Broan B70DHV Ventilating Dehumidifier Installation and Operation Instructions

Introduction

The B70DHV is a ventilating dehumidifier integrated into the heating and cooling system to provide comfort, health, and property protection through:

• Dehumidification
• Fresh Air Ventilation (Optional)
• Air Filtration

Key information fields include Serial Number, Install Date, and Sold By.

Safety Instructions

[WARNING!] This symbol indicates important instructions. Failure to heed them can result in serious injury or death.

[CAUTION!] This symbol indicates important instructions. Failure to heed them can result in injury or material property damage.

The Broan dehumidifier conforms to unified standard UL 60335-2-40 and CSA Standard C22.2.60335-2-40.

[WARNING!] 120 Volts may cause serious injury from electric shock. Disconnect electrical power before starting installation or servicing, and leave power disconnected until installation or service is completed.

[CAUTION!] Read all instructions before beginning installation. Always use caution and wear cut-resistant gloves when handling sheet metal. Improper installation may cause property damage or injury. Installation, service, and maintenance must be performed by a qualified service technician. The dehumidifier is heavy; handle with care and follow installation instructions. Never operate a unit with a damaged power cord. If the power cord is damaged, it must be replaced by the manufacturer, its service agent, or a similarly qualified person to avoid a hazard. This appliance is not intended for use by persons (including children) with reduced physical, sensory, or mental capabilities, or lack of experience or knowledge, unless they have been given supervision or instruction concerning the use of the appliance by a person responsible for their safety. Children should be supervised to ensure that they do not play with the appliance.

Dehumidifier Set Up

Important Precautions

• Install indoors in a space protected from rain and flooding.
• Ensure sufficient space for maintenance and service access; the entire shell may need removal for repairs.
• Avoid directing discharge air at people. Use the dehumidifier in an upright position.
• If used near a water source, ensure the unit cannot fall into water or get splashed, and plug into a dedicated circuit with GFCI protection.
• Do not use the dehumidifier as a bench or table.
• Do not place directly on structural building members without vibration absorbers to prevent noise. Use supports to raise the base.
• A drain pan with a float switch is mandatory if installed above a living area or where water leakage could cause damage.

Location Considerations

• Allow sufficient clearance for unit dimensions and necessary ductwork.
• Allow sufficient clearance for filter removal and to prevent airflow obstruction.
• Ensure clearance for electrical service access, which requires removing the outside shell.
• Locate where the 9-foot power cord can reach a 115 VAC outlet with at least a 15 Amp capacity.
• Locate where field wiring of the low-voltage control is possible.
• It is recommended to use a backdraft damper in the discharge duct, especially when connecting to the HVAC supply ducting system, to prevent supply air from counter-flowing when the unit is not operating.
• The unit may be suspended using a hang kit or alternative from structural members, ensuring the assembly supports the dehumidifier's base. Do not hang from the cabinet.
• Allow for proper drainage and routing of drain pipes.

Clearance Requirements: 6 inches minimum clearance for proper air flow, 13 inches minimum clearance for filter (on either side). Electrical service access is on one side. The unit has a 9-foot power cord.

Duct Connections: A is the Return Air Duct, B is the Supply Air Duct.

Attaching Duct Collars

Fresh Air Ventilation Duct

Fresh air ventilation is optional. Refer to page 10 for setup.

Return Air Inlet

An 8-inch diameter duct collar is attached to the unit.

Supply Air Outlet

The back panel can be rotated for horizontal or vertical supply air flow. The unit ships configured for horizontal flow with an 8-inch collar. For vertical flow, remove the exhaust panel (using a T20 torx bit), rotate it so the collar is on top, align screw holes, snap it onto the base, and secure with six screws.

Diagram Description (Horizontal Flow): Shows an 8" Return Air Inlet (A) and an 8" Supply Air Outlet (B) on the end discharge.

Diagram Description (Vertical Flow): Shows an 8" Return Air Inlet (A) and an 8" Supply Air Outlet (B) on the top discharge.

Electrical Requirements

The B70DHV connects to a common grounded 115VAC outlet and draws 5.1 Amps at 80°F and 60% RH. Locate the unit where the 9-foot cord reaches a 115 VAC outlet with at least a 15 Amp capacity. A GFCI protected circuit is recommended for areas that may become wet. Consult local electrical codes.

Low voltage (24 Volt) controls can be used and must be connected with 18-22 gauge thermostat wire. Controls should be located remotely in the space to be conditioned.

[WARNING!] Remote controls are powered by a low voltage (24VAC) circuit and must never contact or be connected to a high voltage circuit.

[CAUTION!] Do not allow the 24V terminal to contact the COM/DMPR terminals on the B70DHV, as this will damage the transformer.

[CAUTION!] Some screw terminals on the B70DHV may not be used with certain controls and should be left unconnected.

Electrical Precautions

• Do not install controls where they cannot accurately sense relative humidity (e.g., near HVAC registers, exterior doors, outside walls, windows, or water sources).
• Terminals on the B70DHV and control are labeled for clarity.
• Consult the electrical schematic in the CONTROLS Section (page 12) or inside the access panel before making control connections.

Wiring Schematic Description

The wiring schematic illustrates connections for the circuit breaker, dehumidistat, compressor relay, defrost switch, fan relay, compressor capacitor, and fan capacitor. It details the 24VAC control circuit and connections between various components like the transformer, fan, compressor, and control terminals (COM, FAN, 24V, DEHU, DMPR).

Drain Installation

The B70DHV generates condensate. A secondary drain pan with a float switch is required if the unit is suspended above a finished area or an area where water leakage could cause damage. A drain trap is necessary for proper operation. Install a 3/4" threaded male NPT adapter to the drain pan and use a 3/4" PVC pipe assembly for condensate transport, pitched at 1 inch per 10 feet.

An optional condensate pump kit is available for situations requiring lift to dispose of condensate. The pump automatically pumps condensate to a remote location when its reservoir's water level rises to close the float switch. The pump includes a safety float switch that, if the pump fails, opens the common control circuit to stop water production before overflow. Contact a qualified electrician to install this safety float switch.

Note: An optional condensate pump kit can be purchased from a local dealer or online.

Diagram Description: Shows a front view of the dehumidifier with a Secondary Drain Pan, Drain Port, and Drain Trap.

Ducting to HVAC Systems

The recommended installation involves a separate return for the B70DHV in a central area, with the unit's supply ducted to the existing HVAC system's air supply. An insulated duct from outside can provide fresh make-up air (optional).

[CAUTION!] Do not connect with a static pressure greater than or equal to +0.5 WG. Contact technical support for details.

Ducting Considerations:

• All flexible ducting connected to the B70DHV should be UL listed.
• Use short lengths of flexible ducting at connections to reduce noise and vibration transmission to rigid ductwork.
• Use a minimum 8-inch diameter round or equivalent rectangular duct for lengths up to 25 feet. Use a minimum 10-inch diameter or equivalent for longer lengths.
• Grills or diffusers at duct ends must not excessively restrict airflow.
• A length of 8 inches or more of insulated flex duct or vibration-isolating material on the outlet will reduce blower noise.
• For effective dehumidification in branched ducting to isolated areas, use 6-inch or larger diameter branch ducting for two to three areas, and 4-6 inch or larger for four or more areas. Ensure proper airflow from supply to central return locations for even humidity and heat distribution.
• Do not locate the return in a bathroom or kitchen.

Recommended HVAC System Installation

The recommended installation draws air from a dedicated indoor air return and ducts the supply to the existing HVAC system's air supply. Utilize the optional fresh air ventilation duct for outside air.

• Install a dedicated 8-inch air return for the B70DHV from a central area.
• Duct the B70DHV supply to the existing HVAC system supply, including a backdraft damper.
• If the existing system has multiple returns, one can be disconnected from the HVAC system and used as the dedicated B70DHV return. Select a central location that is always open to the structure. Do not use a return from a room with closed doors.
• Do not locate the return in a bathroom or kitchen.
• Controls should be located remotely from the dehumidifier and placed centrally.
• Visit www.Broan-Nutone.com for more installation options.

Diagram Description (Dedicated Return to HVAC Supply): Illustrates the airflow path. Indoor air is drawn through a Motorized Damper into the unit's Return Air Duct. Optional Fresh Air Intake connects to the unit. The unit's Supply Air Outlet is ducted to the Air Handler's HVAC Supply, with a Backdraft Damper installed.

Fresh Air Ventilation

Fresh air ventilation is optional. An insulated duct from outside can connect to a tee in the B70DHV's inlet duct. A ventilation control is needed to program the time and frequency of outside air introduction, based on residence size and occupancy.

• The 6-inch fresh air ventilation duct should tee into the 8-inch round collar on the front of the B70DHV.
• An insulated 6-inch duct can provide up to 55 CFM of outside air.
• Performance can be affected by indoor and outdoor air conditions.
• A 6-inch motorized damper requires a digital control.
• 8-inch ductwork may be needed for higher fresh air requirements.
• In cold climates or low dew point conditions, ventilation can assist dehumidification for year-round drying.

Fresh Air Ventilation With Dehumidifier Off and Fan Only Operation

Outside air mixes with return air before dehumidification. Indoor and outdoor temperature and humidity affect combined outlet air conditions.

Hot Climate Example: Outdoor Air (90°F, 65% RH) mixes with Indoor Air (70°F, 50% RH) via a Motorized Damper (A: Fresh Air Inlet, B: Return Air Inlet) to produce Mixed Air (75°F, 65% RH), which exits as Outlet Air (75°F, 65% RH) through the Supply Air Outlet (C).

Cold Climate Example: Outdoor Air (30°F, 65% RH) mixes with Indoor Air (70°F, 50% RH) via a Motorized Damper (A: Fresh Air Inlet, B: Return Air Inlet) to produce Mixed Air (59°F, 51% RH), which exits as Outlet Air (59°F, 51% RH) through the Supply Air Outlet (C).

Determine Ventilation Requirements

Minimum ventilation requirements are calculated using ASHRAE 62.2-2016. Follow all local and national building and safety codes.

Option 1: Calculating Airflow Requirement Using ASHRAE 62.2-2016 Airflow Equation

ASHRAE Airflow in CFM = [House Area in Sq.Ft. x 0.03] + [(Number of Bedrooms + 1) x 7.5]

Note: Use 'Number of Bedrooms + 1' or 'Number of Occupants', whichever is larger.

Example 1 (Bedrooms): 1800 sq ft house, 3 bedrooms, 4 occupants = [1800 x 0.03] + [(3+1) x 7.5] = 84 CFM.

Example 2 (Occupants): 1800 sq ft house, 3 bedrooms, 5 occupants = [1800 x 0.03] + [5 x 7.5] = 91.5 CFM.

Record the required CFM: ______

Option 2: Calculating Airflow Requirement Using Table 4.1 from ASHRAE 62.2-2016

Record the required CFM: ______

Controls

The B70DHV can be used with controls like the Broan DEH 3000, which monitors and controls relative humidity and ventilation. The B70DHV has a built-in dehumidistat and can also be wired to a remote control. If the unit is outside the desired humidity control area, a remote controller is recommended. For built-in control, place it where it can accurately sense humidity. Adjust the control to maintain the desired humidity level.

Note: The DEH 3000 is sold separately. Other thermostats are compatible.

Wiring Controls

[CAUTION!] Do not allow the 24V terminal to contact the COM terminal on the B70DHV, as this will result in transformer damage.

Circuit Breaker

The unit includes a resettable circuit breaker to protect the 24-volt control transformer. Check for electrical shorts before resetting. Resetting without correcting a short may damage the transformer. Refer to the electrical schematic or the unit's access panel for connections. The reset button is on the back of the unit.

Control Connections

Terminals are labeled for clarity. Some terminals may not be used depending on the control. Consult the electrical schematic or access panel before making connections. A low-voltage control is required.

A 40VA transformer between the COM and 24V terminals powers relay coils for fan and compressors. This transformer can also power external HVAC accessories.

Control Functions:

• Compressor ON / Fan ON: Make contact between 24V and DEHU terminals.
• Compressor OFF / Fan ON: Make contact between 24V and FAN terminals.
• Power HVAC Accessory: Connect the accessory to the DMPR and 24V terminals.

Note: 18-gauge wire is needed between the dehumidifier and the external control.

Air Filtration

The B70DHV uses a MERV-13 filter (0.75" x 9.00" x 11.38"). Check and replace the filter every three to six months. Operating with a dirty filter reduces capacity and efficiency. Do not operate without the recommended filter, as this voids the warranty.

[CAUTION!] Make sure the unit is off before changing the filter.

Changing the Filter

For optimal filtration and efficiency, replace the air filter every three to six months with a MERV-13 rated filter.

Step 1: Remove the filter door by pushing the snap button and pulling the door away from the unit. Pull up to disengage it from the slot.

Step 2: Remove the filter by pulling it straight out. Insert the new filter by pushing it straight in, ensuring the AIR FLOW arrow points into the unit.

Step 3: Replace the filter door, ensuring the opening is fully covered.

MERV Rating Chart

This chart details the Standard 52.2 Minimum Efficiency Reporting Value (MERV) for various filters, their dust spot efficiency, arrestance, typical controlled contaminants, applications, and filter types.

Service

[CAUTION!] Troubleshooting should be performed by a qualified HVAC technician.

Troubleshooting

Symptom: Neither fan nor compressor running. Dehumidification is being called for.

Possible Reasons: Unit unplugged or no power, humidity control set too high, loose internal/control wiring, defective compressor relay, defective control transformer.

Symptom: Compressor is not running. Dehumidification is being called for. Fan is running.

Possible Reasons: Defective compressor run capacitor, loose compressor circuit connection, defective compressor overload, defective compressor, defrost thermostat open.

Symptom: Compressor cycles on and off. Dehumidification is being called for.

Possible Reasons: Low ambient temperature/humidity causing defrost cycle, defective compressor overload, defective compressor, defective defrost thermostat, dirty air filter or restricted airflow, defective fan or relay.

Symptom: Fan is not running. Dehumidification or fan is being called for.

Possible Reasons: Loose fan circuit connection, obstruction preventing fan impeller rotation, defective fan, defective fan relay.

Troubleshooting Procedure for Control Related Issues

[WARNING!] Electrical shock hazard: Electrical power must be present to perform some tests. These tests should be performed by a qualified service person.

This diagnostic method tests control circuit components when the control will not activate the main unit:

1. Detach field control wiring from main unit terminals.
2. Connect 24V and FAN terminals; only the fan should run. Disconnect.
3. Connect 24V and DEHU terminals; fan and compressor should run. Disconnect.
4. If these tests succeed, the main unit is working correctly from a control standpoint.
5. Reconnect field control wiring.
6. Remove control panel cover and detach field wiring from control connections.
7. Connect 24V and FAN terminals; only the fan should run. Disconnect.
8. Connect 24V and DEHU terminals; fan and compressor should run. Disconnect.
9. If these tests succeed, the field control wiring is okay.
10. If problems persist, the control is likely faulty.

Symptom: Low dehumidification capacity (evaporator frosted continuously). Dehumidification is being called for.

Possible Reasons: Defrost thermostat loose/defective, low refrigerant charge, dirty air filter(s) or restricted airflow, excessively restrictive ducting.

Symptom: No ventilation. Ventilation is being called for.

Possible Reasons: Loose connection in ventilation control circuit, loose connection in damper power circuit, defective fresh air damper.

Symptom: Dehumidifier removes some water, but not as much as expected.

Possible Reasons: Air temperature/humidity dropped, humidity meter/thermometer out of calibration, unit entered defrost cycle, dirty air filter(s) or restricted airflow, defective defrost thermostat, low refrigerant charge, air leak (cover/ducting), defective compressor, restrictive ducting.

Troubleshooting Procedure for Performance Related Issues

[WARNING!] Electrical shock hazard: Electrical power must be present to perform some tests. These tests should be performed by a qualified service person.

This diagnostic method checks internal components when a performance issue is suspected:

1. Set humidity controller to most humid or off position. Check if the unit shuts off.
2. If yes, set fan to ON. Check if the fan starts.
3. If fan starts, leave it ON and set humidity to driest setting. Wait up to 5 minutes for the compressor to start.
4. Listen for a distinct buzzing/humming sound of the compressor starting.
5. If the compressor runs continuously, after about 15 minutes, feel for a slight increase in discharged air temperature.
6. Depending on environmental conditions (temp/Rh%), water should be produced within 30 minutes. (Note: Little to no water may be produced if room temperature is 55°F or below, or in low relative humidity areas.)
7. Collecting water over a 24-hour period provides a performance measurement.

Refrigerant Charging

[WARNING!] Servicing the B70DHV with its high pressure refrigerant system and high voltage circuitry presents a health hazard which could result in death, serious bodily injury, and/or property damage. Service must be performed by a qualified service technician.

If refrigerant charge is lost due to service or leak, repair the leak and weigh in a new charge accurately. Recover any remaining old charge before adding new. Refer to the unit nameplate for correct charge weight and refrigerant type.

Warranty

Broan, LLC warrants the B70DHV dehumidifier ("Product") to be free of material defects in workmanship or materials for a period of two (2) years ("Two-Year Warranty") from the date of initial purchase by an original customer or authorized reseller. Product components are warranted for six (6) years from the date of initial purchase.

Limitation of Remedies

Broan's sole liability, at its option, is replacement or repair of the Product or its components. This excludes refrigerant, piping, supplies, transportation costs, and labor for repair/replacement. This exclusion applies even if the express warranty or limited remedy fails of its essential purpose. No representative of Broan or its affiliates is authorized to make any warranty not included in this agreement.

Disclaimer of Warranties

Broan disclaims all express and implied warranties, including warranties of merchantability and fitness for a particular purpose, except for the limited warranty provided.

Warranty Limitations

The warranty extends only to the original Customer and is void upon assignment or transfer. "Defect" does not include issues from misuse, improper installation, improper system design, abuse, lack of care, failure to follow instructions, tampering, improper repair, freezing, corrosion, acts of nature, or other causes not due to Broan's workmanship or material. Warranty periods are not extended by replacements. Costs related to changes required by codes or laws after purchase are not covered.

Customer Responsibilities

To obtain warranty coverage, send a valid warranty claim to Broan before the warranty period expires. Invoices evidencing proof of purchase are required. If invoice dates are unclear, the product's manufacture date will be used. Warranty service must be performed by Broan or an authorized servicer. Contact Broan at 1-800-558-1711 for service. Service is performed during customary working hours. If the product must be shipped for service, the Customer is responsible for packaging, freight charges, and risk of loss.

Limitation of Liability

Broan shall not be liable for any special, direct, indirect, collateral, or consequential damages of any kind related to the product's design, sale, installation, use, repair, replacement, or performance. Broan's liability shall not exceed the purchase price of the product, component, or part in question.

Applicable Law and Venue

Any arbitration or litigation related to the product will be brought exclusively in Dane County, Wisconsin. The Customer consents to the jurisdiction of the federal and state courts located there and waives the right to change venue. The Customer also consents to the exercise of personal jurisdiction by these courts.

Miscellaneous

If any term of this Limited Warranty is found invalid or unenforceable, the remaining terms remain in effect. Broan's delay or failure to exercise a right does not waive its ability to enforce that right later.