Other: Furnace tips (part 4 of 5)

Short, practical technician tips on other for furnace. Check each one against the manual for your exact model before acting.

Model data card replacement

Rheem · 96V and 96MDV communicating furnaces

The model data card is wire-tied to the furnace and should only be removed when the control is replaced. Replacement cards are model specific.

1. Keep the card with the furnace unless the control is being replaced
2. Install the replacement card with the matching model data at connector P6

Natural gas at high altitude: derate

Rheem · Natural gas above 2,000 ft

No high altitude pressure switch changes are needed. Derate the input by 4% per thousand feet above 2,000 ft. Factory orifices are sized for 1100 BTU/ft3 at sea level; regional heating values may remove the need to change them except at extreme altitudes. Above 2,000 ft, follow local codes or NFGC/CSA B149.1.

1. Derate the input 4% per 1,000 ft above 2,000 ft.
2. Check the local gas heating value before changing orifices.
3. Follow local codes, or NFGC / CSA B149.1 where no local code applies.

Never bypass safety switches

Rheem · 96V and 96MDV series furnaces

A safety switch that shuts the furnace down or makes it cycle intermittently points to a real hazard that a qualified technician must fix. Do not reset safety controls without correcting the cause and verifying safe operation.

1. Do not jumper or remove any safety switch from the control circuit.
2. Find and correct the cause before resetting any safety control.
3. Replace safety control parts only with identical OEM parts.

Never operate the system without filters

Rheem · 96V and 96MDV series furnaces

Running without filters lets dust collect in the ducts and at the registers. Dust that reaches the heat exchanger chars and leaves soot on walls, ceilings and furnishings. Soot can also come from certain candles or untrimmed candlewicks.

1. Install air filters before operating the system.
2. Check that filters are in place at every startup.

Never operate without filters or panels

Rheem · R96V furnace

Running the system for long periods without filters lets dust collect in ducts and registers. Recirculated dust chars on the heat exchanger and soils the home. Replace all blower doors and compartment covers after servicing. Do not run the unit without all panels and doors in place.

1. Install or confirm the filter before startup.
2. Replace all blower doors and compartment covers after any service.
3. Do not operate the furnace without all panels and doors secured.

Only current vent instructions apply

Rheem · All 96V and 96MDV series furnaces

Only the current vent instructions in this manual apply. All 90 Plus gas furnaces cannot be common-vented with any other appliance.

1. Use the current vent instructions for the install.
2. Do not common-vent this furnace with any other appliance.

Overheating or gas supply that will not shut off

Rheem · 96V and 96MDV furnaces

If the furnace overheats or the gas supply does not shut off, close the manual gas valve for the appliance before shutting off electrical power. Otherwise an explosion or fire can result.

1. Close the manual gas valve for the appliance first.
2. Then shut off electrical power.

Polypropylene vent products

Rheem · Polypropylene vent systems

Centrotherm Innoflue and DuraventPolypro single-wall and flex products are approved only for single appliance use. Do not exceed listed lengths, diameters or elbows. Use only the terminations listed in Tables 5 and 6. Liners for B-vent or chimney are for non-direct venting only. These products are listed in Canada under ULC-S636.

1. Confirm the product and termination are listed in Tables 5 or 6.
2. Check the vent length and elbow count against Table 4.
3. Follow the manufacturer's instructions for installation.

Provide combustion and ventilation air

Rheem · 96V and 96MDV series furnaces

Combustion and ventilation air must be supplied as required by the National Fuel Gas Code (US) or CSA B149.1 (Canada) and by the combustion and ventilation air section of these instructions.

1. Verify combustion and ventilation air provisions before startup.
2. Follow the combustion air section of the manual for the installation type.

PVC solvent cement safety

Rheem · PVC vent joints

PVC and CPVC solvent cements and primers are highly flammable. Use good ventilation and do not assemble near a heat source or open flame.

1. Ventilate the work area.
2. Keep cement away from heat sources and open flames.
3. Do not use cement that is curdled, lumpy or thick, and do not thin it.

Read the fault display correctly

Rheem · 96V and 96MDV communicating furnaces

Faults flash on for one second and off for half a second, and each fault is shown at least twice. Normal operating codes stay steady on. Check the display orientation first, because an upside-down display changes the reading.

1. Confirm display orientation using dipswitch S1-1 before reading codes
2. Note the code and any second code shown alternately with it
3. Use the fault priority list to pick which fault shows when several are active

Recommended direct vent installation

Rheem · Venting type selection

Direct vent installations are recommended for better indoor air quality, added safety and performance. Non-direct installations must provide combustion air as set out in the National Fuel Gas Code and, in Canada, CSA B149.1.

1. Use direct vent where practical.
2. For non-direct, provide combustion air per NFPA 54 or CSA B149.1.

Recommended elbow count

Rheem · All vent runs

Exceeding the recommended maximum number of elbows can cause nuisance pressure switch operation. Long sweep elbows are preferred. Mixing elbow types is allowed, but standard 90s and 45s used alone at the maximum count may cause nuisance outages.

1. Count elbows against the maximum in the Table 4 elbow column for the model.
2. Use long sweep 90s wherever possible.

Remove the shipping base pan from the top of the unit

Rheem · All 96V and 96MDV series furnaces

The solid metal base pan must be taken off the top of the furnace before it is installed. If it stays in the shipping position it can damage the furnace or other equipment.

1. Remove the solid base panel from the top of the unit before setting the furnace.

Residential garage installation height

Rheem · Furnaces installed in residential garages

In a residential garage, the burners and ignition source must be at least 18 inches (450 mm) above the floor to reduce the risk of igniting flammable vapors. The furnace must also be located or protected from physical damage by vehicles.

1. Confirm burners and ignition source are at least 18 in. (450 mm) above the floor.
2. Locate or guard the furnace to prevent vehicle damage.

Seal and install a base plate when the factory return is unused

Rheem · 96V and 96MDV series furnaces

If the factory return-air connection is not used, it must be sealed with a solid metal base plate. Otherwise carbon monoxide and other contaminants can be drawn into the conditioned air space. Factory base plates are sold as accessories; part numbers are in the furnace spec sheet.

1. Install a solid metal base plate over the unused factory return connection.
2. Seal the base plate and all return air duct connections.

Seal ducts and equipment where fumes or CO can migrate

Rheem · 96V and 96MDV series furnaces

Duct leaks can pull dirt, fumes, odors and carbon monoxide into the living space. Equipment or ducts in garages, storage areas or spaces with fuel-burning appliances must have all joints, seams and openings sealed.

1. Seal all joints, seams and openings in equipment and ducts located in garages or storage areas.
2. Seal equipment and ducts in spaces with water heaters or boilers to prevent depressurization and migration of combustion products.

Seal return air ducts when supply ducts leave the furnace space

Rheem · 96V and 96MDV series furnaces

If supply ducts carry air to areas outside the furnace space, the return air must also come through ducts sealed to the furnace casing and terminating outside that space.

1. Seal return ducts to the furnace casing.
2. Terminate return ducts outside the furnace space.

Side return cut-out not allowed in downflow or horizontal

Rheem · Downflow and horizontal installations

In downflow and horizontal configurations, side return air cut-out is not permitted. Return connections must be airtight to keep toxic fumes and carbon monoxide out of the living space.

1. Use the top return in downflow and the return-air end in horizontal.
2. Seal the return connection airtight.

Sidewall vent kit RXGY-G02

Rheem · Non-direct and direct sidewall termination

The RXGY-G02 sidewall vent kit can be used for both direct and non-direct installations. Figure 20 shows a typical installation with a field supplied reducing coupling. Maximum 18 in of 2 in pipe is shown in the figure.

1. Install the field supplied reducing coupling.
2. Keep the 2 in pipe run within the 18 in figure maximum.
3. Refer to the direct vent sidewall kit option for full directions.

Soapy water for hose installation

Rheem · Horizontal right with right vent conversion

Soapy water makes the drain and vent hoses easier to slide onto fittings during conversion.

1. Wet the fitting and the hose end with soapy water before pushing the hose on.

Support the unit and combustible floor rules

Rheem · All installations

Support the unit when installed. It may be set on combustible wood flooring or on support brackets. Upflow furnaces are certified for combustible floors but must not be set directly on carpet, tile or other combustible material other than wood flooring.

1. Support the furnace with brackets where needed.
2. Do not place the upflow furnace directly on carpet, tile or non-wood combustible flooring.

Suspected gas leak response

Rheem · Gas leak situations on any gas appliance

If a gas leak is present or suspected, the technician must not search for the source. The leak must be reported and the area cleared.

1. Do not try to find the leak source yourself.
2. Do not light appliances, touch electrical switches or use a phone in the building.
3. Leave the building and call the gas supplier from outside.
4. Do not go back in until the gas supplier or fire department says it is safe.

Termination clearances from meters and appliances

Rheem · All venting

Keep the vent terminal at least 4 ft horizontally from electric meters, gas meters, regulators and relief equipment. Keep the furnace combustion air inlet at least 3 ft from the vent of any other gas or fuel appliance or clothes dryer, except for multi-venting.

1. Measure horizontal distance from the vent terminal to meters, regulators and relief equipment.
2. Measure distance from the combustion air inlet to nearby appliance vents and dryer vents.

Thermostat compatibility and wiring

Rheem · Thermostat wiring

Use a thermostat that is not current-robbing. Use 24 volt control wire no smaller than 18 AWG. Run the leads into the blower compartment and connect to the low-voltage terminals shown on the wiring diagram.

1. Use a thermostat that is not current-robbing.
2. Use 24 volt wire of 18 AWG or larger.
3. Connect to the low-voltage terminals as shown on the wiring diagram.
4. Do not mount the thermostat on an outside wall or where drafts, pipes, ducts, sun or fireplace heat affect it.

Use soapy water on hose and tube assemblies

Rheem · Condensate drain hose and tube assembly during conversions

Soapy water makes hoses and tubes slide onto fittings much more easily during drain assembly.

1. Lubricate the hose ends and fittings with soapy water before pushing the hose or tube on.

Vent combustion products outdoors only

Rheem · 96V and 96MDV series furnaces

Combustion products must be discharged outdoors. Connect the furnace only to an approved vent system as specified in the vent pipe installation section.

1. Connect the furnace only to an approved vent system.
2. Follow the vent pipe installation section for pipe and termination requirements.

Vent pipe or heat exchanger leaks

Rheem · R96V furnace venting

Holes in the vent pipe or heat exchanger can let toxic fumes into the home and cause carbon monoxide poisoning or death. The vent pipe or heat exchanger must be replaced if it leaks.

1. Replace the vent pipe or heat exchanger if any leak is found.

Vent termination location guidelines

Rheem · All termination locations

Avoid terminating under a patio or deck, or behind obstructions. Do not terminate on the side with prevailing winter winds. Avoid areas near shrubs. Use a sleeve for brick or masonry penetrations. Use a corrosion-resistant backing plate behind the vent. Condensate can freeze on walls, eaves and nearby objects. Vent piping may run under a deck only if the termination is not under the deck, and it must be insulated.

1. Select a location clear of decks, patios and obstructions.
2. Avoid prevailing winter wind side.
3. Install a sleeve through brick or masonry.
4. Install a backing plate behind the vent.
5. Insulate any vent run under a deck.

Vent termination safety warnings

Rheem · All venting

Do not use vent terminations that are not specified in these instructions. Screens of any kind on inlet or exhaust pipes are not permitted and void the warranty. Do not take combustion air from an attic with power ventilation.

1. Use only specified terminations.
2. Do not install screens on inlet or exhaust pipes.
3. Do not draw combustion air from an attic that has power ventilation.