Top End Dual Fuel Proposals - Look Good?

[dan sw fl]

Beenthere, this is hurting my brain, but I think that I may have an alternative solution using 2 "sensor" locations. It also stays within the 1, 4 , 9, etc. indoor sensors that Honeywell requires.

One of the options on configuring the Honeywell YTH9421C1002/U tsat using setting 340 is to use one real C7189U1005 indoor sensor and the original tsat.

Beenthere, I appreciate your patience as this HVAC idiot works through a solution to a bad uneven house temperature problem.

If you continue to try to work with "this HVAC idiot",
you get what The Owner deserves.

if the root cause - windows - is not addressed,
you get what you get
and don't have a fit.

[jerryd_2008]

If you continue to try to work with "this HVAC idiot",
you get what The Owner deserves.

if the root cause - windows - is not addressed,
you get what you get
and don't have a fit.

Not a very productive response, Designer Dan. I suppose that you are suggesting that I replace 70'+ of Southern exposure windows or maybe installing $1,000's of film on the windows that kill the beautiful view and may or may not fix the sun load. The true "idiot" in this situation is the original designer that I never met. Placing only one HVAC system in this fairly large, walk-out house and then enclosing all of the duct work in dry wall to prevent any cost-effective duct solutions and then placing the tsat in probably the hottest room in the house. Your smart reply reflects no content that I, a quite accomplished designer in another environment, would attribute to an effective designer. Maybe it's just that it's early and you have a bad day in front of you or, if not, you could just skip reading the posts on this thread.

Now back to Beenthere's comment. Installing additional sensors is a matter of what's cost-effective. This house is fairly large, built in 1994, and each sensor requires a wall penetration and hopefully finding a reasonable wiring path back to the tsat digital control in the garage. The two locations that I think will work are above the return in the highly-used, partially buried, lower level that is naturally cooler and the other is in the first floor master bedroom near the wall vent penetration for when the door is closed and which is away from the hottest room. One sensor is an easy install and the other not so much. These two locations are much more reflective of the true temperature of the rest of the house. During the heating season, the average of these two temperatures will be lower than in the hot room and should cause longer run times to reach the tsat setting. The longer run times should also simulate running just the fan for the hot room causing the air handler to mix the hot air from that room and possibly lowering it there without all of that blowing cool air throughout the house with just the fan. In addition, my HVAC pro feels that too many sensors will solve the problem in no specific location which I kind of agree with as long as the selected locations are indicative of the true house temperature.

So, Beenthere, given that we select appropriate senor locations, do you agree that the proposed two-sensor scenario using the average of the tsat and the new sensor location using the tsat 340 setting is at least technically feasible without any undocumented workarounds for Honeywell's tsat/sensor scenarios?

[beenthere]

Nope. Need two sensors, and the stat is not one of them.

Not any harder to install 2 sensors. Then to install one sensor and move the thermostat to another location.

[catmanacman]

http://www.forwardthinking.honeywell..._products.html might be cheaper and easier in the long run to go wireless thay way you can move the thermostat to your liking

[dan sw fl]

Since, duct changes are probably not feasible.

One should look at SOME window film coverage, with addition of 400 square feet film,
peak load might be reduced nearly one ton.

http://www.windowfilmdepot.com/simulator.html
Prestige 50 or 60 should not change the perceived environment.

+ 20% savings in operating costs
+ 20% equipment life extension likely enables a ROI of < 5 years.
+ significant temperature difference is mitigated.

[jerryd_2008]

Nope. Need two sensors, and the stat is not one of them.

Not any harder to install 2 sensors. Then to install one sensor and move the thermostat to another location.

Beenthere, I have read some technical documentation in my day but I am totally confused by the cross statements between the Honeywell YTH9421C1002/U tsat and the C7189U1005 indoor sensor. The tsat doc says for the 340 setting that you can display average of two indoor temperature sensors and indeed that The temperature sensor in the thermostat is disabled when using remote indoor temperature sensor(s):

340 Indoor Temp Sensor

0 Thermostat location only
1 Remote indoor sensor(s) location(s) only
2 Average between thermostat and sensor locations

Indoor temperature sensors will display the temperature at the sensor location or an average of two indoor temperature sensors, not including the thermostat. The temperature sensor in the thermostat is disabled when using temperature sensor in remote indoor temperature sensor(s).


Then the C7189U1005 indoor sensor doc shows figures on page 3 of legal configurations for 1, 4 and 9 sensors and NOT 2.

- First, why would one even want to "display" the tsat temperature in an average if it is "disabled" by adding an indoor sensor?

- The tsat 340 setting talks about displaying the "average of two indoor temperature sensors" which is an illegal, configuration????

- Beenthere says that it is "Not any harder to install 2 sensors" which is an illegal Honeywell configuration????

- Beenthere said in the past that there is an "undocumented work around" for two indoor sensors but I can't find any documentation to provide my HVAC pro.???

- Is it just time for me to say forget it, because I cannot resolve the communication path between Honeywell/this forum/my HVAC pro??? I have no idea what to order for him nor does he and has little interest in researching it.

The close-to-the-vest format on this forum is just pure frustration for a home owner trying to solve a real HVAC problem. I appreciate the concern over do-it-youselfers but I am NOT one and it would be a cold day in .... before I start running wire in my house. The change in focus of this forum a while back is hard for a home owner to navigate.

PS: thank you, catmanacman, for the suggestion, but it sounds like I would have to scrap all of my tsat equipment and start over to do wireless.

[beenthere]

No idea why anyone would want to display an average temp but not use it to control temp.
Averaging of one remote and the stat is useless.
Its not an "illegal" configuration. Honeywell the support that you talked to is residential, not commercial, so they probably don't even know they make the 20,000 ohm sensors.
Thats up to you. To me its simple. Get the 20,000 ohm sensors and install them.

The install manuals are not written by engineers. They are written by people that went to school to learn how to write technical documents. They don't really know how whatever they are writting about works. they just transcribe notes on operation from the engineers. And those notes aren't always clear, so the writer will sometimes adlib it.

[jerryd_2008]

No idea why anyone would want to display an average temp but not use it to control temp.
Averaging of one remote and the stat is useless.
Its not an "illegal" configuration. Honeywell the support that you talked to is residential, not commercial, so they probably don't even know they make the 20,000 ohm sensors.
Thats up to you. To me its simple. Get the 20,000 ohm sensors and install them.

The install manuals are not written by engineers. They are written by people that went to school to learn how to write technical documents. They don't really know how whatever they are writting about works. they just transcribe notes on operation from the engineers. And those notes aren't always clear, so the writer will sometimes adlib it.

Beenthere, I think this is getting through my HVAC thick skull. I have been proceeding along assuming that you were recommending that a very specific 20,000 ohm electrical component was needed along with 2 Honeywell C7189U1005 indoor sensors and that they are to be wired in some undocumented electrical circuit which I couldn't understand why you couldn't describe that circuit for my HVAC pro. I finally located the TR21 wall mounted sensor assembly and think I know what you really meant. Please verify this scenario:

- Buy 2 TR21 indoor sensors with the following description (from Amazon):
Product Description: The Honeywell TR21 wall mount temperature sensor is a 20k sensor that replaces the T7770a1006 sensor

- Install these 2 sensors per the instructions (I hope) in the literature in place of the 4 Honeywell C7189U1005 indoor sensor scenario.

- PS: I assume that I would then set my tsat 340 setting to: 1 Remote indoor sensor(s) location(s) only

If this is what you meant, I still wish to retain my HVAC non-wannabe and HVAC Idiot titles on this forum.

[beenthere]

Now you got it.

[jerryd_2008]

Thank you, Beenthere. I am running on light sleep so I can get testy at times, especially when I go down dumb paths.