Pros & Cons of Trane XL20i Versus XL16i Heat Pump

[dan sw fl]

.105? I used a larger number, gotta link to .105

Yes, stop by & I'll show you my FPL electric bill.

Or see post # 188 for kw & $. = $00.105 kW/hr

[dan sw fl]

double - erratic PC.

[dan sw fl]

Right now my house is at 43%RH @ 74F upstairs and 33%RH $77F downstairs. .

77'F @33% R.H.

How do you get L.A.T. < 47'F?
_ When is the last time your hygrometer was calibrated?

http://www.thermalinc.com/math/wetbulbcalc.htm

[Florida Joy]

.105? I used a larger number, gotta link to .105

This is the info directly from my August FPL bill:

kWh used 2360
Customer charge: $5.90 per month
Storm charge 2.78
Gross receipts tax 6.08
Franchise charge 14.59
**The electric service amount
includes the following charges:
Fuel: $92.49
(First 1000 kWh at $0.033430)
(Over 1000 kWh at $0.043430)
Non-fuel: $135.94
(First 1000 kWh at $0.051840)
(Over 1000 kWh at $0.061840)

[beenthere]

You're in Iowa? How far is that from the Atlantic Ocean and what's the average RH and dew point outside your house in June, July and August? In my neighborhood the average RH is 90% with an 80 degree dew point and average temp of 88-90.

My 12 year old, falling apart Rheem maintains inside RH at 40%, but I haven't seen any new equipment that claims to be able to match or beat that.

90°F drybulb with a dew point of 80°F is less then 73%RH.

[dan sw fl]

Central and South FL is typically > 90% R.H. from 3 AM to about 9 AM.

90% R.H. ..=.. Dew Point is 2'F less than Dry Bulb.

Obviously, opening windows in early morning is NOT an Optimum cooling option for nearly 5 months.

[motoguy128]

77'F @33% R.H.

How do you get L.A.T. < 47'F?
_ When is the last time your hygrometer was calibrated?

http://www.thermalinc.com/math/wetbulbcalc.htm

The humidity sensor in my thermostat agrees. Based on comfort, I also agree. If the humidity were higher, 77F would feel too warm.

THe supply temp isn't 47. I haven't checked it recently, but it's probably in the low 50's. I run the airflow a little low and the ductwork is close to sweating with a dewpoint around 50F in the basement. Airflow is probably around 1200CFM on a 3.5 ton system, so around 350CFM/ton. When I use DoD, that drops about another 100CFM. So about But it does have a TXV and I believe part of the coil surface is getting that cool. Further, the supply temp on my upstairs Infinity probably is under 50F. With revserse stack effect, the upstairs does most of the dehumidification.

[Florida Joy]

Sure you can in 2 ways. 1) 40% RH @ 75F is great, 33%RH @ 77F is even better in terms of energy savings but is equally comfortable. 2) if hte sytme cna reach 40% RH sooner, then more capacity will go into sensible cooling than latent. A smaller coil with the same load, will drain sooner and more water than a larger one.

Right now my house is at 43%RH @ 74F upstairs and 33%RH $77F downstairs. Both are comfortable, but downstairs has lower proportional heat loss. Which is good since it's 10 SEER and oversized.

You're in Iowa? How far is that from the Atlantic Ocean and what's the average RH and dew point outside your house in June, July and August? In my neighborhood the average RH is 90% with an 80 degree dew point and average temp of 88-90.

My 12 year old, falling apart Rheem maintains inside RH at 40%, but I haven't seen any new equipment that claims to be able to match or beat that.

Just for kicks, I looked at the forecast for today's weather in Des Moines, Iowa. The outside RH today will range from a low of 25% to a high of 41%. Compare that to the outside RH for today at my place in Florida.... between 75% and 85%.

It sounds like opening the windows in Iowa would do as well as A/C in maintaining comfort... and with fresher air!

[motoguy128]

That's only because we're in drought conditions. IN a normal summer we regualrly get 70F+ dewpoints. But it doesn't sustain year round like in FLorida. Yesterday the dewpoint was around 40F but it reached 98F. IT made it over 100F ambient at least 6 ro 7 days this summer. I'm in SE Iowa, my design consditions for temperature and humidty are nearly the same as for most of Florida. It just doesn't stay hot here, but we also have something called winter. The dewpoint thsi weekend is expected to jump up to 70F this weekend and some possible thunderstorm (finally!) come through.

I don't open windows in my home very often because of dust, noise and it's a PITA. I have 39 operable windows with storm windows, so even opening 1/4 of them takes a little time since I have to open 2 sashes on each one. W'ere not hoem to close them at the ideal time of around 10-11AM either. I just assume leave them closed and pay an extra $10-20 on my electric bill.

Besides, if you look closer, the dewpoint raises overnight as the ground and plants cool off. It will get up to 70% RH or a dewpoint around 58F, which is much higher than it is inside my house. It's around 47-51F dewpoint.

Don't underestimate the climate in the central midwest. It's much hotter and more humid than most eople give it credit for... but it only lasts for 3-4 months, then it turns wicked cold and that white flaky stuff falls from the sky.

[motoguy128]

But yes, right now with the dry conditions, many in Iowa are not using AC. Although it's suposed to be in the mid to upper 90's again today.

WHen I say dry, maybe some in Florida might not understand what that means. We've had about 1" of rain TOTAL in the last 8-10 weeks. It will take 10-12" just to lift the burning bans.

Compare that to a normal summer period where we average 1" of rain per week. And 2008 I think we got something rediculous like 20" in June alone. LAst June we got at least 10". This barely 2".

[Florida Joy]

Don't underestimate the climate in the central midwest. It's much hotter and more humid than most eople give it credit for... but it only lasts for 3-4 months, then it turns wicked cold and that white flaky stuff falls from the sky.

That white flaky stuff is what'll keep me in Florida now that I'm retired! LOL

BTW, my part of Florida is currently in a drought with burn bans related to a severe rainfall deficit for year to date, thus the readings I gave for today reflect lower outdoor humidity than during a "normal" 6+ month summer season.