Commissioning: Boiler tips (part 2 of 2)

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

Flame failure check at commissioning

NTI · Trinity Tft60, Tft85, Tft110, Tft155, Tft175, Tft200, Tft250, Tft300, Tft399

Proves the flame safety is working after the first lights.

1. Light the boiler at least three times in a row
2. Unplug the single white flame probe wire (leave the orange spark cable alone - about 14,000 V)
3. Let the boiler cycle: it makes 4 ignition cycles and then shows Hold 110
4. Reconnect the flame wire, cycle power and confirm normal lighting

Heating-only use on TRX150 / TRX199: disconnect the 3-way valve motor

NTI · TRX150 / TRX199 heating-only installations

If the boiler is not connected to an indirect water heater, the fitting must be capped and the valve motor disconnected. Otherwise freeze protection may not work.

1. Cap the DHW fitting as shown in the piping figure. A cap is supplied with the boiler.
2. Disconnect the electrical connection of the 3-way valve motor while the boiler runs in central heating mode.
3. This locks the valve in central heating mode so freeze protection works.

Key installation checks before start-up

NTI · TRX150 and related TRX models

Items from the installation checklist that a technician should verify before firing the boiler.

1. Gas supply line at least 3/4 in diameter.
2. Gas line pressure during max and min input stays between 3.5 and 14 in WC for natural gas, or 8 and 13 in WC for propane.
3. CH relief valve rated 30 psi with at least 3/4 in discharge line to an open drain.
4. DHW relief valve rated 150 psi with at least 3/4 in discharge line to an open drain.
5. Vent pitched back to the boiler at 1/4 in per foot.
6. Vent terminations at least one foot above exterior grade and one foot above maximum snow level.
7. Supply voltage matches the rating plate (120V AC).
8. Burner flame checked and combustion verified with a calibrated analyzer.

Limit CO when adjusting high fire, low fire or the gas valve

NTI · TRX boilers, start-up and combustion setting

CO must be checked with a calibrated combustion analyzer during high and low fire adjustments. CO must not exceed 150 ppm at any time. Small changes to the low fire offset or main flow restrictor can raise CO a lot, so do not touch the gas valve without a working, calibrated analyzer.

1. Connect a calibrated combustion analyzer before any high or low fire adjustment.
2. Monitor CO continuously and keep it at or below 150 ppm.
3. Make small adjustments to the low fire offset or main flow restrictor only.
4. Do not adjust the gas valve without analyzer monitoring.

Low water cutoff test

NTI · Trinity Tft60, Tft85, Tft110, Tft155, Tft175, Tft200, Tft250, Tft300, Tft399

Check before leaving the job and each year.

1. Before filling, power up: green POWER and amber LOW WATER lights should both be on and a burner demand should not fire, showing Lockout 67 ILK OFF
2. Fill the boiler; the LOW WATER light goes out; clear the lockout and the burner fires
3. With the burner running, press TEST: the LOW WATER light comes on and the burner shuts off with Lockout 67
4. Once a year repeat the TEST step; every 5 years pull the cutoff and clean the wetted surfaces

Power-on and operating modes

NTI · TRX150

After power-on the display shows the current mode: standby, CH request (supply temperature shown), DHW request (DHW setpoint shown), purging cycle, or post circulation on the CH or DHW circuit.

1. Press the ON/OFF button to power on the boiler.
2. Read the mode shown on the display.
3. If a purge or post circulation is showing, wait for it to finish before judging the system.

Pre-start water chemistry and freeze protection

NTI · TRX150 and related TRX models

Poor water quality or lime scale shortens heat exchanger life. Operating above 135°F speeds up scale build-up. Clean and flush the system before installing the boiler.

1. Flush the system without the boiler connected to remove sediment.
2. Check the return Y strainer and clean it if needed.
3. Test water chemistry on both the CH and DHW sides before start-up.
4. Use only propylene glycol for IWH loops, GRAS rated. Do not exceed 50% glycol unless the manufacturer specifies otherwise.
5. Never use automotive or ethylene glycol antifreeze.
6. Do not use petroleum-based cleaning or sealing compounds.

Reducing vent to 2 in on 150 models

NTI · 150 models

Only 150 models may reduce vent diameter to 2 in.

1. Use a 3 in x 2 in reducing coupling in a vertical run of pipe.
2. Do not use reducing bushings.
3. Do not increase vent diameter on any model.

Solvent cement cure and cleanup before start-up

NTI · Plastic exhaust and intake pipe assembly

Plastic vent joints use very flammable cement and primer, so solvent vapour must clear before the boiler is powered.

1. Do not use excess cement or primer; it can pool inside the pipe.
2. Let vent assemblies cure for at least 8 hours before powering the boiler.
3. Make sure the exhaust pipe is beveled and fully seated in the flue adapter before insertion.

Vent connection with PVC

NTI · PVC venting

Do not push PVC into the boiler exhaust connection.

1. Install the factory supplied 5 in length of 3 in CPVC into the boiler exhaust connection first.
2. Transition to PVC using approved CPVC to PVC transition cement.

Vent diameter by model

NTI · All models

Vent pipe sizing rules by model.

1. All models ship with 3 in vent connections.
2. 150 models may use 2 in pipe.
3. 199 / 199C models must be vented in 3 in pipe.

Zone valve wiring for valve-based systems

NTI · Valve-based heating zones

In a valve-based system each zone valve opens on a call for heat, and its contacts signal the boiler to fire.

1. Wire each zone thermostat to its own zone valve.
2. Make sure the zone valve end switch contacts are wired to the boiler call-for-heat input.

Automatic de-aeration program (A xx, 17 min)

Rinnai · E50CRN; E75CRN; E75CRP; E110CRN; E110CRP

After power-up or a reset the boiler runs a 17-minute air purge, shown as A followed by the countdown. Block 85 (no flow) also triggers it. The manual gives no key combination to skip it; wait it out or power-cycle and it restarts.

1. Display A xx = purge in progress, counting down
2. Burner is released as soon as flow is detected during the cycle

Filling and purging programs (20 min auto-stop)

Viessmann · Vitodens 200-W B2HE 85, 120, 150, 199

Purging cycles the pump 30 s on/off and toggles the diverter valve for 20 min with the burner off. Filling parks the diverter valve in the middle and runs the pump; both stop by themselves after 20 min.

1. Service menu > Service functions > Filling or Purging
2. Program ends automatically after 20 min; exit Service to stop earlier