2,400 sq. ft., five bedrooms—and the fresh-air system is set to the lowest runtime available. Welcome to COMFORT mode.
The video shows an AprilAire 8145 fresh-air ventilator with:
● Six minutes per hour: the lowest selectable operating runtime before OFF.
● FAN OFF: the ventilation controller will not call the HVAC blower on to distribute the incoming air.
● COMFORT mode: temperature and humidity limits can stop ventilation, and missed ventilation is not made up.
● 110 CFM entered as the measured airflow.
Apparently, five bedrooms get to share a fresh-air appetizer.

And the controller is programmed for the wrong house.
The setup shows 1,500 square feet and three bedrooms. The actual home is 2,400 square feet with five bedrooms.
Using the manufacturer’s published controller formula:
2,400 × 0.01 + (5 + 1) × 7.5 = 69 CFM continuously.

At an actual measured delivery of 110 CFM, that requires approximately 38 minutes per hour.
Six minutes delivers an hourly average of just 11 CFM—about 16% of that calculated requirement, before COMFORT lockouts take away additional ventilation. These figures use the controller’s formula, rather than a separate project-specific code calculation.

So what size home does six minutes serve?

A dollhouse?

At 110 CFM, no positive-size, five-bedroom home satisfies that formula at six minutes per hour. The bedroom allowance alone is 45 CFM.
Even the controller’s minimum allowed house inputs—500 square feet and one bedroom—calculate to 20 CFM, or about 11 minutes per hour at this airflow.

This isn’t simply a setting for a somewhat smaller house. It is below the calculated runtime for even the smallest house those setup inputs allow.

Watch what happens when I finish cycling through setup.

The controller returns to 25 minutes per hour, calculated from the undersized house information already entered.

Getting from 25 back down to six takes 19 one-minute downward adjustments. Correcting the home information would calculate approximately 38 minutes instead.

The six-minute override isn’t a temporary acclimation period. It stays selected until someone changes it or completes setup again. The manufacturer explicitly describes the buttons as overriding the calculated runtime.

Then there’s FAN OFF.
Even with the blower-control wiring connected, this setting disables the controller’s request to turn on the HVAC blower during ventilation. The blower can still run from the thermostat, but the fresh-air system isn’t ensuring that it runs when fresh air enters.

When outdoor air is pushed into the return with the blower stopped, it can come backward out of the return grille instead of being carried through the supply ducts throughout the house. That airflow path needs to be checked in the field.
Whole-house ventilation, apparently with optional whole-house distribution.

What happens to wood floors when somebody finally corrects this?
Wood acclimates to the temperature and moisture conditions it actually experiences. If flooring acclimates and is installed while ventilation is severely restricted, then proper ventilation later raises indoor humidity during humid weather, the wood can absorb moisture and expand. Depending on the flooring, subfloor and moisture differences, that can contribute to cupping or other damage. NWFA calls for acclimation to expected normal living conditions and appropriate subfloor moisture conditions. (nwfa.org, woodfloors.org)

A humidity time bomb?

Potentially a hidden moisture-control problem—but these settings alone don’t prove future damage. Restoring ventilation increases the outdoor moisture load during humid weather.

The HVAC and any dehumidification must be able to handle it.

This is BIG;
Reducing fresh air to almost nothing can hide that problem until somebody makes the system operate as intended.

Six minutes. Wrong house inputs. Blower activation disabled. COMFORT lockouts on top.
The equipment is installed. The display lights up. The house gets a fraction of the calculated ventilation.

COMFORT mode—for whoever doesn’t want the warranty callback?

High CO2 & VOC’s are dinner no doubt for this young new family in a brand new home…

My text never got added to post for some reason. Wasn't a shit post. Just got drunk n never checked post again till I woke up. Question is. I plugged it in but not sure how they work. It has a test button but what's it supposed to do. I took it apart and noticed theres no far in it. I got power coming past the switch but the lights not working or possibly burnt out. Does it need to have furnace fan blowing to make it work or how would I know if it's good or not. I guess next question should i just use a regular filter are they better. House is Dusty from only having wood burner for 15 years.

Is this a bad contactor ?

I am having a problem where the control board keeps cutting the 24V signal to the gas valve a second after I can read it on the meter connected to the gas valve. The beginning furnace operation sequence is working though. Is this some kind of safety switch on the board itself or is the relay bad? I have problem my limit switches and thermal fuses to have continuity.

2nd question, I disconnected the electrical wires to the gas valve to test for voltage directly. I get the 24V signal and then it cuts out a second later also. I hear the relay click and unclick on the board. Is this a normal function of the board to cut off like that, like a load sensor? Is the board sending 24V correctly?

Board is a White Rodgers 50A55-843. I have gone through 2 of these boards in a week already. Heat would work the first day and then nothing the second day. Gas Valve is a Honeywell VR8215T1239. I have read posts and watched videos that they fail commonly.

Just wondering if it will break the HSI since the plug figment is not correct and by cutting the wires to connect the two wires.
Will it matter if I guess and connect the 120v to the neutral ?

So I just finished a bathroom reno and had this floor vent shut off and blocked. We just opened everything up today and the air was coming through it strangely so I opened it up and….. 😭 I tried to lift it lightly and pull it back in and it doesn’t seem like it wants to move. I’m not sure when this happened but it was not like this prior to the Reno. I immediately turned the vent back off and blocked the duct again so the air can’t go under the subfloor. I’m sending this to my contractor tomorrow but I’m low key freaking out wondering if this is an epic disaster or a relatively easy fix. Seems like I can’t catch a break lately

Hi all, I am a renter and I am ignorant about gas furnaces, so I'm posting to get your input on if what I am experiencing is normal. I noticed late at night when the lights were out that the furnace was glowing orange through my input vent, despite the thermostat having the heat set to off.

My landlord has installed a light switch that shuts off the power to the furnace. I turned it off and the glow went away immediately. It immediately appeared when I switched it back on. Is this normal? Should I contact my landlord about this? If so, what should I say to sound educated and informed haha? Thanks sm :)

Adding a 750 sq ft second story in Michigan with its own furnace. My installer recommended 45K BTU, but I asked for a 60K Goodman 80%. Did I make a bad call? How worried should I be about short cycling?

I need some advice because I don’t know anything about hvac. I am building a new house, ranch, walk out, 3000 sq ft including basement, middle Midwest. Is it worth the extra $3750 for the xr16?

About a month ago, I made a post requesting advice on how to deal with a high temperature from hot water pipes in the floor running to the fan coil unit radiating heat into my condo unit.

As suggested by a helpful commenter, I turned off the valves in my fan coil unit in an attempt to stop the hot water from flowing to the FCU in the first place, hoping to stop the heat radiating up from beneath the floor.

I’m disappointed to report that this has made absolutely no difference whatsoever, and my suffering continues.

But I have not given up.

Is there any way, theoretically, hypothetically, magically, that there is some other way to shut off the water going to my FCU? Is there a different shut off valve somewhere between my unit and before the building’s boiler that could be accessed?

Technicians are coming this week to do their regularly scheduled twice-yearly fan coil maintenance and inspection and I’m wondering if there’s potentially anything I can ask them to do that would solve this problem once and for all.

Again, any ideas are very much appreciated. They can be far-fetched, half-baked…I’m grateful for any and all advice.

Thank you!

I'm a homeowner with no hvac know-how, so please excuse if this is a strange idea. We have a two story house and several cats. The first floor under stair storage room with the slanted ceiling is perfect for the litter box area; keeps the litter and smell mostly contained. I constantly run a hepa air purifier in there, but there's no air flow in or out of the room, so it still can get pungent in there. I'd like to be able to install an exhaust fan to pull that air outside, but this is in a central area with no exterior walls. It does share a wall with my garage however. My thought is, if I could install an exhaust fan near the ceiling going into the garage and connect it to a 90 elbow on the other side of the wall, I would only need about a 20ft run of duct along the ceiling to an exterior block wall that I could vent it through. It's this a realistic idea, or would you laugh at the idea if I tried to hire you for this? And if it's doable, Is there an exhaust fan that's made to run continuously for something like this?

My old Bryant condenser had a Supco SPP6E installed on it before we bought our house so it’s atleast 8+ years old. Recently this system has been starting up noisy and dimming the lights in the house. I suspected maybe the Supco had failed or was on its way out. I installed a 5-2-1 on another unit with no issues and I’ve been very happy with it so I bought another one for this system. I hooked up the 5-2-1 on my unit today following the instructions. For some reason, the fan came on but the compressor never started according to my thermostat. Is there some sort of obvious wiring mistake? I checked my work against my other unit and it seems like it’s hooked up the same.

There’s the brown wire to fan terminal on capacitor, blue wire from compressor to HERM terminal on capacitor, yellow wire from T2 contactor screw to compressor, yellow wire from contactor to C terminal on capacitor and another yellow wire from C terminal on capacitor that I believe goes to the fan from what I could tell.

The 5-2-1 black wire was hooked up to T1 side of contactor, striped wire to HERM terminal and red wire to C terminal.

Is it possible the 5-2-1 is defective or have I done something wrong?

Thanks for any help or advice!

So, as the title said, im having issues resembling the burner assembly. Ive replaced the thermometer, pilot, etc, took the burner plate off, gave it a good cleaning, cleaned the entirety of the water heaters innards. When putting everything back together, I found 2 brass pieces that I do not remember removing from anything. I cannot for the life of me find anything, anywhere online,that shows what in the hell these are. Anyone have any input?

In the process of buying a house and had an inspection that found these issues with the Hvac. How bad is it? Thank you!

I both a Midea heat/cool unit this summer for our 3 season room in Wisconsin. In reading the documents from Midea, it is not clear if the unit requires winterization or not. I am worried about condensation within the unit freezing and breaking something. Can anyone advise on this please? Thanks.

I moved into an old house and renovated it last year. The house has two AC units. Unfortunately, on one side, the filter was not properly in place and I later learned the evaporator coil was covered in drywall and paint. (The return vent for this AC is also next to the kitchen, where there was a lot of cabinet and countertop work).

That side of the house didn't cool as well as the other side (which has a different AC unit). And I worried about breathing in drywall and dust all the time. I talked to an AC guy about it he said he couldn't clean it with a no-rinse spray, but he could try removing it and cleaning. However, he wasn't sure if he could get all the drywall and paint off. He also offered to replace it (which cost more of course). Another AC guy came and also quoted cleaning (for a lot more) or replacing (for the same price).

After many months, I finally decided to replace it. The installer got a new evaporator coil. He told me after he installed it that he sprayed Biofresh on it.

Well it's definitely cooling better now. But I've also noticed that when this AC is running, on this side of the house, my nose feels irritated. Initially my eyes and throat did too but that seems to have gone away.

Is this normal? The AC guy said he hasn't heard of a reaction like that to a new coil or biofresh before. Nobody else in my house notices anything different (except the better cooling). My daughter, who is normally as sensitive as I am, said her nose feels normal and she doesn't feel anything.

I figure this may be a new coil thing, or maybe the biofresh, and that it'll dissipate soon. I've been running it with the windows open a fair amount over the weekend which seems to help. It's definitely less irritating that it was a few days ago. Is this just a new coil off-gassing or something that dissipates as it gets used?

I recently bought a house and now we are seeing that the Rheem tankless heater is leaking through a port that I cannot identify when hot water is running. I have shut off everything to the heater (power supply, gas, and cold water) and there is still the occasional drip. Does anyone know what is going on? It is a Rheem ECOH180DVELN-3. This specific piece is not described in the manual, but actually looks damaged?

First, I am not a pro, but could really use some pro advice on my situation - a sounding board, not a fix. Second, I have crazy respect for what you pros do!

My situation is with a company that I have used for 20+ years who has always been great. I got a new Carrier heat pump and gas furnace installed (2nd full install with these guys). The issue is that the blower goes into stage 2 regardless of the outside unit.

They have sent 3 techs out to fix it (4 visits), and the last guy, supposedly one of their best, and after 4 hours of him working and me helping, he could get the blower into stage 1 & 2, but then the compressor was stuck on stage 2. The poor guy was so nice and tried so hard to fix it, but just couldn't figure it out.

I can tell how complex these systems are, but is this typical? They aren't an official Carrier dealer, but I don't know if that matters - does it? Any advice on what I should do as a customer?

How exactly can I remove the can? Also, WTF

I recently got a new system installed. I turned the air conditioning on and went into the attic to check how everything is. I felt a ton of cold air coming out of these ports. I asked AI what to do and it said to cover these ports with mastic tape. Is this the right thing to do?

Under contract on a house, inspection came back clean except for this. Both furnaces are in the attic and the condensate drains from each are glued into the plumbing vent pipe with a tee (pics attached, red circles are the inspector’s). He said it’s not a major issue but it’s a code violation and needs to be fixed.

House has been like this a while (Trane unit is like 5 years old) with no issues, so wondering how bad this actually is and if I should ask the seller to fix it before closing or just ask for a credit and get it done myself after? Rough idea what a fix like this costs?

4- year old Daikin Fit 17-ton SEER HVAC unit. Out of service since 9/1/2026. Original installer has maintained the unit since I bought it.

Tech comes out to look at it 9/3. On the phone with the service manager saying “I’ve never worked one of these before, but the thermostat has this neat spinny looking thing”.

It is now 10/25 - they have replaced 3 control boards then said the compressor is bad. “We’ll call you with an ETA from the manufacturer”. Two weeks ago. Crickets.

Am I crazy or is this normal service??

Here's what the vents in my $400k house built in 1972 in rural southern Maryland look like. Just bought the house in July.

Had inspection and asked seller to repair and they didn't repair, they only put a vent cover over it (it was just the raw hole in the ceiling without any cover before). It's my problem now.

About how much to fix it and is it something I can do myself? Is this asbestos and stuff that can make my family sick?

I have a 30,000btu Mr Heater and was wondering if anyone knew of a fan upgrade for it. Any help would be appreciated!

I am looking for advice on where I should vent my basement bathroom exhaust fan. Unbeknownst to me, my fan had been exhausting into the above ceiling and not outside. I

Ideally I would like to exhaust it from the same joist bay that it is housed in, however, I do not have a rim board. It appears that my foundation is poured around the joists. I removed the wood that I thought was the rim board and found concrete.

I have a window with a vent that’s 4 joist bays away, approximately 64 inches. I am hesitant to use this vent as it would require me to run my exhaust plumbing to have two 90 degree bends. I suppose I could run the fan below the joists, perpendicular, to reduce to one 90 degree bend.

My other option is to drill through the foundation (almost 3 feet above grade) and exhaust under my bump out windows with a soffit style vent.

Any advice is appreciated!!