Allied service menus, test modes and resets

Turning off gas to the unit

Furnace · A95, A93, 95G1, 92G1UH

Use this procedure before any service.

1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the unit if service will be performed.
3. Remove the upper access panel.
4. Move the gas valve switch to OFF.
5. Replace the upper access panel.

Applies to: Service shut-down

Source: Allied 92G1UH installation manual, p. 46. Written in our own words; check the manual for your exact model.

Watchguard automatic reset after ignition lockout

Furnace · A95/A93/95G1/92G1UH

The integrated control has an internal Watchguard. After one hour of continuous heat demand it resets an ignition-failure lockout, usually caused by low gas line pressure.

Applies to: Integrated control ignition lockout

Source: Allied 92G1UH installation instructions manual, p. 46. Written in our own words; check the manual for your exact model.

Check gas connections for leaks

Furnace · A95/A93/95G1/92G1UH

Test every factory and field gas joint after piping is finished.

1. Use a commercial leak-detection soap solution.
2. Never use an open flame to find leaks.
3. Rinse the piping after the test is done.
4. Isolate the furnace from the supply during any test at or above 1/2 psig.

Applies to: Gas piping

Source: Allied 92G1UH installation instructions manual, p. 35. Written in our own words; check the manual for your exact model.

Combustion check

Furnace · A95, A93, 95G1, 92G1UH

Check combustion only after the furnace has run at least 15 minutes with correct manifold pressure and gas flow. The maximum carbon monoxide reading should not exceed 50 ppm.

1. Run the furnace at least 15 minutes with correct manifold pressure and gas flow.
2. Take the combustion sample beyond the flue outlet.
3. Compare the CO2 reading with the CO2 table for the fuel type.
4. Confirm CO is no higher than 50 ppm.

Applies to: All sizes

Source: Allied 92G1UH installation manual, p. 47. Written in our own words; check the manual for your exact model.

Duct static limit for heating mode

Furnace · A95/A93/95G1/92G1UH

The furnace is not certified for heating mode (blower on heating speed) when external static pressure is above 0.5 in. w.c. Higher static can cause improper limit operation.

1. Measure external static pressure with the blower on heating speed.
2. If it is above 0.5 in. w.c., correct the duct system before commissioning.

Applies to: All 92G1UH installations

Source: Allied 92G1UH installation manual, p. 17 (PDF p. 17). Written in our own words; check the manual for your exact model.

Gas valve lighting procedure

Furnace · A95, A93, 95G1, 92G1UH

The furnace uses a hot surface ignitor and must not be lit by hand. Do not use this furnace if any part was underwater.

1. Set the thermostat to the lowest setting.
2. Turn off all electrical power to the unit.
3. Remove the upper access panel.
4. Move the gas valve switch to OFF. Use only your hand on the lever.
5. Wait five minutes to clear any gas. If gas is smelled, stop and call the gas supplier from a neighbor's phone.
6. Move the gas valve switch to ON.
7. Replace the upper access panel.
8. Turn electrical power on and set the thermostat to the desired setting.
9. Repeat these steps if needed to purge air from the gas line on first start.
10. If the unit will not operate, turn off the gas and call a service technician or gas supplier.

Applies to: First start and relighting after gas shut-off

Source: Allied 92G1UH installation manual, p. 45-46. Written in our own words; check the manual for your exact model.

Gas valve pressure testing

Furnace · A95/A93/95G1/92G1UH

The gas valve can be damaged by test pressure.

1. Disconnect and isolate the gas valve before pressure testing the line.
2. Do not test above 1/2 psig (3.48 kPa) at the valve.
3. Use the 1/8 in NPT plugged tap on the valve for gauge connection.
4. If the manual main shut-off valve will not hold test pressure, use the isolation method shown in Figure 48.

Applies to: Gas valve

Source: Allied 92G1UH installation instructions manual, p. 35. Written in our own words; check the manual for your exact model.

Let solvent fumes clear before startup

Furnace · A95/A93/95G1/92G1UH

Fumes from PVC cement can ignite during the system check.

1. Allow fumes to dissipate for at least 5 minutes before placing the unit into operation.
2. Keep solvent cement away from ignition sources and keep the area ventilated.

Applies to: After cementing vent joints

Source: Allied 92G1UH installation manual, p. 19 (PDF p. 19). Written in our own words; check the manual for your exact model.

Priming the condensate trap

Furnace · A95, A93, 95G1, 92G1UH

The trap must hold water before the first run so condensate drains properly. Pour 10 fl oz (300 ml) of water into the trap, or prime it by firing the burners.

1. Light the unit following the lighting procedure.
2. Set the thermostat to call for heat and let the burners fire for about 3 minutes.
3. Set the thermostat to end the heat call.
4. Wait for the combustion air inducer to stop.
5. Call for heat again and let the burners fire for about 3 minutes.
6. End the heat call and wait for the combustion air inducer to stop.

Applies to: First start-up

Source: Allied 92G1UH installation manual, p. 46. Written in our own words; check the manual for your exact model.

Remove the bottom panel for bottom or side return

Furnace · A95 / A93 / 95G1 / 92G1UH

The furnace ships with the bottom panel in place. It must come out for horizontal or upflow bottom-return installs.

1. Remove the two screws holding the bottom cap.
2. Pivot the bottom cap down to release the bottom panel.
3. Remove the bottom panel.
4. Reinstall the bottom cap when done.

Applies to: Upflow with bottom return or horizontal installs

Source: Allied 92G1UH installation instructions manual, p. 15. Written in our own words; check the manual for your exact model.

Remove the shipping bolt on 1/2 HP blower units

Furnace · A95 / A93 / 95G1 / 92G1UH

Units with a 1/2 HP blower have one rigid leg with a shipping bolt and white plastic washer. Remove them before start-up.

1. Check the blower motor size. This procedure applies to 1/2 HP units only.
2. Remove the shipping bolt and flat white plastic washer from the rigid leg.
3. Confirm the rigid leg does not touch the blower housing after removal.
4. Do not run the furnace until the bolt and washer are removed.

Applies to: 1/2 HP blower motor units

Source: Allied 92G1UH installation instructions manual, p. 13. Written in our own words; check the manual for your exact model.

Start-up and performance check list

Furnace · 92G1UH

Checklist to complete at commissioning and record on the sheet.

1. Record the model and serial number.
2. Check gas supply pressure and gas manifold pressure.
3. Check line voltage and supply voltage, and confirm electrical connections are tight.
4. Confirm gas piping connections are tight and leak tested.
5. Confirm intake and exhaust joints are primed and glued, terminations are correct, pipes are supported and horizontal runs are sloped.
6. Confirm the condensate trap is primed and the line is sloped; check heat cable if fitted.
7. Confirm the supply and return ducts are sealed, insulated if needed, and the filter is installed and clean with grilles unobstructed.
8. In heating mode, measure combustion CO2 and CO (ppm), indoor blower amps, supply and return duct temperatures, and total external static.
9. Calculate the temperature rise from the supply and return duct readings.
10. In cooling mode, measure indoor blower amps, supply and return duct temperatures, and total external static on a dry coil, then calculate the temperature drop.
11. Check the condensate and drain lines and vent pipe for leaks.
12. Confirm the thermostat is adjusted and programmed, and explain operation to the owner.

Applies to: 92G1UH furnace

Source: Allied 92G1UH installation instructions manual, p. 59-60. Written in our own words; check the manual for your exact model.

Thermostat heat anticipator setting

Furnace · A95/A93/95G1/92G1UH

If the thermostat heat anticipator is adjustable, set it to the amp draw listed on the wiring diagram attached to the unit.

1. Read the amp draw on the unit wiring diagram.
2. Set the thermostat heat anticipator to that value.

Applies to: Heating thermostat setup

Source: Allied 92G1UH installation instructions manual, p. 46. Written in our own words; check the manual for your exact model.

Canadian installations: combustion air to other appliance clearance

Furnace · A95/A93/95G1/92G1UH

CSA B149 requires a minimum distance between the combustion air intake inlet and the exhaust outlet of other appliances.

1. Keep at least 12 in. (305 mm) between this unit's combustion air intake inlet and another appliance's exhaust outlet.

Applies to: Canadian installations

Source: Allied 92G1UH installation instructions manual, p. 27. Written in our own words; check the manual for your exact model.

Conditions for using the furnace as a construction heater

Furnace · A95 / A93 / 95G1 / 92G1UH

The manual discourages construction heating. Allowed only when every condition below is met.

1. Install the vent system permanently per these instructions.
2. Control the furnace with a room thermostat. No fixed jumpers for continuous heating.
3. Provide and seal the return air duct to the furnace.
4. Keep return air between 60°F (16°C) and 80°F (27°C).
5. Keep air filters in place during construction and replace them at completion.
6. Set input rate and temperature rise to the nameplate.
7. Provide 100% outdoor combustion air through temporary ducting, not connected directly to the furnace.
8. Clean the heat exchanger, components, duct system, filters and evaporator coil after final cleanup.
9. Verify ignition, input rate, temperature rise and venting per these instructions.

Applies to: Furnace used for heating during construction

Source: Allied 92G1UH installation instructions manual, p. 9-10. Written in our own words; check the manual for your exact model.

Do not vent into an existing stack or use screens

Furnace · A95/A93/95G1/92G1UH

Exhaust must not discharge into a stack that serves another gas appliance. Screens or perforated metal in exhaust or intake terminations cause freeze-ups and can block them.

1. If a vertical discharge through an unused stack is required, insert PVC pipe into the stack until its end is even with the top of the metal stack.
2. Do not install screens or perforated metal on exhaust or intake terminations.

Applies to: Exhaust and intake terminations

Source: Allied 92G1UH installation manual, p. 19-21 (PDF p. 19-21). Written in our own words; check the manual for your exact model.

EAC and HUM accessory terminals on the control board

Furnace · A95, A93, 95G1, 92G1UH

The EAC terminal is a 120 V output that is energized whenever the indoor blower runs. The HUM terminal is a 120 V output that is energized in heating mode when the combustion air inducer runs. Each takes up to 1 amp; larger loads need an external relay.

1. Connect an accessory rated up to 1 amp directly to EAC or HUM, with its neutral on a provided neutral terminal.
2. For a load above 1 amp, use an external relay and do not connect it directly to the terminal.

Applies to: Accessory wiring on the integrated control

Source: Allied 92G1UH installation manual, p. 42. Written in our own words; check the manual for your exact model.

Electrostatic discharge (ESD) precautions

Furnace · A95, A93, 95G1, 92G1UH

Electrostatic discharge can damage the furnace electronic controls. Put the furnace, the control and the technician at the same static potential before service.

1. Touch bare metal on an unpainted part of the unit, such as the gas valve or blower deck, before any service work.
2. Touch all tools to the same unpainted surface before using them near the control.

Applies to: Installation and service of the integrated control

Source: Allied 92G1UH installation manual, p. 42. Written in our own words; check the manual for your exact model.

Exhaust tee and direction notes

Furnace · A95/A93/95G1/92G1UH

Figure 32 shows the exhaust tee termination. Do not use an accelerator with the tee. The exhaust must never point toward the combustion air inlet.

1. Connect the exhaust termination tee to the 2 in. or 3 in. PVC flue pipe as shown.
2. Do not install an accelerator when an exhaust termination tee is used.
3. Rotate the exhaust 45 degree elbow to the side away from the combustion air inlet if needed to keep exhaust away from neighbors.
4. Never direct exhaust toward the combustion air inlet.

Applies to: Sidewall exhaust terminations with optional tee

Source: Allied 92G1UH installation instructions manual, p. 32. Written in our own words; check the manual for your exact model.

Field electrical connections and overcurrent protection

Furnace · A95, A93, 95G1, 92G1UH

Wiring must meet Class I limits and be protected by a fuse or breaker matched to the unit nameplate. Maximum overcurrent protection allowed is 15 A.

1. Use a fuse or breaker sized from the nameplate maximum current, never above 15 A.
2. Install a separate properly sized disconnect near the furnace.
3. Use at least 18 gauge wire rated Class II for thermostat connections.
4. Ground the unit per local code, or the NEC (ANSI/NFPA 70) in the USA or CSA C22.1 in Canada. A green ground wire is in the field makeup box.
5. Check polarity and ground, because the integrated control is polarity sensitive.
6. Leave enough thermostat wire to remove the blower for future service.
7. If the makeup box is moved to the right side, plug the unused left side opening after removing the plug from the right side.

Applies to: Power supply and thermostat wiring

Source: Allied 92G1UH installation manual, p. 42. Written in our own words; check the manual for your exact model.

Gas piping layout (left side, right side, horizontal)

Furnace · A95, A93, 95G1, 92G1UH

Gas piping can enter from the left side (standard), the right side (alternate), or run for horizontal applications. Only black iron pipe may be routed inside the cabinet. A drip leg, ground joint union and manual main shut-off valve go in the supply line.

1. Install a manual main shut-off valve and a drip leg in the supply line.
2. Install a ground joint union in the supply piping.
3. Route only black iron pipe inside the cabinet and seal the cabinet opening with the bellows grommet.
4. Plug the unused side of the gas valve when piping from the other side.

Applies to: Gas piping, all sizes in this manual

Source: Allied 92G1UH installation manual, p. 40. Written in our own words; check the manual for your exact model.

Gas type approval and LP conversion

Furnace · A95/A93/95G1/92G1UH

The furnace is set up for natural gas only. Use only the gas type listed on the unit nameplate. LP/propane needs a separate conversion kit, which is ordered separately.

1. Check the nameplate for the approved gas type.
2. Install the LP conversion kit before operating on propane/LP gas.

Applies to: All A95UH, A93UH, 95G1UH and 92G1UH units

Source: Allied 92G1UH installation manual, p. 8. Written in our own words; check the manual for your exact model.

Gas valve connection torque

Furnace · A95/A93/95G1/92G1UH

Do not overtighten the gas piping at the valve.

1. Use two wrenches so the valve is not twisted.
2. Do not exceed 600 in-lbs (50 ft-lbs) when attaching gas piping to the valve.

Applies to: Gas valve

Source: Allied 92G1UH installation instructions manual, p. 35. Written in our own words; check the manual for your exact model.

High altitude installation

Furnace · A95, A93, 95G1, 92G1UH

In Canada, installations above 4,500 ft are under local authority jurisdiction. At 4,501 to 10,000 ft a pressure switch change may be needed, and orifice conversion kits may apply. Combustion air pressure switches are factory set and need no adjustment.

1. Check the altitude of the installation against the altitude tables.
2. Order and install the required pressure switch and orifice kit for the unit size and altitude.
3. Do not adjust the combustion air pressure switch.

Applies to: Installations above 4,500 ft

Source: Allied 92G1UH installation manual, p. 47-48. Written in our own words; check the manual for your exact model.

Limits and switches that are factory set

Furnace · A95/A93/95G1/92G1UH

Primary limit, pressure switch and the two flame rollout switches are factory set and should not be adjusted. The primary limit is on the vestibule panel. The pressure switch sits on the cold end header box and proves combustion air inducer operation before ignition. The two rollout switches are manual reset and are on the front of the burner box.

1. Do not adjust the primary limit or pressure switch.
2. If a rollout switch has opened, check for an exhaust or intake obstruction before pressing its manual reset.

Applies to: Furnace safety controls

Source: Allied 92G1UH installation instructions manual, p. 46. Written in our own words; check the manual for your exact model.

LP/propane leak detector

Furnace · A95/A93/95G1/92G1UH

LP/propane odorant can fade, and LP gas settles near the floor, so it can be hard to smell. An LP leak detector should be installed in every LP application.

1. Install an LP/propane leak detector in all LP installations.

Applies to: LP/propane installations

Source: Allied 92G1UH installation manual, p. 8. Written in our own words; check the manual for your exact model.

Massachusetts carbon monoxide detector and venting requirements

Furnace · 92G1UH

Requirements for side wall, horizontally vented gas equipment in Massachusetts dwellings where the vent termination is under 7 feet above grade.

1. Confirm a hard-wired CO detector with alarm and battery backup is on the floor level where the equipment is installed, and a battery or hard-wired CO detector with alarm is on each additional level.
2. If the equipment is in a crawl space or attic, the hard-wired detector may be on the next adjacent floor.
3. If the requirement cannot be met at completion, the owner has 30 days to comply, and a battery-operated CO detector with alarm must be installed during that time.
4. Detectors must meet NFPA 720 and be ANSI/UL 2034 listed and IAS certified.
5. Install a metal or plastic sign on the exterior at least 8 feet above grade, directly in line with the vent terminal, reading GAS VENT DIRECTLY BELOW. KEEP CLEAR OF ALL OBSTRUCTIONS. Lettering must be at least 1/2 inch.
6. Leave the installation instructions and venting instructions with the appliance.

Applies to: 92G1UH furnace installed in Massachusetts

Source: Allied 92G1UH installation instructions manual, p. 61. Written in our own words; check the manual for your exact model.

Preventing exhaust icing in extreme cold

Furnace · A95/A93/95G1/92G1UH

Long vent runs through unconditioned space can form ice at the termination below about 20 F (6.7 C) and stop the unit from running.

1. Make sure run times are at least 5 minutes, which clears most icing problems.
2. If icing persists, install heating cable on the exhaust piping and termination. Heating cable kits are available; check the unit spec sheet for part numbers.

Applies to: Exhaust terminations in cold climates

Source: Allied 92G1UH installation instructions manual, p. 27. Written in our own words; check the manual for your exact model.

PVC versus ABS connections at the furnace

Furnace · A95/A93/95G1/92G1UH

Intake and exhaust connections on 92G1UH are PVC. ABS pipe needs transition solvent to join the PVC fitting in the unit.

1. Use PVC primer and PVC solvent cement when running PVC vent pipe.
2. When using ABS vent, bond to the unit's PVC fitting with transition solvent cement.
3. Use all-purpose cement only when fittings and pipe are the same material.
4. Use low-temperature solvent cement in cold weather.
5. Do not use hammer blows to insert pipe.

Applies to: Vent pipe material selection

Source: Allied 92G1UH installation manual, p. 18 (PDF p. 18). Written in our own words; check the manual for your exact model.

Return air must not come from a room with a gas appliance

Furnace · A95/A93/95G1/92G1UH

Pulling return air from a room with a gas water heater, gas appliance or wood fireplace creates negative pressure. Flue gases can then be drawn back down the vent and produce carbon monoxide that is spread through the duct system.

1. Do not draw return air from a room that contains another gas appliance or combustion device.
2. Seal the plenum to the furnace cabinet with fiberglass strips, caulk or equivalent when using bottom or side return.

Applies to: Return air plenum installations

Source: Allied 92G1UH installation manual, p. 17 (PDF p. 17). Written in our own words; check the manual for your exact model.