The VisionPRO is a good thermostat for just about any setup. Have your contractor set them up to control the dual fuel setup with outdoor temperature sensors. Model # on the VisionPRO's: TH8320U1008/TH8321U1008. I am curious, though... Is there any reason you're not considering a variable-speed furnace blower? In that case, you could use the VisionPRO IAQ thermostat, which can slow the blower down to dehumidify on demand. What refrigerant type are the XR13's (model numbers would tell)? How was sizing figured? Load calculations would be a good idea for best performance and efficiency (from proper sizing).

Thanks for guidance regarding setup with outdoor temperature sensors. Refrigerant is R410. Concerning variable speed airmover, despite many posts on this forum recommending variable speed for comfort enhancement, I've received enough anecdotal evidence of increased probability of either motor or control board(s) failures as system ages resulting in expensive repairs to repel me from having variable speed systems installed. I've even heard of instance where equipment maker changed control board design obsoleting it so that when moter replacement was necessary due to failure, it was necessary to replace motor, sensor module, plus control module resulting in a very expensive repair. Some may consider my caution short-sighted but I am choosing to forego some equipment sophistication in the interest of long-term reliability.

Carrier was famous for obsolete, unavailable & inapplicable parts.

At least not so for Trane & American Standard, I can assure you their parts are backwards compatible. I can recall one instance of an updated fan but it just required a $13 patch harness to match system.

My thoughts as a former distributor, the failures were far and few between, the benefits far outweighs the worry and concerns.

FYI: as a part, motors and modules are sold separately as a part and capable of being field programmed at the counter.

IÂve heard of auto transmissions failing in automobiles but that doesnÂt make me live with a standard.

I haven't heard of any reliability issues with the ECM motors that weren't caused by poor installation and/or poor ductwork systems. I agree with zl700. It is of course your decision, though. There isn't anything wrong with a PSC blower to me, but I personally think variable-speed is the way to go. Sounds like you were fed some scare tactics from those who lack experience with v/s motors.

In my opinion, one of the most important controls' an air conditioner room TH can have, -is "a room temperature setpoint with a half degree incremental adjustable temp differential settings, up to a 3 or 4 degree temp spread."

When humidity is controlled, the "Human Comfort Zone Chart," on the linked page below, allows for a decent temp spread.

Let's say your initial RM TH setpoint is 76-F, if you used the widest differential of 4-F, the unit would cycle off at 72-F even if the humidity was still above that controller's setpoint. If outdoor temps drop too low & you are not home or at the office you wouldn't want the unit to run into a freeze-up situation.

This is entirely different from Cycles Per Hour (CPH) settings. The incremental adjustable Temp spread differential T-stat, adjusts to the room & weather temp conditions, CPH settings do not.

Seasonal loads, both sensible & latent, vary from light, & average to heavy throughout the entire cooling season in all climate zones.

For those reasons, humidity & unit short-cycling can be controlled much better using an adjustable temp on/off room TH.

"The settings vary from an initial half or one degree F to as much as 4-F, 'with half degree' incremental settings."

Even when an AC is properly sized the weather variation requires a method to reduce short-cycling & improved humidity control. You can control the "Human Comfort Zone" by using 20" or smaller low energy fans to move the dryer conditioned air.

In extreme humidity climates a separate dehumidifier would probably be cost-effective over trying to do it all with the A/C.

The "Human Comfort Zone Chart" is on the linked page. - udarrell

Here is a link that might be useful: Optimal EER & SEER Efficiency

My favorite thermostat of all time is the one we installed in our new house. It's a 'Ritetemp' from Home Depot. The item that puts it above ALL others, in my opinion, is the two way radio-based remote control that works anywhere in the house and gives a confirming beep when the thermostat receives the command. No more getting out of a warm bed into a cold room...or waking up hot and having to trudge to the 'stat to fix things....My schedule varies enough that a programmable unit doesn't really do the job for me. The Ritetemp is also programmable...

Udarrell...

Thanks for your link on EER and SEER. I've suspected that my system was calculated slightly oversized but here in Volusia county FL, code requires you to follow what the energy calcs say...which are also reviewed by the county engineers. (3.5 ton, 2000 sq ft). My A/C guy points out that oversizing is common to avoid the unpleasant possibility that during a heat wave, a heat-soaked house won't cool properly (or not be able to keep warm in an uncharacteristic cold snap). As I've added more heat-stopping strategies I suspect I'm making the situation worse. The thought occurs to me that I could 'de-rate' the system by switching to the next size smaller compressor (keeping same condensor unit). What's your take on this kind of tampering? My observation seem to indicate that 3 and 3.5 systems have the same part numbers on the ancillary components...the only difference being the size of compressor and quantity of coil. Having several A/C buddies and not being particularly concerned with warranty issues since I always do the grunt work myself and just leave the refrigerant work to my friends, the cost of my fidding is pretty marginal compared to what I may save over the long run in reduced power use.

Go with a Vision Pro. Thats all i install now and my customers love them. One of the cool features is if there is a setting you want to change, pull it off the wall...have a seat in your favorite chair...and have at it. It just snaps right back on and your good to go. Another nice feature is the backlight. You can set it for a dim glow when its idle but when you touch the screen, it brightens. Very cool and very state of the art. IMO

Hope this helps

hikker

stat must be compatible for dual fuel systems most likely with an outdoor sensor.

I have to say though that you would be better off with HP and matching var speed air handler with your area's hot summers and relatively mild winters. I live in your neighborhood, have fairly new dual fuel system, and last winter I estimate I used only 50 therms of nat gas. Dual fuel is overkill for this area and the gas furnace will rarely be used for backup heat. Plus electric rates are reasonable and most people expect the spread between nat gas and electric rates will only widen.

I respectfully suggest you rethink dual fuel as a good equipment choice.

IMO

Udarrell...

Thanks for your link on EER and SEER. I've suspected that my system was calculated slightly oversized but here in Volusia county FL, code requires you to follow what the energy calcs say...which are also reviewed by the county engineers. (3.5 ton, 2000 sq ft). My A/C guy points out that oversizing is common to avoid the unpleasant possibility that during a heat wave, a heat-soaked house won't cool properly (or not be able to keep warm in an uncharacteristic cold snap). As I've added more heat-stopping strategies I suspect I'm making the situation worse. The thought occurs to me that I could 'de-rate' the system by switching to the next size smaller compressor (keeping same condenser unit). What's your take on this kind of tampering? My observation seem to indicate that 3 and 3.5 systems have the same part numbers on the ancillary components...the only difference being the size of compressor and quantity of coil.

The problem with existing high SEER systems is that the compressor won't have enough volumetric capacity to handle the larger amount of refrigerant & the boil off in the evaporator at low enough pressures & temperatures.

Look at

The older condensers' say a 7 or 8 EER had larger BTUH capacity compressors that could handle the rapid boil off heavy E-Coil heatloads at reasonable pressure/temperature relationships

You could put a smaller compressor on a lower SEER condenser system & it could work okay at somewhat higher temps/pres.

If you want less BTUH, I would buy a 14-SEER condenser & make sure the evaporator had a TXV metering device. Then a slower blower speed, which will also lower static pressures in the duct system. You can go a low as 350-CFM per ton of cooling, or as high as possibly 450-CFM per ton of cooling. Having several A/C buddies and not being particularly concerned with warranty issues since I always do the grunt work myself and just leave the refrigerant work to my friends, the cost of my fiddling is pretty marginal compared to what I may save over the long run in reduced power use. garymunson-2008
Also here is my solution for those who can't afford the high SEER systems.

If I were not retired I would be picking up as many 10 & 12-SEER condenser's in good condition & no burn outs, etc., that I could Then I would totally recondition them with a new scroll compressor & new fan motor.

Some 12-seer systems when Sized just Right, with the correct options will deliver 13-seer, & should NOT have been eliminated from mfd!

In the chart on my linked page below, Delta- T is temp-split.
- udarrell

Here is a link that might be useful: System Sizing for Optimal EER & SEER Efficiency

Thanks for all replies. Responding to tigerdunes advice regarding dual fuel overkill for this geographic area, I hope to use the gas furnaces backup very little. A driver in my decision to go dual fuel instead of electric strip backup for heat pumps is the fact that this is a retrofit job with two separate systems. The cost and intrusion of running 220vac from panel to both units to power heat strips is unattractive. Downstairs in crawl would not be too difficult but upstairs unit would be a challenge.

hikker

the electrical service for backup heat strips can present a challenge. I do suggest though that you consider the XV80 var speed furnace over a sgl stg conventional blower furnace. the two stg var spd furnace even at 80% would be well worth it.

IMO