A. GENERAL
These high altitude conversion kits are to be used only with
S8/A8 gas furnace models utilizing either natural gas or LP
gas as fuel.
These instructions describe the conversion of these furnaces
for installations exceeding an altitude of 4000 feet above sea
level.
Due to the lower density of air at higher altitudes, there would
be insufficient negative pressure developed by the induced
draft blower to maintain normal operation. Therefore, to
compensate for the less dense air, pressure switches must
be changed to prevent nuisance lockouts and/or cycling of
the induced draft blower on high speed. Please note that
with the reduced firing input rates required for high altitude
installations, the induced draft blower has ample capacity to
provide sufficient combustion air for proper and safe operation.
Refer to the National Fuel Gas Code - latest Edition 11.1.2
- High Altitude and Table E.1.1(d).
Installer’s Guide
High Altitude Conversion Kit
ALL phases of this installation must comply with NATIONAL, STATE AND LOCAL CODES.
For S8 and A8 Furnace Models
Models:
BAYSWT14AHALTAB, BAYSWT15AHALTAA, BAYSWT16AHALTAB, BAYSWT17AHALTAA,
BAYSWT18AHALTAA, BAYSWT19AHALTAA, BAYSWT20AHALTAA, BAYSWT21AHALTAA,
BAYSWT22AHALTAA, BAYSWT23AHALTAA, BAYSWT24AHALTAA
IMPORTANT - This document is customer property and is to remain with this unit. Please return to service information pack
upon completion of work.
B. CONVERSION
These instructions below apply to S8/A8 gas furnaces only.
1. Check for damage to kit contents, and check for all items
listed in Table 1 on page 2.
2. Disconnect electrical supply to furnace.
3. Remove the wiring connections from the pressure
switch(es) in the furnace. Mark the wires if needed to
properly identify the replacement.
4. Remove the pressure switch(es) sample tube from the
switch assembly.
5. Remove the pressure switch(es) from the furnace.
6. Install the new pressure switch in the same location and
manner as the old pressure switch.
7. Connect the pressure switch sample tube and electrical
connections.
8. Reconnect the electrical supply to the furnace.
C. CHECKOUT
Adjust input rate and manifold pressure according to the
furnace Installer’s Guide. Install correct main burner gas
orifice according to this document. Fill out the information on
the conversion label (part number A343079P01) and attach
the label to the exterior of the furnace door. Once the furnace
has been correctly rated for the high altitude installation, and
the pressure switch has been changed, the furnace installation
shall be checked for proper installation and performance. Refer
to the furnace Installer’s Guide for checkout procedure.
D. NOTES
1. The use of high altitude calibrated pressure switches in sea
level applications is not permitted.
2. The high altitude pressure switches are factory calibrated
and sealed. Field adjustment is not permitted. If the factory
seal is broken, the product warranty may be voided.
This conversion kit shall be installed by a qualified
service agency in accordance with the furnace
manufacturer’s instructions and all applicable codes
and requirements of the authority having jurisdiction.
If the information in these instructions is not followed
exactly, a fire, an explosion or production of carbon
monoxide may result causing property damage,
personal injury or loss of life. The qualified service
agency is responsible for the proper installation of the
kit. The installation is not proper and complete until
the operation of the converted furnace is checked as
specified in the furnace manufacturer’s instructions
supplied with the kit.
18-CH97D1-3A-EN
Before proceeding with the conversion, the gas supply
must be shut off prior to disconnecting the electrical
power.
This product can expose you to chemicals, including
lead, which are known to the State of California to cause
cancer and birth defects of other reproductive harm.
For more information go to www.p65Warnings.ca.gov.
