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Fax dual calculated

is gym burger with true tech tools today we're going to go over one of the coolest tools I've seen in a long time the field piece sdp - dual index psychrometer this is probably one of the must-have tools that I've seen that every technician should really get into their toolbox does some really cool things not only including wet bulb and dry ball but also enthalpy directly on the instrument and differential enthalpy which makes it very easy to calculate capacity in the field the SDP 2 comes with the instrument a supply air probe return air probe a blow molded case and a couple of cones to hold the probes and the duct when you're making your measurements the probes both have vinyl covers on and you just slide the vinyl cover off to expose both the thermistor and the capacitive humidity sensor the instrument measures both temperature and humidity at the same time and uses that to calculate wet bulb temperature dry bulb temperature relative humidity and you can send those readings to either an HD 3 or directly to an SMA and for 4 targets of recalculation the probes are marked at each end for the return air and supplier returners red the suppliers Chrome and the same thing with a plug in the returners red again and the suppliers unmarked so we're gonna go ahead setting up the SDP - is really easy all you have to do is plug in the two probes and again just pay close attention to which one goes in the supply which goes in a return they are keyed so you're going to see that there's a small arrow here on the front and you line that up with a front of the instrument and plug that in take the next one same thing line up the air over the front plug it in then have to get them both plugged in just press and hold the power key the instrument will power up and we're ready to go take a measurement the SDP 2 comes with a couple of probe stops we're going to use to hold the probes and to return air and a supply air duct if you've watched it in my videos before you've seen me make a lot of measurements of my duct work so I already have holes here so I'm going to go ahead and screw this in to the return air and it screws in so it locks in tight really good and tight then I'm going to back out the set screw here and then I could pull the probe out slide the probe into the duct and then go ahead and lock that down about mid position in my duct work so that I get a good sampling of the return air the wire that come on the probes are really nice and long so in this case we're gonna put this one in to supply probe and when we install this in the supplier duct you want to make sure that you're far enough away from the evaporator coil that the airs had time to mix so you can see here I'm several feet away for my furnace there's had time to turn in there I don't want to be too close to the coil when I make the measurement or I'm going to get some oddball readings in there air has to mix and turn a little bit before we get a good measurement up so I drilled a hole here and now I can put the probe into the duct I'm gonna go ahead and point the sensor here into the air stream so I get a really nice fast response for the supplier temperature measurement again I'm going to clamp this in here snug alright so when you look at the instrument itself there's just a couple things I want you to know here parameter allows us to select our our units of measure so in parameter here I'm gonna BTUs per pound now I just went to dry ball relative humidity wet ball do point back to BTUs per pound and I haven't set up right now for differential there's a small Delta here I'll show you in the display in a second here I'll zoom in a little tighter but then here on the bottom here we've got our our delta button it'll show us now our max minimum readings min max which is our actual reading right now and then hold and then back to differential power back light button and then our sync button if we're going to sync this up with an H g3 or an SMA and for for real-time target superheat calculations okay so right now I have the instrument set up to measure differential enthalpy and you can see we have a very tiny change in enthalpy and that's just the drift of the instrument that's that's pretty normal there could be a small amount of residual cooling in my ductwork and duct in there I'm not sure when the last time my air conditioner kicked on here if you leave the probe set the ambient air and I'll actually go down to zero I've seen it happen over and over again so that the instruments very very accurate well we're going to go ahead and we're going to turn on the cooling and we're going to take a look at the differential enthalpy and I'm going to show you very quickly how to do a field calculation of the capacity of the piece of equipment okay so we got the cooling started and you can see very quickly as the cooling coil is cooling off that the enthalpy or the change in BTUs across the coil is changing very quickly so we're going to let this run for just a minute and stabilize now this is an ECM motor so it's ramping up slowly into profile and that's why we're seeing this pretty substantial change in enthalpy we're gonna see that drop back down here as the Laura gets up to speed this is a two-stage appliance so we're on second stage right now and we're going to let this run for a few minutes and we're going to see where the enthalpy settles out okay so the unit's been running for about 10 minutes or so and it's sort of stabilized here at about 7.2 7.18 pts per pound change in enthalpy across the evaporator coil so we're going to go ahead and do a quick calculation and see what the actual BTU capacity is so just for ease I went upstairs here just to show you what's going on here mode AC to someone's second stage cooling and you can see here I have an ECM motor with a communicating stat and we're moving about a thousand 78 CFM of airflow so I'm going to go ahead and use that number for a calculation just to make this quick and easy okay so now that we got CFM and enthalpy the calculations really easy BTU output equals four point five times their CFM times their change in enthalpy and so we're going to go ahead and calculate that out real quick so four point five times ten seventy eight times are changing out the P which is seven point one seven equals 34 781 that's the capacity the field capacity I'm measuring right now of my points if I divide that by in the nominal capacity which is 36 thousand BTUs that's about 96% of its rated capacity now it's not abnormal for us to be a little bit below a rated capacity especially on a day like today it's about 70 degrees outdoors so I don't have a lot of condenser pressure driving that refrigerant through my metering device and even though I have at TXV you know I may not have full capacity out of the TX being second the second thing that's important remember is my return air temperature is about let's see what it is here we'll go ahead and change the parameter here and we're gonna get off this and go to return air dry ball is about 71 degrees and at 71 degree return our dry bulb is also going to reduce my capacity a little bit and same thing with my relative humidity which is running we're a max here so I'm going to go and get off the max reading and min min max okay relative humidity returns about 58% which that's that's decent that's not too bad so we're running right about where I expect to see but 96% of our rated capacity pretty spot-on for what we'd expect to see as results while we're doing the measurements in the field okay so one of the other really neat things I want to show you here is we're gonna go ahead and shut the system off so it's going to take just a second I said somebody have to turn the thermostat to the off position and I want you to keep a close eye on your enthalpy and I want you to see what's going on here because this is just one of the cool things and you start getting to make multiple measurements and measure supply and return air simultaneously that you'll get to see so you can hear my ECM ramping down and you can see my change and enthalpies going away and it'll go away really quickly because the cooling is going to stop and essentially we're going to lose that change in heat so this is dropping down we'll give this just a second and you can see how quickly after the inter shuts off that are changed and enthalpy goes away but that's really not what I want to show you so let's give this just a minute to get down close to zero and then I'm going to go ahead and make a change on the instrument okay the fan just slowed down a little bit more and you can see my change in enthalpy is down to about 1.4 1.5 which is you know about a sixth of what it should be let that go a few seconds longer here and we'll get it down below a change in one okay we're getting pretty darn close there now that we're down below changing one here I want to show you something that's interesting so when I look at my change in enthalpy it's like really low but when I look at my change in dry bulb now we're a differential drive oh I still have a change of 10 degrees right 10 degrees now I'm gonna go over here and I'll hit parameter again and have a look at my relative humidity you have a change in 42% now if you look what happened here I went from 58 returned air which is what we're at before and it would now we're at a hundred percent relative humidity well what happened here is we went from mechanical cooling to evaporative cooling and even though there's no change in energy across the coil let's go back look at enthalpy real quick and we're min/max meinhold and hit the wrong button here let me go back to parameter which is returned wet bulb dewpoint BT is per pound I'm gonna get off max-min now we're back to the regular reading you can see 26 4 to 2603 even though there's almost no change in enthalpy if I go back to dry ball temperature you can see I still have a 10 degree change in dry ball temperature now remember Energy's neither created nor destroyed so what happened here is that the cold water and a coil it's it's now evaporating that water the warm air from their turns going across that coil it's evaporating that water and we're actually getting a little bit of free cooling now you're getting free cooling but you're getting that sacrifice of dumping the relative humidity that we just removed are just retained on the coil back into the back into the supply of the house so if your main concern is controlling the relative humidity you may want to consider shutting that fan off if your main control is cooling and especially sensible cooling and like for an Arizona or something like that where you don't have a lot of humidity to deal with you might want to put that back in the house then we can keep that fan on continuous circulation now for me and I'm in Ohio we're pretty humid here but that gain and humidity is pretty negligible I mean I look at it as you know we pulled it out what was running whatever drain down the drain drain down the drain whatever was on the coil still on the coil once the unit shuts off I'm just getting a little bit of free cooling evaporative cooling but humidity is going to rise a little bit again anyway but because I have a two-stage system it runs so much that the controlling the humidity is not really an issue so I run my fan all the time so I can take advantage of my electronic air cleaner but I just thought you might think this is cool because at first it caught me off guard it's like holy cow that relative humidity went all the way up to 100 percent relative humidity you can see it's still there that coil is really saturated so we're continuing to put that water in there but what's really cool again is when you look at that dry bulb temperature that's wet bulb no change of wet bulb there's my dew point temperature Beaches per pound there's my dry ball I still have if I go differential here nine point five degree change across the coil so as long as that fans running I'm getting a little bit of cooling out of the system still and again only at the sacrifice of adding the relative humidity back into the ductwork so one more really slick feature of the SDP two is the fact that it has target evaporator exit temperature calculation and also target differential temperature both sort of the same thing but I want to show you how this works so I go ahead and press the the target evaporator temp what happens here is it shows me the target evaporator temperature is 52 point 5 degrees that's what this te ET is and you can see that I'm right there perfect within zero to the tenth degree of what it should be I press that button again and it shows me my target temperature drop is one point seven or seventeen point two degrees and I'm within three degrees right now of what that calculation should be and I think I just switched from from below to my high stage of my appliance here so that's why we're seeing this small change then I hit it again and I go back to my return air dry bulb and supplier dry bulb and then you know get cycle back to the units so really really cool feature here allows me to see things like you know if my evaporator is performing properly if I have air bypassing my coil and how far away I am from that temperature you know right now you can see it's coming right back down in the line where we'd expect it to so it allows me to very quickly assess if I have a problem so this is really slick because it's sort of a verification of correct well measuring capacity is probably one of those powerful tools are going to ever use to show your customer how efficiently the system is working although the capacity does vary with the outdoor air and the load when you have charge and air flow problems you'll see huge variations in the capacity in fact air capacity typically will be very low anything we do with air flow and especially in low air flow will cause a direct decrease in system capacity and if we're overcharged or undercharged will also see direct impacts on capacity Disney field piece SPD - and a couple other instruments like the field piece sta - and an estimate for you can get a system working almost factory perfect every single time the key is again correct air flow correct charge and then testing the system to make sure that it operates the way that it was engineered to operate if you do those couple of steps and you get that right every time the first time you will get system operation like you've never seen before not only we increase your customer comfort but you're going to find problems that result in billable hours that you can make money on so again take a close look at the SPD to take a look at the sta - we have a really good kit that combines all three instruments together to reduce cost but I can't say enough about this instrument CNN throw fee for the first time seen it measured directly was really really cool and then you know along the way - you start to gain a better understanding of what's happening in the doctor work what's happening with the psychometrics what's happening with a wet ball the dry ball of the humidity and it really starts to make air conditioning come together so this is Jim Burton with true tech tools I really hope you enjoyed the video it was fun to do and I like I said I learned a little bit myself along the way but if you have any questions or comments please feel free to post them in the video below and if we can do anything else to make your job easier let us know