Trane vs. Lennox & Duct Question
Which of the following two systems would you recommend? I'm curious to hear of the benefits the Trane system would offer over the Lennox, since I am currently leaning toward the Lennox XP21.
XP21-048 heat pump
CBX32MV-060 air handler
"EvenHeater" 20 KW heater package
4TWX6048G1 heat pump
TAM7A0C48H41 air handler
15 kW heater package
XL802 t-stat (no humidity control)
Question on ductwork size: The Lennox dealer plans to install a 20 kW heater package (this dealer verified this to be the required size by doing a load calc), and the Trane dealer worries about getting the required airflow (2000 cfm?) for the 20 kW heater given my existing ductwork. The duct sizes installed are:
-20x14 return including 8" tapped in just before media filter serving basement
-16x8 (after transition from 14x8 off plenum), 8x8, and 12x8 supply
Dealer says the return is capable of 1650 cfm + 250 from the 8" for the basement. I did not ask him about the supply -- can it handle enough airflow for a 20 kW heater?
Thanks for any thoughts you can offer regarding the two systems I have to consider.
The dealers "general discomfort" about duct work sizes make me uncomfortable since he should KNOW and not Guess concerning the capacity of the existing duct!
the Trane dealer worries about getting the required airflow (2000 cfm?)
His general remarks seems to be a warning shot that he is not responsible if it doesn't work!
He should know and tell you what he would do to make it work
You have got to learn from other people's mistakes! Because God knows you don't live long enough to make them all yourself !!!!!!!!
I would keep looking for dealers.
Originally Posted by rdh126
A 20kw will work on most brands' 3 ton air handler so don't know where he got the needing 2000 CFM from!
Originally Posted by BaldLoonie
Yep, from 1150CFM up temp rise would be less then 55ฐF.
20,000 w*3.41 w/btuh = 68200 btuh
Heat pump: 48,000 btuh
68200+48000 = 116200 btuh.
116200 = 1.08*CFM*(55 F rise) -> 1956 CFM @ 55 F rise... does it get down to 13 F where you live?
You can call me Sam
It should be a crime to be a mechanical engineer in San Diego
Summer Design Temperature: 83 F Dry Bulb ~ 69 F Wet Bulb (California Climate Zone 7
B.L. No offense intended, and I've been out of the business for sometime, but are you sure a 3 ton (blower) AH will handle 20Kw?
Originally Posted by BaldLoonie
Thanks for the responses thus far. Good to know that it does not seem like getting enough airflow for the heat will be an issue. I assume the 20 kw would be the worst case scenario should we ever lose the heat pump when it's below freezing out. The dealer explained that it would have 4 stages so that it wouldn't all be used at once. I have been offered the XP16 and XP21 Lennox units as well as the XL15i, XL16i, and XL20i Trane units as my complete set of options. I thought I had narrowed it down to the XP21 and XL16i, but welcome any opinions or suggestions.
Location is Maryland. ~2500 sqft home with 700 sqft finished basement partially below grade
second_opinion -- why do you think I should find new dealers? I felt pretty good about the ones I had out despite a few discrepancies between them, most of which I have been able to clear up. Both seemed competent in their work. The Lennox dealer spent more time and took measurements for a load calculation prior to giving the quote, and also made several recommendations regarding ductwork to improve flow, particularly in the basement. The Trane dealer will do a Manual J and also balance the ductwork with a flow hood device as part of the installation price. This sounded interesting, but this dealer also proposed removing the 3 supply trunk dampers as opposed to replacing them (one is broken and I had asked for them to be replaced). I'm curious how the system would be balanced without dampers, but the cost "credited" upon selecting this company for the installation made it seem like a time-consuming task that could be worthwhile. Can you offer any thoughts on this? Thanks.