Operating instructions

12/23/2011 7 EI711A
Airflow
Page 1 specification chart shows maximum temperature rise at 55° F. This is simply good HVAC
practice and duct works/furnace blower design. The WarmFlo Select controller and its sensing will take
care of itself but there is more to the story. It is true that the WarmFlo Select modulating control and the
supply sensor adjust the electric heat or element capacity based upon temperature. But if you do not have
the required CFM airflow (example 20 kW, 1200 CFM), you may not be getting the full capacity from the
unit. Another even more serious situation (because of improper airflow) is when all stages are on at
colder temperatures and the unit is cycling on mechanical safety hi-limit. When cycling on the hi-limit
probe, the WarmFlo Select supply sensor basically gets confused because at one point it is way up in
temperature and then the elements simply disappear and it dips down, the net result probably is switching
over to standby at premature intervals. There is no substitute for adequate airflow capacity and plenum
baffling.
Also see the last section titled “System Airflow” which is part of the final power-on procedure.
Mechanical Installation – Downflow
Furnace type – this unit must be installed in as DOWNFLOW application only. Do not turn the
WarmFlo Select upside down or install this unit in the cold air return.
Verify that all transitions have angles less then 30°, the WarmFlo Select is centered within the plenum,
and there are no odd shaped angles or odd shaped transitions within the plenum.
If the width or depth is greater than approximately 1” of the WarmFlo Select element pattern, side and
back deflectors may be required. Use the same general deflector requirements and techniques normally
described in the WarmFlo Select upflow section, previous step 2.
If the DOWNFLOW furnace is setting directly on the floor, the furnace will have to be raised for
insertion of the WarmFlo Select unit. This will require a field designed and constructed plenum. This
plenum must have sufficient strength to carry the weight of the existing furnace.
Must use the model with “D” in the fourth digit. The basic instructions represented above apply, but the
location of inserting this WarmFlo Select in relationship to the refrigerant coil will depend upon whether
it is air conditioning or heat pump.
Heat pump – in order for the heat pump to function properly, this electric heating unit must be on the
warm side of the HP refrigerant coil. The exact location (related to the coil output) and spacing will
determine the type of coil and the overall ducting situation. If you need to locate this WarmFlo Select
under a standard A-coil drip pan, you must allow at least 12” space between the top of this unit’s control
box and the bottom of the drip pan. With this arrangement the 15” unit is the best choice, but you must
build in the sides with a baffling arrangement. Since the A-coil drip pan bottom opening is relatively
small, there is no problem bringing the plenum down to a 15” width regardless of the size of the A-coil.
Again proceed through the 8 steps as they apply – see EA104.
Note: The duct sensor (ST) is installed on the warm side or airflow after this unit. Use spacing
dimensions as shown in Step 6 above.
The WarmFlo Select is designed with a special double plate at the element mounting. Cool air from the
blower must blow between these two plates. Therefore, the WarmFlo Select must be inserted into the
base plenum such that the mounting plate is even with the edge of the hot air outlet hole. Do not
necessarily line up the WarmFlo Select control box with the furnace cabinet front. The concern is the
hole in the plenum mating with WarmFlo Select elements.