I have not had a manual J done. However, based on the past 10 years experi ence with a 4 ton A/C system, I've been able to keep the humidity down and be cool during the summer here in central Florida. However, there are usua lly a few times during the summer - when it is extremely hot outside and/or we have many guests - oven on all day - people coming in and out, etc. whe re we have not been able to get the temperature below 79 or 80. These days , I swore I would get a 5 ton unit when it was time to replace it. But now I am having second thoughts because I am more concerned with short cycling and having higher humidity.
One installer said this is not a big concern, because a 5 ton, dual stage c ompressor with variable speed air handler would work at a reduced rating to help keep humidity low and would only boost up to full capacity when it wa s needed during those few times a year. And he also mentioned being able t o control humidity with the thermostat.
on the past 10 years experience with a 4 ton A/C system, I've been able to keep the humidity down and be cool during the summer here in central Florida. However, there are usually a few times during the summer - when it is extremely hot outside and/or we have many guests - oven on all day - people coming in and out, etc. where we have not been able to get the temperature below 79 or 80. These days, I swore I would get a 5 ton unit when it was time to replace it. But now I am having second thoughts because I am more concerned with short cycling and having higher humidity.
because a 5 ton, dual stage compressor with variable speed air handler would work at a reduced rating to help keep humidity low and would only boost up to full capacity when it was needed during those few times a year. And he also mentioned being able to control humidity with the thermostat.
Your mother and I both love you very much.
She and I both notice you did not ask any questions, which is fine.
The OP says he is having second thoughts about getting 5 tons versus 4, despite an installer opinion that dual-stage compressor should not short cycle.
How explicit does the OP need to be here?
His question is obvious: Is the installer correct?
Why do old timers here find it neccesary to jerk people's chains?? Why not just HELP the OP?
Funny -I'm an old timer myself. I've probably been on the newsgroups, and v arious bbs, longer than most here - since 1987. Not specifically al.hvac, but alt.home.repair. I have noticed people are a lot less helpful and a bi g increase in trolls.
But anyway, I actually posted, and then deleted this post because an instal ler came back with the Manual J calculations for my home. He actually meas ured all the windows and doors to get accurate inputs. From the calculatio n, it shows I need a 4.8 ton for max cooling (92 F outside, 75 F inside).
Hi, If you over size the system, it'll short cycle and that'll lower system efficiency as well. Better talk to trust worthy expert installer. I am OT too. Fortunately I retired from Honeywell, I can draw from guys still working there regarding matters like this, LOL!
I too am an old timer, using Darpanet at my work many decades ago, and running a BBS with my son in the early 80's.
The alt.hvac newsgroup in particular has a history of snarky and obnoxious non-helpful trolls even dating back 10-15 years. Sadly some other groups seem to be slowly sinking into a cesspool as well, with the home repair group suffering the impact of some really shit-filled traffic originated by only a few but sustained by active feeding.
The reply to the original post which pathetically tried to be clever and taunt you from the religious storming fellow near Palmyra NY is an utterly inconsiderate piece of ironic conceit. Sad because he's a very knowledgable and supposedly pro hominem devout person, yet his jerky answers betray him time after time.
BTW, I have 4 tons dual stage in an 1800 sq ft ranch in the Northeast. No short-cycle issue here and fast cool down is a real plus.
Not everybody agrees but I would say your system is sized about right. On the worst day it won't quite keep up but the rest of the time it does fine. If you size it for the worst day it will short cycle in milder temperature.
It is possible newer systems with variable output can compensate, I don't know enough about using them in residential. We have only commercial at work, and older systems in our residential.
There might be some reasons to lean either over or under "calculated" size.
Some years ago I figured I didn't need no expert to install a mini split AC. So I started by diligently following the sizing guide I found on a Consumer Reports web site. I forget the size that it came up with after taking the type of construction, number/type of windows, sun facing, my area of the country, insulation type/quantity, room use, etc..
spent a few hours dicking with the silly thing, only to come up with a number that seemed totally too large based on the results I saw with my relatively new (undersized) window unit.
Knowing from the get-go that smaller means more efficient I opted for the same capacity as the window unit figuring that for the 10-15 days a year that I might be too warm it was a reasonable trade-off.
I have never in the last 5 years had a too warm condition. Not one day did I regret my decision. The mini-split AC lowered my electric bill significantly.
What the mini split seems to do is get rid of moisture lickety-split, compared to the window unit... Where I was setting the window unit to
68 to have ~72 in the room I can set the mini split to 80 after its been running awhile, and stay very comfortable. Likewise the water dribbling out the drain could water my garden - something that the window unit with its water-slinger fan design wouldn't do.
Does that sound reasonable to an expert?
When you do these calculations do you take into account the moisture removal rates of various systems? The CR site that I got for doing calculations didn't say anything about humidity removal.
I live in coastal NC and chose the heat pump version which comes with a slightly larger (and supposedly more-better moisture removal) evaporator (inside the house gizmo) for the same size compressor.condenser that the same capacity AC only uses.
And BTW I would have used an expert to do the installation, I wasn't trying to do it on the cheap (the hardware already cost plenty so I'd rather have had a pro do it for the peace of mind) but back then the local boys didn't want to touch mini-split at all, and had nothing but derogatory things to say about it. I notice that that has changed today.
My wife is going to ditch the fuel oil heating system and window AC units (at her house) for a mini-split multi zone system that will be installed by a pro.
I've been reading alt.hvac for many years, Stormin Mormon has been one of a handful that actually provide answers to homeowners or lay people. A few years ago I had a spiel I forget now, about hvac techs lack of self confidence and having to keep what they know to themselves, just so they could feel good they now something the poster doesn't. Anyway Stormin wasn't one of those, maybe he's having a bad day, or just being cute. Mikek
"Just being cute" is exactly why I barked. Stormin may indeed "actually provide answers to homeowners or lay people" just as you say, but in this and some other cases I see the exact opposite.
I am not a particularly religious person, but the Bible's Golden Rule of 'Do Unto Others as You Would Have Them Do Unto You' strongly suggests, even to me, that you treat strsngers / homeowners / lay people with respect. Someone like Stormin who self-advertizes his Jesus connection with EVERY post in his signature should walk the walk rather than just talk the talk.
The only reason you were here was to publicize Your religious beliefs and received adverse treatment from the pro's accordingly. Nothing that you did not ask for.
He is a handyman. Even did locks and other odd jobs. Never married. A bit overweight. Not very knowledgeable on his own professed religion. He did take a lot of heat from the professionals when everyone was still here,\.
I take it that you are too damned lazy to form your own NG. What are you going to do if we remove this one? Obviously we no longer need it..and the Webpage will be dead also in the near future. If you need some of those APPS...you better get them now. Paul Milligan is dead and no one wants to maintain his page.
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