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Old 08-22-2019, 10:36 AM   #1
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Updating a raised ranch w/ single zone forced air


I have a 30 year old raised ranch. It has a forced air setup w/ central a/c, all on a single zone.


The upper level has floor registers in each room, with every room also having a return register.



The lower level has two 8" ceiling registers in the main area and a 6" ceiling register in a 10x10 bathroom/laundry room. There is a return in the ceiling of the main area.



There are also two 8" ceiling registers in the built in garage (same level as the lower level).


The setup is adequate, but it's difficult to get all areas comfortable -- the lower level is always 10*F colder than the upper level. In the summer it seems like a waste of air conditioned air, in the winter, it's difficult to get the lower level warm enough to be comfortable.


I'm having the entire system replaced soon, I have three contractors coming to quote, but I want to be able to understand my options so that I can make the most of the time.


What options do I have for splitting my upper and lower levels into zones?



I'm not opposed to opening the ceilings to install dampers for the lower level as I think the 3 registers there are likely individual branch runs from a main trunk. In the garage I'm not so sure, but being only two registers I'm hoping there is some option besides simply closing the register.


I'm also not opposed to hearing "this is not going to be worth it", and then adding some electric heat strips to the lower level to bring up the warmth down there in the winter, and then just accepting the fact that it's an ice box in the summer :D
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Old 08-22-2019, 12:05 PM   #2
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Re: Updating a raised ranch w/ single zone forced air


I don't think you need zoning, I think you need some duct modifications to get more supply air heating the main floor. They should have dampers so you can do seasonal balancing.

You also need low level return so the heat doesn't just rise up to the ceiling.

Zoning can be a patch and can cause more problems than it solves if not done by a really good contractor.

The ducts have to be re-done from scratch and at a minimum 2-stage equipment used for good performance when one zone is calling.

Without zoning you should be able to get away with just tweaking the existing duct system.
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Old 08-22-2019, 12:43 PM   #3
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Re: Updating a raised ranch w/ single zone forced air


Is a vent in a garage allowed anywhere"
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Old 08-22-2019, 12:46 PM   #4
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Re: Updating a raised ranch w/ single zone forced air


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Is a vent in a garage allowed anywhere"
Good point.

No!
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Old 08-22-2019, 01:02 PM   #5
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Is a vent in a garage allowed anywhere
Not anywhere under the IRC.

Quote:
R309.1.1 Duct penetration.
Ducts in the garage and ducts penetrating the walls or ceilings separating the dwelling from the garage shall be constructed of a minimum No. 26 gage (0.48 mm) sheet steel or other approved material and shall have no openings into the garage.
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Old 08-22-2019, 01:20 PM   #6
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Originally Posted by Nealtw View Post
Is a vent in a garage allowed anywhere"

I assume it was allowed back in 1989 when the building was constructed -- so the question then becomes, does it have to be removed when replacing the air handling / furnace or is it permitted to stay as part of a replacement.


I didn't explicitly state it, but there is no return in the garage, only supply.


Personally I close the registers in the garage during all but the coldest months to avoid pumping conditioned air into that space. For the coldest months my main concern is that there is plumbing in the walls/ceiling between the garage and house, including a 4' x 2' drywalled bump out (into the garage area) that I believe is a chase for the main sewer stack (and possibly a few supply pipes).



If I were to remove the garage supply vents -- which keep it about 20*F below the interior temp of the house during winter -- I feel like some other method to introduce at least minimal heat to that space is a must, otherwise if it's allowed to drop to hard freeze temps I may be risking plumbing freeze ups (not to mention it's likely to make the bedrooms above less comfortable).
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Old 08-22-2019, 01:25 PM   #7
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Originally Posted by bubbler View Post
I assume it was allowed back in 1989 when the building was constructed -- so the question then becomes, does it have to be removed when replacing the air handling / furnace or is it permitted to stay as part of a replacement.


I didn't explicitly state it, but there is no return in the garage, only supply.


Personally I close the registers in the garage during all but the coldest months to avoid pumping conditioned air into that space. For the coldest months my main concern is that there is plumbing in the walls/ceiling between the garage and house, including a 4' x 2' drywalled bump out (into the garage area) that I believe is a chase for the main sewer stack (and possibly a few supply pipes).



If I were to remove the garage supply vents -- which keep it about 20*F below the interior temp of the house during winter -- I feel like some other method to introduce at least minimal heat to that space is a must, otherwise if it's allowed to drop to hard freeze temps I may be risking plumbing freeze ups (not to mention it's likely to make the bedrooms above less comfortable).
We do everything we can to seal the garage so auto off gasses can not get into the house. Even when the furnace is installed in the garage, it gets it's own room with an exterior sealed door.



When the furnace is not running and the bathroom fan is running where is the air coming from?



Install a baseboard heater for those real cold days.
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Old 08-22-2019, 01:37 PM   #8
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Re: Updating a raised ranch w/ single zone forced air


Id remove the vents.
Anytime the house pressure is less than garage air pressure (furnace not running), you are going to have air flow into the garage vents and out the house vents.

Its a good way to get noxious fumes, CO, CO2, smoke, etc, into your house.
In extreme cases, it could be fatal.
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Old 08-22-2019, 02:01 PM   #9
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Originally Posted by Nealtw
When the furnace is not running and the bathroom fan is running where is the air coming from?

One of the other things we're considering while we're replacing the system is the domestic hot water -- when the dryer is running the WH is not drafting correctly -- so along w/ the HVAC I'm planning to either power vent the existing tank WH or just replace it w/ tankless that has a dedicated combustion intake from outside.


Quote:
Originally Posted by Oso954 View Post
I’d remove the vents.
...
In extreme cases, it could be fatal.
Yeah, I've been debating it, but I probably will remove them regardless of whether they're allowed in an update... I'll look at some options for maintaining the garage at ~50F by electric.


...


I love having a garage, but hate that it's under our bedrooms... I already park the car in the driveway most nights unless hail or snow is possible.


...I've had panic moments some evenings where I realize I'm laying on my keys in the living room and worry that I just triggered the remote start for the car while it's in the garage directly under my infant son's bedroom.
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Last edited by bubbler; 08-22-2019 at 02:02 PM. Reason: huge typo
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Old 08-22-2019, 02:10 PM   #10
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Originally Posted by bubbler View Post
One of the other things we're considering while we're replacing the system is the domestic hot water -- when the dryer is running the WH is not drafting correctly -- so along w/ the HVAC I'm planning to either power vent the existing tank WH or just replace it w/ tankless that has a dedicated combustion intake from outside.




Yeah, I've been debating it, but I probably will remove them regardless of whether they're allowed in an update... I'll look at some options for maintaining the garage at ~50F by electric.


...


I love having a garage, but hate that it's under our bedrooms... I already park the car in the driveway most nights unless hail or snow is possible.


...I've had panic moments some evenings where I realize I'm laying on my keys in the living room and worry that I just triggered the remote start for the car while it's in the garage directly under my infant son's bedroom.
All our furnace areas get fresh air intake here, but now with the H E furnaces you will have that anyway. I think,
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Old 08-22-2019, 02:25 PM   #11
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Re: Updating a raised ranch w/ single zone forced air


Nealtw,


The furnace will have an outside intake for combustion air -- I had one installed in my last house, two PVC pipes outside, one for input air and one for output. I imagine if I have the tankless WH installed there will be 4 of these pipes outside.


I doubt a replacement system would have a method to bring in fresh air to mix w/ the conditioned air, the house probably isn't "tight" enough to require it and I'd imagine it's a bit of a bear to accomplish withe retrofits -- there's only so much exterior wall space in the 8x8 HVAC room to be making penetrations for the A/C pipes, plus the A/C electric, plus the four PVC pipes for the combustion air...
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Old 08-22-2019, 02:30 PM   #12
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Re: Updating a raised ranch w/ single zone forced air


Quote:
Originally Posted by bubbler View Post
Nealtw,


The furnace will have an outside intake for combustion air -- I had one installed in my last house, two PVC pipes outside, one for input air and one for output. I imagine if I have the tankless WH installed there will be 4 of these pipes outside.


I doubt a replacement system would have a method to bring in fresh air to mix w/ the conditioned air, the house probably isn't "tight" enough to require it and I'd imagine it's a bit of a bear to accomplish withe retrofits -- there's only so much exterior wall space in the 8x8 HVAC room to be making penetrations for the A/C pipes, plus the A/C electric, plus the four PVC pipes for the combustion air...
If your dryer is spoiling draft at the tank, you need air.
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