HVAC Advice: Where HVAC Mechanics and Techs can offer advice.

This post will serve to collect the current ruleset of r/hvacadvice as of October 2023.

r/HVACadvice exists to give end users, homeowners, renters, and others a place to ask their questions about HVAC systems, filters, pricing, and troubleshooting.

1) When posting in this sub, please include in brackets the type of fuel and make and model of the unit. Also please post as many pictures of the unit and components as possible. Something you may not think is important to your problem may be important to us to figure out what is wrong.

2) Mods, homeowners, and end users should be the only people making posts in this subreddit. If you are a tech and have a question, go to r/hvac, even if it seems like a stupid question.

3) ALL HVAC techs offering advice should be verified to get "Approved Technician" flair. This ensures that the people giving the advice are qualified to give it. Using imgur or some other hosting service, send the mods a picture that includes your license, EPA card, or a qualifying certificate along with a piece of paper that has your Reddit username and the date. All identifying information, such as phone or license numbers, names, or companies should be redacted. This is basically the verification system used on gonewild but applied to good purposes, not just awesome ones. Once you have your flair, please feel free to delete your picture.

• If you are giving advice from an unflaired account, it may be removed at a moderator's discretion.
• All advice given must be safe. An immediate ban will be given to anybody who, in the moderator's assessment, is knowingly giving out unsafe advice. If a reply to your question seems sketchy, "report" the post, and a mod will check it out.
• All advice given must be public. Anyone asking you to PM them or who messages you with a solution that they don't want to post in the sub is quite possibly advocating a potentially dangerous fix. Don't engage them, and report the post to the mods.
• Mods have the right to revoke your flair based on bad practices/bad advice at our discretion. You will receive a Probation flair, and after 6 months, you may get your flair back. If you lose your flair again, you will be permanently banned.

4) Absolutely no advertising is permitted. You can not link to your blog. You can not promote a product. You can not post your company's contact information, or the contact information of any specific service provider for any reason.

• It must also be noted that Reddit automatically removes posts or comments containing links from Alibaba, link-shortening websites, amazon (almost always), and image-hosting services other than imgur, among others. The mods do not have time to police removed comments or posts to check if the link was okay and we will not reapprove them, so just don't post links.
• Offers of jobs or requests for employees are prohibited.
• You can not link to the service that you are making. You can not link to a survey for people. You can not ask about lead generation. You can not link a poll. No companies offering a service on this sub are allowed. Your post will be removed and you will be banned.

5) Some things are not safe to DIY and are not open to discussion. An up-to-date list will always be located on the subreddit's sidebar.

6) Keep in mind that those who chose to answer your questions are doing so out of the goodness of their own heart and spending their very valuable time trying to help you. Please be kind and respectful and you will be treated the same.

7) Basic civility is required. No politics, name-calling, or other nonsense.

• Follow reddiquette and be polite.
• We will remove shitty comments and ban assholes. This rule should count as your only warning.

Any questions or comments about these rules, or suggestions or complaints, should go here.

A few days ago, I made a post about my system freezing up. Few of you suggested it was a the TXV. Well tech came out and said the refrigerant was just low. Topped up, and system seemed fine for about 48hrs. Until at night (7-8pm) a bit after and noticed it wasn't cooling anymore. We set it to 68, and it wouldn't get below 73-74. Air out of ducts is room temp, so it seems like the system is just circulating ambient air and not actually cooling anything.

I did take out the compressor capacitor and tested it. Its producing 45/5 Mfd as expected... so its not that. The coils are not getting cold, and I don't have the capabilities (or desire) to test the compressor itself, or test pressures. Besides just having the tech come back out, which yes I am going to have them do, any other suggestions in the meantime?

I did notice a (maybe new?) sound from the compressor unit, sounds like a high pitched humming. In my other post i explained I rent, and just moved in a few months ago, so this is the first couple weeks of warm temps to use the system. https://imgur.com/a/WzMW85E This is the sound I am hearing. I can't recall hearing this before the tech came out the first time, but may have not noticed it before. Let me know if that sounds normal at all.

My inclination is that refrigerant isn't moving at all. Neither sides of the lines feel particularly cold, or hot, and seemingly no condensation occurring at the coils.

Would love to hear suggestions. I know the tech can do what they need, and can solve it when they come by, but just looking to learn some new things. Would enjoy hearing anyone's thoughts or insights.

I am a homeowner with a heat pump + gas backup (gas furnace's blower motor is used for the heat pump too). There is a HZ432 zone board with 2 zones wired up — the zones are the first floor and second floor of the house. Things have been working mostly fine since we had the heat pump installed last summer (replacing an old AC unit that had died) and we have felt some airflow from all registers at various times.

However, sometimes I seem to hear a louder-than-average whooshing/whistling noise coming from the furnace. When this happened today I took at look at the furnace (located in a first floor crawlspace) and here is what I noticed:

• I felt quite a bit of air leakage from small gaps where the coils/ducts are attached to the furnace.
• The zone board showed a green light for zone 1 and red light for zone 2, as well as a green fan light. Both zones have Ecobee thermostats and when I checked the Ecobee app it said that both were calling for fan only (Ecobee has a setting to run the fan for a few minutes each hour to circulate air).
• I also tried putting my hand near registers on both floors and I felt no airflow (or just a tiny bit, almost none). I noticed a red light at the second floor damper (unfortunately it's located behind a grille in a closet and difficult to see a label for what the light means). I didn't see any lights at the first floor damper, which is adjacent to the furnace.
• As I was watching it, the fan light clicked off, both zone lights went green on the zone board and the blower stopped running.

This makes me think that sometimes both of the dampers might be closed at the same time, causing the fan to force air out of any small gaps in the system, and seems like it could be bad for the system. Or something else is going on with the dampers that I don't understand. Is this something to be concerned about? Is there anything else I should try to help diagnose the issue?

AC unit started doing this out of no where recently. Any ideas on what’s going on? Unit has been off since this video to prevent damage. Nest is giving a Y (cooling) wire error code after it fails to start up.

I live in an apartment and the tenant before me left behind an Insignia Portable Air Conditioner. It works well, however, it leaks a lot of water. The portable AC has 2 drain ports in which water comes out of both, causing it to leak all over the floor. I have 1 drain hose covering 1 drain port that I have going into a bucket, but the other drain port just leaks water. If I get another drain hose will this solve the problem and is this safe? I’m not sure if it’s safe to have 2 drain hoses because I have zero knowledge on this.

American Standard in specific. Looking at one so i can run my generator.

I have a rheem furnace 2013-2015 and a 1990 trane xe 800. The pipe on the ac is freezing up and has ice all on it, and our indoor blower doesn’t function, what should I try first to repair it?

Looking for a new hvac system for my 2600 sq ft ranch house. Considering heat pump but idk if it is sufficient in winter. Have a 2 ton ac unit right now.

Any businesses or brands recommended for the area?

I'm trying to understand more about a concern about getting a high efficiency (rebate eligible) heat pump.

We have ducting running between the first and second floor of our house, all in conditioned space only. It has about 13 vents, some going up from the second story floor and some going down from the first story ceiling.

In getting estimates for our heat pump, one contractor has said he has seen multiple other houses have condensation issues from high efficiency units. I'm not sure I understand. If I get a 3 ton unit with a HE heat pump, to replace a 3 ton unit, what would cause the condensation? Heat pumps don't put out extreme temperatures, generally, so the temp difference in the ducting would be low. I tried multiple ways to get answers out of the contractor but ended up still confused. Is there someone who can help explain the potential issue here?

I have a leak in my suction line and because of the area it's in i need to use press OR replace the line set and run on exterior of home. So I've cut out the bad section of pipe (there was a solder joint right next to the pinhole ) I already own an m12 press which i believe should be compatible with rls jaws and rls fittings

Next, i can't figure out what pipe to use It's 3/4 OD. Initially i was going to just use some copper i had around the house. But 3/4" in plumbing is not 3/4 OD

I'm pretty sure i can buy 50-100 feet of tubing, or chop up a full line set online or supply house

But can't i just buy a foot from somewhere? Even an 8 foot section?

Good Afternoon,

I would like to install a Midea U Smart Inverter Window AC with MShield in my bedroom.
Right now Costco has the 12,000 BTU and 8,000 BTU units on sale.
I want to make sure I get the appropriately sized unit, reading here has taught me that there is no benefit in over-sizing the unit.
I think 8,000 is the right move but want to make sure I am correct.
Room details are below.
I appreciate any help, thank you!

room is 305 sq ft
height is 7.25 feet
1 south facing window
1 north facing windows
2 west facing windows
poorly insulated
1950 built house
IECC climate zone 4A - mixed humid