My local Trane contractor and I were discussing the use of an XL19i versus an XL16i for a zoned system. After received some feedback on this forum I decided to ask a Trane field representative who is employed with the Trane distributor.
He advised me that only the Trane Integrated Zone System has the ability to "talk" to the variable speed fan and modulating dampers. Based on this he said only the Trane proprietary zoning system would work properly with a VS fan. He also said that if a contractor used a non Trane zoning system he would lose all ability to control the fan and, as a result, the fan would operate at full CFM capacity.
He further said this would result in “'excess air' which can only be managed by gross duct oversizing or bypass. As the variable speed fan motor has the ability to overcome resistance to air flow generally up to 40% greater than non-variable speed, the negative effect of bypassing air (as in conventional zone systems) is compounded. An analogy is like driving you car with the gas pedal to the floor, and modulating your speed by how hard you depress the brake."
So his first response was to advise me about the advantage of the Trane zoning system when using a VS fan and the problems any other zoning system would have with a VS fan.
Then he responded to the XL19 versus XL16 issue.
He said that the Trane zoning system is instructed to modulate the CFM on an understanding there is a 50/50 split between first and second stage CFM, and that this more closely matches the split on the XL19 system. As the XL16i provides an approximate (depending upon selection) 70 / 30 capacity split, the Integrated Zone System will not offer the correct airflow distribution when matched with an XL16i, especially on 1st stage, which statistically is 70-80% of the equipment run time.
So his conclusion was that Trane really didn't have a good zoning product for the XL16i. Therefore go with the XL19i.
I've made up my mind on the system (zoned XL19, XV90 or 80).
I just wanted to see if there was any response to the Trane rep position on:
1) How zoning systems work with a VS fan (Trane system-good, others-bad). Are there other zoning system (Honeywell, etc.) that work well with VS?
2) Staying away from XL16 with zoning?
He was talking trane equipment only.
And is probaly giving you good advise for his product.
Carrier has the infininty system that works very well with their VS blower.
We use bypass systems on York VS blowers, they work well.
And the fan speed is controled by the EWC zone control panel.
His anology wasn't quite right.
Did you really thing a Trane distributor rep would tell you a different manufactures zone system would work as good as a TRANE :) LOL...
beenthere, I was pretty confident that I would get a Trane oriented answer so that didn't come as a surpise. My problem locally was to find any dealer who would talk zoning. There is only one local Carrier dealer and he wouldn't follow Manual J and wasn't too keen on zoning (I figure if the dealer already have his mind made up I didn't want to change it, at least not with my house). Pretty much the same story for the only Bryant dealer.
The Trane dealer was the only local dealer who accepted zoning as a reasonable alternative (he also has zoned his house and his son's).
So, there are other zoning systems that coordinate, or communicate, with a VS fan, correct?
Thanks for the feedback.
1) No other zoning system can give the PWM signals to the Trane fan to slow the blower. You'd have full fan for the stage of cooling all the time. Thus, you'd need to use a bypass with the other zoning systems or size the ducts to be able to handle a LOT of air.
2) No zoning with the XL16i for the reasons presented by the FSR. Airflow is too low for first stage compressor operations.
I do like their IZS. The Trane IZS a great system. For intelligent design and capabilities, the Trane IZS and Carrier Infinity Zoning are way ahead of the competition.
I should have been clearer that certain Manufacturers have a more dedicated way to control their VS blowers.
Which is what I meant when I said he was taling Trane only.
JR, do you need a special Trane OEM stat to control the 91i.
No. Any two-stage stat will control.
However, you can't slow the blower with any other zoning device. The Trane IZC will slow the blower to 70% of the requested CFM stage. The IZC will give a PWM signal to the furnace/air handler on the BK circuit.
The other zoning systems will only give Y1 and Y2 24V signals. Thus, full airflow for the given stage.
jrbenny, why does Trane not yet have a zoning system for their more recent AC units? Just a lack of demand? I really wanted a Scroll compressor and R-410A but I can't get that with zoning.
Beats me. I'm on the fix it side...not the design it side.
I'm rather surprised they haven't upgraded the control board. It shouldn't be that hard to design, but they just might not want to spend the $$. The IZC wasn't a big mover when I worked for Trane. OEM's don't invest capital in slow movers.
I really wanted a Scroll compressor and R-410A but I can't get that with zoning.
lennox xc21 a/c unit, g61mpv furnace, harmony zoning
t527ed, problem is there is only one Lennox dealer in my town and they don't do new residential construction.
This has been one of the more interesting challenges of my new construction project - finding a particular authorized dealer who will do new construction who will accept Manual J and who really believes in zoning. In my town of over 500,000 that boiled down to one dealer who just happens to be a Trane dealer.
York Affinity is also scroll, 410a, availible in 2 stage.
And can be controled by a number of different zone control systems.
JR, I must be getting tired.
Your saying if the stat sends a call for first stage cool, the blower will run slower, but if a zone panel sends that singnal it won't.
Yes, you are tired.
I am saying...
Thermostats and non-Trane zone systems send 24V signals on the Y1 Y2 and G circuits. Set programmed blower speeds based upon those inputs are delivered.
The IZC will send those signals PLUS a signal on the BK circuit. The BK input is the override signal to lower or raise blower speed based upon system load.
The non-Trane zoning systems (Arzel, Hwell, etc) don't have a BK output for tweaking blower CFM.
JR, thanks, I missed that point last night.
You just don't get the full benifit of Tranes VS with other stats and zone controls, now I get it. Finnally. :)