HVAC Belt Tension
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- Опубліковано 10 лип 2024
- Bryan explains how to install and adjust belts. Belt tensioning is a critical part of commercial HVAC work, though they’ve slowly been disappearing as blower motors and fan motors become more direct-drive.
A common belt myth is that you need to tension a belt so that it has an inch of deflection. Many factors can affect deflection, including the pressure you apply to the belt, the belt’s length, and what the belt is made of.
There are no hard, fast rules of thumb for working with belts. However, we recommend using the Browning app to help you if you’re unfamiliar with belts and typical procedures with them.
If you’re working with an adjustable drive pulley (sheave), DO NOT adjust the pulley itself to set the belt tension. Instead, you have to adjust the foot mount on the motor to set the belt tension. Before you replace the belt, check the pulley condition; the problem could lie there, not with the belt. Replace the pulley if it is damaged.
When you adjust the two halves of the pulley closer together, you can expect more airflow. When you adjust them to sit further apart, you decrease the airflow. So, you must measure airflow to set those halves correctly. We don’t typically adjust those in the field, but we have to adjust the motor base inward if we want to replace a belt.
When the old belt comes off, we want it to be loose. Of course, we must also put the new belt on loosely and tension it appropriately once we finish the replacement. You’ll want to avoid overtightening the belt, so a tensioning tool will be especially effective here.
A proper tensioning tool allows you to apply a set amount of force and then look at a fixed amount of deflection. Browning makes a tool specifically designed for this purpose. (Product link: www.regalbeloit.com/products/...)
You should not set your belt tension based on blower amperage; the blower motor could run well below its peak conditions. Instead, you want the belt to be as tight as possible without slipping or squealing under peak-load conditions. Overall, if you need to do significant adjustments, you may as well replace the belt. Always inspect the whole system if there is slippage, too.
Browning belt tensioning instructions: regalbeloitliterature.callmss...
Browning video on How to Check if your V-Belt is Properly Tensioned: • How to Check if your V...
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I needed this. Thank you Bryan.
Here's a tip I learned from my Boss, even though he isn't a mechanic. He learned it from a mech in AZ. I've used it successfully a number of times. Presuming the pully isn't totally warn out, just shiny, you can clean it and re paint it. I use rattle can primer and rust oleum. Works well, I have fixed rigs that would slip the belt no matter how tight( new belt ). Down side is it needs to dry for a day. But, if you can't get a new pully for some reason....
Being in S.FL and the FL. Keys. Most of the time I was adjusting the speed and the charger but now after this.🤔🤔🤔😎 I will follow the recommend advice 👌👍😉😀 thanks 😊
Good Topic ! Good video. ( Ftngot ) after doing this for 40 years ive found that overtightning a Belt WILL Do Far More damage than a Slightly loose Belt.
Overtighning - WILL damage / destroy Bearings
Undertightning - a Belt May slip at times. creating little to no damage. maybe a Pulley replacement overtime. alot cheaper than bearing job or motor replace.
ive Learned in 40 years to just replace Belts When they get stretched. i No Longer adjust inexpensive belts anymore.
Cheaper for customer & better.
also - when possible - use a belt tensioning guage as seen in this video to get it right from the get go.
Tech tip - Clean the Groove - Use a Wire brush & use sandcloth to remove the shine off Belt Pulleys for a better Grip.
Tech. tip #2 - a Cog belt will Get a Better grip than a standard belt. Try a cog belt if u have one that slips under proper tension.
Thank you so much for this! I hate to admit, I don't know much about the details of mechanical systems; so seeing the way the belt did not flex much at all helped me realize, whoah crud this belt was way under-tensioned. Was squealing like mad; now not squealing anymore!
I have an old furnace that hasn't seen a tech in 20 years. I hear a clunk occasionally whan blower starts, so I want to inspect the onit, and check belt tension. I like your common sense approach to belt tension, so that's what I'll do.
thank you sir for the time and knowledge you spend on the video's really appreciate it. I learn more here than my job which is bad lol
Great tip on the Browning app!
Great tips. Thanks Bryan
spot on! I did not know about the pully gauge, added to the tool list.
Good job Bryan thanks for bringing this topic up. My $0.02 - First decide which you, and your customer, would prefer to replace the belts or the motor. Belts are cheap, replace them e'rry 6 months, preferably during the biannual inspections. If the belts are set too tight the bearings will take the hit due to load, if the belts are sloppy loose or the sheaves are worn the bearings will suffer due to shock. If the belt is riding on the bottom of the sheave the sheave needs to be replaced, the belt should ride on the sides of the sheave. When rolling the fan the belts should fide smoothly through the sheaves, if the belts get stuck in the sheave the sheave needs to be replaced. Most belts are made of Kevlar so that belt dust will eat the bearings if it gets in them. Never roll belts on or off, that can set them up to do weird things like flipping over while running. ->I've seen that.
Don’t roll on or off the belt… every tech in the field 👀👀👀
agree
😂 😂😂😂
Hey Brian great video do you think you can post more on commercial units and RTU like this one
What he said! 👍🏼👍🏼
ME TOO!
I always check for misalignment with a straight edge because it may look like it's tracking but off just a little, prematurely wearing the belts or pulley.
Tensioning practice is key but if you leave an adjustable sheave in place you're asking for belt alignment issues. Every belt change you should be checking the belt alignment as well as tension. It is also wise to check the rpm of the driven pulley after initial commission or T&B has been done so you can make sure it doesn't change when you you replace a belt or against standards adjust or replace the adjustable sheave. Belt tensiok is only the tip of the iceberg if you want to do it properly
1/2 inch deflection per foot in shaft centers length was what the USAF taught Us decades ago on cv non vs drives
Overtightening a belt will cause all kinds of damage and can get expensive. Undertightening will result in slippage, which is usually detectable.
The modern refrigeration and air conditioning book is key on learning about belt tension...one side should be running smooth while the other side should have a slight flapping to it...hope I explained it right.
Beautiful! "Slight flapping" is a great explanation! Just came to this video after having an AC freeze over, because the belt was not tight enough and far too little airflow was going through the coils; I thought i may need to go tighter still because of this 'slight flapping' but if its to be expected, great! Thank you!
no mention of alignment or checking the motor amps to prevent overcurrent motor damage
If the motor is over amping you can adjust the sheave to reduce amperage correct ? A 50 year old nursing home I recently went out there
The motor had been replaced recently was spinning the wrong direction and more than double fla. the hood filters get sucked up against to roof of the hood. MAU Gutted make up air. Who knows what the original hp motor and cfm was, but I did check the up draft in the hood by pouring a pitcher of water on the hot grill to make sure it was all going up in the hood even after reducing the amps in half to below name plate.
Why can I never get multi-belt systems to have the same tension on every belt? One is always slack no matter how much I line up the two sheaves…!
To increase air flow you want to decrease motor pulley size or no ?
how does the gates ultrasonic works
Tampered with adjustable sheaves can trip motor overloads because motor is trying to push too much air.
👍
Some techs need to learn how to align the pulley. Make one for that.
how you know so much?? WIZARD!!
Had a fun one today:
- Unit would run for a couple hours and shut off.
- VFD showing the error code for motor thermal overload, and locking out.
- Motor not getting hot at all.
- 3 of the rooms with returns for the unit had outside doors that were constantly opening. (In HOU, so this means adding humidity too)
- Megger would read bad leads immediately following a lockout, but given a little time it would return to a good reading.
Anyone wanna take a stab at what it was?
That’s weird. Was it a faulty motor ? I’m curious.
@@Alex-jo2oi Nope, as per usual you get the really weird problems when multiple issues intersect. Issue number one is that the unit wasn't properly leveled, and was a little bit tilted towards the blower compartment. Issue two was that someone had replaced the motor sheave with a larger one than factory and not adjusted it, so it was moving more air than it should have (somehow it wasn't over amping, motor may have been aftermarket as well).
The end result was that it was pulling water off the coil and said water was pooling in the blower compartment. Every morning when it would start up with the occupied signal, there would be enough moisture in the VFD compartment (which wasn't air tight from the blower section) to make it wig out, trip, and lock out.
@@TheMinecraftACMan sounds like a headache
Ahh. “It’s an $11 belt. As long as and the sheaves are aligned. Tension will wear the belt and PM contract will cover a new belt”
Beer can cold and calibrated fingers ,welcome to the institutional maintenance program.
🥃🥃🍺🍺🍺🍿🏌🏻♀️
Stay safe.
Retired (werk'n)keyboard super tech. Wear your safety glasses.8
0:55 he says “rule of thumb”. This is a disgusting phase people use that’s extremely sexist. I can’t believe people use this phrase in 2021. Absolutely disgusting behavior and words like this have no place in a professional space.
lol
Change your name to just a girl