Static vs. Velocity Pressure 1

Source: flowmeterdirectory.com Pitot Tube Source: flowmeterdirectory.com 2

NSOP .30

TFSOP .36

Finding the Correction Factor

Plate Pressure .18

Corrected Flow To calculate corrected flow, multiply raw flow x correction factor; Raw flow of 769 CFM X .91 = 700 CFM. 8

21.8 kW Furnace 64.0 ºF Flow? 793 cfm (average ΔT=87 ºF) 593 cfm Return plenum 64.0 ºF Elec . Air Cleaner Flow? 793 cfm (average ΔT=87 ºF) 593 cfm (center ΔT=116 ºF) 477 cfm (max ΔT=144 ºF) 1832 cfm (min ΔT=38 ºF) 634 cfm (fan-assist) 656 cfm (flow plate) ΔT ≈ 109 ºF Supply plenum 176.7 208.5 147.0 134.9 180.2 149.9 101.6 135.3 124.0 Average: 150.9 ºF

3.5 Ton Heat Pump 87.8 87.3 88.1 87.8 87.7 87.5 87.6 87.5 86.7 Return Supply Average: 87.6 F Measured 3.9 kW input Flow? Depends on actual compressor efficiency If assume COP=3 (rated) then flow = 1688 cfm (almost 500 cfm/ton) If assume COP=2 then flow = 1126 cfm (ok?) Return EAC flow = 956 cfm (fan-assist) flow = 973 cfm (flow plate) 65.7 F COP ≈ 1.7 !!

Refrigerant Charge Subcooling protocol (cooling or heating season). Typical target around 10º F in heating or cooling (but verify with manufacturer) Tech shall list manufacturer-provided targets on field form Alternate method: in winter (below 65º F ambient), record operating suction/discharge pressure and compare with manufacturer-provided targets If no mfr. targets given, describe verification process on form Record line set adjustments Record temperature split (between return and supply air streams) after 15 minutes operation. Make sure strip heat is not on for heating season test.

Refrigerant Charge Procedure (summer) 325

Winter charge evaluation “Winter” defined as outdoor temperature below 65º F. Weigh-in for line set adjustment Can check subcooling (check in same place as for cooling– on liquid line just before entry into outdoor unit). Only works for systems with TXV on outdoor coil and need to have manufacturer’s target value for comparison. OR… Measure outdoor temperature and discharge/suction operating pressures and compare with mfr’s tables

Charge Evaluation (summer and winter) Too much subcooling vs. target (more than 3º F over target), remove refrigerant until within 3º F of target Not enough subcooling (more than 3º F under target), add refrigerant until within 3º F of target. Temperature split: should be at least ½ of outdoor temperature in heating (20º F if 40º F outside) and generally 17-22º F in cooling.

Water Source Heat Pumps Measure pressure drop across system and calculate GPM If GPM in expected range (usually about 1.5 GPM/ton of capacity), measure loop temp. split and compare with mfr’s target value Measure air side temp. split and compare with expected values If loop temp. split and/or air side split is not at mfr’s expected value(s), measure superheat/subcooling, make adjustments, and retest.

Refrigerant Charge Procedure (winter)

Good Installation Practice Braze carefully; use nitrogen while torching and protect TXV, etc. from heat Evacuate system to 500 microns, break with nitrogen, repeat Use new vacuum pump oil each time ($5/pint is cheap insurance)

Calibration Check thermocouples and pressure gauges regularly for accuracy Ice test for thermocouples Saturation test for manifold gauges

Heat Pump Controls Strip heat Compressor Discharge air sensor

The Big No Nos Wiring in strip heat to operate on a Stage 1 heating call Not installing an outdoor (lockout) thermostat to limit use of strip heat during mild conditions Locking out the compressor at any temp. above 0º F. Using a discharge temp sensor which brings on strip heat when it is not needed

Heat Pump Control Requirements (strip heat) Strip heat can never operate on Stage 1 heating call Install outdoor thermostat or equivalent control and set at 40°F 23

Outdoor Thermostat– The Basics Remove this wire when using outdoor t’stat Close on fall switch keeps off strip heat until outdoor temp below activation point. Note system can still activate strip heat if there is a call from outdoor unit (defrost) or homeowner switches to emergency heat

Pay attention to the small print

Courtesy Proctor Engineering Group

Courtesy Proctor Engineering Group

Heat Pump Controls: Compressor Lockout Heat pumps provide heat even at low outdoor temperatures All manufacturers provide output tables at 5º F (and even lower) IPCO requires compressor to operate down to 0º F Factory setting for most new thermostats is to never lock out compressor

Installer Setup ENTER INSTALLER SETUP 1. Press the SYSTEM key 2. PRESS and HOLD the two unmarked keys as shown until the display changes approximately 5 seconds Jeff

IPCO Program Settings Step 0170 establishes type of system and number of stages (Option 7 is two heat/1 cool heat pump; Option 12 is 3 heat/2 cool heat pump) Step 0340 specifies there is an outdoor sensor; Option 2 must be selected to make the sensor an active control of strip heat. (Option 1 causes display of outdoor temperature but not active control of strip heat.) Step 0350: compressor lockout. Factory setting is “not enabled,” which means compressor will always run regardless of outdoor temperature (IPCo program requirement is compressor on above 0º F outdoor temp.) Step 0360: strip heat lockout temperature (35 or 40) Pro 8000 only goes to 40º F; IAQ goes lower

Outdoor Sensor Needs wires sep. from rest of 24v bundle Mount out of sun; best on north side of house up under eave Mount to avoid contact with rain/snow Check temp display on tstat and compare with measured outdoor temperature; should be within 2% (so within ± 1º F if 50º F outside)

Checking Sensor Reading at Thermostat Should be within 5% (1-2º F) of actual outside temperature

IAQ Schematic EIM Vision Pro IAQ Y1 Y2 G RH RC R 2 3 1 C V1 T2

Differences Between VPro 8000 and IAQ Setup Steps The main difference is that the strip heat lockout is in Step 0342 (vs 340). Set at “2” in both cases. There are other differences in basic system setup Step numbers (they are similar but not all the same). IAQ also has auto-discover feature for communicating fan coils Note Trane and Lennox touchscreen stats use very similar programming Steps

Wireless Option Honeywell and others now have kits with wireless outdoor sensor and indoor thermostat Wholesale price point of entry-level system about $225.

More Heat Pump Controls Single-stage compressors: discharge air sensor control not allowed Typical Heat Cycle 2000 4000 6000 8000 10000 12000 12:00 12:02 12:04 12:06 12:08 12:10 12:12 12:14 12:16 12:18 12:20 12:22 12:24 Time Power, Watts comp resist fan 36

HP Controls (final spec) Set discharge sensor to 85°F for multi-compressor stage systems/zoned systems or install outdoor t-stat if warmer staging temperature used Some zoning controls do not accommodate and outdoor sensor/close on fall switch (dial-type); check with manufacturer rep if not sure. If you cannot control strip heat operation above 35º F (except for emergency heat/defrost), this control combination is not allowed in IPCo’s program

Installation Worksheet – Page 1

Installation Worksheet: Airflow

Heat Pump Controls Page

Refrigerant Charge Procedure (summer) 325

Refrigerant Charge Procedure (winter)

Water Source Heat Pump Form