HVAC (heating and AC) question

[Galitzyaner]

it's for combustion air, and yes the room needs to either, be a certain size, or be connected via vents to a room that is big enough, or have a vent to outside to bring fresh air in (it may not have to be hooked up directly to the furnace)

Is the return air (see top image, lower right of furnace) venting to a large room good enough?
Or does the whole machine (i.e. where that "fresh air inlet" is) need to be in the "large" room?

My concern is back drafting, a natural draft flue is bad in a tight house. A power vent is better (which i think this system has, and direct vent is best.

I don't think it has a power vent. Unless this is something that only turns on when the heat is running?

Thanks for your input!

[CountValentine]

Where is the furnace located? How big is the room?
This has a whole section on ventilation.
https://resource.gemaire.com/is/content/Watscocom/Gemaire/rheem_r801ca_en_ii.pdf

[notyettaken]

Where is the furnace located? How big is the room?
This has a whole section on ventilation.
https://resource.gemaire.com/is/content/Watscocom/Gemaire/rheem_r801ca_en_ii.pdf

see page 14-16.

Is the return air (see top image, lower right of furnace) venting to a large room good enough?

the return air does not help because the combustion air intake does not connect to it.

Or does the whole machine (i.e. where that "fresh air inlet" is) need to be in the "large" room?

yes 50 cubic feet per 1000 btu
if it is in a smaller space the manual (page 14-16) says how big of a vent is needed to connect to a larger room.

I don't think it has a power vent. Unless this is something that only turns on when the heat is running?

yes only when heat is running.
however I'm not sure how much pressure the blower on this unit makes. so I would be concerned about it in a tight house, see page 15

If the confined space is within a building with tight construction,
combustion air must be taken from outdoors or from an area
freely communicating with the outdoors.

[Alexsei]

My central AC unit covers main floor + basement, however my basement ends up being 4-5° cooler than the main floor, my playroom is so cold that kids turn on the baseboard heat there 🔄. And this is with the basement diffusers closed. What's next step?

[notyettaken]

My central AC unit covers main floor + basement, however my basement ends up being 4-5° cooler than the main floor, my playroom is so cold that kids turn on the baseboard heat there 🔄. And this is with the basement diffusers closed. What's next step?

Set the fan to on (instead of auto) this will mix the upstairs and basement air and equalize them.
Also make sure there is a return (intake) in the basement .

[Alexsei]

Set the fan to on (instead of auto) this will mix the upstairs and basement air and equalize them.
Also make sure there is a return (intake) in the basement .

Yes, there's a return in the basement. Will try setting the fan to on

[CountValentine]

Yes, there's a return in the basement. Will try setting the fan to on

This will help when the AC is off, but it will still be colder.

[yungermanchik]

And this is with the basement diffusers closed. What's next step?

Try sealing some of them  with these:
https://www.homedepot.com/p/Frost-King-15-x-8-3-Pk-Magnetic-Vent-Covers-MC815/100345609

[Alexsei]

Try sealing some of them  with these:
https://www.homedepot.com/p/Frost-King-15-x-8-3-Pk-Magnetic-Vent-Covers-MC815/100345609

I have round diffusers that I can close pretty well

[aygart]

Be careful with closing vents since it can cause condensate on the ducts

[Alexsei]

Be careful with closing vents since it can cause condensate on the ducts

So what's the solution add zoning with dampers?

[aygart]

So what's the solution add zoning with dampers?

Closing off at the trunk line

[Alexsei]

Closing off at the trunk line

Permanently? Semi permanently?

[aygart]

Permanently? Semi permanently?

You can put a manual damper there depending on access

[somefield]

So what's the solution add zoning with dampers?

Arzel Zoning. They have the simplest retrofit branch damper solution.

[CountValentine]

Arzel Zoning. They have the simplest retrofit branch damper solution.

What is the cost for something like that?

[somefield]

What is the cost for something like that?

Hard to say. Each install is custom to that specific home/office (i.e., number of zones & dampers).

[CountValentine]

Hard to say. Each install is custom to that specific home/office (i.e., number of zones & dampers).

Was just wondering ballpark figures for say a two story, 4-bedroom house. Going to guess it is not cheap.

[notyettaken]

Set the fan to on (instead of auto) this will mix the upstairs and basement air and equalize them.
Also make sure there is a return (intake) in the basement .

@Alexsei did this help?

[Alexsei]

@Alexsei did this help?

Yes about 2-3 degrees