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Techman

Techman

Joined on December 30, 2005

Last Post on July 23, 2014

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Old Stuff

@ July 23, 2014 9:37 AM in FREE ,FREE, NO CHARGE ,Schrader Tee.

How old is Charles's Law and Boyles and Watts . Those Laws still apply. Are you a believer now? Or does my 1965 Carrier book need an update. You can still get your FREE Schrader and SGMI , are you ready?

No formula

@ July 22, 2014 8:57 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

how is this? I guess this is a figment of my imagination. Come on ,now your reaching for straws .

No FORMULA

@ July 22, 2014 8:49 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

Hows this.

NO CHART?FORMULA? for SC?

@ July 22, 2014 8:32 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

Read this and tell me again!

FREE

@ July 22, 2014 5:42 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

I agree about measuring the 12* SC at the cond unit, and using the Saturated Temp and then mathing out the #'s to check for the nameplate SC#'s.But what about systems that require a higher SC? You don't leave  a boiler PRV at the factory set point of 12# (SC) for a 1 story house as compared to a 4 story house . So KindaSorta the same applies to the SC, always has!

I always, usually, most times diagnose the refrigerant system 1st. My gauges will tell me if there is a problem somewhere inside the house , then i'll go over that other stuff . 6 of one, half a dozen of the other.
Come on Spence ,send in a picture
Carrier having/using that SubCooling formula doesn't mean a thing?

Refrig stuff

@ July 22, 2014 12:01 AM in Height vs SubCooling vs Freon Charge

ice, the PD comes from flow resistances ,just like hydronics, . The heat of compression is just one of the SuperHeats that the freon picks up on its way thru the comp, and out thru the discharge line, then desuperheating then condensing then SC ,then too muck PD in the LL and there will be "flashgas" and less cooling.

Ice, funny you should mention a Submarines hi press air tanks. On my sub we had 3000 psi air , it was my duty function to open certain valves ,to let in a certain ammount of hi press air, for a certain time peroid ,to raise the sub on a certain angle or on an even keel. Or not, depending on how much trouble I wanted to get into . LOL

SubCooling Carrier Style

@ July 21, 2014 11:42 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

In Carriers "Handbook of Air Conditioning System Design" there is a formula for figuring SC. On an operating r-12  system.
 100* Cond Temp =116.9psig.
press at TXV        =87psig  which = 82* Saturation Temp
SC required         = 100*f  - 82*f  =18f* SC
                                                                             

FREE Schrader T and a FREE SGMI

@ July 21, 2014 10:14 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

to you Spence, both FREE ,both get installed @ the AHU. As Meplumber said, there will be a full LL at the cond unit and a mix at the top ,if you are staying at the mfrg's Nameplate SC of 12* for a high lift. Seeing is believing,no,yes!?!?
The PD sure does get figured into a SC calculation , the PD gets converted into a TEMP drop.

FREE Schrader T and a FREE SGMI

@ July 21, 2014 10:13 PM in FREE ,FREE, NO CHARGE ,Schrader Tee.

to you Spence, both FREE ,both get installed @ the AHU. As Meplumber said, there will be a full LL at the cond unit and a mix at the top ,if you are staying at the mfrg's Nameplate SC of 12* for a high lift. Seeing is believing,no,yes!?!?
The PD sure does get figured into a SC calculation , the PD gets converted into a TEMP drop.

FREE T

@ July 21, 2014 9:59 AM in FREE ,FREE, NO CHARGE ,Schrader Tee.

Simple, so that 10 techs get to see the actual press drop between the cond unit and the TXV. Oh yea, and that press drop gets figured into SubCooling , somehow, doesn't it? And the actual press going into the TXV is used when using a TXV " extended capacity charts" for troubleshooting. Gonna get your  FREE T Spence? Come on! And those 10 techs may tell ten more techs. But then again , I been wrong lots of times!

Ice,

@ July 21, 2014 7:21 AM in Height vs SubCooling vs Freon Charge

you are correct.You sound like a ReferHead!!!! As the height rises, the 1/2psi press drop rule causes a press drop. So, on a vertical LL that goes up 30' there will be a 15 psi press drop at the top of the riser . Now ,heres the tricky part , that 15psi press drop causes a drop in TEMPERATURE at the sametime.

Not cool

@ July 21, 2014 6:59 AM in Not Cool: Techman & Meplumber:

Happy to be of help, Dan's idea of knowledge sharing at work.

This is where knowing what the system freon pressurers were would have cleared up this problem sooner. For your own sake and understanding of AC , try to get an actual press reading . The loside press would have been low for a given set of conditions.

HvsSCvsFC

@ July 20, 2014 9:00 AM in Height vs SubCooling vs Freon Charge

Being a stickler here. SC is a process AFTER the condensing process has STOPPED condensing. SC is to insure a full LL at the TXV ,not at the CondUnit. A full LL @ the cond unit DOES NOT insure/guarrante the the LL is still full at the TXV . So another system is undercharged if you are relying on the SGMI at the cond unit, this is on systems with more than 15' of vertical rise of LL.

FREE ,FREE, NO CHARGE ,Schrader Tee.

@ July 20, 2014 8:34 AM in FREE ,FREE, NO CHARGE ,Schrader Tee.

to the first 10 tech's that post a picture ,here on the wall, of an installed Schrader T that is installed just before the TXV along with two pressure readings. One press reading will be  from the cond unit and the 2nd press reading will be from the installed Schrader T at the AHU. Send me your address and I will send you a free 3/8 solder type Schrader T . Oh yea, the liquid line has to have at least a 20' vertical rise.
Paul S , you get a Schrader T even if you are #11 or higher.

H vs SC vs FC

@ July 15, 2014 5:58 AM in Height vs SubCooling vs Freon Charge

What is SC? What is it used for? Why do we care about SC ? When should we be concerned about SC? Why are SC #'s  being stamped on unit nametag's more and more these days? Who cares about SC in the first place? Who has ever played with SC?
Electricity - do you use a voltmeter to verify to see WHAT the voltage is ( 208-230- 212- 240-246- - - - - ) ?
TXV  -  do you check to VERIFY that the TXV  is indeed getting a full boat of refrigerant ? And it ain't being done out there by the cond unit. Other than units inside of the Mfrg's lineset rules.!

not cool

@ July 14, 2014 10:31 AM in Not Cool:

ice, lets say the 3t -36k is what you need and the problem is the bigger, hi eff evap coil ,then a 3 1/2 t cond will be "oversized", but ,that oversized comp will pull the lo side press down lower. Lower loside press means colder Freon temps causing better dehumidification.
Or the heat gain calc will show that you need a 3 1/2 t (42k btu)system and your existing system is undersized.

sizing

@ July 14, 2014 5:00 AM in line-set sizing etc

The cond unit comes w/ an installation manual, check it out. Most units will work properly w/ a 25'vertical rise, and 75' length. The pipe size increases in size as the length increases.There is a pipe sizing chart in the manual,based on rise vs length vs tonnage. There are no traps required when the evap is above the cond unit, traps are required when the cond is above the evap. But, there is a requirement for a riser at the AHU , its an anti-syphon loop.

not cool

@ July 14, 2014 4:38 AM in Not Cool:

A simple test here.Turn the t'stat down to 75-76* at nite and let it run all thru the next day. Do you have a humidity tester? What is the design temp for Miami ? A properly sized AC will run forever at OAT above design temp. The IAT will rise as OAT goes above design air temp's.  

not cool

@ July 13, 2014 8:18 PM in Not Cool:

Or a 3 1/2 t cond unit w/ the 3t indoor unit . Can your ducts handle the new 4t AHU which moves 1600 cfm . A proper heat gain estimate might be needed.

not cool

@ July 13, 2014 3:30 PM in Not Cool:

Sizing of the AC. In the 70'S and into the 80's a 1200 sq ft house was a 3ton load and that was 1200 cfm. Then came tighter homes. True 3t is 36k btu's , in the N.E. that was KindaSorta 12k for dehumidification and 24k for temp (sensible) at stabilized conditions. That 10 seer vs the newer 14seer, the higher seer uses a larger evap coil, which raises the suction press a little which raises the lo side temp also.That higher temp reduces the amount of moisture removal.  What is the SensibleHeatRatio in Fla.?
Ice, one more time cause I'm a little slow. The supply duct coming off of the AHU is about the same size as the AHU? KindaSorta, the discharge air opening of the AHU is about 12 x 16 and that should be the plenum size also, then a few feet away (or so) a transition piece goes up in size to the main trunk size.
Hi to lo it goes. Moisture goes to dryness and moisture also goes to coldness. The vapor barrier is supposed to be on the warn side of the equation, in the prevalent season. If the moisture gets into the wall it can condense in the wall.

notcool

@ July 13, 2014 11:05 AM in Not Cool:

Hay ice, since you haven't sent picture's, YET, I gotta ask. Is supply duct,plenum, coming off of the new AHU the size of the opening of the AHU or is the duct much bigger than the opening of the AHU ?

Not Cool

@ July 13, 2014 5:34 AM in Not Cool:

Being a ReferHead means that you know about the green scale vs the purple scale means the pressurers are different but the temps are the same. At the moment I have 6 different colored drums on board my truck  and 6 more  different colored drums in the shop. Just r22 and r410a, ha!!  I wish it was that simple! There are MANY colored scales but only one temp scale. Get a digital thermometer that has a decimal point in in , like 72.4*F NOT just 72*F . Open the louvered doors before you remove/repair/replace them. Got a picture or two ,of the outdoor unit also. Have the AC guy give you a set of readings the next time he's there along w/ in/out temps and a reading of the discharge air off of the outdoor unit.
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