Owner`s manual

Scotsman Wood Furnace – Instruction Manual
Scotsman Nov-05
18
Before attempting installation, determine if there is suitable space
available in the furnace area for the furnace connection outlined herein.
The external static pressure in the warm air duct to the house of the
original system must be measured prior to any changes to the system.
These are to be reset to the same values after the add-on procedure to
maintain airflow through the oil furnace.
An important requirement of this type of installation is that when installed in an existing
system the main ducts may have to be lowered to assure proper and safe clearances
from combustible material. (See Fig S101-1).
After all connections are made a static pressure test and/or temperature measurement
must be made in the outlet plenum of the wood furnace. This is a simple procedure and
is outlined as follows using a Dwyer Model 25 or equal inclined manometer:
Drill hole in wood outlet plenum.
Level inclined manometer and adjust to zero, insert manometer tube (Pressure end).
With all duct work and doors in place static pressure should measure 0.2 in (50 Pa) with
blower running.
Pressure may be corrected by the following measures:
1. Change blower pulley size (usually decrease)
2. Change blower motor pulley (usually increase)
3. Increase return air duct area (if restricted)
CAUTION – Current draw by blower motor should be checked after making any pulley
change. If motor now draws greater current than that shown on the nameplate a larger
more powerful motor must be installed.
IMPORTANT – DO NOT change the blower.
As an alternative to the static pressure test method, the installer may make adjustments
on the basis of temperature measurement. For this test wood furnace must be at full
operating temperature.
Take one temperature measurement in the front of the oil furnace plenum 12” to 16” up
or approximately center. Take a second measurement in the wood furnace plenum
(same position). Subtract one measurement from the other to arrive at a temperature
difference (TD). The TD must be between 40º F and 100º F during normal operation,
and ideally around 80º F. The same adjustment procedure for pulleys applies for
correction when using this method.
CAUTION – Most thermometers have a large time lag in reaching accurate measuring
levels. It is important that this interval be measured for your thermometer by immersing
it in boiling water and observing the time required for it to reach correct reading.