03/19/2009
15
BI502
The time between stage turn on depends upon where the controller logic memory was after the last
thermostat call or following a power up reset condition. The longest time between staging is from the
power up condition because the logic does not have a history of previous thermostat calls. Once the
history of several thermostat calls has been established within memory, it automatically returns to the last
active stages, with an approximate 5 seconds between stage turn on. However, during power up the logic
needs to search a number of times before it finally declares the next stage.
In this power up reset situation (with the call for heat) the timing is:
-
Stage 1 – 90 sec. full on
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If no stage 1 modulation (pulsing), 2 min.
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Stage 2 on
-
If stage 2 is on with no stage 1 modulation (pulsing), 4 min.
-
Stage 3 on
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If stage 3 is on with no stage 2 modulation (pulsing), 4 min.
-
Stage 4 on
Note
: The above is worst case and high mass mode. For low mass it is faster, etc.
A clamp-on amp meter at the service input can be used to “visualize” the stage 1 modulation and/or stage
2, 3, and 4 functions.
Staging disables at specified outdoor temperatures
– the factory setup allows all four stages to come
on at outdoor temperatures below 90° F. Using download reprogramming, an outdoor temperature can be
set for each stage allowing the disable of specific stages above the preset temperature.
Delay, transfer from standby to electric
– if the unit was operating in SB for more than 1 minute, the
follow-up transfer back to electric engages a 2-minute delay before any of the electric stages are
activated. The pump will react to the call for heat, but the elements will stay off for 2 minutes in order for
the pump to cool down the standby boiler vessel.
SB (Gas) 5-Minute Safety
– when in the standby mode (see previous section) there is now a 5-minute
timer which begins at each heat call. If after the 5 minutes the ST sensor is less than 80°, the logic board
itself goes into an automatic reset and restart. This simply means it attempts to begin the heat cycle using
electric in case the boiler did not ignite or “out of gas”. However, if it is in the SB mode because of Load
Control it will still remain SB and try the gas boiler again. The system will never go back to electric if
you have a Load Control on-peak.
-
This can be disabled, see previous PC Software section.
EB-WO VERSUS EB-WA COMPARISON
The only difference is the outdoor sensor capability and programming associated with outdoor sensing
outlet temperature ramping or preset value. Both model series use plug-in chip Version 6.2*, but
specifies 4-digit code for this temperature sensing programming.
Model Series
Outdoor Sensor (OT)
6.2* Code
Front Panel Decal
Install Manual
EB-WO Required,
connected EB-WO
UAI839
BI502
EB-WA Not
required EB-WA UAI843
BI506
