educate me so I can replace my system?

I have a 2800sq ft house with a 4-ton 18-yr old York system with the air-handler and ductwork in the -attic-. It's getting near the end of its useful life and I'm interested in replacing it. What I hope you can help me with is what I should be asking the contractors who are bidding on the job - in terms of system features (obviously you can't size it here). The two contractors I've selected have top-notch local reputations (one did the last installation and the system has run flawlessly)

My priorities are:


a) reliability - I'm happy to give up a bit of efficiency for fewer gadgets. I just don't want it to ever break.

b) I understand (please help me here) that the new systems are variable speed? I think it would be great to have a system that worked like a 5-ton for the 95Deg 95% humidity days, but worked like a 3-ton for the 70s-deg humid days (where my system often cools way before it's dehumidified) - what should I be asking for?

c) I have a spacegard filter which I hope to transfer to the new system, and as a result run the fan 24/7 (it -does- make a difference) - any features I should ask for to support this sort of operation?

As far as load calculation - do I need a detailed one, or can I work from the point of view that the existing 4-ton system did a reasonable job for most of its life.

Any other features I should make sure are part of the package?

Thanks very much
/j

Just print out your post and give it to the contractors,they shouldn't have any problem discussing your wants.

If one of them has a system that won't ever break,let me know what it is.

http://www.johnmills.net/work/advice.html

read, I'm to tired to type it here

a. Not realistic,get a ten year parts and labor,mfrs. extended warraty,for peace of mind.

b.What you are talking about is a two speed compressor,variable speed fan and a great control system,like Carrier Infinity.Exactly the gadgets,though very dependable,that you stated you didn't want.


c.To run the fan 24/7,you need those gadgets again,things like shuts down the fan after cooling cycle to let water drain,VS fan,and ability to select hi,med,low fan in the off cycle.

If the systemed cooled on the hot days ,it's not undersized,but it could be oversized,any improvements to insulation,doors ,windows,etc.,it's very likely too large.


Safest thing is to have the load calc. done.

I have no problem with 'dependable' gadgets. I read the link you pointed to me to, didn't seem on point.

I run the fan 24/7 now - no big deal. Maybe what i need to learn about are those' gadgets' you're referring to so I can ask for the right ones.

THe system cooled on hot days, could have done better on the hottest ones.

The contractor I have coming suggested a system with SEER 13 is that in the right ballpark?

dash - your advice in b) and c) is right on target - any other things to make sure i get or don't get?

/thanks
/j

Quote:

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Originally posted by jeffw_00
I

My priorities are:


a) reliability - I'm happy to give up a bit of efficiency for fewer gadgets. I just don't want it to ever break.

b) I understand (please help me here) that the new systems are variable speed? I think it would be great to have a system that worked like a 5-ton for the 95Deg 95% humidity days, but worked like a 3-ton for the 70s-deg humid days (where my system often cools way before it's dehumidified) - what should I be asking for?
Any other features I should make sure are part of the package?

---

For real humidity control during cool humid weather, consider a whole house dehumidifier. When it's 70-75^F outside, a two speed will remove a little more moisture but not provide <50%RH like a dehumidifier does. The two speed systems are expensive and complicated. They require a skilled, specifically trained tech for installation and service. For the price of the two speed a/c, a simple high SEER a/c and a whole house dehumidifier is available. The simple combo can provide any desired temperature and %RH regardless the weather. This allows for <50%RH without any a/c operation. If humidity control is promised, get it in writing. Maintaining low humidity is important for comfort, mold and dust mite control.

Thanks - on one hand - the humidify problem isn't that frequent or severe that I really need the separate dehumidifer solution, on the other hand - you raise an interesting point.

I got the idea anecdotally that 2-speed systems were, like, the norm today. If they're only in the riskier high-end, maybe I'll just go with a single speed replacement?

/thanks
/j

Quote:

---

Originally posted by jeffw_00
I have no problem with 'dependable' gadgets. I read the link you pointed to me to, didn't seem on point.


If that page didn't seem on point then I sure feel sorry for any qouting contractors.


/j

---

no, no - it was relevant - but my specific question of 'what to ask for, what to avoid" wasn't really addressed there.

Sometimes this board gets rather flippant, don't you think 8-}

I've tried to do my basic homework, but I don't live in the HVAC world, a few pointers in the 'what to make sure you get, what to not let them sell you" was really what I'm looking for.

Thanks!
/j

13-17 seer.

Variable speed blower.

Honeywell "vision pro" t-stat.

10 year parts and labor warranty.

Consider R-410 instead of R-22. (get quotes both ways)

Thanks Miami Mike, this is great stuff

1) Variable speed blower - does this mean the system (or the stat) controls the speed (my current system has a 3 speed blower, I can set the system-off fan speed to low or medium, it's always high when the compressor is running)

2) what is the difference between R-410 and R-22 (i assume these are refrigerants)

thanks! i'm learning
/j

the infinity r-410 two phase condenser a variable speed air handler with a humidistat installed along with the thermostat. york has a nice line of equipment

yes, my current unit is a York - never had a day of trouble with it. So R-410 and R-22 are different York Infinity condensers?

ok