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We didn't have a HVAC thread so here goes. I work primarily on large commercial and industrial systems, so the majority of my contributions to this thread are going to be that. This thread may or may not me an excuse for me to post pictures of all the cool stuff I get to work on, but feel free to contribute or ask questions about your system. Just a few primers: * Never disable any safety devices on your HVAC system. They are there for a reason and you can burn your house down, die, be seriously injured, or all of the above if you disable them and something goes wrong. * Refrigerant sprayed/leaked onto your skin will give you frostbite and is made up of hazardous chemicals. Do not mess with the refrigerant side of systems unless you know what you are doing. * Electricity is dangerous. Seriously. It will kill you, and it will hurt the whole time you are dying. Again, if you don't know how to safely work with it, DON'T. Always turn off the power to whatever you are working on. Buy a quality meter and learn how to use it BEFORE you touch live electrical. * Gas leaks will blow your house up, burn it down, or burn you. Shut the gas off before you take any pipes apart and make sure the space is well ventilated when opening up any lines containing fuel gas. * Youtube will not teach you everything. Just because you see someone do something in a video doesn't mean it is the right way to do things in your particular case. I am not liable if you break something and it costs you your savings to fix. This video is a good primer on how A/C systems work. It doesn't teach you everything, but you will learn the basic concepts. https://www.youtube.com/watch?v=_lFUlA1PZ8U The systems I work on the most have a capacity 150-600 times larger than a standard unit you would have at your house but they work using the same basic principles. Most of the time they are chillers, which chill water which is then pumped through the building to coils like the evaporator described in the above video. I do work on smaller units, but not as often. I work in rooms like this a lot:  Sometimes on huge boilers half the size of a city bus:  Other times, it's large fan blades for a cooling tower:  Motor bearings on a 540 horsepower electric motor off a chiller:   Sometimes it's coils so clogged with bird poo poo that the machine won't run due to lack of airflow:  Or just a simple gas valve replacement on my parents' heater: 
iForge fucked around with this message at 06:11 on Jan 24, 2016 |
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Jan 23, 2016 05:17
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Just some pictures of what I am working on right now. It is a teardown/rebuild of a centrifugal compressor 450 ton Trane Centravac chiller. The rating of tons is not weight, but the heat transfer that 450 tons of ice melting can do in 24 hours. Some of these parts are aluminum and weigh 50-100 pounds. Others are steel and weigh upwards of 1200 pounds.       Hung my hat up for the weekend. 
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Jan 23, 2016 05:35
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ExplodingSims posted:Oh cool, and HVAC thread. I guess I can contribute here too! I have never worked on an ammonia system and as far as I know, we don't have any customers under contract that have ammonia systems so I won't be touching one any time soon. Glad to see someone else in the trade contributing, I've done very little with commercial refrigeration so feel free to talk about that all you want! I mostly do large tonnage chillers, cooling towers, packages, splits, and the occasional boiler.
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Jan 24, 2016 06:07
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Thanks for doing that, I was going to get around to writing something up eventually. Well done!literally a fish posted:Someone bring me a Rolls-Royce Merlin. I found a better supercharger. Could have gotten a slug of oil in the wrong spot from being upside down and bent/broke something when it started, or it could coincidence and just died. Send me a video of it on whatsapp if you think of it.
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Jan 24, 2016 22:09
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slap me silly posted:I'm just here for the pictures and boy are they awesome. I don't know much about residential codes and installs since I do commercial/industrial, but I'd imagine it's a small unit with a/c + gas heat like my apartment. Also, have some pictures of a failed babbit sleeve bearing and scoring on the shaft! This bearing was absolutely bone dry, but that doesn't make sense as the system won't run if it doesn't see oil pressure and there were no clogs in the 3/8 line that feeds oil to the bearing. The pressure transducer 10 inches away from the bearing tests fine. More investigation required, but now to figure out how to get a 1600 pound motor out of this basement, crate it up, and ship it to North Carolina to be rebuilt. Fun fun! Shaft diameter where the bearing rides is around 6.5 inches.   The lighter scoring is from the labyrinth seal rubbing, the deeper scoring inside that pocket is where the bearing sits. 
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Jan 27, 2016 23:10
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Nice work, Sims! I've been busy as hell and not doing anything picture-worthy. Parts came in for the motor on that Trane Centravac I've been working on, so reassembly starts tomorrow. I'll snap pictures if anything interesting arises
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Feb 8, 2016 04:13
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very nice! I'm just starting a rebuild of a 1280 ton centravac at a hospital. Trane had it apart 3 years ago to do bearings but its leaking so the hospital is having us come in and fix what they didn't get right. Going to be very interesting, the motor weighs 3200lbs and there is very little room to work.
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Feb 24, 2016 22:16
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I haven't been up to anything worth posting, really. I got pulled off that chiller rebuild job, so no pics of that. Spent almost a month at a data center going through 96ish 30 ton Liebert units, 10 air handlers, 3 rooftops, making a list of the needed repairs, and then fixing most of the stuff. Not allowed to take pictures in there by their security policy so I don't have pics of anything. Mostly replaced chilled water valve actuators, bearings, and fixed a few leaks on the coils.
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Apr 10, 2016 15:26
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Ive been working at secure sites a lot lately. Can't have a phone in those datacenters, so I can't take pics of the stuff I find. Prepped a motor to come off a chiller today. 4160v ~800hp motor was smoking over the weekend so they shut it down. They had a company come out and test it in place, but we all knew it would have to come down. It is grounded and needs to be rewound, and the customer wants to buy spare motor from us just incase this happens to one of their 5 other identical chillers. The new motor is probably $70,000, and the rewind is probably $30,000. Add in labor, and this breakdown is costing them (ballpark) north of $110,000. Business is good.
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Jun 2, 2016 03:44
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Tore down a compressor off a Vilter low temp chiller at a local ice arena. I'm guessing that it got a slug of liquid. All pistons, liners, and the crankshaft are a loss. It will get rebuilt next week when the parts come in, but I'm not sure if I will be there for it.   
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Jun 11, 2016 22:12
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angryrobots posted:Good idea, worth a shot but no dice. Still misbehaving. Check that the relay or contactor is staying pulled in, and if its getting a steady 24v. Ran into a bad transformer last week that was causing a similar problem. Check all electrical connections while you are in there as well.
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Oct 16, 2016 04:27
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Seconding proper disposal of that thermostat. Most HVAC supply houses in my area take them off your hands for free and properly dispose of them. YMMV
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Jul 13, 2017 16:14
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davebo posted:We moved into this much-larger-than-my-old-house house in April, and as expected it was nothing but problems, but at this point most of those have been fixed or replaced. Got a new HVAC unit for the upstairs which was very efficient keeping it cool in the Summer, in terms of electric costs this 4,100 sqft house wasn't much more than my old 1,500sqft. Now that things are cold I got hit with a $450 electric bill last month, and realized that the thermostat wasn't set properly to gradually ramp up the heat pump, so it was defaulting to auxilliary heat. So we got that sorted but when it gets cold it's still resorting to auxiliary a fair amount. I'm keeping track of Pepco's daily usage on the website and it's definitely less than last month, but not by as much as I was hoping. So my first question was just does that sound normal for a large house built in 1957? I probably need to have the insulation in the attic redone and that might help. Sometimes you can smell some burning dust the first few times you run a gas heater for the season. If you smell gas or fumes get a qualified hvac guy to check your heat exchanger for cracks sooner than later, if you smell fumes, you could be breathing carbon monoxide. As far as your first question, where do you live? Us knowing the current outdoor air temperature for your area is important for the answer you want
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Dec 12, 2017 22:41
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Turn off the power to your furnace first. Verify the blue isnt hooked to anything already and land it on the C terminal. Hook the other end of blue to the C terminal on your new stat, turn power back on. If you have questions, post a pic of the control board where the thermostat wires are connected inside your furnace. IMO the nest stats are better than the ecobee, but pick whichever you want.
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Feb 7, 2018 15:02
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Charles posted:No I think I'll get another quote then. Is this just for a/c or are they replacing the furnace as well?
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Feb 12, 2018 16:50
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US Motors has their Rescue brand line for rare and hard to find replacements for old systems if you cant find a universal replacement for yours
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May 4, 2018 02:36
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Dandywalken posted:Is this an ok thread to ask about getting into the service -side of HVAC as a career, or is the A/T forum better suited? Fire away
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May 25, 2018 01:59
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Seconding the Union apprenticeship, I got a ton of knowledge out of mine. Depending on your location relative to harrisburg, the philly local is huge and has plenty of work. Some trade school or community college courses will look good on your application, but as was already said, the UA is realizing that a lot of guys are retiring in the next 10 years with not enough techs coming in to replace them so a big hiring push is coming.
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May 25, 2018 16:10
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DkHelmet posted:Welp, my AC unit is dying. I've been getting water buildup inside the furnace and my AHS contractor just declared the evap coil and drain pan dead. Since the unit's 25+ years old I'm not crying too much, but it's not worth it to replace 6 lbs of R-22 on a 25 year old condensor. While I'm in there I'll get the furnace updated for something made this century as well. I personally do not like goodman units and prefer to go with the ICP (Carrier) offbrands. Arcoaire is a really good unit for the price. I put one in my parents house (3 ton) last summer and came in just under $3000 for parts (did not charge them labor.) I'm going to go ahead and ballpark that you were given a price of $9500 if it was a big name, a bit less for a smaller local contractor. Whatever you have installed, I recommend you have them add a low pressure cutoff safety if the unit doesn't have one. They cost like $15 and take 3 extra minutes to install, and if all your refrigerant leaks out the compressor doesn't run till it dies as well. Many residential units don't come with them. If you want to PM me pictures of estimates I can look them over. iForge fucked around with this message at 03:02 on Jun 1, 2018 |
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Jun 1, 2018 03:00
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It doesn't look that dirty, you are likely experiencing a loss of fan or low refrigerant charge. Set your thermostat very low so the unit doesn't shut off, make sure the fan is running, and let it go for an hour or so. You might need to leave the system off for a couple hours to let the house warm up. if it still ices up and you know the fan is running and you are getting good airflow, you know its a refrigerant issue. While it is running for a while, check the larger of the two pipes that go to your outdoor condensing unit. If the larger is "beer can cold" you are in the ballpark for proper refrigerant charge. Its not an exact science that way, but it sounds like you don't have the tools to do the proper tests. You can buy some no-rinse evaporator cleaner off amazon if you can get in there to spray it. Don't get it in your eyes, wear goggles, etc.
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Jul 2, 2018 21:34
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mcgreenvegtables posted:I had it set to 75 because I knew it would never get that low. I woke up and the thermostat read 78 and the coils were frozen over. Also forgot to mention the cold side line at the compressor was frozen over as well, for the inch or so that wasn't covered by insulation. As long as you don't bend the fins, go hog wild with the brush.
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Jul 5, 2018 02:32
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mcgreenvegtables posted:Update if anyone is interested. Refrigerant and other parts are commonly marked up by contractors but $140/lb is absurd. If memory serves right, I pay around $22/pound for R-22 last I bought it around a month ago. If I was doing the repair, I would have charged no more than $40/pound. I'd find a new contractor.
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Jul 6, 2018 01:36
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Jaweeeblop posted:
Very possible that I am remembering wrong, since I buy with a corporate account and don't really have to pay attention to price. I did just look and we sell it to the customer for $30/lb so we must get it well under $22
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Jul 9, 2018 18:04
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kid sinister posted:Eh, as it turns out, the original company that installed it didn't go out of business like I thought, they just moved to the other side of the county. The must be somewhat reputable if the guy was trying to upsell me to Amana. 99% certain that is going to stand for max working pressure 680 (PSIG).. Without you having the tools to take the necessary measurements anything we say here is really spitballing. However, I find it odd they were adjusting a 7 year old txv. Generally the failure modes of a txv are that the head/sensing bulb lose their charge and dont work at all, or the screen in them plugs up and restricts flow. Otherwise, there isn't really anything else to go wrong. Sounds like the guy was just trying whatever he could without knowing for sure. I recommend getting a reputable company to come look at it.
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Aug 8, 2018 02:15
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kid sinister posted:So I did that. I got the original installers out. The stupid thing just needed refrigerant. He had to reverse what the first guy did, but now it's blowing cold again! Cheap too. Now just bear in mind, systems don't consume refrigerant, so that means you have a leak somewhere and unless they fixed it you will have the same problem anywhere between a couple months to a couple years down the road.
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Aug 10, 2018 01:56
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kid sinister posted:How bad does that happen compared to a car AC system? Car ACs bounce and shake around a lot more, so some loss is expected over the years. It depends entirely on the size of the leak and where it is in the system as you can imagine. If (when) it happens again, decide if its worth it for you to have someone spend the time to find and fix it, or if a top-up every year or every other year is better.
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Aug 10, 2018 23:23
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Pimblor posted:is it fair to say car ac units last as long as they do thanks to the rubber hoses in-between the hardpipes? That rubber is a requirement. Your engine is on somewhat flexible mounts and will move around a little bit, so there has to be some flex in the lines that go to the condenser and the evaporator. If everything was hard piped, it wouldn't last a week.
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Aug 11, 2018 13:12
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the third option is going to be your best bet to stop that oil can effect. You can use some thin flat bar or angle iron from home depot and screw it to the outside of the duct where it is flexing.
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Nov 22, 2018 15:24
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Check filter once a week, change as needed until conditions improve. Using a lovely fiberglass filter increases your risk of clogging up your a/c coil, as well as having a lower indoor air quality. I end up changing mine every 2 months, and I get the filters in bulk for $3 each
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Nov 27, 2018 14:46
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Big K of Justice posted:Hey, I'm poking my head in here looking for vacuum pump recommendations... Yellow Jacket is the gold standard for HVAC pumps. I prefer the 6cfm 2 stage "superevac" model (part number 93560). It is on the upper end of your price scale but they are robust and I have evacuated everything from residential split systems to centrifugal chillers with the two I have. If you have a friend with access to account pricing at a hvac supply house or grainger you will likely get it cheaper than online. United Refrigeration had them on sale for $415 in December, unsure what they are now.
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Jan 29, 2019 03:41
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Kaiser Schnitzel posted:Following up on this, as I'm looking at replacement fans, does static pressure matter at all if I'm just trying to exhaust the hot air from the building/generate through air flow? Should I just be looking at CFM at 0" static pressure or is there a certain amount I should be looking for? Math says the building is around 75,000 cu. ft. so I've been looking at something 15-20000 CFM for a 3-4 minute air change. Replace the motor with the same horsepower and speed that it originally had. You can buy and mount a larger motor pulley to speed the fan up. You will have to buy a longer belt as well. you can use this calculator to experiment, I wouldn't recommend going any more than 10% faster. iForge fucked around with this message at 00:53 on Mar 29, 2019 |
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Mar 29, 2019 00:50
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MRC48B posted:non comedy option: This one will do nicely.
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May 30, 2019 23:42
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| # ¿ Apr 26, 2024 01:31 |
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SourKraut posted:Thanks! I'm just nervous how it compares against a 100% speed unit, something like a vacuum cleaner, etc., since we have a dog who has a seizure disorder and hates certain high-pitched whines. She can easily lay outside though when our existing old builders-grade 100% speed Goodman unit is going 10-15 feet away. Let me preface this by saying that while I do have some knowledge here, I am not a residential tech. I do commercial/industrial service work. Bear in mind, the more expensive your install, the longer it takes to break even on energy savings. The more complicated the equipment, the more parts there are to fail at some point, and the higher the cost of those replacement parts and the labor time to troubleshoot/install goes up as well. I tend to lean more towards simplicity rather than energy savings for the long haul. That being said, if I were to pick one, I would go with company 2 option 1. You are getting a much longer labor warranty with a company that has been in business for a long time and will most likely continue to be in business for the length of your warranty. The equipment quality of that option is on par with the rest of your options and you have a cheaper install cost with similar energy savings through variable speed components. A residential tech may chime in here and correct me, thats just my 0.02
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Oct 20, 2019 14:29
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