 AM
I picked the Amana system. Im going with the AHS8 single stage 80% furnace and the
ASC13 A/C unit.
Any idea why the AHS8 does not appear on Amana's website??
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