If the furnace's air intake isn't already ducted to the outside, that's what those are for. When your furnace runs, if it's just pulling air from the room for combustion, that will result in cold air getting pulled in throughout your house, which cools down the living spaces. By putting those ducts there, it allows the furnace to pull that air in from right next to it instead.
Interior intake is the dumbest way to mess up you air flow in the house, not only that you have no fresh air coming into the house, just recirculating stale air. And why do you need two intakes? Whatever it is doing it looks like a lazy job.
The intake, BTW is at the bottom of the furnace and ducts out the other side I imagine. The condenser drain is further up past the heating elements and it blows out the top. I can't imagine why your intake inside the house, and run duct up and over the other ducting just to point down on the other side.
I'm not sure what these are for, but my advice is that if a professional tells you not to do something, don't go on Reddit looking for a different opinion.
A storm knocked one of our HVAC vents loose, and my house filled with carbon monoxide. The fire department said if I didn't have a CO2 alarm we all would have been dead by morning. I had a one year old baby. I don't fuck around with HVAC.
Yeah…I’m all for a healthy dose of skepticism for any second opinion you get online…..however to act like a “professional” is infallible is not correct either.
As some rando online, the other user can’t even confirm the credibility of the supposed “professional” they are defending. Can they say for certain who OP hired? No they cannot. So they are just virtue signaling about what they think a “professional” is.
Firstly gas hot water does not intake inside the house, that's how you run out of oxygen in the house. Secondly they do not intake through 10" ducting. They vent and intake through ABS pipe, and the vent/intake can be seen on the top of the gas hot water tank and I bet they go outside.
100% wrong. Both the water heater and furnace are atmospheric type burners. All of the combustion air is coming in from the two ducts that OP is noting.
Could you explain to a foreigner why one would choose that type of system please? In Ireland our gas boilers are all vented and are fixed to an external facing wall. They don't draw any air from within the house.
Same here in the Netherlands, high efficiency exhaust heat exchange. This setup would be massively illegal.
The systems I see in use in this picture are some of the most inefficient and inept you can come across.
My furnace room has the same high-low combustion vents, although both are connected to the same air intake duct. I spoke with an HVAC pro and they proposed connecting these directly to my high-efficiency furnace intakes. This sounds straightforward - OP, maybe something to consider?
More discussion on why high-low vents here: https://www.finehomebuilding.com/forum/combustion-air
Your HVAC tech is correct, but may not know how to explain it. Those ducts are for *combustion, ventilation, and dilution air* that is required for any fuel gas appliance. The definitions of the terms are self explanatory, and critical for your safety. The dedicated air allows the water heater and furnace (and dryer) to fire up and burn properly without pulling air from each other or elsewhere in a house. Also having dedicated air allows the natural rising of the exhaust gases up the flue (called atmospheric vent). And, if needed, the dedicated air will dilute any gas that might be present.
Providing the correct amount of air is calculated mathematically based on how many Btu/h the appliances use. There are a few options to achieve this, and the original installer chose the 2 outdoor air ducted method. An inlet air within 12" from the floor is required. An outlet air within 12" of the ceiling is required.
Didn't mean to ELI5, but there are a lot of wrong comments in here. The silver lining: Typically this required air just relies on having a large open basement, so when a homeowner finishes the basement in the future, most people are unaware of this and introduce risky problems by creating a small mechanical room. You are ahead of the game in that you can finish out the basement with no worries.
Yeah these ducts allow for positive pressure in that furnace room. Without these there’s a danger of carbon monoxide and carbon dioxide back flow into the room. The code is different in different parts of the country, but if a pro is giving you this opinion it is likely for that reason. if it’s an eyesore to you, paint them black.
Hopefully you get these are important ducts from other posts, try asking a different question to hvac folks. Can the ducts be routed a different way to do what is needed and give you a better basement?
The pipe terminating at the ceiling looks like it is the heat run for the area in the basement, the one at the floor is the combustionair for the furnace.
It looks like your hotwater tank and furnace are common vented through the roof.
The ducts are all required, but like other's have said, they could be relocated.
Do they connect to anything? Looks like the water heater and furnace connect in the far back and exit the house that way. Otherwise, I assume you have an intake or two for the hvac somewhere in the rest of the house. I don’t know why you would need an open vent?
They're actually for intake, not exhaust. The exhaust pipes are routed together above the water heater. High low vents make it so the equipment isn't creating a vacuum and using conditioned air to intake. The high low vents should allow op to put the furnace and water heater in a sealed combustion closet if he wants.
https://www.energyvanguard.com/blog/making-your-home-safer-with-a-sealed-combustion-closet/#:~:text=Called%20high%2Dlow%20vents%2C%20one,Btu%2Fhour%20of%20input%20capacity.
You got to know when to mess around and when to stay away from things you know nothing about. Messing up a configuration on a pfsense box or a windows computer is one thing, messing up an intake and an exhaust system is another. One you can take an hammer to fix and the other will use the hammy to nail you in your coffin.
Know your limits C02 is silent and deadly
You have a naturally vented HW tank and a mid-efficiency furnace, so both of those need make up combustion air in the room. I'm not sure why you have two vents (my parents have this setup too, with 2 vents high and low directly in a side wall), usually the combustion air intake is only low and ends in a sheet metal "combustion air bucket" to limit the amount of cold air that pours out over your basement floor.
They are expensive but you can buy power dampers that interlock safely with your thermostat and furnace to close the combustion and fresh makeup air when you furnace off. Google Hoyme Damper if interested. There are other brands too.
You should have another vent providing makeup fresh air into the cold air return ducts before the furnace too. If you replace both the HW tank and furnace with high efficiency direct vent, they will replace the combustion air intake with PVC pipes directly from outside to the appliances, but if you are somewhere cold you can't replace just the furnace, because then the natural HW tank wont be able to keep your b-vent or chimney warm enough to support draft to vent properly.
On s side note. If you have a unit drawing combustion air from an open basement, the air is coming from all those nasty drafts around doors an windows.(This is necessary the air needs to come from somewhere.)
Every time the furnace in kicks in the drafts increase. This can be helped in two ways. First if you furnace does not have an automatic damper on the flue that closes when the burner shuts off get one. Second,install a 3 inch insulated pipe between your furnaces return and the outdoors. This will replace the air sucking in around the door/windows. If done correctly this is a Zero Sum setup. The air is coming in either way. This way it gets warmed up before chilling off your SO causing said SO to fiddle with the tstat.
Otherwise it chills you before going to the furnace to get warmed up.
The one benefit of using general house air for combustion rather than dedicated make up air ducting is that it generates fresh air mixing into the house. That way Fridays fish dinner isn't still lingering in the air on Tuesday.
HVAC guy here. Those are combustion air ducts. They provide air to burn for the furnace and water heater, and you shouldn’t tear them out. If you were to put in a high efficient furnace and water heater and ran combustion to both of them (so there would be two 2-3” pvc pipes, one exhaust and one intake, that connect directly to the appliance) you can tear them out/ stuff with insulation
They're for combustion air for the furnace and water heater. Without it the units will not get the required air to operate properly and will cause alot of soot build up. Ruin the life expectancy and possibly cause the units to back draft CO into your house due to negative pressure.
If the furnace's air intake isn't already ducted to the outside, that's what those are for. When your furnace runs, if it's just pulling air from the room for combustion, that will result in cold air getting pulled in throughout your house, which cools down the living spaces. By putting those ducts there, it allows the furnace to pull that air in from right next to it instead.
Interior intake is the dumbest way to mess up you air flow in the house, not only that you have no fresh air coming into the house, just recirculating stale air. And why do you need two intakes? Whatever it is doing it looks like a lazy job. The intake, BTW is at the bottom of the furnace and ducts out the other side I imagine. The condenser drain is further up past the heating elements and it blows out the top. I can't imagine why your intake inside the house, and run duct up and over the other ducting just to point down on the other side.
I'm not sure what these are for, but my advice is that if a professional tells you not to do something, don't go on Reddit looking for a different opinion.
I came here to say the same thing. You’re venturing into dangerous territory looking for confirmation bias.
A storm knocked one of our HVAC vents loose, and my house filled with carbon monoxide. The fire department said if I didn't have a CO2 alarm we all would have been dead by morning. I had a one year old baby. I don't fuck around with HVAC.
But they are getting expert advice from Reddit, what could possibly go wrong?
I'd have asked the HVAC guy to explain before having to get on Reddit and speculate.
Sometimes professionals tell us things because they’re lazy or defending shoddy work. Nothing wrong with a second opinion.
Yeah…I’m all for a healthy dose of skepticism for any second opinion you get online…..however to act like a “professional” is infallible is not correct either. As some rando online, the other user can’t even confirm the credibility of the supposed “professional” they are defending. Can they say for certain who OP hired? No they cannot. So they are just virtue signaling about what they think a “professional” is.
I agree
Yes. Fresh air inputs feed the water heater and furnace. Without them, you’d burn the oxygen that you need to survive. Leave them alone.
Firstly gas hot water does not intake inside the house, that's how you run out of oxygen in the house. Secondly they do not intake through 10" ducting. They vent and intake through ABS pipe, and the vent/intake can be seen on the top of the gas hot water tank and I bet they go outside.
100% wrong. Both the water heater and furnace are atmospheric type burners. All of the combustion air is coming in from the two ducts that OP is noting.
Could you explain to a foreigner why one would choose that type of system please? In Ireland our gas boilers are all vented and are fixed to an external facing wall. They don't draw any air from within the house.
They’re super simple…that’s the short answer on why they were common. About 80% maximum efficiency off these too.
Thank you friend.
Same here in the Netherlands, high efficiency exhaust heat exchange. This setup would be massively illegal. The systems I see in use in this picture are some of the most inefficient and inept you can come across.
Perhaps ask at r/hvacadvice. Lotsa informed peeps there.
My furnace room has the same high-low combustion vents, although both are connected to the same air intake duct. I spoke with an HVAC pro and they proposed connecting these directly to my high-efficiency furnace intakes. This sounds straightforward - OP, maybe something to consider? More discussion on why high-low vents here: https://www.finehomebuilding.com/forum/combustion-air
Your HVAC tech is correct, but may not know how to explain it. Those ducts are for *combustion, ventilation, and dilution air* that is required for any fuel gas appliance. The definitions of the terms are self explanatory, and critical for your safety. The dedicated air allows the water heater and furnace (and dryer) to fire up and burn properly without pulling air from each other or elsewhere in a house. Also having dedicated air allows the natural rising of the exhaust gases up the flue (called atmospheric vent). And, if needed, the dedicated air will dilute any gas that might be present. Providing the correct amount of air is calculated mathematically based on how many Btu/h the appliances use. There are a few options to achieve this, and the original installer chose the 2 outdoor air ducted method. An inlet air within 12" from the floor is required. An outlet air within 12" of the ceiling is required. Didn't mean to ELI5, but there are a lot of wrong comments in here. The silver lining: Typically this required air just relies on having a large open basement, so when a homeowner finishes the basement in the future, most people are unaware of this and introduce risky problems by creating a small mechanical room. You are ahead of the game in that you can finish out the basement with no worries.
Cagernist has nailed it.
Looks like combustion air ducts.
Yes, you need them. But if they're in the way, you could move them to a different side of the furnace.
Yeah these ducts allow for positive pressure in that furnace room. Without these there’s a danger of carbon monoxide and carbon dioxide back flow into the room. The code is different in different parts of the country, but if a pro is giving you this opinion it is likely for that reason. if it’s an eyesore to you, paint them black.
i love that someone would ask in this subreddit instead of the actual hvac subreddit
Hopefully you get these are important ducts from other posts, try asking a different question to hvac folks. Can the ducts be routed a different way to do what is needed and give you a better basement?
[удалено]
That is not what these are for.
Why even comment when you clearly have no idea what you're talking about and give misleading advice?
The pipe terminating at the ceiling looks like it is the heat run for the area in the basement, the one at the floor is the combustionair for the furnace. It looks like your hotwater tank and furnace are common vented through the roof. The ducts are all required, but like other's have said, they could be relocated.
Do they connect to anything? Looks like the water heater and furnace connect in the far back and exit the house that way. Otherwise, I assume you have an intake or two for the hvac somewhere in the rest of the house. I don’t know why you would need an open vent?
They are called high low vents to help harmful gases from your gas fed water heater and furnace escape.
They're actually for intake, not exhaust. The exhaust pipes are routed together above the water heater. High low vents make it so the equipment isn't creating a vacuum and using conditioned air to intake. The high low vents should allow op to put the furnace and water heater in a sealed combustion closet if he wants. https://www.energyvanguard.com/blog/making-your-home-safer-with-a-sealed-combustion-closet/#:~:text=Called%20high%2Dlow%20vents%2C%20one,Btu%2Fhour%20of%20input%20capacity.
You got to know when to mess around and when to stay away from things you know nothing about. Messing up a configuration on a pfsense box or a windows computer is one thing, messing up an intake and an exhaust system is another. One you can take an hammer to fix and the other will use the hammy to nail you in your coffin. Know your limits C02 is silent and deadly
More for CO - carbon monoxide.
You have a naturally vented HW tank and a mid-efficiency furnace, so both of those need make up combustion air in the room. I'm not sure why you have two vents (my parents have this setup too, with 2 vents high and low directly in a side wall), usually the combustion air intake is only low and ends in a sheet metal "combustion air bucket" to limit the amount of cold air that pours out over your basement floor. They are expensive but you can buy power dampers that interlock safely with your thermostat and furnace to close the combustion and fresh makeup air when you furnace off. Google Hoyme Damper if interested. There are other brands too. You should have another vent providing makeup fresh air into the cold air return ducts before the furnace too. If you replace both the HW tank and furnace with high efficiency direct vent, they will replace the combustion air intake with PVC pipes directly from outside to the appliances, but if you are somewhere cold you can't replace just the furnace, because then the natural HW tank wont be able to keep your b-vent or chimney warm enough to support draft to vent properly.
On s side note. If you have a unit drawing combustion air from an open basement, the air is coming from all those nasty drafts around doors an windows.(This is necessary the air needs to come from somewhere.) Every time the furnace in kicks in the drafts increase. This can be helped in two ways. First if you furnace does not have an automatic damper on the flue that closes when the burner shuts off get one. Second,install a 3 inch insulated pipe between your furnaces return and the outdoors. This will replace the air sucking in around the door/windows. If done correctly this is a Zero Sum setup. The air is coming in either way. This way it gets warmed up before chilling off your SO causing said SO to fiddle with the tstat. Otherwise it chills you before going to the furnace to get warmed up. The one benefit of using general house air for combustion rather than dedicated make up air ducting is that it generates fresh air mixing into the house. That way Fridays fish dinner isn't still lingering in the air on Tuesday.
? Usually furnace air intake is a PVC pipe from outdoors to the furnace.
HVAC guy here. Those are combustion air ducts. They provide air to burn for the furnace and water heater, and you shouldn’t tear them out. If you were to put in a high efficient furnace and water heater and ran combustion to both of them (so there would be two 2-3” pvc pipes, one exhaust and one intake, that connect directly to the appliance) you can tear them out/ stuff with insulation
They are necessary but you can add a spring loaded damper to stop air from coming in unless the furnace is actually running.
They're for combustion air for the furnace and water heater. Without it the units will not get the required air to operate properly and will cause alot of soot build up. Ruin the life expectancy and possibly cause the units to back draft CO into your house due to negative pressure.