HVAC VAV boxes

[2359Damon]

This is one of the worst demonstrations of what a VAV box is. There are several types of VAV boxes and that was not identified from the beginning. All you really showed was the operation of a heat strip. Call it what it is. What an idiot. Was it a pressure independent box? Single duct? What was the inlet velocity pressure requirement? DDC? Some people know just enough to be dangerous........

[RhythmicStorm]

At the begining of the video you say that this equipment removes humidity !

Perhaps it reheats the air back to set point if additional cooling is required to dehumidify the space. Heating the air does not remove humidity.

[MrDodgelove]

Maybe one day you can do piu units

[Swedediesel]

what is this VAV box for? is it only electrical heat strips in there or is there some heat exchanger too? i mostly work on small split heatpumps so i don't have much experience from larger HVAC systems.

[DrZarkloff]

@Swedediesel This particular VAV box has electric heat strips. It has a damper that opens when there's a call for heat or cool and closes when there is no call.

[Swedediesel]

@DrZarkloff so it's just an electric heater with a damper that controls the airflow? there is no evaporator or condenser built into this?

[DrZarkloff]

@Swedediesel That's exactly what this is. Some chillwater and boiler water VAV boxes are fan coils that have the cooling and/or heating coil inside with a variable speed fan.

[death2opposeme]

very good vid, i had to subscribe to your channel. i wish you would have explained the control board in detail on this vid. id like to know more about the ac - dc or dc - ac, opto's and bridge rectifiers etc. im 25 btw, and only a little over a year into the service side. i love hvacr, just right now its not paying to good. have to start from the bottom i reckon.

[DrZarkloff]

@death2opposeme Thanks for watching. I'll try to do a more detailed video on the control board some time.

[helphvac]

Hi Dr.Zarkloff!!

I am learning HVAC, a bit old student but I love it. Your video has helped me very much! Thank you for all your uploads on the videos. I visit your site everyday to learn, and while I am at it, I click on the ads too. Do you answer to questions if I post them? Your videos are really great and you explain it so well. Thank you again! Have a great day :)

[DrZarkloff]

Thanks for watching and clicking on the ads, too.

[richgriffin77]

I was hoping you'd do a VAV show! My facility has even more basic boxes because it's in Hawaii and doesn't need the heating function. I spend alot of time in the ceiling with them because the volume dampers are underdesigned for the operating pressure in one building and continually blow the damper apart or even strip the damper shaft from the armature collar.

I've learned a lot of ways to jury rig them until the HVAC techs show up! I dread that banging sound in the ceiling.

[DrZarkloff]

I feel you pain. I wish the engineers would figure out a different way to install the VAV boxes. Cramped ceilings are painful.

[winkhvac]

nice video dr. z

never see that before

[ballejosRB11]

i m an hvac technician as well i do mainly comercial resturants what would you need a vav box for and how does it work

[richgriffin77]

ballejos, the Good Dr. could answer this better, but basically a VAV box is used if you have a building with many zones with different heating or cooling needs that are served by one air handler. The VAV box controls air volume to a zone and branch ducts from it have smaller dampers that restrict or bypass the air to an indivudual room.

[richgriffin77]

So the supply air temperature from the air handler is constant when cooling, and the 'temperature' is controlled by changing the air volume at the box and dampers.

[Reznik83]

Hi Dr. Z just found your videos, I'm going to school right now on HVAC-R and was wondering do you just make videos on A/C and Refrigeration or do you do Furnaces to?

[madtairam]

excellent, thanks.

[local614bro]

Does it have t-stat or t-mister on the board (or inside cabinet) if not what controls it?

[DrZarkloff]

It has a t-mister in the duct. I'll have to include that in my next video.

[V8Jagnut]

good vid but i would like to know more on them.

[DrZarkloff]

Thanks. I do plan to make more VAV videos.

[itscool1968]

whares the cover for the control box ?

and ya like putting youre fingers a little close to the power termanals dont ya:)

we dont need a charge out of jim vidoe:)

[DrZarkloff]

I took it off for the video.

[wirejacker]

good call, i think i would have used a pencil or something. i was thinking - what if he sneezed or had a spasm from breathing in too much R22 over the years !

[itscool1968]

chevy s 10? whares my rocking chevy van creaks and rattles and all:)

[DrZarkloff]

It's hard to keep the camera steady in my work truck. lol

[mechanicwarrior20]

you should make a video about how VAV boxes operate and the theory behind them.

[DrZarkloff]

Thanks. I do plan to make more VAV videos.

[mechanicwarrior20]

Owe those VAV boxes bring me back memory's

I remember last year I had to rewire about 20 VAV boxes because the installers did not correctly wire up the VAV hot water proportioning valves " three wire control" or the hot water perimeter heating on off control " two wire control" since it was tied in with the VAV box controller.

that was when I worked for that university.

[rolando7120]

which university did you go to?. I'm an associates graduate but the only HVACR univercity i know is Ferris State in Michigan.

[mechanicwarrior20]

In Canada it's a bit different however I attended NAIT ( Northern Alberta Institute of Technology) and have an HVAC Diploma.

[eggman9713]

VAV with electric reheat. I hope power is cheap where this is located. Typically up here when I design a VAV system its hot water reheat. I don't think I have ever designed a VAV electric reheat system come to think of it.

[DrZarkloff]

The school board has many types of VAV systems. Some have the chillwater and hot water from the boiler going to them. Some have just the hot water going to them. This one is about as basic as they come.

[PX213]

An Enviro-Tec box. I used to rep these in Louisiana. I'd recognize that logo on the door tag anywhere.

Just a standard SDR-EH?

[DrZarkloff]

Bingo. I know that it's an Enviro-tec box. I'm not positive about the model number. I'd have to look. More than likely, you're right.

[suprservtech]

great video thats the first vav i have seen in fla

[DrZarkloff]

They're very common with chillwater systems, like this one.

[pclle]

are belimo actuators popular down south?

[DrZarkloff]

Yes, especially as a replacement actuator.

[67tr876]

great vid man

[DrZarkloff]

Thanks.

[101heaters101]

Good Video Dr. Z

[DrZarkloff]

Thanks.