Retrotec DM32X User manual

Pressure Gauge Operation Manual
For Model DM32X
rev-2022-05-27

Page 2 of 80
© Retrotec 2022
Made by Retrotec
1060 East Pole Road
Everson, WA USA 98247
For support:
Call 1 [phone] in USA
[phone] outside USA [email protected] or
Fax [phone]

Page 3 of 80
© Retrotec 2022
Copyright © 2012-2022 Retrotec
All rights reserved.
This document contains materials protected under International and Federal Copyright Laws. This book contains
material protected under International and Federal Copyright Laws and Treaties. Any unauthorized reprint or use of
this material is prohibited. No part of this book may be reproduced or transmitted in any form or by any means,
electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system
without acknowledging Retrotec. as the original source.
Retrotec makes no warranties with respect to this documentation and disclaims any implied warranties of
merchantability, quality, or fitness for any particular purpose. The information in this document is subject to change
without notice. Retrotec reserves the right to revise this publication without obligation to notify any person or entity
of any such changes.
Infiltrometer, FanTestic, and DucTester are Trademarks of Retrotec. Other Trademarks or brand names mentioned
herein are trademarks or registered trademarks of their respective owners.
Wireless communication is certified under Wi-Fi 802.11 with ASD Model Test Plan with Test Engine for IEEE 802.11a,
b, and g Devices (Version 1.0).
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of
the FCC Rules. These limits provide reasonable protection against harmful interference in a residential installation.
This equipment generates, uses and can radiate radio frequency energy, and if not installed and used in accordance
with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that
interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or
television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to
correct the interference by one or more of the following measures:
•Reorient or relocate the receiving antenna.
•Increase the separation between the equipment and receiver.
•Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
•Consult the dealer or an experienced radio/TV technician for help.
Caution: To satisfy FCC RF Exposure requirements for mobile and base station transmission devices, a separation
distance of 20 cm or more should be maintained between the antenna of this device and persons during operation.
To ensure compliance, operation at closer than this distance is not recommended.
The antenna(s) used for this transmitter must not be co-located or operating in conjunction with any other antenna or
transmitter.
This device complies with Industry Canada license-exempt RSS standard(s). Operation is subject to the following two
conditions: (1) this device may not cause interference, and (2) this device must accept any interference, including
interference that may cause undesired operation of the device.
Le présent appareil est conforme aux CNR d'Industrie Canada applicables aux appareils radio exempts de licence.
L'exploitation est autorisée aux deux conditions suivantes: (1) l'appareil ne doit pas produire de brouillage, et (2)
l'utilisateur de l'appareil doit accepter tout brouillage radioélectrique subi, même si le brouillage est susceptible d'en
compromettre le fonctionnement.

Page 4 of 80
© Retrotec 2022
Table of Contents
Important equipment-related safeguards..................................................................................................... 7
1. Introducing the Retrotec DM32X Digital Gauge ............................................... 8
2. Gauge overview .............................................................................................. 9
2.1 Make connections to the gauge ....................................................................................................... 9
2.2 Charge the battery in the gauge..................................................................................................... 10
2.3 Power the gauge on and off ........................................................................................................... 11
2.4 Read Results and control the gauge from the DM32X Gauge App Home screen ..........................11
2.5 Observe icons to monitor gauge status.......................................................................................... 12
2.5.1. What speed is being sent to the fan on the “Fan Speed” output?........................................12
2.5.2. Over what time period is the Result being averaged? ..........................................................12
2.5.3. Result display can be frozen to write down values ............................................................... 13
2.5.4. How much battery life is left in the gauge?...........................................................................13
2.6 Use keys on the Home screen to control gauge operation............................................................13
2.6.1. [Channel A] Pressure Reading................................................................................................ 13
2.6.2. [Channel B] Pressure Reading or Result ................................................................................14
2.6.3. Set the [Range/Device] connected to the gauge ................................................................... 14
2.6.4. Estimate Results with [@ Pressure]....................................................................................... 16
2.6.5. Setting “n value” for @Pressure extrapolation .....................................................................17
2.6.6. Capture and apply a Baseline using [Settings]....................................................................... 17
2.7 Gauge compensates for sensor drift with Auto Zero .....................................................................17
3. Get Results directly from the gauge............................................................... 18
3.1 Connect Speed Control Cable between the gauge and fan............................................................18
3.2 Connect pressure tubes to gauge................................................................................................... 18
3.3 Control the test and read Results on the Home screen ................................................................. 18
3.3.1. Tap [Range/Device] to match Range on Device in use .......................................................... 18
3.3.2. Tap [Range/Device] [Change Device] to change Device in use.........................................19
3.3.3. Tap [Set Speed] to run the fan at a particular speed.............................................................19
3.3.4. Tap [Jog] keys to adjust speed up or down incrementally ....................................................20
3.3.5. Tap [Set Pressure] to achieve a particular enclosure pressure .............................................20
3.3.6. Tap [Area] or [Volume] to enter dimension for particular Results........................................21
3.3.7. Tap “Hold” to hold readings and results................................................................................ 22
3.3.8. Tap [Channel B] or [Settings] to change Result or units to be displayed ..............................22

Page 5 of 80
© Retrotec 2022
3.3.9. Tap [@ Pressure] to estimate Result at a different pressure ................................................23
4. Change [Settings] for gauge operating parameters........................................ 26
4.1 Capture [Baseline] Pressure ........................................................................................................... 26
4.2 Set [Area] if using a Result per Area............................................................................................... 27
4.3 Set [Volume] if using ACH............................................................................................................... 28
4.4 Use metric units for dimensions..................................................................................................... 29
4.5 Set the [Default @ Pressure] .......................................................................................................... 30
4.6 Set [Time averaging] period ........................................................................................................... 32
4.7 Change Result and units to be displayed........................................................................................ 33
4.8 Set up Ethernet connection............................................................................................................ 34
4.9 View and update the [Firmware] version, check serial number ....................................................34
4.10 Reset gauge .................................................................................................................................... 35
5. Remotely run tests and save results with Retrotec software ......................... 36
5.1 Connect single gauge to a computer with Ethernet cable ............................................................. 36
5.2 Connect multiple gauges to a computer via WiFi Hotspot, USB Tethering, or Bluetooth® ...........37
5.3 Connect computer or phone to the DM32X “WiFi” Hotspot ......................................................... 37
5.4 Make the DM32X join an existing “WiFi” network......................................................................... 39
5.5 Run a test using rCloud from the DM32X gauge ............................................................................ 39
6. Firmware Updates & Embedded Resources ................................................... 41
rResources App............................................................................................................................................ 42
7. Verify your gauge accuracy between factory calibrations .............................. 45
8. What to do if you have trouble with the gauge ............................................. 48
8.1 Pressing power button may not turn gauge On if battery is fully discharged................................48
8.2 Calculated Result will be wrong if the Range and Device installed on fan are different than those
selected on the gauge ................................................................................................................................. 48
8.3 Moving tubes might cause fluctuating pressure readings ............................................................. 49
8.4 Fans with a single tube have results adjusted by gauge ................................................................49
8.5 Pressure can overshoot when using the Set Pressure key ............................................................. 50
8.6 Check if large fixed errors are caused by pinched tubes................................................................ 51
8.7 Check if large fixed errors are caused by water in the tube...........................................................51
8.8 Check if large fixed errors are caused by sun heating the tubes....................................................52
8.9 Check if wind is causing fluctuating pressure................................................................................. 52
8.9.1. Use the [@ Pressure] key to reduce the effects of wind.......................................................52
8.9.2. Use Time Averaging feature to reduce the effects of wind...................................................52

Page 6 of 80
© Retrotec 2022
8.9.3. Let Time Averaging take effect before making readings .......................................................53
8.9.4. Use Baseline feature to reduce the effects of a constant wind ............................................53
9. Technical Specifications................................................................................. 55
Appendix A: Understanding Pressures on the Gauge........................................... 57
Differential Pressure.................................................................................................................................... 57
Positive vs. Negative Pressure ..................................................................................................................... 57
Why static and fluctuating pressures occur, causing bias........................................................................... 58
Managing fluctuating pressures created by wind ....................................................................................... 58
Reduce uncertainty in results by taking lots of readings............................................................................. 59
Appendix B: Flow Equations used with Devices................................................... 60
Appendix C: Manually estimate Flow if required test pressure cannot be reached
............................................................................................................................ 65
Cannot Reach 50 Pa Factors ........................................................................................................................ 66
Cannot Reach 25 Pa Factors ........................................................................................................................ 67
Appendix D: Details about the @Pressure extrapolation function....................... 68
“n value” for @Pressure extrapolation ....................................................................................................... 69
Errors occur in estimated flow if gauge and actual “n” don’t match .......................................................... 70
Appendix E: Tables to adjust Flow values for temperature difference ................. 73
Appendix F: Tables to correct Flow if range selected did not match the installed
range ................................................................................................................... 75
Appendix G: Measure Supply or Exhaust flow with a gauge and box .................. 76
Glossary............................................................................................................... 78

Page 7 of 80
© Retrotec 2022
Important equipment-related safeguards
Read and save these instructions
When using electrical appliances, basic safety precautions should always be followed. If Retrotec equipment is
used in a manner that does not follow the information provided in this manual, safety to the operator and
equipment performance may be impaired.
The risk of fire, electric shock, and injury to persons may result during cleaning of the gauge. To avoid these risks,
unplug or disconnect the gauge from the electrical power supply and turn the gauge off before cleaning. Clean
only by wiping with a soft dry cloth. There are no user serviceable parts on the gauge.
To protect against the risk of fire, electric shock, and injury to persons during gauge operation:
Do not operate any gauge with a damaged electrical cord. Discard gauge or return to an authorized service
facility for examination and/or repair.
Do not run cord under carpeting. Do not cover cord with throw rugs, runners, or similar coverings. Do not route
cord under furniture or appliances. Arrange cord away from traffic and where it will not be tripped over.
Do not place this equipment or power cord in water or other liquid.
Use only the included power plug to charge and/or operate the gauge.
Turn the unit off and unplug the charger (if in use) from electrical outlet before moving.
For use under indoor conditions only, where there is no exposure to water or dusty substances or explosive
materials or flammable materials.
Do not use equipment for other than its intended use.
Equipment is intended for diagnostic testing and must be operated by a qualified operator.
Failure to follow these instructions carefully may result in bodily injury, damage to property and/or equipment
failure. Failing to operate equipment as intended may void warranty and compliance with CE mark and other
listings.

Page 8 of 80
© Retrotec 2022
1. Introducing the Retrotec DM32X Digital Gauge
The beloved DM32 became the industry's first manometer with smart capabilities, wireless connectivity,
and a touch screen interface. Its accuracy, durability, and ease-of-use made it the industry's favorite gauge.
While still keeping your favorite DM32 features such as an ergonomic design and color-coded ports, we
have now re-engineered it with all new technology, features, and abilities. Meet the DM32X: air tightness
testing and building diagnostics will never be the same again. This refreshing new testing experience will
open new doors and extend your diagnostic abilities.
The gauge will conveniently control the speed of fans that create flow such as Blower Door Fans,
DucTesters and other flow devices. It will also calculate the flow rate going through these devices as well as
many passive devices such as flow grids. Results can be displayed in any series of units used anywhere
worldwide.
New Features Include
•5.5" 1080P HD OLED display with Gorilla Glass capacitive multi-touch.
•A thinner, more ergonomic shell design.
•Real-time graphic display of pressure readings over time. Taking pressure points is one thing, being
able to see what’s happening tells you a more accurate story.
•Multiple datalogging options.
•Digital Signal Processing (DSP) improves pressure reading stability.
•Fast 3A charging & data transfer on USB-C Long range (10m) Bluetooth® connectivity.
•Built-in testing and training apps. Run rCloud auto testing software natively.
•Embedded & online manuals, videos, & resources.
•Display can be viewed horizontally or vertically.
•Operate and read competing fans.
•Photorealistic images of all devices and ranges.
•Words in square brackets indicate keys that must be tapped on the touchscreen to operate the
gauge.
DM32X digital gauge has been turned on and is ready for action.

Page 9 of 80
© Retrotec 2022
2. Gauge overview
The front of the gauge has a capacitive multitouch screen, with an On/Off button at the top right side, and
a battery charging indicator light at the bottom.
The top of the gauge has four color-coded pressure tube ports, and a Control output port (for fan speed)
The bottom of the gauge has USB-C port for battery charging and gauge-computer communications.
The touchscreen serves as both the information display and the keypad for the gauge. The information
displayed depends on selections a user makes by touching the screen. This manual uses square brackets []
to indicate where to touch items on the screen.
2.1 Make connections to the gauge
Physical connections from the gauge to a calibrated fan are on top of the gauge. Physical connections to a
computer or power adapter are on the bottom of the gauge.
An Ethernet-style cable from the fan speed output control port connects to a calibrated fan to control its
speed. The cable supplied for this purpose with Retrotec systems is yellow.
Pressure tube ports on the top of the gauge are color-coded to distinguish where pressure tubes are
connected. Retrotec has a specially designed pressure tube port that grips pressure tubes well, but
releases them without tearing after long-term use. This exclusive connector is designed by Retrotec to
make contact with both the tube internally and externally with a shallow taper.
Connect tubes and Speed Control Cable
Table 1: Physical connections from gauge to fan are on top of gauge
gauge port connection
1
“Fan Speed” control cable port
Connect the yellow Retrotec-proprietary Speed Control Cable
2 Blue pressure port: “input B (+)”
Often has no pressure tube connected. For duct testing, a blue pressure tube
leads from the gauge into the ducts.
3 Red pressure port: “ref B (-)”
Connect the red pressure tube from the gauge through the Door Panel to the
outdoors.
4
Yellow pressure port: “ref A (-)”
Connect the yellow pressure tube from gauge to yellow port on a Retrotec fan
5 Green pressure port: “input A (+)”
Connect green pressure tube to green port on Retrotec fan, if applicable. No
pressure tube will be here if Retrotec fan does not have a green pressure port
Pressure tubes should be clean and not stretched in order to make a proper connection. If a pressure tube is
damaged, simply slice a short piece of tube off the end to ensure a clean fit. Tubing can crack in cold weather, but can

Page 10 of 80
© Retrotec 2022
be heated in hot water before being handled. Be careful to dry all water from the tubing prior to connecting since
water in the tube is a major source of measurement error.
Connections on the bottom of the gauge provide a USB-C charging input, which can aslo connect the gauge
directly to a PC.
Connect charger or remote computer control
2.2 Charge the battery in the gauge
The gauge is charged at the factory, but you can plug it in to ensure a full charge before each test. Connect
the USB cable to the AC power adapter to charge the gauge battery. Charging using the AC power adapter
is the only way to fully charge the gauge. Plugging the gauge into a computer USB port will extend the
length of the charge but the gauge will eventually need to be recharged using the AC power adapter.
With the AC adapter, a full charge will be completed in about four hours. A fully charged gauge will last for
approximately 8 hours without a recharge. For details see 2.5.5
DM32X charging port
When connected to the computer USB port, the gauge still discharges very slowly. Connection to the
computer USB is just a way to extend the time available on a charge, so that you can run longer tests if you
have a computer nearby.

Page 11 of 80
© Retrotec 2022
2.3 Power the gauge on and off
Warning: Gauge does not turn on immediately. You don’t need to press the button
hard. The light above the power button will turn on, indicating that the gauge is on.
This will be followed by the bootup screen
The bootup screen is visible until the gauge self-check sequence finishes and
automatically displays the Home screen.
The Home screen shows the main DM32X Gauge App, the Retrotec Resources
App, and the rCloud app.
Click on the DM32X Gauge App.
DM32X Gauge App
Upon the DM32X gauge app start up, the DM32X Gauge App Home Screen will display the Device, Range,
and Result to be displayed settings that were set on the gauge before it was last powered off, so the user
can immediately start testing if they are using the same equipment.
2.4 Read Results and control the gauge from the DM32X Gauge App
Home screen
The DM32X Gauge App Home Screen is the main display that allows a user to control the gauge. The
gauge includes convenience functions to support operation of pressure measurement systems with
calibrated fans, and calculate results for air leakage testing.
In this manual, words that are in square brackets indicate keys that can be tapped to change something on
the gauge.
DM32X Power On/Off Button

Page 12 of 80
© Retrotec 2022
2.5 Observe icons to monitor gauge status
2.5.1. What speed is being sent to the fan on the
“Fan Speed” output?
The % Speed indicates the percentage of the fan’s total speed capacity
that the gauge is directing the fan to achieve (50% Fan Speed shown in
the Fan Speed Image Example).
2.5.2. Over what time period is the Result being
averaged?
When Time Averaging is active, the gauge will display the time that the [Channel A] and [Channel B]
Readings are averaged over. 1 second Time Averaging is shown in 7. Regardless of the time averaging
setting, the display will update every second.
Time Averaging periods of 1s, 5s, 10s, 30s can be selected directly, or another time to spend averaging can
be entered manually.
Fan Speed

Page 13 of 80
© Retrotec 2022
Tip: When changing the fan speed, set pressure, or taking a reading after making any other changes, wait for twice
the Time Averaging period to elapse before taking a reading. Taking a reading too quickly can lead to recording
incorrect results.
2.5.3. Result display can be frozen to write down values
When the [Hold] button is tapped, display values are frozen to the values that were present when the
display was tapped.
HOLD button
2.5.4. How much battery life is left in the gauge?
The battery life indicator at the top right corner of the screen shows how much life is left in the
rechargeable battery inside the gauge. A fully charged battery will last approximately 8.5 hours before
needing recharging. Gauges will discharge faster if WiFi or Bluetooth® is being used.
The gauge battery is charged via the USB-C cable port on the gauge bottom of the gauge. The fastest way
to charge the gauge is to plug the USB-C cable into the provided power adapter and into a wall outlet.
Plugging the USB-C cable into a USB port on your computer will also charge the gauge, but at a much
slower rate, and will only extend the length of time before needing to use the AC adapter (the draw can be
higher than what most computers normally provide on the USB output).
When the battery is charging, a light on the bottom of the gauge (near the charging port) will flash. Once
the light stays fully on, the gauge is fully charged.
With the gauge plugged into the wall outlet, the battery charges at 3A, and will take approximately 1.8
hours to fully charge a depleted battery.
When the gauge is plugged into mains power on a completely depleted battery, it may take a few minutes
to gain sufficient charge to have enough power to show the splash screen. If you press the power button
and the screen flashes without showing the splash screen, this indicates the gauge is still in the process of
gaining enough charge and will start shortly. Plugging the gauge into the computer when the battery is
depleted will not provide enough power to restore the gauge, it must be plugged into mains power.
The Lithium-Polymer rechargeable battery provided with the gauge can last up to 4 years or 6,000 cycles.
Once the battery becomes unable to hold a charge, it must be changed. Changing the battery will require
return to the factory, conveniently at about the same time that the gauge will need a factory re-calibration.
2.6 Use keys on the Home screen to control gauge operation
2.6.1. [Channel A] Pressure Reading
The [Channel A] display always shows the pressure difference between the blue pressure port “input A”
and the red pressure port “ref A”. If the pressure tubes are connected as illustrated in Retrotec’s Door Fan
Operation manual, [Channel A] shows the building pressure.
The pressure units can be displayed in units of Pa, psf or in WC. To change the units for the [Channel A]
Reading, from the DM32X App Home Screen, simply tap on the Channel A current display. Or tap [Settings]
[Pressure Units][Pressure:] until the desired units are displayed.
•The [Channel A] Reading will be negative if there is a higher pressure on the “-“ (red) pressure port

Page 14 of 80
© Retrotec 2022
•The [Channel A] Reading will be positive if there is a higher pressure on the “+“ (blue) pressure
port
2.6.2. [Channel B] Pressure Reading or Result
The [Channel B] display can show the pressure difference between the yellow pressure port “ref B” and the
green pressure port “input B”. If the pressure tubes are connected as illustrated in Retrotec’s Door Fan
Operation manual, [Channel B] shows the Fan Pressure.
•The [Channel B] pressure will be negative if there is a higher pressure on the “-“ (yellow) pressure
port
•The [Channel B] pressure will be positive if there is a higher pressure on the “+“ (green) pressure
port
The gauge can also use the pressure on Channel B to calculate and display different results for the [Channel
B] Result, such as:
•Pressure: Pa, psf or in WC
•Flow: CFM, L/s, cu m/s, cu m/h
•Flow/Area (Permeability): CFM/sq ft, CFM/100 sq ft, CFM/1000sq ft, (cu m/h)/sq m, (L/s)/sq m
•Air changes per hour: /h
•Equivalent leakage area extrapolated to 10 Pa, “EqLA10”: sq ft, sq in, sq cm
•Equivalent leakage area, “EqLA”: sq ft, sq in, sq cm
•Effective leakage area, “EfLA”: sq ft, sq in, sq cm
•Effective leakage area extrapolated to 4 Pa, “EfLA4”: sq ft, sq in, sq cm
•Equivalent leakage area per enclosure area at 10 Pa, “EqLA10/area”: sq in/sq ft, sq cm/sq m)
•Effective leakage area per enclosure area at 4 Pa, “EfLA4/area”: (sq in/sq ft, sq in/100sq ft, sq ft/sq
ft, sq cm/sq m)
The [Channel B] display is also a key: when tapped, the “Result to display” on [Channel B] will change. In
the list that shows up, tapping a [Result] to highlight it (in brighter red), will select it as the displayed
[Channel B] Result of choice. Once highlighted, the [Result] can be tapped repeatedly to cycle through all
the different units available for display of that Result.
Refer to Retrotec’s Residential & Commercial Airtightness Requirements document for Results required
according to various standards, codes, and regions.
2.6.3. Set the [Range/Device] connected to the gauge
“Device” refers to the calibrated fan or other device being used to conduct the current test in conjunction
with the gauge. It is important to make sure that the correct Device is selected because the calculation for
each of the Results is based on equations that are different for each Device.
“Range” or “Range Configurations” are the rings or plates installed on a calibrated fan to limit the air flow
through it, so that the fan can achieve a measurable Fan Pressure, even when moving only a small amount
of air (for more information, see Retrotec’s Manual-Door Fan Operation). Select the Range that matches
the Range Ring or Plate that is installed on the fan to ensure that the gauge performs accurate calculations
and displays correct results.
Retrotec calibrated fans connected to the gauge with a Speed Control Cable can have their speed of
operation controlled by the gauge through the “Fan Speed” control output.
Fans manufactured by TEC (such as the DuctBlaster or Minneapolis Model 3 or 4) can be controlled by the
gauge “Fan Speed” control output if an optional Retrotec-TEC Fan speed control Adapter is connected

Page 15 of 80
© Retrotec 2022
between the gauge and the TEC fan, in line with the Speed Control cable as shown in the image below.The
Minneapolis fan speed control must have the cruise input.
Connecting the pressure tubing to your TEC fan as described in Retrotec literature allows the gauge to
correctly calculate results.
Control a TEC fan using the gauge and Fan Speed Control Adapter (part FN275, produced by Retrotec)
“5000”
“6000”
“300”
“400”
“200”
“1000”- yellow tube only
“2000”- yellow tube only
“3000”- yellow tube only
“3000SR”-yellow and green tube

Page 16 of 80
© Retrotec 2022
“MN DB” “MN 3/4” “Exhaust” (Fan Flow Meter)
Images of devices compatible with the gauge
2.6.4. Estimate Results with [@ Pressure]
The [@] pressure key enables the gauge to calculate and display the estimated [Channel B] Result that
would be achieved, as if the target pressure was reached (also known as “extrapolation”). The [@
Pressure] key only appears on the Home screen if [Set Speed] or [Set Pressure] functions are used and the
gauge is measuring pressures on Channel A and B.
•This function is useful in situations when the fan has reached 100% speed and the enclosure
pressure still has not reached the target pressure.
•Additionally, this function is useful since the measured [Channel A] pressure will usually be slightly
over or under the desired/set pressure, making it difficult to report results that exactly at the
specified pressure.
Tapping [@ Pressure] will toggle the extrapolation function on or off. The label under [Channel B] display
will change to indicate whether [@ Pressure] “is On” (e.g., CFM@25.0Pa) or “is Off” (e.g., CFM).
Details of how the gauge calculates the flow at exactly the target pressure, when [Channel A] has not
reached exactly the set target pressure, can be found in Appendix D.
•If the [Set Speed] function is used, [@ Pressure] extrapolates the [Channel B] Result to the [Default
@ Pressure] set in the “Settings” screen, using the “n value” chosen in [Settings].
•If the [Set Pressure] function is used, [@ Pressure] extrapolates the [Channel B] Result to the
pressure entered for [Set Pressure], using the “n value” chosen in [Settings].
The @ Pressure function provides unique advantages over non-extrapolated results:
•There is no need to achieve an exact [Channel A] pressure (e.g. to a precision of 0.1 Pa)
•[Channel B] Results can be obtained even if the test pressure cannot be reached**
**Although the gauge can extrapolate results to any pressure, it is more accurate when the actual
enclosure pressure read on [Channel A] is close to the target pressure. As a rule of thumb, extrapolation
can be used if the actual enclosure pressure reaches at least 80% of the target pressure. If 80% cannot be
reached, more fans are needed to complete the test (See Retrotec’s Manual for Large Building Multi Family
Testing).
Example #1 - Inaccuracy
A 50 Pa building pressure is desired, but only 20 Pa can be reached (due to severe leakiness). In this
instance, the extrapolated results for flow “@ 50 Pa” do not represent the reality of the testing conditions
and might be highly inaccurate.
In the same situation, a 45 Pa building pressure is achieved. The extrapolated “@ 50 Pa” pressure is now
much more accurate, and provides an acceptable result.

Page 17 of 80
© Retrotec 2022
2.6.5. Setting “n value” for @Pressure extrapolation
The “n value” is a number set between 0.5 and 1.0 that is used in the calculation when extrapolating
[Channel B] results to a pressure that is not the pressure read on [Channel A]. It can be changed by tapping
[Settings][…] [Ducts=0.6, House=0.65]. Set it to 0.65 for houses, and 0.60 for ductwork. Set to 0.5 for
tests using the Retrotec House or duct simulator, air handler flow and any large hole that is not composed
of long thin cracks.
Technical details about the “n value” are shown in Appendix D.
2.6.6. Capture and apply a Baseline using [Settings]
Some buildings have an initial pressure imbalance between the indoors and outdoors, prior to any testing.
This pressure imbalance is called the Baseline pressure, bias pressure, or static pressure. The Baseline
function allows the user to capture the Baseline pressure under the existing test conditions. See Section
4.1 for illustrations of how to capture a Baseline. Once captured, the gauge will automatically subtract the
Baseline pressure from all subsequently measured pressure readings, and will display only the adjusted
pressures on the screen. The gauge averages Baseline pressure for a user-defined duration.
Tip: A 30 second Baseline acquisition is typically enough to establish an accurate baseline measurement. If the
building conditions change during the test, the baseline should be cleared and a new measurement should be taken.
2.7 Gauge compensates for sensor drift with Auto Zero
Over time, the pressure readings on [Channel A] and [Channel B] can start to drift away slowly from the
true pressure value. The longer the gauge remains on, the larger this error could become. The “Auto Zero”
is a feature on the gauge that will automatically correct these errors at regular intervals. By default, Auto
Zero occurs every 30 seconds. When using set speed or set pressure, the AutoZero interval is three
minutes.

Page 18 of 80
© Retrotec 2022
3. Get Results directly from the gauge
3.1 Connect Speed Control Cable between the gauge and fan
Refer to section 2.1 which describes the connection ports from the gauge to a
device such as a Retrotec calibrated fan. The connections for pressure tubing
between a DM32X and a device are the same as the connections between a
DM32X gauge and that device.
Refer to Retrotec’s Manual-Door Fan Operation for detailed illustrations on these
connections, depending on what kind of test is to be performed.
3.2 Connect pressure tubes to gauge
3.3 Control the test and read Results on the Home screen
•Tap [Range/Device]to select the Range Configuration in use
•If the Range Configurations associated with the Device in use do not appear, tap [Change
Device] to change the Device first
•Tap [Settings] to display gauge settings that can be changed
•If the [Area] or [Volume] key appears, tap to enter a value for conditioned area or volume, which
will be used to compute the result displayed on [Channel B]
•Tap [Set Speed] to run the fan at a particular speed
•Tap [Set Pressure] to achieve a particular enclosure pressure
•Tap [Hold] to Hold results being displayed
•Tap [Channel B] to change the “Display Results”
•Tap [@Pressure] to estimate a [Channel B] Result at the set pressure
To jump to screen illustrations showing how to use each function, click on the hyperlink in the above list.
3.3.1. Tap [Range/Device] to match Range on Device in use
Change Range for selected Device

Page 19 of 80
© Retrotec 2022
3.3.2. Tap [Range/Device] [Change Device] to change Device in use
Change Device in use
3.3.3. Tap [Set Speed] to run the fan at a particular speed
The gauge can automatically control the fan speed on Retrotec systems to achieve a specific fan speed,
entered by the user.
Set gauge speed control output
Fans manufactured by TEC (such as the DuctBlaster or Minneapolis Model 3 or 4) can also be controlled if
an optional Retrotec-TEC speed control Adapter is connected between the gauge and the TEC fan in the
Speed Control cable as shown below. Pressure tubing needs to be attached to the gauge using the
Retrotec conventions described in the Retrotec literature.

Page 20 of 80
© Retrotec 2022
3.3.4. Tap [Jog] keys to adjust speed up or down incrementally
Adjust speed up or down 10% using [Jog] keys
3.3.5. Tap [Set Pressure] to achieve a particular enclosure pressure
The gauge can achieve a target enclosure pressure entered by the user. The gauge controls pressure by
automatically adjusting the speed control output based on the pressure reading on Channel A.Retrotec
fans can be controlled directly from the gauge.