Central Air Replacement Advice?

[DeerSlayer 241]

I'm in a similar situation, so rather than starting a new thread I'm building on this one. Im looking at a 4 bedroom colonial without central a/c and baseboard heat. It's approximately 1800 square feet. If I do split units, how do i cool 4 bedrooms, the hallway, hallway bathroom, and downstairs? Basement is unfinished, but I might finish it down the line.  The other questions; is it feasible to run ductwork, and how will the cost compare to split units? 

You don't cool the hallway or the bathroom, you leave the doors open and the air will migrate in those rooms. If you want to do a ducted system you put everything up in the attic, and drop registers from the ceiling in each room. The return goes in the hallway ceiling. Downstairs is always tricky. Usually you have to sacrifice a closet for a trunk. Or you can do mini splits in the downstairs.

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[Krdshrk 3,877]

Could he run the ductwork for the AC in the basement for the 1st floor?  I know the registers for my new house are in the floor.

Or would that require a 2nd AC Unit?

[Zeke 5,504]

Unico also an option.$$$

 

[ChrisJM981 924]

5 hours ago, DeerSlayer said:

You don't cool the hallway or the bathroom, you leave the doors open and the air will migrate in those rooms. If you want to do a ducted system you put everything up in the attic, and drop registers from the ceiling in each room. The return goes in the hallway ceiling. Downstairs is always tricky. Usually you have to sacrifice a closet for a trunk. Or you can do mini splits in the downstairs.

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That makes sense. Do I need to put an attic fan with a thermostat to keep the ac unit cool? Just asking since I know it gets super hot in attics during the summer. 

[Zeke 5,504]

5 minutes ago, ChrisJM981 said:

That makes sense. Do I need to put an attic fan with a thermostat to keep the ac unit cool? Just asking since I know it gets super hot in attics during the summer. 

attic fans don't hurt. Look int Remington solar units. Need air flow / vents etc.

consider your attic a broiler. Some can get hot enough to poach a chicken. That heat is radiating down, also.

[DeerSlayer 241]

Could he run the ductwork for the AC in the basement for the 1st floor?  I know the registers for my new house are in the floor.

Or would that require a 2nd AC Unit?

Yes then 2 systems would be needed, that's common as well. As long as the basement wasn't finished it can be done. And he doesn't mind spending double.

 

 

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That makes sense. Do I need to put an attic fan with a thermostat to keep the ac unit cool? Just asking since I know it gets super hot in attics during the summer. 

No we insulate all the ductwork in the attic, and the air handler is insulated from the factory, for just that reason.

 

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[DeerSlayer 241]

attic fans don't hurt. Look int Remington solar units. Need air flow / vents etc. consider your attic a broiler. Some can get hot enough to poach a chicken. That heat is radiating down, also.

 

Heat rises, and if the attic has a Ridge vent or gable vents, with vented soffits there's no need for an attic fan these days. The attic floor itself should also be insulated. Attic fans are great for houses without central air. They're a waste of electricity if you do have central.

 

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[DeerSlayer 241]

Unico also an option.$$$

 

If he didn't already have baseboard heat, it would be a good option. They do both heat, and air with high velocity ductwork. There's a hydronic coil in them, you run one zone of heat to the coil from the boiler. Those systems are expensive, and are prone to breakdowns though. They do work well when you're not waiting 2 months for a replacement computer board. Out of all of them the Space pack is probably the best and most reliable. But it's also the most expensive. Personally I hate working on them. It's always electronics that fail, damper motors, fans, boards ect. I'm not a fan...

 

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[Zeke 5,504]

22 minutes ago, DeerSlayer said:

Heat rises, and if the attic has a Ridge vent or gable vents, with vented soffits there's no need for an attic fan these days. The attic floor itself should also be insulated. Attic fans are great for houses without central air. They're a waste of electricity if you do have central.

 

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Solar  with a plug in option.

dropped atic temps 30 -40.

next is insulation, but that job sucks!

 

heat does rise. But how much escape are you getting out of 4" of ridge vent obstructed by rafters and vent material.

[DeerSlayer 241]

Solar  with a plug in option.
dropped atic temps 30 -40.
next is insulation, but that job sucks!
 
heat does rise. But how much escape are you getting out of 4" of ridge vent obstructed by rafters and vent material.

A lot of air moves through that Ridge vent if there are baffles installed down to the soffit. That's part of the install method for a Ridge vent. If insulation is blocking the soffit vents then they don't do shit.

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[Zeke 5,504]

9 minutes ago, DeerSlayer said:

A lot of air moves through that Ridge vent if there are baffles installed down to the soffit. That's part of the install method for a Ridge vent. If insulation is blocking the soffit vents then they don't do shit.

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How many cfm is " a lot"?

my attic fan is rated at 1550 cfm . 

I would argue that is more than normal convection 

[DeerSlayer 241]

If you have central air, and your attic is insulated properly, as well as your ductwork (which is code), then an attic fan, really isn't doing much of anything useful. I will say they're nice when I have to go upstairs into an attic, in the middle of summer to fix a broken AC system...

 

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[DeerSlayer 241]

How many cfm is " a lot"?

my attic fan is rated at 1550 cfm . 

I would argue that is more than normal convection 

It works like a chimney would. Just a constant draft from negative to positive pressure. If you don't have proper ventilation in the attic like soffits, baffles, gable vents, Ridge vent ect... then yes an attic fan is a must have.

 

How many cfm does a properly installed cobra vent move? The answer is enough.

 

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[HBecwithFn7 296]

8 minutes ago, DeerSlayer said:

A lot of air moves through that Ridge vent if there are baffles installed down to the soffit. That's part of the install method for a Ridge vent. If insulation is blocking the soffit vents then they don't do shit.

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Hey, long time no type!  Perhaps you can help with a dilemma I may soon face.

My central unit in FL was installed in 2008, but the compressor was refurbished in 2011... both long before I bought the place in Sept. of 2015.   I don't know if that's "old" or not.  I do, however, believe the expansion coil and blower are original equipment (from when the house was built in 2003). 

Problem: I've had to get the system recharged every 6 mos.  I've been told that there's a leak somewhere in the coil.  About $1,100.00 to replace the coil (which I hope includes pressure testing the lines).  This is an HVAC with Heat Pump unit.  And  one simply cannot live in FL without decent HVAC. 

That said, I have a decision to make.  I have a screened porch on the back of the house (part of the main slab on grade) with which I do absolutely nothing. It's just there for "storage" right now. Storage of things that aren't climate sensitive. I don't go outdoors while on the property unless it's for lawn maintenance, etc. Eventually, I might want to enclose this porch and turn it into a great room, under HVAC.  Anticipating this, I've put off replacing the coil, until I decide whether or not I want to replace the entire system with something new, and maybe upgrade the compressor by half a ton to accommodate the new enclosed space (it's a 3 Ton at present, covering 1130 Sq Ft. internally, not including the garage).  For now, it's just cheaper for me to recharge the system every 6 months, until I make a decision (I'll PM you shortly on the details).

Just curious as to your thoughts.  Would be worth doing the HVAC upgrades in advance/anticipation of the enclosure work?  Are there easier/cheaper ways of enclosing the screen porch and making it HVAC'able  without a full enclosure (i.e. block/stucco walls)?  Said full enclosure would increase the Sq. footage of the floor plan and, of course, the "assessed valuation" for tax purposes (but down here, that's not a huge priority).  

 

Thoughts?

 

 

[Howard 538]

Attic fans are great, or they are terrible.  I mean that 100%.  The problem with most attic fan installations is they end up pulling conditioned air out of your home and venting it out the roof.  If you go in your attic and pull back insulation you will see lots of penetrations in most houses from wiring, duct work, plumbing stacks and often just gaps in Sheetrock.  If you run an attic fan in a house like that it will pull air from all those openings.  I had a foot of loose fiberglass blown into my attic on top of the existing fiberglass bats.  Before I did that I pulled up all the batting and caulked around every single penetration and totally sealed the attic from the house below.  Now the attic fans with correct baffles does a great job of keeping the attic cooler without sucking out conditioned air.

[ChrisJM981 924]

1 hour ago, DeerSlayer said:

Yes then 2 systems would be needed, that's common as well. As long as the basement wasn't finished it can be done. And he doesn't mind spending double.

 

 

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No we insulate all the ductwork in the attic, and the air handler is insulated from the factory, for just that reason.

 

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Basement isn't finished, and I haven't looked into cost yet. An attic setup will most likely be how I do the second floor. If it's cost prohibitive then split units it is for the first. We're submitting our offer today, so I'll see how that goes before I get too involved. I am going to need recommendations for a home inspector though. That might be a seperate thread. 

[DeerSlayer 241]

Basement isn't finished, and I haven't looked into cost yet. An attic setup will most likely be how I do the second floor. If it's cost prohibitive then split units it is for the first. We're submitting our offer today, so I'll see how that goes before I get too involved. I am going to need recommendations for a home inspector though. That might be a seperate thread. 

I know a great guy for that. Let me know when you want his contact info.

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[DeerSlayer 241]

Hey, long time no type!  Perhaps you can help with a dilemma I may soon face.
My central unit in FL was installed in 2008, but the compressor was refurbished in 2011... both long before I bought the place in Sept. of 2015.   I don't know if that's "old" or not.  I do, however, believe the expansion coil and blower are original equipment (from when the house was built in 2003). 
Problem: I've had to get the system recharged every 6 mos.  I've been told that there's a leak somewhere in the coil.  About $1,100.00 to replace the coil (which I hope includes pressure testing the lines).  This is an HVAC with Heat Pump unit.  And  one simply cannot live in FL without decent HVAC. 
That said, I have a decision to make.  I have a screened porch on the back of the house (part of the main slab on grade) with which I do absolutely nothing. It's just there for "storage" right now. Storage of things that aren't climate sensitive. I don't go outdoors while on the property unless it's for lawn maintenance, etc. Eventually, I might want to enclose this porch and turn it into a great room, under HVAC.  Anticipating this, I've put off replacing the coil, until I decide whether or not I want to replace the entire system with something new, and maybe upgrade the compressor by half a ton to accommodate the new enclosed space (it's a 3 Ton at present, covering 1130 Sq Ft. internally, not including the garage).  For now, it's just cheaper for me to recharge the system every 6 months, until I make a decision (I'll PM you shortly on the details).
Just curious as to your thoughts.  Would be worth doing the HVAC upgrades in advance/anticipation of the enclosure work?  Are there easier/cheaper ways of enclosing the screen porch and making it HVAC'able  without a full enclosure (i.e. block/stucco walls)?  Said full enclosure would increase the Sq. footage of the floor plan and, of course, the "assessed valuation" for tax purposes (but down here, that's not a huge priority).  
 
Thoughts?
 
 

Sizing in Florida is very different than how we size. We go approximately 1 ton per 500sq foot here. Down there they usually go larger. If the A coil is the only thing leaking I would just replace it. And have the lineset pressure tested as well. Which is something we all do when changing a coil. You can't just jam a larger ton condenser and coil into an existing system that's sized for 3 tons. You're ductwork may not be large enough for the additional tonage. And the additional room isn't included in your ductwork sizing. Chances are everything would need to be made larger to work. Or you could just add one minisplit to the sun room and not have to worry about the rest. Would be my advice.

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[HBecwithFn7 296]

1 hour ago, DeerSlayer said:

Sizing in Florida is very different than how we size. We go approximately 1 ton per 500sq foot here. Down there they usually go larger. If the A coil is the only thing leaking I would just replace it. And have the lineset pressure tested as well. Which is something we all do when changing a coil. You can't just jam a larger ton condenser and coil into an existing system that's sized for 3 tons. You're ductwork may not be large enough for the additional tonage. And the additional room isn't included in your ductwork sizing. Chances are everything would need to be made larger to work. Or you could just add one minisplit to the sun room and not have to worry about the rest. Would be my advice.

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Thanks!  I kinda like the mini-split idea. There are a number of different options there.

[DeerSlayer 241]

Thanks!  I kinda like the mini-split idea. There are a number of different options there.

It's nice because that room is then zoned separate. You don't have to use it, unless you're out there, and they're supper efficient. You can get one with like a 34SEER rating.

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[HBecwithFn7 296]

Just now, DeerSlayer said:

It's nice because that room is then zoned separate. You don't have to use it, unless you're out there, and they're supper efficient. You can get one with like a 34SEER rating.

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Well, if I go with the full blown enclosure project and erect block/stucco walls like the rest of the house (i.e. surround the slab with them) and put new roofing (and insulation) over it, it will be my new "great room" where my office desk etc. will be, as well as some other storage. So It will probably need the same constant ambient temp. as the main house.  Still, Perhaps I can cut back a little in the main house while I'm in there.   There's also a window that leads to the master bedroom that I might open fully as an access way (and put a security door there). The possibilities are endless, at this point.  

[Krdshrk 3,877]

Looks like the home builder put in 2x RHEEM RA1330AJINA 2 1/2 Ton, 13 SEER, 410 Refrigerant AC Units.

Not sure how good they are but hopefully they're decent...

[fapipa 3]

On 6/17/2017 at 2:24 PM, HBecwithFn7 said:

Thanks!  I kinda like the mini-split idea. There are a number of different options there.

It can also serve as a backup for when the primary AC inevitably breaks down, usually at the most inopportune time.

[DeerSlayer 241]

Looks like the home builder put in 2x RHEEM RA1330AJINA 2 1/2 Ton, 13 SEER, 410 Refrigerant AC Units.

Not sure how good they are but hopefully they're decent...

Should be fine for about 12-15 years, if you have them professionally serviced annually.

 

If I were you, I would use stone around the pads instead of dirt. When it rains the mud will splash onto the coils. And inhibit air flow.

 

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[Krdshrk 3,877]

53 minutes ago, DeerSlayer said:

Should be fine for about 12-15 years, if you have them professionally serviced annually.

If I were you, I would use stone around the pads instead of dirt. When it rains the mud will splash onto the coils. And inhibit air flow.

 

I'll lay down some stone after closing.

 

[checko 180]

Should be fine for about 12-15 years, if you have them professionally serviced annually.
 
If I were you, I would use stone around the pads instead of dirt. When it rains the mud will splash onto the coils. And inhibit air flow.
 
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Do you do work in warren county? Me and my gf were looking to get quotes done

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[DeerSlayer 241]

Do you do work in warren county? Me and my gf were looking to get quotes done

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Yep

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[checko 180]

Sweet ill pm you when were ready.

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