4-IN-1 PIN/PAD RH
MOISTURE METER
USER’S MANUAL
MMH800
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
Please read this manual carefully and thoroughly before using this product.
TABLE OF CONTENTS
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 –3
Key Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
What’s in the Case . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 –4
Setup Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Install Battery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 –6
Measuring Moisture Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Accounting For Temperature and Humidity . . . . . . . . . . . . . . . . . . . . 6
Checking Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 –8
Maintenance Tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Warranty Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Return for Repair Policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
INTRODUCTION
Thank you for purchasing General Tools & Instruments’ MMH800 4-in-1 Pin/Pad RH
Moisture Meter. Please read this user’s manual carefully and thoroughly before using
the meter.
The MMH800 is designed for use in woodworking, water damage restoration, building
construction and home renovation. Examples include:
• Checking for moisture on or below the surface of carpets
• Measuring the surface moisture and/or moisture content of wood, drywall
or concrete before painting, wallpapering, sealing or treating
• Locating water leaks in roofs, floors and walls
• Selecting dry lumber
Because it can measure ambient temperature and humidity in addition to moisture
level, the MMH800 is particularly suitable for water damage restoration projects.
It measures: 1) temperature; 2) relative humidity; 3) moisture level using a pin sensor;
and 4) moisture level using a pad sensor. The meter has both kinds of sensors, with a
pair of pins on top and a split metal pad on the back.
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Which sensor should you use?
It depends on the application. The pad sensor is the only choice for measuring surface
moisture of materials like finished wood, paint or wallpaper that cannot be marred by
pinholes. If measurement accuracy is important, the pin sensor is the better option
because pins can detect moisture below the surface that the pad sensor cannot.
However, for hard materials like wood or concrete, the meter’s readings mostly
represent surface moisture content. For softer materials like soil, paper or powders,
readings are more likely to reflect the average moisture level of the material between
its surface and the penetration depth of the pins.
KEY FEATURES
• Pin (intrusive measurement of moisture content) and pad
(non-intrusive measurement of surface moisture) sensors
• Separate 3-digit displays of moisture level and temperature + humidity
• Selectable wood or building materials measurement mode
• °F/°C switch
• Wide measurement range and high accuracy
• Audible and visual indications of high, medium and low moisture levels
• Holds moisture level readings for convenient viewing later
• Pin cover doubles as calibration checker
• Auto power off function
• Battery charge indicator
WHAT’S IN THE CASE
The MMH800 comes in a custom hard carrying case along with a 9V battery, two pairs
of extra test pins (10mm and 15mm long), and this user’s manual.
PRODUCT OVERVIEW
The figure on the next page shows all of the controls and indicators on the front of the
MMH800, as well as the locations of the sensor and battery compartment on its back.
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A. Calibration holes
B. Protective cover
C. Replaceable test pins
D. low/medium/high
moisture level icon
(high moisture shown)
E. Wood icon
F. Building materials icon
G. Beeper enabled icon
H. Dual function button:
Power on/off (press
and hold for >3 seconds);
Backlight on/off (press briefly)
I. Temperature and humidity split-
screen display
B
C
D
E
F
G
H
I
FRONT
Q
P
O
M
L
K
J
A
N
J. Battery compartment cover
K. Dual function button: Beeper on/off (press and hold for >3 seconds);
Moisture reading hold/release (press briefly)
L. button: Selects wood or building materials
M. button: Toggles between temperature units
N. Split metal pad sensor
O. icon: Indicates display is locked or “frozen”
P. icon: Battery charge indicator
Q. Temperature/humidity sensor vent
BACK
SETUP INSTRUCTIONS
INSTALL BATTERY
To open the battery compartment, turn the meter over and use your thumb to slide the
battery compartment cover (Callout J) down and away from the unit.
OPERATING INSTRUCTIONS
To power on the meter, press the button and hold it for at least three seconds.
(To power off the meter,
follow the same instruction.)
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MEASURING MOISTURE LEVEL
To measure the moisture level of wood or a building material, first make sure
that its icon appears on the left side of the display. If it does not, press the
button briefly to toggle between wood and building materials. Next,
decide which sensor to use (the meter’s pins or pad) after considering their pros
and cons presented in the introduction. Either 1) Gently press or push the pins at the
top of the meter on or into the material or 2) Press the split pad sensor on the back
against a flat area of the material, making sure that both sides of the pad touch the
surface being measured.
The MMH800 provides three indications of a material’s measured moisture content:
1. A percentage reading on the upper display.
2. One, two or three droplet icons ( ) on the left side of the upper display to indicate
whether the reading is low, medium or high for the material. The moisture-level
range for each category is different for wood/paper and building materials; see the
Specifications section for the exact percentages.
3. If enabled (the factory default), the meter’s repeating beeper will sound at one of
three rates (slow, medium or fast) corresponding to the measured moisture level
(low, medium or high). The audible changes make it very easy to pinpoint areas of
peak wetness.
To hold a measurement, press the button briefly. This “freezes” the display and
makes the (lock) icon appear at the right of the reading. This feature makes it
possible to make a measurement in a dark place, hold the reading, and display it later
in a better-lighted area. To release the lock, press the button briefly again. This
makes the icon disappear.
The meter’s beeper is enabled by default. To disable the beeper, press the
button and hold it for at least three seconds. This makes the icon at the lower
left of the display disappear. To re-enable the beeper, press and hold the
button again for at least three seconds. Each time the meter is powered on, the unit
reverts to the default state: beeper enabled.
Some measurement tips:
1. To locate the source of a leak behind wood, plaster, drywall or a ceiling, make
measurements at different locations. The leak is where the meter displays the
highest reading.
2. Never use force to drive the test pins into a hard surface.
3. When measuring the moisture level of soil, surface readings will be lower than
readings with the test pins deep in the soil.
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ACCOUNTING FOR TEMPERATURE AND HUMIDITY
Measurements of wood moisture level are skewed by two variables: ambient humidity
and the density of the wood species.
For example, the humidity level affects the dryness of interior wood considered
“acceptable” for finishing. In the steamy Deep South, where 60% relative humidity is
the norm, fine carpenters have learned how to work with wood with 11% moisture
content. But in bone-dry Nevada, Utah, and Arizona, where 30% humidity is common,
the same piece of wood would have to have less than 6% moisture to be considered
ready for finishing.
Moisture levels are just as important to know when joining wood. If two work pieces
have different moisture levels when they are joined, when they dry out they will
contract by different amounts at different rates. In the extreme, the result could be a
warped board or a weakened joint. Temperature also affects moisture levels to the
extent that it affects relative humidity levels.
The MMH800’s split-screen lower display provides real-time temperature and humidity
readings. Both measurements are made and displayed continuously whenever the
meter is powered on.
The meter’s default temperature unit is degrees Celsius (°C). To change the
measurement unit to degrees Fahrenheit (°F), press the button. Each time the
meter is powered on, the unit reverts to the default °C.
CHECKING CALIBRATION
The MMH800 is factory-calibrated for measuring the moisture level of wood and
building materials on different scales. To check the calibrations, remove the
protective cap from the top of the meter, taking care not to stab yourself with the two
sharp pins beneath it. Then flip the cap over and place the two holes in its top over the
meter’s two test pins.
The upper display should read 17.5% ±3% with the meter in wood measurement mode
and 16.4% ±3% in building materials measurement mode. You can toggle the
button to check both calibrations without removing the protective cap.
If either calibration check produces a readout outside the stated range for that mode,
and the meter is still under warranty, call General’s Customer Service Department at
212-431-6100 to arrange to return the meter for service or replacement.
SPECIFICATIONS
Moisture Level Measurement Range 5 to 50% for wood/paper; 1.5 to 33% for building
materials
Measurement Accuracy ±(3% of reading + 5 digits) in pin measurement mode
Measurement Resolution 0.1%
Temperature Measurement Range 32° to 140°F (0° to 60°C)
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Temperature Measurement Accuracy ±5.4°F (±3°C)
Humidity Measurement Range 25 to 95%
Humidity Measurement Accuracy ±5% below 75%RH; ±10% above 75%
Display Type/Size 99.9 count LCD with 0.56 in. (15mm) high digits
Droplet Icon Ranges Low/Medium/High moisture: >5%/12%/16% for wood
Auto Power Off After 3 minutes with 0% reading
Low Battery Warning Level <7.25V
Operating Temperature 32° to 122°F (0° to 50°C) @<80% relative humidity
Dimensions 7.13(L) x 2.17(W) x 1.57(H) in. (181 x 55 x 40mm)
Weight 4.06 oz. (115g) without battery
Current Consumption <20mADC
Power Source 9V battery (included)
and paper; >1.5%/17%/20% for building material
MAINTENANCE TIPS
When the icon at the upper right of the display changes from two solid bars to
one flashing bar, it’s time to replace the 9V battery that powers the meter (although
measurements will remain valid for several hours after the icon first appears).
When the tips of the meter’s factory-installed 5mm test pins show signs of wear,
replace them with a pair of 10mm or 15mm pins included in the case.
Remove the battery when storing the meter for an extended period of time.
Do not drop or disassemble the meter or immerse it in water.
WARRANTY INFORMATION
General Tools & Instruments’ (General’s) MMH800 4-in-1 Pin/Pad RH Moisture Meter is
warranted to the original purchaser to be free from defects in material and workmanship
for a period of one year. Subject to certain restrictions, General will repair or replace this
instrument if, after examination, the company determines it to be defective in material or
workmanship. The warranty period begins on the date of purchase. You are encouraged
to register your product online. General will extend your warranty an additional 60 days if
you register at www.generaltools.com/ProductRegistry.
This warranty does not apply to damages that General determines to be from an
attempted repair by non-authorized personnel or misuse, alterations, normal wear and
tear, or accidental damage. The defective unit must be returned to General Tools &
Instruments or to a General-authorized service center, freight prepaid and insured.
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Acceptance of the exclusive repair and replacement remedies described herein is a
condition of the contract for purchase of this product. In no event shall General be liable
for any incidental, special, consequential or punitive damages, or for any cost, attorneys’
fees, expenses, or losses alleged to be a consequence of any damage due to failure of, or
defect in any product including, but not limited to, any claims for loss of profits.
Register now at www.generaltools.com/ProductRegistry to receive a 60-day extension to
your warranty.
RETURN FOR REPAIR POLICY
Every effort has been made to provide you with a reliable product of superior quality.
However, in the event your instrument requires repair, please contact our Customer
Service to obtain an RGA (Return Goods Authorization) number before forwarding the
unit via prepaid freight to the attention of our Service Center at this address:
Remember to include a copy of your proof of purchase, your return address, and your
phone number and/or e-mail address.
8
99 Washington Street
Melrose, MA 02176
Phone 781-665-1400
Toll Free 1-800-517-8431
Visit us at www.TestEquipmentDepot.com
Specifications subject to change without notice
NOTICE - WE ARE NOT RESPONSIBLE FOR TYPOGRAPHICAL ERRORS.
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©2013 GENERAL TOOLS & INSTRUMENTS
MAN#MMH800-condensed
8/5/13
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