Economizer Fundamentals

[@bearlythere]

Excellent! I completely agree with Adrienne that starting at the beginning is the only way to really help folks understand economizers - thanks so much for working this!

[@orlandorizzo5780]

even tho its educational and its a good video you have a soothing voice .. I was about to sleep lol

[@Jason-wc3fh]

I've seen different placements of the mixed air sensor in different Jade video's. This one is showing it after the return air/economizer air before the a/c coils. Other videos show it being installed after the coils, right next to the blower. How do we know which is correct? Obviously one is going to see the temperature drop when the mechanical a/c is running, whereas the other will not.

[@davidarneson6749]

Great question Jason. It is best to put the mixed air sensor in the mixed air, before the coil if you can. Sometimes, however, this is difficult to do. If so, then you can put it after the coil. Jade automatically senses that the mixed air sensor is upstream or downstream from the coil. When it knows that the sensor is downstream from the coil, Jade will use the MA sensor for mixed air sensed temperature (located after the coil) when the cooling is not on. But when the cooling IS on, it will use the temp from the outdoor air sensor as the mixed air temperature when the compressor is running. This works fine, as the return air damper is closed when mechanical cooling is on.(I copied the following from a white paper that goes over this, and it refers to the mixed air sensor as the control sensor as it could be placed before or after the coil) (This feature was added years ago with firmware version 1.13) When the control sensor is placed in the DA, the Jade will maintain the temperature to the MA set point (input by the installing technician or default of 53F) +/- 1F. When a second stage of cooling (Y2 IN) is called for then the Jade will open the OA to 100% open and close the RA damper 100% closed then turn on stage 1 (Y1 out) of mechanical cooling. If the system is using 2-speed fan the function 2SP FAN DELAY (adjustable 0 to 20 minutes default 5 minutes) will delay turning on Y1 out for the duration of the 2 speed fan delay. CAUTION: Jade will use the temperature of the outside air to control and report the control sensor (MA on LCD) temperature and control the OA and RA dampers. In this case the OA damper is fully open while RA damper is fully closed so the temperature in the MA box is very close to the OA temperature. If the thermostat call is not satisfied with the OA dampers wide open and the first stage of mechanical cooling is running, then Jade will turn on the second stage of mechanical cooling (Y2 OUT) after the STG3 DLY (stage 3 delay) time has expired ( 0 min, 5 min, 15 min, then 15 min intervals, default is 2 hours). If the DA temperature goes out of the range (set point +/- 1F) then the OA and RA dampers will modulate to maintain to 30Fto 40F below the below the OA temperature. In this case the Low Temperature Lock out needs to be set to a temperature where the (OA temperature - 30F to 40F) will not allow the coil to freeze. The changeover temperature and/or enthalpy boundaries must be taken into consideration. Example 1: Using the ES3 boundary unit will economize below 70F and 42.3 RH. If the OA temperature is 50F the unit will economize on a call for cooling (Y1 IN). If there is a call for additional cooling in space then on Y2 IN the Jade will open the OA dampers and the DA temperature should be approximately 50F. This temperature should be low enough to cool the space and the thermostat should be satisfied. Example 2: Using the ES3 boundary unit will economize below 70F and 42.3 RH. If the OA temperature is 70F and RH is below 42.3 RH the unit will economize on call for Y1 IN. If there is a call for additional cooling in the space then on Y2 IN the Jade will open the OA dampers and the DA temperature should be approximately 70F. If this does not satisfy the call for cooling then the Y1 OUT will turn on the mechanical cooling. To avoid freezing the coil the LOW Temperature Lockout should be set to a temperature where the OA temperature minus coils temperature drop will lock out the mechanical cooling from turning on (Y1 OUT).

[@PBS-nm1uu]

thank you for this explanation, please make more videos

[@StupidPeasant]

When it's 70*f outdoors and 40% RH, and the old time "B" setting is on, as in the example, it does not seem like there would be enough cooling. That's probably why they were always set to "D" or disconnected completely. A lot of energy was wasted over the years because of such a ridiculous poor Honeywell interface. I am glad to see these new controls, though it took California to force it.

[@davidarneson6749]

Thanks Kevin. Yes many analog economizers were disconnected. Too often this was done when the outdoor air damper was stuck open. Jade is much easier to use....and can alert you when there is a problem like that. In regards to 70F and 40% RH... this really is up to individual preference. The dew-point with those numbers is about 45F... Economizing at that point is fine for some people. However, someone from a dry environment like the SW might find that uncomfortable. That, of course, is why there are different curves to choose from.

[@markvee8818]

Do we need to install a sptd relay for co2 sensor?

[@davidarneson6749]

No, a C7232 or C7632 Co2 sensor with a 2-10Vdc output signal can be wired to the IAQ 2-10 terminals, or a TR40 Co2 sensor can be used, which communicates over the Sylk bus on the S-Bus terminals.

[@om6789gg]

@@davidarneson6749 Hi for the C7232 Co2 sensor do we only need to use Red and Black wiring?

[@davidarneson6749]

@@om6789gg Hi Omar. You need to power the C7232, but you also need the analog output going to the economizer. So you will use red and black for power going to IAQ24V and IAQCOM on the W7220 economizer. Then yellow (OUT1) goes to IAQ 2-10 on the economizer.

[@om6789gg]

@@davidarneson6749 Thank you!

[@samthecat.broadcast]

The Intellidyne CAC 2400 is a much better RTU HVAC Economizer