Oh, yea... one more question.
Contractor A will change the line set.
Contractor B say he will change the 'suction line'.
When a line set is changed, do they only change the 'suction line' or is Contractor be just trying to save some money by not changing the smaller line. Should both be changed since I am going from R22 to 410 (and it is required that I go from 7/8" to 1 1/8")???
Gary

goddi

what area of country do you live?

what is your electric rate?

depending on where you live, your climate, cost of electricity, due to today's high nat gas costs an 80% eff furnace is a dinosaur unless paired with a heat pump.

going to your questions.

if you live in an area that has high humidity, then you want the HW VisionPro IAQ stat. It has the "dehumidify on demand" feature and Trane does not offer this stat. don't get hoodwinked. this is the way to go if you want superior dehumidication in your home.

post mdl number of furnace. I assume a load calc both cooling and heating has been performed. that's alot of BTUs. I have never heard about the dual return. doesn't mean it's not true.

the complete lineset should be replaced if at all possible. this is just good insurance and relatively speaking is inexpensive- especially for size and new refrigerant. insist upon it.

the 10 yr Trane ext warranty is good only if you need it. you do want the Trane warranty though, not a dealer warranty, or any other third party warranty. Trane will mail you the certificate.

IMO

What area of country do you live?
-- Northern VA (just outside DC)

What is your electric rate?
-- 6.32 c/kWh annual average

If you live in an area that has high humidity, then you want the HW VisionPro IAQ stat. It has the "dehumidify on demand" feature and Trane does not offer this stat. don't get hoodwinked. this is the way to go if you want superior dehumidication in your home.
-- I asked about using the VP IAQ. He said the Trane fans run at only one speed, as opposed to the Carrier fans that can be programmed for slower speeds for dehumidifcation. So he says the Trane 802 would do the same thing as the Carrier T-stat.

Post mdl number of furnace.
--condensor:4TTX5060A1000A
--XV80 2 stage-TUD120R9V5K
--Coil-4TXCD064BC3 (24.5")
--ARI site gives SEER=14.50 and EER=12.00 and est. annual operating cost at $335.

I assume a load calc both cooling and heating has been performed.
--Nope...none of the 8 contractors will do it.

That's alot of BTUs.
-- My current one is 162kBTU!

I have never heard about the dual return. doesn't mean it's not true.
-Hmmmmmm...

The complete lineset should be replaced if at all possible. this is just good insurance and relatively speaking is inexpensive- especially for size and new refrigerant. insist upon it.
--I'll check why he said "suction" and not the entire lineset.

The 10 yr Trane ext warranty is good only if you need it. you do want the Trane warranty though, not a dealer warranty, or any other third party warranty. Trane will mail you the certificate.
--Yes, it will be a Trane warranty.
Thanks...Gary

Gary

"I asked about using the VP IAQ. He said the Trane fans run at only one speed, as opposed to the Carrier fans that can be programmed for slower speeds for dehumidifcation. So he says the Trane 802 would do the same thing as the Carrier T-stat."

simply not an accurate statement. The Carrier Infinity/Bryant Evolution controller can slow the vs blower and give superior dehumidification for your area which you definitely need. The HW VisionPro IAQ stat is definitely indicated for your climate and without a doubt is the preferred stat. It has the "dehumidify on demand" feature which the others don't. Ask the dealer. If truthful, he will verify this fact!

"I assume a load calc both cooling and heating has been performed.
--Nope...none of the 8 contractors will do it.

That's alot of BTUs.
-- My current one is 162kBTU"

you need a load calculation. what size is your home as well as its layout? what size is your current AC?

I would not go with an 80% furnace unless paired with a HP. Change the XL15i AC to the HP model. That way you leverage the inexpensive electric rate and the savings of the HP will quickly cover the cost difference.

post back.

IMO

Simply not an accurate statement. The Carrier Infinity/Bryant Evolution controller can slow the vs blower and give superior dehumidification for your area which you definitely need. The HW VisionPro IAQ stat is definitely indicated for your climate and without a doubt is the preferred stat. It has the "dehumidify on demand" feature which the others don't. Ask the dealer. If truthful, he will verify this fact!
--I will check back with them.

You need a load calculation. what size is your home as well as its layout? what size is your current AC?
--I completed the HVAC software program. I got Heat Gain=39,841 and Heat Loss=92,495. I tried to put in the worst conditions. 1st & 2nd floors=2,718 sq.ft. + unfinished basement=1,242 sq.ft.

I would not go with an 80% furnace unless paired with a HP. Change the XL15i AC to the HP model. That way you leverage the inexpensive electric rate and the savings of the HP will quickly cover the cost difference.
--I don't want to go with a High Efficency unit because it would be very difficult (in not impossible) to install the new tubing required. And I don't want to be too different from the other houses on the street. All have 5 Ton A/C; one I know has a 135kBTU furnace (Carrier). Others, not sure yet.

Thanks... Gary

goddi

assuming your figures are correct, you definitely don't need a five ton AC and I question the heating BTUs.

Here is a climate synopsis for your area from the Trane site.

Climate averages for: WASHINGTON, DC, 20001
Hot weather Cold weather
Average days per year above 75: 122
Average high temperature: 87.4
Average days per year below 40: 91
Average low temperature: 31.7

What comfort/design temps did you use in and out for summer cooling and winter heating? the unfinished basement is not conditioned living space?

as far as av high temp for DC, I would use 94-95 degrees.
you would know better as far heating design temp.

an 80% furnace eff for your area is OK as long as paired with a HP. If you decide against the HP, then I would get a more eff furnace like the XV95-one or the other. An 80% by itself is just not adequate but I know people do it. Keep in mind for every $100 spent on nat gas, you throw away $20.

IMO

Assuming your figures are correct, you definitely don't need a five ton AC and I question the heating BTUs.
--If everyone in your development have a 5 ton and you have a 3.5 ton, when you go to resale, you have to answer too many questions. I don't want to be too different from the rest. And the duct work is designed for a 5 ton.

What comfort/design temps did you use in and out for summer cooling and winter heating?
--Outside design conditions:
Temperature: Summer=95 Winter=10
Summer grains of moisture: 102
Daily range:medium
--Inside design conditions:
Temperature: Summer=74 Winter=72
Relative Humidity=50%

The unfinished basement is not conditioned living space?
--It is unconditioned living space. I lean toward 5 tons and higher BTUs because future owners may finish the basement.

An 80% furnace eff for your area is OK as long as paired with a HP. If you decide against the HP, then I would get a more eff furnace like the XV95-one or the other. An 80% by itself is just not adequate but I know people do it. Keep in mind for every $100 spent on nat gas, you throw away $20.
--The higher efficiency units require the additional tubing and it would have to exit under a very low deck, which is impossible to get to from the outside. And I am trying to keep it simple. I understand you think 80% is a dinosaur, but it is a great leap forward compared to my 22 year old system...
Gary

goddi

several final thoughts and I will leave it with you.

1.it is just as bad to be oversized as undersized for AC cooling whether from a straight AC or HP

2.I would not size HVAC for an unfinished basement that may or may not ever be finished. especially for a future owner of the home. let them put in a small separate system.
You should think about this strategy long and hard because oversized HVAC is more costly to operate, can affect equipment life, and yield poor inside comfort.

3.a properly sized HP will pay for itself considering your inexpensive electric rate.

4.if not a HP, ask dealer about placement of venting for the high eff gas furnace. I have to say it one more time-an 80% without a HP is a dinosaur.

that's all.

Good Luck!

IMO