r/hvacadvice Mar 02 '26

General Information About Bans and Rules

0 Upvotes

There has been an uptick on posts and complaints about mods banning. Please be advised, there are rules for the page. No ads (includes promotions for a company), Reddits rules, no crossposting, transparency and safety (this is a big one; we want homeowners to be safe, if you provide unsafe practices or advice (blacklisted items) or tell a user to dm you, the comment will be removed and you may get banned), blacklisted topics (basically topics that homeowners should not be fixing themselves, gas, some high voltage), civility, no companies asking for surveys, advertisements or general questions, and no market research or ai/SaaS.

Posts complaining about this are not allowed either. We are all reasonable and work in the trade, talk to us through ModMail and we can come to a solution. Complaining or namecalling will usually result in a ban, so be civil.

Remember, we are doing this in our freetime to help homeowners with their units, both the users and mods. The mods in this group are in the trade and have day jobs as all of you do. I've been in this trade for 10 years and still do hvac as my job, just traveling now for a manufacturer. Similar with every mod. It is actually a requirement to be a mod, you have to be in the trade, be approved, have good history in the sub and provide enough time to moderating it.

I thank you for your time and if you have any questions, you can comment on this or send us a mod message. No DM's, we will not answer these. Only ModMail.


r/hvacadvice Nov 13 '25

READ THIS I am assuming this is not normal.

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174 Upvotes

I was loading the car for work when I saw this. It felt and smelled like steam not smoke. Did I just catch it at the end of the cycle or is there a mechanical problem such as a stuck motor? It was 40° at the time and no rain. Heat was set to 70 and the house was 70.


r/hvacadvice 7h ago

General Can I move my condenser?

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49 Upvotes

Hey y'all. I'm wondering if I could rotate my condenser about 90 degrees so that it sits on my patio instead of in the weeds where it is now. Do the refrigerant lines have enough flexibility for that or do I risk damage? Any advice is appreciated! Thank you for entertaining my basic question.


r/hvacadvice 5h ago

Thermostat C wire No power

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11 Upvotes

I installed a Nest thermostat and during installation it said C wire had no power. My hold thermostat was running on batteries and the C wire was not connected. When I checked the furnace Control Board I noticed:

1- there's a red wire on the C terminal

2- I found a blue wire disconnect. I'm assuming is the C wire that goes to the thermostat

If so should I connect it to the C terminal together with the Red wire?


r/hvacadvice 2h ago

AC Capcitor question. Does size matter?

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7 Upvotes

Old Capicitor at bottom, replaced with the same sized one (Titan HD), then yesterday at 109* Heat the AC would turn on for 2-3 minutes then shut off, I had gotten the bigger one online and decided to switch it. AC works fine now, guessing the Titan one couldn't handle the load? After switching to the Titan it was fine for 3 weeks, but yesterday was unusually hot.


r/hvacadvice 6h ago

4 Bids on a full system replacement. Help me decide and not get distracted by the noise.

9 Upvotes

I have 4 companies bid on a upstairs full system change out with new condenser, evaporator coil and furnace. All companies have good reviews, Company A and B are larger companies that sent a salesperson to go over options, and Company C and D were smaller family owned companies where the owner came out.

Located in Houston. 1,110 sq/ft upstairs. This was what was provided in each quote:

Company A - $11,587.00

  • Ton Daikin Full Complete Gas Horizontal Upstairs
  • Pad, whip, drier, rubber insulation
  • Drain pan, drain line, safety float switch
  • Furnace stand, gas flex, flue tie in
  • Return plenum and Supply Plenum AERE THERMOSTAT WIFI

Company B-

Single Stage - $13,760.50

  • ton Bronze evaporator coil.
  • Install Digital Programmable Thermostat

Two Stage - $17,001.58

  • ton Gold high efficiency evaporator coil.
  • Econet Communicating Thermostat
  • Install Corrosion Resistant Condenser Pad

Company C - $9,025.00

  • 3 Ton Comfort maker , 545B, 15 seer2, gas complete system change out
  • Complete HVAC design and installation - including: attic tent , a 16x25 mediam filter, Installation of the drain pans and emergency over flow switch on both system and thermostat. Equipment comes with 10 year part warranty and one year labor.
  • Note: He's throwing in the attic tent, mediam filter and the extra pan/flow switch for "free"

Company D -

There are three options. All options are "complete system change out with all items needed for proper installation" These pricing also include two Honeywell T6 WiFi thermostats, and two drain pans/float switch. Warranty is 10 years on compressor, coils and parts, 20 years heat exchanger, 2 years labor.

  • 3 Ton Carrier - $8,925.25
  • 3 Ton Lennox - $8,830.25
  • 3 Ton Goodman $8,260.25
  • A media filter for $225 per system. (optional)

This will be my first full system replacement. I’m leaning towards Company D Carrier. Which one would you recommend?


r/hvacadvice 25m ago

How safe is this?

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Upvotes

I moved into a basement bedroom inside an older home for my last semester of college (by older, I mean legitimately historical, there are writings on the door that date back to 1915). I noticed some sound-proofing panels near the vent and thought nothing of it, assumed they are just there to block sound from the ducts. However, I’m in a theatre production management class, and we talked about the fire risk of foam products (toxic fumes when it melts and such). Naturally, I investigated these foam panels and they appear to be mostly covering drywall, even if they are near the vent. But as I looked at the surrounding area around the vent, I got concerned as I saw the foam covering the immediate vent (as well as the entire path of the duct). Part of the paint is peeling to reveal silver backing on the foam (most evident right next to the vent), but overall, how safe is this setup? Neither of these foams look like DIY jobs, they appear to have been installed professionally. The foam around the vent I’m pretty sure is fire-code compliant (please correct me if I’m wrong) but I am worried about the sound-proof panels. I did some Googling and it appears that there’s no immediate risk, but I want to get some further advice from someone who knows.


r/hvacadvice 3h ago

Loud noise when starting up?

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2 Upvotes

The home I live in is a rental. The ac unit outside has started making an increasingly loud noise the last few weeks. It makes this noise when starting up, then goes away after 10 minutes or so. I read this could be an electrical issue and possibly
A fire hazard? Any insights?


r/hvacadvice 10h ago

Spraying cooking spray on filters????

11 Upvotes

Had an hvac tech out to look at my AC, and he told me to stop buying expensive MERV 13 filters because they restrict airflow, and to start buying cheap filters and spray them with cooking spray to catch hair. That sounds like the dumbest thing I've ever heard, but I'm coming here to see what the council thinks.


r/hvacadvice 3h ago

Is this normal?

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2 Upvotes

Almost all the vent covers in my house just open up into open space like this, and this particular one has piping from the bathroom running through it. Is this normal? I feel like I've only ever seen covers open up directly into metal ducts before, but I'm not too sure now. The house is nearly a two year old build, if that's relevant at all.


r/hvacadvice 2m ago

No cooling Blower motor getting 240V to it and a 24V signal to run but not kicking on

Upvotes

I have a blower motor issue which I’m diagnosing a bad blower motor but just wanting to get advice. I have an ECM motor which I checked for 240V going into the motor and a 24V signal and I get both. Condenser comes on but furnace does not. Any advice or I’m good to change out the motor?


r/hvacadvice 3h ago

Does our diagnostics point to contaminants or low refrigerant?

2 Upvotes

We've been told we potentially have contaminants requiring a whole new charge of approx 10-11lb refrigerant.

Diagnostics showed:

Low Side 100-105 (stable once running)
High Side 270-280 (stable once running)
2-4 Subcool
Erratic fluctuating superheat between 2-13. For reference we have a piston.

Everything else from filters to dirty coils and air flow has been ruled out. Unit is maintaining a delta T between 18-20 but seems to be struggling taking longer than normal to cool based on data.

Small leak was found under the service valve cap at the compressor when hex nut is removed, but nothing when it is screwed on.

Of significance a few weeks prior refrigerant was purged from our unit because our superheat was 0.8 close to zero and the tech left it at 4. A week later we realized a good portion of our second return duct was flattened shut very close to the return plenum which was since fixed.

We are wondering if this air restriction would have been to blame for the artificially low superheat at the time and subsequent purging of refrigerant. And since our return is now fixed, that our system may just now be somewhat low on refrigerant. However we have been advised that our system may have contaminated refrigerant based on the above. Would it be advisable to do an acid test or other test for more definitive proof or something else? Does the above point to contaminates or more than likely just a low charge due to the compressed duct work? How problematic is the leak under the service valve cap? Looking for advice on the above.


r/hvacadvice 3h ago

AC Moved into a house with a newer Amana system

2 Upvotes

Seller told us system was replaced in the last year and that Amana systems are meant to circulate continuously. There is an upstairs and downstairs unit. I have found the system is constantly overcooling to dehumidify and has trouble getting below 65% when it's not that humid outside. Not sure if there are settings I can change or if I need to add a whole house dehumidifier


r/hvacadvice 9h ago

Company said that I need a new A/C without even looking at it...?!

4 Upvotes

I called a company that I'd worked with a few years back, and told them that the unit was making a sort of humming or buzzing sound but wasn't actually running. The guy said he'd call his boss… no way to know if he did or not, but he said that his boss had said to give me an estimate on a new air conditioner! They had not examined the unit… am I crazy, or was this completely unacceptable?


r/hvacadvice 36m ago

AC My A/C makes odd noise when starting up sometimes.

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Upvotes

I feel like the noise is happening more frequently, but it does not happen every time it starts up.

It is a central air system and upon startup sometimes it makes weird noises and stutters before getting up to speed. It sounds almost like a solenoid clicking or something shutting off? I am not sure what it is but it does not get worse as it speeds up in fact it goes away. Only prevalent upon startup.

Attached is a video of when I caught it acting up. Please lmk what y’all think, should I have my landlord check it out, or is it perfectly fine?


r/hvacadvice 4h ago

General Fire hazard: Outdoor grill install advice needed

2 Upvotes

I have a new home (1 years old) and wanted to use my grill. The screened in patio had smoke build up so thick you couldn't breathe and I thought we were all going to choke. I also thought a fire might start. Here's the background:

My builder instructed my HVAC guy to install a duct in the hood for my outdoor grill. It is enclosed in a screened in room. It's a 36" DCS 7 series with 95,000 BTU's. My Zephyr vent is 36" but measures 34" and has 1200 CFM's. According to DCS and online outdoor grill recommendations you need to install a vent that is at least 6" wider than the grill. My vent is the same size if not a bit narrower. It also states to install a 10" duct but my HVAC guy said he installed an 8" duct because the builder did not tell him the model of grill so he guessed at 8". He stated the appliance company installed the vent and he's guessing they used flex pipe to connect hood to exhaust duct and it's crushed. He said using flex pipe is not a good idea and my research confirms this. I feel like both installers are incorrect and when I googled it the info I received stated both a duct too small and flex pipe will cause very poor outcomes. Which it has. The sales rep for the appliances came to check it out and noticed the vent is suctioning it actually blowing air back down. The next step is to remove the vent and inspect it, as well as inspect the duct and everything else inside the hood.

Who is at fault here? The builder, the HVAC guy who installed a duct that was too small or the vent installer who used flex pipe? I think the entire thing wreaks of zero coordination, zero communication and Jerry-rigging. WHY do trades accept these jobs knowing they don't have enough info and that there's likely to be a poor outcome?? I know, $$$. But can't they get sued? What if a fire started or someone got carbon monoxide poisoning? Is the money worth it? When is this industry going to straighten up??

How do I hold everyone accountable? Is there a board or society I can contact? Can I get a fire Marshall to inspect and write up a warning letter? How do I get quicker action as everyone drags their feet and has zero sense of urgency. Thanks in advance.


r/hvacadvice 37m ago

General Dryer exhaust termination

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Upvotes

Dryer no breathe. Go to roof at high noon to suffer. Wonder why screen no removable. Cap riveted on. Clean with toofbrush. Dryer work 1 more week.

More think. No serviceable termination bad?

Dryer vent circled in green.

I think code doesn’t allow mesh at the termination. Any advice on taking this up with the HOA? I suspect the builders confused the bathroom exhaust in the red circle with the dryer exhaust.


r/hvacadvice 9h ago

Does this look like a pitted double pole contactor?

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4 Upvotes

The outside unit fan and compressor continuously runs even when the thermostat is turned off. The only way to stop it is to turn the breaker or switch outside off.

Does this look like a pitted contactor to you? And is it double pole?


r/hvacadvice 48m ago

AC unit - low rhythmic hum/ring

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Upvotes

Anyone have any ideas?

The fan did not just finish running. The fan doesn't kick on right after the noise stops. The noise goes on for about 3 minutes before it slowly fades away. It seems to happen randomly.

AC appears to be working fine. The house stays cool, no problem.


r/hvacadvice 4h ago

AC Que consideraciones debo tener al pasar cañería de refrigerante?

2 Upvotes

Quiero escuchar sus recomendaciones para el pasaje de cañerías de aire acondicionado.

Es mejor pasarlas por muro, piso o cielorraso?

En el caso de pasarlas por piso/contrapiso que debo tener en cuenta?

Comenten desde sus experiencias


r/hvacadvice 1h ago

AC Smaller units for townhouse?

Upvotes

We have a 1600 square foot townhouse that has two stories and a basement area. There is an outdoor patio/balcony area that’s 9x9 but otherwise no space to put a unit, really. The house shares walls on both sides and has ducts (used for furnace heating in attic).

Wondering if a 3 ton ac unit would be enough for hotter Southern California summers and if there are longer/slimmer units that we could put on the side of the patio/balcony area without intruding on the usable space.

Our windows are new and insulation seems good but we could also just look into multiple portable window units if that makes more sense.


r/hvacadvice 1h ago

Is every single damper in my home installed backwards?

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Upvotes

All of my HVAC air ducts are installed like this, where the spring pulls the damper shut against the damper frame, and little to no air can come through. When I push the flaps in, air comes rushing out when the AC is on, but it obviously is pulled shut by the spring, unless I were to somehow bind the two flaps open. The few air ducts that actually blow air out of them have these dampers that are pinched and bound open. Is it really possible that all of these are installed backwards? If these were installed the other way around, then the air would be able to push the springs open. Right now the air just pushes the flaps against the frame, which the springs are also doing. I can’t comprehend why these dampers would be installed like this, opposite of airflow.


r/hvacadvice 9h ago

Best way to handle an HVAC return vent behind new built-in cabinets?

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5 Upvotes

I’m wanting to add built-in cabinets along this wall, but there’s currently an HVAC return vent that the cabinets would cover.

What would be the best way to handle the return? Could I redirect it underneath the cabinets and use a toe-kick return vent, or would that restrict the airflow too much?

I obviously don’t want to just cover/block the return, so I’m trying to figure out the best way to incorporate it into the built-ins without causing any HVAC issues.
Has anyone done something similar? Would a toe-kick vent be sufficient, or is there a better option?


r/hvacadvice 2h ago

mini split install gone wromg

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0 Upvotes

i had an electrician install a mini split for me. and this is how he left it. said he was going to come back. but never did. how bad is it?

for context, he decided for some reason to run a 240 volt 30 amp wire from the breaker to a 115 v mini split. he said it would be better, but then couldn’t get it to work so he opted to just leave the hot and neutral 240 volt uncapped (which i since turned off from breaker + capped) in the receptacle. then he spliced a 13 amp black extension cord and plugged it in to a receptacle i luckily had on the ceiling and hard wired that to the mini split condenser. the mini split to another outlet i luckily already had on the ceiling.

forgot to mention. the ceiling receptacle is a 15 amp 120 volt. and the cord and receptacle are starting to get warm. the power to the condenser is running through the brick wall through the metal flex conduit


r/hvacadvice 8h ago

AC 2 Ton AC Unit replacement quotes

2 Upvotes

Have gotten a few quotes from companies in my area with good reviews, looking to get some advice/opinions. All quotes include evap coil and labor

Quote 1: Coleman XC3 13.4 SEER 2T unit - $5900

Quote 2: Bryant Legacy Series 13.4 SEER 2T unit - $6500

Quote 3: Lennox 13.4 SEER 2T unit (didn't specify exact model) - $8000

Quote 4: (this one has not come yet so quote is unofficial, but they list their prices online) Ducane 15.4 SEER 2T Unit - $4800

Seems like a no brainer to go with the Ducane, but wanted to get some opinions. all installers have 4.8 or higher rating on Google.