Large air handler maintenance.

[davidtaylor]

Do y'all mind if a noob ask some questions? The hospital where I work recently gave me an opportunity to work in the HVAC department but the training I received from the local community college didn't cover large air handler maintenance.

[beenthere]

Made this its own thread.

[btuhack]

Ask away.

Get your post count up for pro status...better answers

[Paul Bee]

What do you want to know?

[timebuilder]

Specifically, what difference between what you were taught about smaller air handlers do you feel might not be sufficient for a larger unit?

Target your question, so we can fashion an answer.

[dandyme]

ya'll skeerd 'im off



if my crystal ball wasn't in the shop getting repaired, I'd be able to tell ya'll what the ??'s were

[timebuilder]

ya'll skeerd 'im off



if my crystal ball wasn't in the shop getting repaired, I'd be able to tell ya'll what the ??'s were

Holy cow, if we scared him he needs help working in a hospital environment, lol!

[davidtaylor]

Sorry everybody. I was trying to reply to a thread about pillow block bearings and and started a new topic by mistake.

But since I got you all here...

I was looking for advice on the proper way to grease bearings and how often.

When I inspect the bearings what signs should I look for that would tell me they need to be replaced?

[spyder00087]

to check the bearings you need to loosedn the motor on its track to allow some slack in the belts. Rolling the belts off will strain the bearings or break something. once the belts are off try to move the shaft up and down (blower). if there is play then the bearings are shot.
also ensure the blowert wheels are clean, the motor sheave and pulley have no grooves, and proper tension on the belt(s). a belt tension tool is good to have.

[timebuilder]

Check the bearing manufacturer websites for info. Browning and Fafnir are major makers. Different theories have emerged over the years about how much and how often. The air handler manufacturer may also have info.

[dandyme]

I thought we had beat this into submission.............


bearing manufacturer is the best source for the amount/interval info

it will be dependent upon environment & usage

[western]

I've grease bearings every 3-6 months depending upon environment about 1-2 squirts. I usually check for any play in the bearing and use a laser to check for any gain in heat. Obviously any noise would be a red flag. I heard people use ultrasonic equipment for checking bearings anybody have tried these?

[flange]

on newer units, bearing lube info is in submittals, and usually posted in fan plenum. if not, call manufacturer and get type of grease and frequency, usually dictated by load and/or rpm's of supported shaft.

[snipe70e]

I've grease bearings every 3-6 months depending upon environment about 1-2 squirts. I usually check for any play in the bearing and use a laser to check for any gain in heat. Obviously any noise would be a red flag. I heard people use ultrasonic equipment for checking bearings anybody have tried these?

This is a good start. I never loosen and remove the belts, our crew is not that big. Check the shives , belts. Bring a rag with you. Wipe the grease fitting before and after greasing (I know it is basic, but). When done with the fan wipe any grease off the outside of the bearings. Spin motor and fan by hand felling for any rough spots. If the fan has discharge dampers check their operation. Check motor bearings. Check motor starter or drive. Yearly megg the motor. Take a set of amp readings. If motor has a starter take voltage readings accoss the starter. Clean fan plentum and check filters.

[btcstudenthvacr]

This is a good start. I never loosen and remove the belts, our crew is not that big. Check the shives , belts. Bring a rag with you. Wipe the grease fitting before and after greasing (I know it is basic, but). When done with the fan wipe any grease off the outside of the bearings. Spin motor and fan by hand felling for any rough spots. If the fan has discharge dampers check their operation. Check motor bearings. Check motor starter or drive. Yearly megg the motor. Take a set of amp readings. If motor has a starter take voltage readings accoss the starter. Clean fan plentum and check filters.

Same boat here, I am a one man band. I do the same as above but I change belts yearly check bearings after the old belts come off...I grease every 6 months. I prefer to use mobil 1 synthetic grease. Burnt contractors due to cycling are about all I normally find with good maintenance.

[Tech Rob]

The most important things are usually the most simple.

Look around and listen. Thumping, grinding, whistling, squealing, vibration, etc. are all abnormal conditions for any air handler, large or small.


You cannot use just any old grease you have laying around for everything. One could write novels about lubricating bearings, but basically, you just have to know 3 things:

• What kind of grease is in the bearings? What does the manufacturer recommend?
• How much grease to use? Most manufacturers call for a certain volume of grease to be added. You have to know how much grease your grease gun will pump with each stroke relative to how much the bearing needs.
• How often to grease? Determined by the rotational speed, size of the bearing, environment, temperature, wet or dry... You get the picture. Every application is different so there is no rule of thumb.

Keep them clean. Don't be afraid to put your waders on and climb in there with a shop vac. Scrape and vacuum everything. Wipe the excess grease off of the fan bearings and make sure that you can get at everything safely. It's not a glamorous job, but take pride in it anyway.

Until you get more experience being around large commercial equip., I wouldn't worry too much about controls, meggers and such.

[western]

Another very important thing is to check the cleanilest and integrity of the blower wheel. Especially on older units. Bearings, motors, pulleys may be availiable locally but shipping in an oem blower wheel may down a unit for days or a week.

[davidtaylor]

Thanks for the responses everybody. Tech Rob, luckily I'm training with a veteran who does exactly what you recommend. When he was hired over two years ago he had the responsibility of maintaining equipment that hadn't seen a grease gun or a filter change in years. He is always stressing the importance of keeping up with the PM schedule and that "good enough" isn't always the best approach.

It's a challenge to an older guy starting a new career but I enjoy it and I'm learning more and more every day.