Sq ft of upstairs please...

Hard to believe you require the 80 KBTU furnace for upstairs.

Furnace will be located in attic?

Pan to be furnished? New refrigerant lineset or old to be reused? Any filter cabinet?

You will note one quote is for upflow furnace, other is down flow, both different evap coils.

What thermostat? The XV 80 while a great 80% eff two stage var speed furnace should have a true two stage thermostat. Don't get hoodwinked here on a shortcut that cripples a nice furnace's capabilities.

Post back.

IMO

This post was edited by tigerdunes on Mon, Apr 29, 13 at 19:48

Hello. Thanks for the quick response. Very helpful. Will definitely push on the thermostat.

BTW -- Quote A is definitely the less expensive quote.

- Upstairs is approx. 1,500 square feet.
- The furnace will be in the attack.
- The thermo part number was not provided. Will get it.
- two drain pans
- will resuse the refrigerant lines (both quotes)
- wil resuse the gas line
- includes mastic seal transitions (whatever that is...)
- Permit for mech and electrical
- remove all equipment
- float switch (2)
- Condensate Line
- Breakers
- electrical circuit
- condenser pad
- flue piping
- 1 year maintenance
- Warranty - 5 years labo; 10 years parts and 10 years compressor

Now some more questions:

1) Why would they suggest two different furnaces? Which one should I have for my system with furnace in the attic above my second floor?

2) Why would they suggest two different coils? Do you think they both provide the same basic answer which his a 16 SEER systems that qualifies for the $300 rebate?

Thanks again!

Also -- which of the two furnaces look like the right one for me? From quote A or quote B. Or do they both work somehow?

I appreciate the insights and help!

OK.... it looks like I need a down flow furnace for my attic placment. Which one of these is the proper down flow furnace?

Quote A: Furnace = tud2b080acv3

Quote B: Furnace = TDD2B080A9V3

In my opinion neither furnace work because they are too big. You are paying for a 2-stage furnace which will operate 90% of the time in the low stage. Did either one of these contractors do a load calculation? What size furnace do you currently have and does it short cycle?

I assume the furnace will be installed horizontally which would allow either an upflow or downflow furnace. I would think the contractor would get the same type of furnace as the one being replaced. One of these contractors plans to turn the furnace in the opposite direction. There may be a good reason for this, or it may be a mistake. You should find out the reason.

The quotes are incomplete without a specified 2-stage thermostat. I also suggest getting a 4 inch media filter. It means going into the attic once a year to replace it.

Ask for the AHRI directory number. This will indicate what the SEER rating is for the system. I may be wrong, but I suspect the furnaces have been over sized in order to achieve the 16 SEER rating. In my opinion this is not worth a $300 rebate.

Augie

What size and efficiency systems both up and down do you have now-cooling and heating? Any specific issues with existing systems?

I will assume you have conventional furnaces now. If you replace only outside condenser and inside evap coil and pair with existing furnace, you are just as well off staying with basic 13 SEER condensers.

If you want higher SEER 15+, you must go with either two stage var speed furnace or at very least a single stage furnace model with high eff x-13 blower.

I also question the sizing of the furnaces you were quoted. I will give a pass to the dealers on furnace models because these Trane furnaces whether down flow or upflow are adaptable to horizontal application which I suspect is what you have now. In other words, not a big deal.

I do take exception to Mike's statement above about a two stage furnace running on low stage 90% of the time. Not true unless you have a true two stage thermostat. In fact if you use the timer on the furnace, you would be running probably 90% of time in high stage. A pet peeve of mine what dealers do to homeowners in this area. And yes a two stage stat costs more but will easily pay for itself.

At this moment AHRI site is down. I will look up a system using both two stage furnace XV80 and single stage high eff blower XT80 for upstairs.

I also recommend a pleated filter media cabinet that Mike suggested.

IMO

This post was edited by tigerdunes on Tue, Apr 30, 13 at 7:32

You are right Tigerdunes. I assumed the OP was getting a true 2-stage thermostat. An over sized 2-stage furnace controlled by board timing is going to be operating mostly in the high stage and short cycling. It is not a good situation.

Thanks everyone for the great inputs thus far. My current 15 year old system is a carrier brand with a traditional gas furnace.

Otherwise -- I am stumped as to why two of the largest dealers in the area are both suggesting the 80 BTU models.

I appreicate any additional feedback that you may have. I am new to this and want to make the right investment.

"What size and efficiency systems both up and down do you have now-cooling and heating? Any specific issues with existing systems?"

It would be helpful if you answer this question above.

How would you describe your home's insulation qualities.

IMO

Don't know about my existing furnace but will try to find out. The AC unit is a 2.5 ton model.

I am guessing that it is a pretty low efficiency furnace now but I guess that doesn't help much.

It heats just fine during winter (don't like excessive heat..... don't like to set much above 60 at night during winter) but it is a bit warmer upstairs in the summer than downstairs ... but believe this is somewhat normal as we get some really hot days here in the summer.

Interested in both size input and output of existing furnace.

How would you describe your home's upstairs insulation qualities?

AHRI site still down.

Will get you some matching systems later.

IMO

This post was edited by tigerdunes on Tue, Apr 30, 13 at 10:51

Update... let me know what you think....

There was some concern that the furnaces were too large. I was just told by that one of the recommended furnaces is:

- 52,000 BTU on low cycle (May run 85% of the time)
- 80,000 BTU on high cycle

Also - The thermostat to be used is a Honeywell 8000 which I have been told is a two stage heat model. I have not double confirmed elsewhere.

Your contractor should do a load calculation to determine what are the heating and cooling requirements for your house. This is done by entering the information about the house into a software program specifically designed to do this calculation. My guesstimate for a 1500 sq. ft second floor for a 15 year old house in NC would be in the 30,000 to 40,000 BTU range. It could be lower since I believe your winter outside design temperature is about 35 degrees.

If the furnace has an input of 80,000 BTU on the high stage and is 80% efficient, then the output is 64,000 BTU. You can see that the output could heat two of your upper floors and still keep it 72 degrees.

There are several versions of the Honeywell 8000 thermostat. Not all are capable of controlling a 2-stage furnace. You will have to get the specific model number to confirm it.

I may be mistaken but I don't believe any of the 8000 series HW stats are true two stage thermostats. I think Honeywell's consumer literature is quite misleading. Yes, they work but you will be controlling the staging from the timer on the furnace control board not based on demand that a true two stage stat operates that allows low stage to run 90+% of the time.

And then there is the dehumidify on demand feature that works with a two stage var speed furnace a nice feature.

Why cripple a nice furnace's capabilities with the wrong stat?

No need to oversize furnace, the 60 K XV80 would be just fine. I believe that's 32 K on low stage, about 48 K on high stage.

Hey Ryan, wish you would comment on this topic!

IMO

This post was edited by tigerdunes on Tue, Apr 30, 13 at 13:00

There are a few varieties of VisionPRO 8000 thermostats. The TH8110 is just a 1H/1C thermostat that is not meant to control multistage heating/cooling. The TH8320/TH8321, however, will proper control the 2 stages of heat from the furnace based on demand, similar to the algorithm used in the IAQ. What the 8320/8321 will not due compared to the IAQ is stage the back-up heat (the IAQ in that sense is a 4H/2C thermostat) -- that would be on a timer. Not relevant here as you have a condenser (not heat pump) and 2-stage furnace. The IAQ also has the nice feature of dehumidification on demand, as mentioned, to signal the variable speed blower to reduce speed for further dehumidification. All of these attributes, however, are heavily dependent on how the installer configures the thermostat and control wiring. Another reason why a proper installation is critical.