# American Standard or Comfortmaker Furnace



## kenmac (Feb 26, 2009)

jmff said:


> Any opinions on American Standard compared to Comfortmake furnaces? This is for new construction we are looking at two furnace/ ac systems for our project. The comfortmaker is a DLX 90 100,000. and 80,000. BTU. Single stage each with a 3 ton and the American Standard are 1000,000. and 60,000.00 with a 4 ton and 2 1/2 ton. 90% efficianty. also single stage. Both quotes include humidifiers and air cleaners. The cost is almost exact. All ducting will be insulated. This is for a Southern Michiagan home. Both are up flow furnaces. Thanks for any help you can give.


 

I would want to know why 1 is quoting a 4 ton & 1 a 3 ton. Generally American will cost a little more . 4 ton a/c should cost more than a 3 ton. 
That said . Has anyone performed a heat load calc. on the home ? I wouldn't get hung up on brand as much as I would the install or the person/ co. installing.. 

Ok I had to go back & re read, 1 installer will be using 2 -3 ton units & the other installer will be using a 4 ton & a 2.5 ton. 

Been a long day..

I would still check out the quality of work / Warranty of both installers & want to see a heat load cal.


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## beenthere (Oct 11, 2008)

Size of furnaces sounds about right for a 4,500 to 5,000 sq ft house.
That isn't tightly constructed.


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## jmff (Apr 12, 2009)

*american standard or comfortmaker furnace*

Thank you for both responses. Is a heat load cal the same as a manual J calculation. Anytime I asked for a manual j, they ran as though I had the plague. I stopped asking. Our project is a little more complicated. The furnaces will be placed in new construction but will have to be connected to older ducting (below slab). The new section will be very well insulated (foam insulation) but portions of the old home are poorly insulated. The sf for the area the systems will be servicing is about 3300 but there are areas with high ceilings with lofts, lots of windows (anderson) and we are on a lake (in case that makes a difference). We have had 3 quotes (the third was a Carrier) and all quotes were very similar and within $500.
Again thanks for your responses and if you have any more input it would be greatly appreciated.


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## beenthere (Oct 11, 2008)

Yes, a load calc, and a Manal J are the same.

If you want, you can do your own.

HVAC CALC

Pay the fee, and find out what size you really need.

It can save you money both in the upfront installation cost and equipment cost. And in the operating cost.

You may want to go to a couple manufacturer sites. And find the names of contractors in your area.
Then screen them over the phone, to see if they do Manual J load calcs, and if they will check your existing duct. And desgn any new duct to Manual D.


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## jmff (Apr 12, 2009)

I will give that a try. Thanks!


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## jmff (Apr 12, 2009)

*Manual J REPORT HELP*

Ok, as suggested by beenthere and kenmac we did a manual J on our house but I was wondering if I could get some help as to how to read it and decide on furnace size. SF of the house is 3255 sensible gain is 35,045, latent gain 3,636, total heat gain 38,681 (3 tons) and total heat loss 76,329. We originally were going to have two units as stated in previous posts and are now wondering if one unit a 125,000 C9MPD COMFORTMAKER DLX 90 WITH A 3 1/2 OR 4 TON AIR CONDITIONER would suffice. The hvac man we are talking to seems to think this would work fine. The one unit would save us quite a bit of money plus we could use the extra space.
On the manual J calc, we didn't do room by room, we put in outside walls, all windows, doors and skylights. Is this sufficiant? What does this manual j calc report say? Or do I need to go back and be more thorough. Thanks for any help, need to decide soon.


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## beenthere (Oct 11, 2008)

What were your indoor and outdoor deseing temps for both heating and cooling.

There is a derate used on the A/C, depending on the design temps.


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## Yoyizit (Jul 11, 2008)

beenthere said:


> Size of furnaces sounds about right for a 4,500 to 5,000 sq ft house.
> That isn't tightly constructed.


You have a link or recipe for this, a per sq. foot formula that relates house size to BTU/Hr?


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## jmff (Apr 12, 2009)

Hello Beenthere, We used the set Detroit Michigan for the temp which are summer outside temp 88 winter 6 and indoor temp summer 75 and winter 72, which is probably a bit too warm for us.

Helo Yoyizit, no I don't have a recipe or a link, just got the sf from the Manual J calc.


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## beenthere (Oct 11, 2008)

Not really.

But, even in MI, a new 5000 sq ft house, shouldn't need that much heat. They only get a little colder then here. And 2 60,000BTU 90%+ will heat that without a problem.

If it does. Its not tightly constructed. And the insulation is lacking.


Although, for a large home, 3000 sq ft plus. It makes mre sese to install 2 units, then it does to install one.


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## beenthere (Oct 11, 2008)

You'll need a 4 ton, to meet your sensible heat gain, at those design conditions.
Both a 3 and 3.5 ton would be too small.


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## jmff (Apr 12, 2009)

Hello beenthere, I am a little confused you mention that 2 60,000 units would be plenty to heat a 5000 sf home and a 4 ton ac would be necessary to cool the home. Would that suggest 2 heating systems and one a/c system? 
A little bit more information, of our 3255 sf the new construction is 2280 sf about 1140 which is the 2nd story and below on the first floor which is another 1140, very tightly constructed with foam insulation. 675 sf first floor to the south of the new construction has been recently renovated and well insulated with new 3 pane windows and doors. Off th e southeast is an unheated sun room. The remaining sf of the 1st floor that extends to the east has been renovated over the years with probably ok insulation, this area will be roofed on our next construction phase. Attached to this area is a seperately heated studio.

Our installer so far as suggested 
1-100,000 btu 3 ton for the 1st floor and
1- 80,000 btu 3 ton for the 2nd floor

or 

1-125,000 btu and 1 4ton ac for the entire house


other installers suggested the same for the 1st floor except with a 4 ton a/c and a 60,000 2.5 ton for the 2nd floor.

With the house information given and the results from our Manual J calc what would your suggestion be?
Thanks for all your help so far and as always am very appreciative of any other help you have to offer.


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## beenthere (Oct 11, 2008)

I would probably go with 2 furnaces. Probably both 60,000 BTUs.

And then install 2 A/Cs also. And size each to the load of the area it handles.
Often, the second floor ends up needing more cooling then the first floor(heat rises). But not always.

That is one of the reasons to do a room by room heatloss/gain calculation.

It tells you what rooms/area needs the most heat and cooling.
Along with how many CFM those rooms/areas need.

This does cost more upfront.
But provides a better temp control then a single unzoned system.

If your contractor is good at zoning. Then a single 120,000 90+% furnace, and 4 ton A/C should work very well.
But you should also consider using 2 stage equipment then.


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## jmff (Apr 12, 2009)

Sorry to be a pain, but since heat does rise and with our first floor so much larger and spread out, why wouldn't we need a larger unit on the first floor? That is if we go with the 2 systems?

The installer that suggested the 125,000 for the whole house also said he would use a down flow unit instead of the two upflow unit.

We don't know how well the installer is at zoning, we have used his services and they have been quick to service and so far we have no complaints.


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## beenthere (Oct 11, 2008)

You said your total heatloss for the house was 76,329BTUs.
A 60,000BTU input 90% furnace has an output of 54,000 BTUs.
Thats 70% of your total heatloss.


Without a room by room, or floor by floor load calc, I can't tell if your first floor needs 42,000BTUs, or 52,000BTUs.

But, insulated the way you say the new 1140 sq ft of first floor is.
That area probaby doesn't need more then 26,000BTUs. How much the rest of the first floor needs is hard to say.

Will it need more then the remaining 28,000BTUs that a 60,000BTU 90% has available(31,000 if 95%)..
A full room by room load calc will tell you.

While it may seem like it takes a lot of time to do one.
Keep in mind. That a correctly sized furnace, needs smaller duct then an oversized one. So it also saves you money on the installation cost.
Making the time spent on the room by room load calc well worth the time.


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## jmff (Apr 12, 2009)

Thanks beenthere, you have been a lot of help!!


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