HVAC Pressure Controls

[ocotlan2]

can you please post a video on trouble shooting furnaces.

[bertoe59]

Great learning videos.

[death2opposeme]

got anything on "headmasters" or w/e the technical name is??

[DrZarkloff]

@death2opposeme I keep the headmaster request for the next time I have to work on one.

[tkbone69]

nice keep it up...........

[thereceman]

good info. motor protector, havent seen one. thanks

[lubime10]

Dr. Z could you please start with a circuit diagram if is possible, sort of a theory introduction section before you move to the practical section.

thank you.

[DrZarkloff]

Thanks. I try to show stuff that you probably won't in school.

[hvachoyt]

Dr. I'am having difficulty understanding how to calculate Low Pressure Switch(Ranco) cut in cut out, given a evap temp,humidty,TD.A example would be given R134 with evap temp-25-45F.Without a chart is there a way to figure out cut in and cut out?

[dennisthemenaceru]

about setting 375 psig on cutoff switch, when does self release valve opens if the unit has one, on r22 system?

[DrZarkloff]

I don't know what you mean about a self release valve. If the pressure switch opens at 375 psig then it will re-open at a lower psig like about 200.

[dennisthemenaceru]

some comm. rooftop units have release valve spring type i thought it opens at higher 300s-400 psi

[TheBdog2009]

Jim,

Thanks again for posting these video's IM in school again learning more and more about HVAC/R industry and I pass the word along to all my class mates and even my Instructor to help aide in the training process. Thanks again!

B

[DrZarkloff]

Thanks for watching.

[edgardpb1]

can i put a txv in a heat pump

[DrZarkloff]

Many already have two.

[askrd5]

thanks again doc

[tazzjr74]

very cool intro dr z another great and informatinve vid

[DrZarkloff]

Thanks

[Drewsdays]

lol didnt expect the beginning

[DrZarkloff]

Thanks.

[itscool1968]

nice job jim but i i dont like how those black wires flex so easly in the crip on connectors in that switch you showed with the cover off.

[DrZarkloff]

Thank. I had to replace that switch anyway.

[itscool1968]

what was wrong with it in the video it souned like the system it was controlling was running or was that a close by system

and can you make a short video of the fixed switch so we can see how a pro does it:)

[DrZarkloff]

I had the power off at the time. The sound that you heard was the unit next to it.

[DearestBecky]

The green screen looks great. Good going, Babe.

[hvacman77]

How about a Video on 410 systems Dr.Z

[DrZarkloff]

Soon I hope to have one.

[THEtechknight]

I must have missed something, on the fan control, you say its for running the AC in cooler temps. Why do you need to throttle the fan on/off? so it doesnt freeze up?

[DrZarkloff]

Exactly. The evaporator could freeze up with the cooler subcooling and the cooler evaporator temperature.

[cubanito725]

another great video drzarkloff, that's why you're the best thanks a lot...

[DrZarkloff]

Thanks for the compliment.

[Aussie50]

I have a few old control panels from Semi-hermetic compressors with those cool pressure controls and gauges!. the ones I'm not sure about using are the Honeywell Pressuretrol's

they use a wire wound variable resistor and swinging arm (pressure controlled) to send a signal to the control PLC and I'm not sure how to wire them up, do I go for voltage drop or frequency output?

[DrZarkloff]

They probably require the matching control board if the thermistors send an ohm value to the main board.

[V8Jagnut]

very cool vid. keep them comeing

[DrZarkloff]

Thanks.

[mechanicwarrior20]

good video, and may I mention to other viewers if ever notice that a high pressure switch or low pressure switch has tripped, Always make sure to diagnose as to why the condensing unit has tripped on either low or High head. I wish some people would understand that these switches are intended as a safety device.

And should never be just reset continuously if there is indeed a problem.

[DrZarkloff]

Good point. Thanks.

[fyescas777]

That intro was awesome.

[DrZarkloff]

Thanks.

[StinkyBammerHater]

Hey Doc how do I get my foot in the door to work on commercial stuff like you do? I have about 5 years residential installation experience and about one year residential service experience but I want to work on commercial systems because I think that's where more money is at. How di you get started?

[DrZarkloff]

I used to work for a behavior health care facility and a nursing home that did all of the HVAC in house. I was the man with the EPA card.

[leeanator]

Lol..i love your vids

[DrZarkloff]

Thanks.

[MagicPatrick1]

Was that first series of high pressure switches on a 2 stage unit? Say 7.5 ton? Reason I ask, is many have the automatic on the first stage for the simple fact the condenser fan motors are wired to the first stage (5ton) contactor. Then the manual reset will actually lock out the 2nd stage (2.5ton) entirely. If the condenser is dirty, stage 1 loses ground. 2 comes on, 1st trips out, fans shut off and then trips the 2nd.

[DrZarkloff]

I had to replace the first stage compressor some time ago. I installed the auto reset high pressure switch because That's what I had on my truck at the time. It worked out pretty cool for the video, though.

[PutSome5tankOnIt]

I've seen residential AC equipment with the LPS and HPS switches located on the discharge line, downstream of the outdoor coil. That set-up probably doesn't monitor the suction side of the system very well.

Another great video, Doc. That's why you're the best.

[DrZarkloff]

Thanks. The LPS does need to be in the suction line. I've seen some commercial 15 ton Carrier heat pumps with the LPS in the discharge line. I just doesn't make much sense to me either.

[Darvin1964]

Great vid. Thanks

[DrZarkloff]

Thanks.

[cyberlight22]

lol green screen right?

[DrZarkloff]

Yeah. I got Pinnacle Ultimate 12.

[cyberlight22]

cool