Tx I&O Manual │Troubleshooting
DHW setpoint (Installer Menu setting 2-07) – 120 to 140ºF recommended.
o If the radiator symbol is flashing on the display, the DHW priority time may have expired. Cycle power
and consider increasing the DHW priority time (Installer Menu setting 2-09).
Indirect Tank with Tank Sensor:
o Verify DHW Mode is set to 1 (Installer Menu setting 2-08).
o Verify there is a Tank sensor wired to COMMON and DHW (boiler terminals 3 and 6), see Figure 12-2.
Tank sensor temperature, DHW temp, is viewed from User Menu reading 1-03.
o Compare DHW setpoint (User Menu reading 1-04) with the DHW temp (User Menu reading 1-03). DHW
Tank demand is generated when the DHW temp drops 4ºF below the DHW setpoint; after which burner
demand starts when the boiler outlet temperature (displayed on Main Screen) drops below the Current
target temp (User Menu reading 1-01) by 15ºF. Current target temp for a DHW Tank demand is equal to
DHW setpoint + 40ºF; if necessary increase DHW setpoint (Installer Menu setting 2-07) – 130 to 140ºF
recommended.
o If the radiator symbol is flashing on the display, the DHW priority time may have expired. Cycle power
and consider increasing the DHW priority time (Installer Menu setting 2-09) and/or DHW setpoint
(Installer Menu setting 2-07).
o If the faucet symbol is flashing on the display, verify the DHW circulator is operating – DHW circulator
should be wired to DHW PUMP and L2 NEUTRAL (boiler terminals 9 and 12/13); see Figure 12-2.
o Verify plumbing is in accordance with Figure 10-4 or 10-4.
Indirect Tank with Tank Thermostat:
o Verify DHW Mode is set to 2 (Installer Menu setting 2-08).
o Verify there is a Tank thermostat wired to COMMON and DHW (boiler terminals 3 and 6), see Figure
12-2.
o Verify there is a demand from the thermostat; when the demand is on, DHW temp (User Menu reading 1-
03) will indicate “On” (or 242⁰F/117⁰C); when demand is off, DHW temp will indicate “Off” (or 14⁰F/-
10⁰C). If uncertain about thermostat operation, place a jumper between terminals 3 and 6; the faucet
symbol will flash on display when there is a DHW demand.
o Compare DHW setpoint (User Menu reading 1-04) with the boiler outlet temperature (displayed on Main
Screen); burner demand starts with the boiler outlet temperature drops below the DHW setpoint by 15ºF.
If necessary increase DHW setpoint (Installer Menu setting 2-07) – 160 to 190ºF recommended.
o If the radiator symbol is flashing on the display, the DHW priority time may have expired. Cycle power
and consider increasing the DHW priority time (Installer Menu setting 2-09) and/or DHW setpoint
(Installer Menu setting 2-07).
o If the faucet symbol is flashing on the display, verify the DHW circulator is operating – DHW circulator
should be wired to DHW PUMP and L2 NEUTRAL (boiler terminals 9 and 12/13); see Figure 12-2.
o Verify plumbing is in accordance with Figure 10-4 or 10-4.
4) Display Normal but DHW is not hot enough – perform the following steps:
Increase DHW setpoint (Installer menu setting 2-07):
o Tx Combi (Tx151C & Tx200C) – recommended setting = 120 to 140ºF.
o Indirect Tank with Tank Sensor (DHW Mode = 1) – recommended setting = 130 to 140ºF.
o Indirect Tank with Tank Thermostat (DHW Mode = 2) – recommended setting = 160 to190ºF.
Tx Combi (Tx151C & Tx200C) – DHW flow rate is too great; compare DHW flow rate (User Menu reading
1-05) with Tables 11-1 and 11-2. If necessary, restrict overall DHW flow rate.
Indirect Tank – verify plumbing is in accordance with Figure 10-4 or 10-4.
5) Display indicates an error (Err), lockout (Loc) or warning (Att); reference Table 17-3 in Section 17.0.
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