Electro Industries WARMFLO II, Installation And Operations

11/05/2008 1 

HD320 

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WarmFlo Terminology, Key Terms 

ST

 – supply temperature sensor.  This is the warm air or duct sensor (boiler – supply outlet 

water). 
 

OT 

– outdoor temperature sensor.  Provides the WarmFlo board with outdoor temperature 

information. 
 

DT

 – desired temperature to overcome building heat loss, the diagonal line on heat loss curve.  

The front panel efficiency knob selects one of 8 curves to determine DT at specific real time OT. 

 
DT Flat 

– this is an internal reference point, as WarmFlo establishes this mode it in essence sets 

the operating point at 125° F. (Analyzer or software may have any value from 123 to 125). 
Electric element modulation and staging are still in effect. The staging will be based upon the ST 
sensor detecting and operating around the 125° point. 
 

Note

: All four stages do not automatically go to full on. 

HL

 – actually this is the same as “DT Flat”.  This perceived hi-limit temperature value (130°) 

within the control logic, measured by the ST.  This is over and above the 155° probe or 170° 
mechanical hi-limits. 
 

Full electric (or Full EL)

 – this setting causes the modulation and staging to operate at “DT 

Flat”.  When first selected or turned on, the WarmFlo logic may first go through a process of 
building up to the “DT Flat” value.  Do not expect the outlet temperature to immediately jump up 
to this highest value.  However, on consecutive thermostat calls it will immediately step to the 
“DT Flat” temperature value. 
 

Note

: This is essentially the same as DT Flat and again all four stages do not 

automatically go to full on. 

Staging Disable Temperature – 

in all OT active sensor applications (DT cal) there is a setup 

program temperature to "hold off" each stage for warmer heating conditions. In other words, the 
OT sensor must be reporting a temperature below these values before the stage is allowed to 
come on. In WarmFlo Analyzer or PC software terminology this is called – STG1 DIS, etc. 
 
The stage-up situation relating to all of the above "DT Flat" operation is controlled by these stage 
enable temperature set points. This statement must be carefully related to all of the above. 

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In other words, if the OT is reading 42° and the front panel is set to "full electric" the ST 
is looking to operate at 125°, but only stage 1 will be on. 

 
If for heat pump applications Stg 1 is set at 50°, there will be no electric element or standby 
furnace above 50° OT. 
 

Note

: For HP roomstat multi-wire thermostat application, the OT temp. set point must be 

below normal desired cooling. 

E tab (board top center)

 – in most WarmFlo products and TS Series boiler products there is a 

troubleshooting tab marked "E". When applying 24-volt (or jumpered to "W" tab) this input 
function immediately forces all four stages on and bypasses all temperature sensing or element 
modulation sequences.  If used verify blower also functions properly.