I need a part (high limit switch) for one of my furnaces, but no one local (that I can find) with the part in stock will sell to homeowners. A clogged air inlet tripped the limit switch, and the switch now won't reset.
A couple things, first, very few dealers and even fewer distributors will sell to homeowners. My company does, because I think it's silly and there are better ways to protect your business interests. For example, good customer service and qualified technicians, but I digress. If you can get by for a couple days I can have my office ship you whatever you need. However, and I'm not trying to be condescending, but your diagnosis is suspect. In 20 years of making a living fixing HVAC equipment, I've never seen a limit trip due to a plugged intake, nor is there any connection between the two. Can you share more about the equipment and the symptoms?
Wera bbs needs to take up a collection to create a fund for JBraun for being the beebs HVAC go to guy. Now if he would just make house visits.
Nice to hear, I was looking for a Honeywell board for my furnace a few years ago and you would have thought I was trying to buy nuclear secrets or something. It was literally a plug and play item. Finally had to call a HVAC buddy we work with a lot and he ordered it for me from the supply house while I stood there at the counter and waited. It may have been the biggest waste of time ever. I did get it for cost though which was about 40% off what I would have paid as a walk in.
Yes Daniel Surovets and Alec.... They have taken care of my house and other friends for decades... Call and tell him Perrone sent you... 678.640.7257
He may have been talking about return air, not combustion intake air. I've seen high limit switches trip out with dirty filters enough times, but the only one I've ever had that was a one and done was a flameout sensor on a pool heater.
Don't know the exact part you are looking for but I once bought a Honeywell part for my oil burner on Amazon....paid for the overnight shipping and got it the next day. I'm not an Amazon fan, usually, but it was worth the $$.
Honest question: What's the relationship between furnace efficiency and likelihood of a limit switch failing?
Nothing. Older 80% furnaces are naturally vented. Hence they don't have a combustion air intake like a higher efficiency power vented unit does.
So only 95's would even have a limit switch on the combustion intake, even though he's never seen one fail, correct? That's what I was thinking, but I'm leftside on the whole HVAC learning curve. (Damn new house has two-stage. WTF?! Why is it blowing cold* air?) *relative
Might just be a terminology issue. When he mentioned the high limit switch, I assumed he was referring to the primary limit. It’s installed between the heat exchanger cells to shut the furnace down when it overheats. Usually it's a plugged filter, which may have been the "intake" he was referring to, as @pickled egg mentioned. When I heard that the unit had a plugged intake, my assumption was that he was referring to an intake pipe. High efficiency units are direct vent, meaning they use a pipe that draws in combustion air directly to the burner. 80% furnaces don't have that. If the intake plugs, the unit has a pressure switch that will not allow it to run. It's basically a diaphragm connected to a micro switch that closes at a certain preset negative pressure. All modern furnaces will have a flame rollout switch near the burner compartment, which I suppose could be called a “limit”. It's there as a fail safe, and unlike a primary limit, will not close on it's own. It will either be a manual reset switch or a fusible link thats' one and done. The reason it's needed is that the pressure switches are usually connected to the inducer motor housing, or the collector box, or both. If the furnace has a massive heat exchanger failure, meaning a huge crack, it can pull air through the crack instead of through the intake. The pressure switch will not know the difference, so the furnace will fire anyway. Usually when that happens, the flame will "roll out" of the burner compartment. The switches are there to kill it so it doesn't burn your house down.
By the way, @dsapsis , Your air should be roughly the same temperature on low as it is on high, there will just be less of it. Temp split isn't just for comfort. If the furnace is running too cool, the flue gasses will condense in the primary heat exchanger instead of the secondary. It's not designed to handle moisture, especially acidic moisture, so it will cause it to fail. If the air is that cool out of your vents, it's a red flag. Goodman made a unit that had two stages of burner and only one stage of blower. Maybe that's what you have, but if you do the first stage should be disabled...
Nah. 13 years in Contracting has worn me out. My next venture is education. I want to build a school that turns out technicians that are actually qualified to go straight into the work force. It’s crazy that no one has done it right yet.
I'm in the job hunt/ career change and saw HVAC techs at the company I use for my HVAC needs made more than I did. They don't hire unless you have experience according to the job ad ( which I don't think I believe.) One guy that came out had an apprentice I assume because all he did was stand there and watch. Anyways, I think you are on to something and it would make me take a much more serious look at getting into hvac. If I got into a trade it'd be, learn the trade with the goal of going out on my own.
Sounds like a great business model. Also needed in the forklift industry for good electrical technicians.