Other: Furnace tips (part 5 of 5)

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

Vertical and horizontal termination height

Rheem · Non-direct and direct vent terminations

Maintain at least 12 in (31 cm) above the highest anticipated snow level or grade, whichever is greater. Canadian installs must follow CSA B149.1-10, Sect. 8.14. Terminations more than 24 in above the roof penetration need additional support. Couplings are required on the exterior and optional on the interior. Reduce 3 in pipe to 2 in before penetrating the roof.

1. Confirm termination height above grade and expected snow level.
2. Add support for any vent run more than 24 in above the roof penetration.
3. Install couplings on the exterior section.
4. Reduce 3 in pipe to 2 in before the roof penetration.

Burner box cover reinstallation

Trane · Burner box service

Use this method when the cover is removed to service the flame sensor, hot surface igniter or orifices.

1. Insert the top flange of the front cover under the lip inside the box.
2. Rotate the front cover inward, making sure all side flanges are outside the box.

Category IV direct vent classification

Trane · All direct vent furnaces

These furnaces are Category IV: positive vent static pressure with flue loss under 17 percent.

1. Use a venting system that is gas tight and water tight.
2. Direct vent models are approved for manufactured/mobile housing only when used with BAYMFGH100A.

Close coupled return below 36 in

Trane · Upflow furnaces in horizontal applications

A close coupled return with the filter directly under a bottom side return is not recommended because of noise.

1. If used anyway, attach 1/2 in mesh metal hardware cloth to the inside bottom of the filter grille to protect the technician's hands from the blower.
2. Do not install the filter in the return duct directly above a horizontal furnace.

Condensate drain freeze protection

Trane · Condensate drain installations

A frozen condensate drain shuts the furnace down.

1. Use 1/2 in. or larger PVC or CPVC drain piping.
2. If the drain runs outside conditioned space, apply UL listed heat tape rated 5 or 6 W/ft at 120 V.
3. Use self-regulating or thermostatically controlled heat tape, installed per manufacturer instructions.
4. Use a corrosion resistant condensate pump if a pump is required.
5. Where the furnace is above a finished ceiling, route the primary drain vent overflow into an auxiliary drain pan.

Corrosive atmosphere and construction debris warning

Trane · All furnaces

Condensate mixed with chlorides or fluorides from paint, varnish, stains, adhesives, cleaners or cement corrodes the heat exchanger quickly.

1. Do not install the furnace in a corrosive or contaminated atmosphere.
2. Keep the furnace from being used as a construction heater until the construction heater conditions are met.

Do not use field fabricated venting parts

Trane · All venting installations

Only factory supplied venting components may be used. Field fabricated parts can damage the vent and cause carbon monoxide poisoning or death.

1. Use only factory supplied venting components.
2. Do not run return air through the side of the furnace cabinet on horizontal applications.

Downflow filter brackets and horizontal filter location

Trane · DH1 downflow and horizontal installs

Downflow furnaces come with factory brackets to mount filters in the return duct. Horizontal filters must be placed remotely, not in the return duct directly above the furnace.

1. Mount the factory brackets to hold the filter in the return duct.
2. Locate the filter remotely from the furnace in horizontal applications.

Flexible connectors and vibration

Trane · All UH1/DH1 furnaces

Flexible nonflammable connectors reduce transmission of vibration, which can amplify noise through ducts.

1. Use flexible connectors on return and discharge connections.
2. Use removable plenums if only the front is accessible.

Gas leak testing method

Trane · All furnaces

Do not check for leaks with an open flame.

1. Check all gas connections with a commercial leak-detection soap solution.
2. See the Gas Piping section (pages 31-32) for the full procedure.

Owner shutdown warnings

Trane · Owner instructions

Advise the owner on gas shutoff and freeze protection.

1. If electrical, fuel or mechanical failure occurs, shut off the manual gas valve before turning off electrical power.
2. During cold weather shutdowns, protect water pipes and receptacles from freezing.
3. Contact the designated service agency for failures.

Propane gas hazard and gas detector

Trane · Propane-fired furnaces in low or confined spaces

Propane is heavier than air and can collect in low areas or confined spaces. Odorant can fade, so a leak may not be noticed by smell.

1. If the furnace is in a basement, excavated area or confined space, recommend the customer have the gas supplier install a gas detecting warning device.
2. The manufacturer does not test or endorse any detector brand.

Propane is heavier than air and odorant can fade

Trane · Propane gas furnaces in basements or confined spaces

A gas leak can collect in low areas or confined spaces, and odorant can fade so the leak is not noticed. A gas detecting warning device is strongly recommended for basement, excavated or confined installs.

1. Recommend that the customer contact a gas supplier to install a gas detecting warning device.
2. Note that the manufacturer does not test detectors and makes no claim about any brand.

Shut off gas supply during failure

Trane · AUH1B furnaces

If electrical, fuel or mechanical failure occurs, close the gas supply before removing electrical power.

1. Turn off the gas at the manual gas valve on the supply piping.
2. Then turn off electrical power to the furnace.
3. Contact the designated service agency.

Turn off power before servicing filters

Trane · All UH1/DH1 furnaces

Moving parts can cause injury or death, so power must be off before servicing the filter.

1. Switch the furnace power off before removing or changing the filter.

Upflow 5 or 6 ton above 1800 CFM needs multiple return openings

Trane · Upflow 5 or 6 ton airflow models

On upflow 5 or 6 ton airflow models where required airflow exceeds 1800 CFM, return air openings and filters are needed on both sides, on one side and the bottom, or on the bottom only.

1. Confirm return openings and filters are provided per one of the three allowed layouts.
2. Use the Table 5 filter sizes for the cabinet width.

Wiring basis for a one-stage heating system

Trane · One-stage heating furnace wiring

The field wiring example shown is for a one-stage heating thermostat with no cooling. Supply is 115 V, single phase, 60 Hz, per local codes.

1. Wire to 115 V, 1 phase, 60 Hz per local codes.
2. Use a one-stage heating thermostat with no cooling for this wiring example.
3. Check the wiring diagram on p. 28 for the humidifier and EAC connections.