Honeywell TH8321 Humidity Control Question.

[Florida Joy]

No offense to you, but I'd like to see it for myself to be sure. I hate being sold something that's "supposed to" do somthing and then later find out I was misled or misinformed. Could you please give me the page number in the installation guide or a link online that covers blower speed control for the VisionPro IAQ?

Thanks!

Never mind. I found it. It's in a wiring diagram for the VisionPro IAQ that refers to "Air Conditioning". I would guess the same wiring would apply for Heat Pumps.

Fig. 16. Typical hookup of variable speed blower for
dehumidification in low speed (contacts normally closed).
NOTE: Connect DHM2 to low-speed fan terminal on air handler
for dehumidification with air conditioner and a
low-speed fan.

[Florida Joy]

Under 40% in Florida? Ain't goona happen with standard heat pump of any brand or seer.

So I'll have to set the tstat lower on the new equipment to maintain the same comfort level, I guess. My 13 year old Rheem 10 SEER maintains 38-40% RH during the summer. In the "shoulder" seasons, it gets up to 50% because it runs less.

[beenthere]

OK, I've gone through the installation guide for the VisionPro 8000 Series (includes TH8321 with humidity control), the installation guide for the VisionPro IAQ, and now the THX9321/9421 Prestige® IAQ, which has the HD touchscreen.

Neither of the VisionPro products include blower control options for dehumidification. Both the VisionPro TH8321 and IAQ products dehumidify by overcooling. On the other hand, the Prestige® IAQ does have settings and wire terminals to run the blower on "low" speed and will overcool to 3*.

So, to take advantage of the VS blower for dehumidification with a non-communicating condenser, it appears I need to specify the Prestige® IAQ, not the VisionPro IAQ. Is that correct?

No. I install the Vision Pro IAQ on a lot of VS blowers. It does what I said.

[kdean1]

At our house I use the Prestige thermostat to control a Honeywell TruDRY dehumidifier so we don't have to over-cool the house. You would benefit from a two-stage condensing unit and a variable speed blower when it comes to de-humidifying.

[Florida Joy]

No. I install the Vision Pro IAQ on a lot of VS blowers. It does what I said.

Thanks! A couple of posts back I said "I found it".... in the installation guide for the Vision Pro IAQ.

[Florida Joy]

At our house I use the Prestige thermostat to control a Honeywell TruDRY dehumidifier so we don't have to over-cool the house. You would benefit from a two-stage condensing unit and a variable speed blower when it comes to de-humidifying.

No thanks on the dehumidifier. I'm considering 2-stage but have to include ROI in my decision matrix.

[SBKold]

So I'll have to set the tstat lower on the new equipment to maintain the same comfort level, I guess. My 13 year old Rheem 10 SEER maintains 38-40% RH during the summer. In the "shoulder" seasons, it gets up to 50% because it runs less.

I wonder how accurate your humidity reading is as I would have to say that is far drier than typical. In mid summer anything lower than 45% would require near constant runtime- and almost no infiltration.

[Florida Joy]

I wonder how accurate your humidity reading is as I would have to say that is far drier than typical. In mid summer anything lower than 45% would require near constant runtime- and almost no infiltration.

Per recent infiltrometer/blower door test, my house CFM @ 50PA = 2172 and my summer ACH = 0.30. I have a small digital thermometer that measures humidity which I recently purchased at Lowes, and I believe it is pretty accurate. If I take it outside, the humidity reading is exactly the same as what's being reported by my local weather station.

Yes, during the hot summer my system runs non-stop about 12 hours a day.

[Florida Joy]

Never mind. I found it. It's in a wiring diagram for the VisionPro IAQ that refers to "Air Conditioning". I would guess the same wiring would apply for Heat Pumps.

Fig. 16. Typical hookup of variable speed blower for
dehumidification in low speed (contacts normally closed).
NOTE: Connect DHM2 to low-speed fan terminal on air handler
for dehumidification with air conditioner and a
low-speed fan.

One more question (may not be the last...lol). Would this feature of the VisionPro IAQ work equally well with an air handler using the X-13 ECM motor? As I understand it, the X-13 is an ECM (as opposed to PSC), but it's NOT a variable speed motor. However, it appears to have 5 taps, each for a different speed. If the tstat DMH2 were connected to a lower speed tap than the one used for "normal" cooling, wouldn't that serve the same dehumidification purpose?

I'm simply trying to determine if the VS blower is worth the extra cost if I choose to go with a single stage condenser.

[SBKold]

Yes it can be utilized to work with X13 but requires a extra field supplied relay.

[Florida Joy]

Yes it can be utilized to work with X13 but requires a extra field supplied relay.

Cool! Is that something your everday, run-of-the mill installation tech should be capable of setting up with a "field supplied" relay?

[SBKold]

Cool! Is that something your everday, run-of-the mill installation tech should be capable of setting up with a "field supplied" relay?

Honestly probably not. Its pretty easy though.

A true variable speed will take a lot of variables out of setup of the new handler.

A x13 will require consulting blower chart provided to installer to choose proper speed tap (s)