I'm 100% sure on the model numbers.
Originally Posted by beshvac
I am planning on going with the 355BAV. Just a matter of making sure I get the right size (either 42080 or 42060). Does the fact that I have a new 3 Ton Bryant 116B A/C unit have any bearing on the furnace size decision? I'd think not but just double checking.
no, both furnaces will work.
Yes the furnace does have a bearing, however from the other poster it sounds like both will work.
Originally Posted by Clocker
In my state the furnace blower capacity is more important than the BTU's of the furnace because not many houses will be over BTU capacity for heat loads but many will need larger blowers for the air conditioning.
If you have a 3 ton AC, the furnace needs to have at least a 3 ton blower drive.
For a 3 ton drive to actually move 1200 cfm, good duct-work is a must.
General public's attitude towards our energy predicament: "I reject the reality of finite resource depletion and substitute it with my own; energy is infinite, we just need an alternative storage medium to run the cars on. The economy can grow indefinitely - we just need to "green" everything! Technology is energy! Peak what?"
Listen to AMD, he is correct, Get your house tested, then you'll know what to do
When it comes to load calcs, garbage in = garbage out.
Window frames can leak more than the windows themselfs; if it's very drafty, caulk around the trim. (removing the trim and spray foaming is an option, but it's probably labour intensive + expensive) Removable caulk is available for operable windows.[/QUOTE]
AMD Gives good advice. Your Load is bogus with out testing the core assumptions.
For a reliable load on your old leaky house will need your:
1.Ducts tested for losses/gains and leakage. On an old house such as yours with out Duct testing your load will be nothing less than a SWAG.
2.You will need your old house's leakage tested with a Blower Door. With out this test your "load" is just a SWAG again. By doing this you may be (will be) shocked at just how leaky your house is.
Note: Improvements in Air Sealing, Duct work, and Insulation will certainly have much higher ROI's than your furnace and AC. These improvements will also allow you to downsize your system with total confidence.
3. Also, loads vary wildly with wind conditions and direction.
4. Get these tests Done and get them done by some one who knows how to do them or your "load" is just that, a load of sht.
"The test is only as good as the tester" Famous ACCA Certified Trainer
Smaller is better. Larger is just a waste of money, since you won't get the comfort you paid for from it.
Since it's 2-stage, wouldn't it be somewhat better to be on the big side rather than small so the furnace can stay in the quieter 1st stage more?
I talked to a neighbor a few doors down. His house was built about a year before mine but is about 150s.f. bigger. The 3 places he talked to a couple years ago said they didn't need to do a Manual J so he spent several hours attempting to do his own calc. (he's a Mech. Engineer so he's pretty good with calculations). The contractors all used 'rules of thumb' and the size of the original furnace to base their recommendations on. Turns out he came to the same conclusion as the contractors.
He's very happy with the constant comfort level from the setup, especially compared to his old on/off 80%er. He also stated he didn't notice any short cycling. Given our construction is essentially the same (he had an extra layer of insulation blown in the attic which I'm too lazy to do) I'm comfortable that the 80K BTU system is the way to go for us.
Here's an interesting article about contractors, Manual J, and rules of thumb... http://www.dr-fix-it.com/arc_heating.html
Seems that finding contractors who want to do Manual J is a rare. I can see why as it probably costs them more time and money than it's worth to them.
So I will get a few more quotes and see what the contractors say when I ask for Manual J. But this is what I expect I'll end up with unless I see a compelling reason to change it:
Bryant 95i 80K BTU
Bryant fan powered humidifier (never was happy with the perf. of my General 1042 bypass humidifier)
Bryant Media 2000 Air Cleaner <-----ANY PROBLEMS WITH THIS?
Extended 10 year labor warranty
Your neighbor probably added a lot of fluff/safety in his load calc.
I don't know. He's pretty cheap and he actually built the house...so he has a lot of in depth knowledge about the construction. Either way, he's really happy with all aspects of the system performance, so that's good enough for me.
What about that thick Bryant filter? Much thicker than the 16x25x1 that I'm used to. How often are those usually replaced?
He's probably happy, cause he doesn't know how much better it would be with the smaller size furnace. Many people do live the philosophy ignorance is bliss.
Originally Posted by Clocker
OK, OK, OK, But...
OK, You are correct and your article is also pretty much correct also.
Originally Posted by Clocker
My point was, even if you do a Manual J. It its just a dog and pony if you don't know the primary assumptions, and you have no clue unless you test.
The older the house the less you know and the wilder the tolerances are, so even if you get the boys to do the manual J act, it has no more meaning than your rule of thumb guy.
On the other hand, you have stated you have "crappy leaky windows" and one would assume a leaky house. If what you stated is correct, there is certainly no need for a load as it will have no credibility. To the degree you care about your long term costs and comfort you could take a more detailed approach, get the tests done and then your Load Calc and over all decisions will have some basis.
It's sounds to me you are really not that concerned with comfort, or why not fix the crappy windows?
Also, never trust the neighbor, especially an engineer.
I know where they're coming from, though. I used to like working on computers. I would keep tweaking, adjusting, overclocking, updating drivers etc. etc. just to get 110% performance out of the system. Finally woke up and realized I was spending more time obsessing about it than I was actually enjoying it. It just happens when you know a lot about a subject and want it to be absolutely the best it can be. It's nice of all these guys to provide their input and share their bountiful knowledge. With HVAC there are soooo many variables that there's always something that can be tweaked or optimized better. The experts here are just offering their valuable time to help and are attacking the question at hand from every angle.
Unlike them, I'm not looking for my system to be 100% optimized on the bleeding edge of efficiency, I just want something that works really good and I can be confident that it keep my family warm with maybe just a little bit of margin. Given the research I've done, I'm pretty confident I'm there.
On the other hand, some people can never accept the possibility that they might be wrong even considering the fact that they have never even seen my house or know where I live.