Gas/Propane Basics
As we look into some more modern systems
and what specific problems they present, it
is important to understand the basic fundamentals
associated with these systems.
Most of our modern heating equipment in some way
or another involves electronics and the use of flame
rectification as a safety and flame-proving system.
It doesn’t matter if it is a forced warm air furnace
or a forced hot water boiler—the same basic system
is used to perform safe ignition followed by consistent
operation throughout the entire call for heat.
There are, however, different ways the system is
applied from intermittent pilot application to direct
spark ignition and including hot surface ignition
(HSI). Each has its own distinct advantages and
problems. We’ll now attempt to resolve those burner
problems related to these systems, as well as offer
corrections and diagnostics.
We will start with the basics and then continue to
operation, typical problems, diagnosis, troubleshooting
procedures and a final solution to a particular
problem. It’s easy to jump to conclusions with these
systems and just change parts to hopefully solve
a problem. That is, however, time-consuming and
costly.
I invite you to visit our new Facebook page Timmie’s
Tips on Gas at facebook.com/groups/timmiesgastips.
I look forward to seeing you there.
We are presently doing a series on Honeywell
Smart Valve™. We will pick up where we left off in
the last article and cover Smart Valve™ The Third
Generation. We will walk you through the step-bystep
process of operation with these controls.
SmartValve™ Third Generation
The third generation of SmartValve™ became
available to the original equipment manufacturers
(OEMs) in late 1998/early 1999. It includes the
SV9510/SV9520 and SV9610/SV9620.
The SmartValve™ works in conjunction with the
Honeywell Electronic Fan Timer ST9160. It uses direct
burner ignition line voltage igniters, such as the
Norton 271, which has been used on HSI for many
years. The new igniter used is the Norton 601.
The SV9540/SV9640 is also used with the EFT
ST9160 control. It uses the same 24-volt igniter system
used on SmartValve™ Generation I and II.
There is also a SmartValve™ SV9540Q used with
Electronic Fan Time ST9162. This is a two-stage system
that will be covered in a later discussion.
Timmie McElwain
President, Gas Appliance Service
timmcelwain@gastcri.com
The Gas Side—
Honeywell SmartValves™: Part 8
SV9510/SV9520; SV9610/SV9620
SmartValve™ System Controls
Application
The SV9510/SV9520 and SV9610/SV9620 Smart-
Valve™ System Controls combine gas flow control
and electronic direct main burner ignition sequencing
functions into a single unit. The ignition
source is a 120V HSI lighting the main burner
flame. Two types of 120V igniters may be used, as
seen in Table 1.
Table 1: SmartValve™ System Controls Hot Surface Igniter (HSI) Type
Model No. Hot Surface HSI Warmup (seconds)
Igniter Type First Try Subsequent Tries
SV9510 Norton 271 17 27
SV9520 Norton 601 5 10
SV9610 Norton 271 17 27
SV9620 Norton 601 5 10
The control provides all gas ignition safety
functions by controlling gas flow, ignition source
and a 120 VAC combustion air blower. The control
also monitors the appliance airflow-proving
switch and limit string to assure proper appliance
operation.
The SmartValve™ System Controls provide
pre-purge, post-purge and timed trial for ignition
with multiple ignition trials and auto reset from
lockout. Diagnostic LED indicates system status.
The control communicates directly with the
ST9160 Electronic Fan Timer (EFT) in typical
forced warm air furnace applications. It will also
interface with the 208907 Terminal Board, providing
compatibility with power-stealing thermostats.
Alternately, it directly interfaces with the
appropriate power supplies and a system thermostat
for additional appliance applications. When
controlled directly by a thermostat, the control
does not provide a post-purge function, as power
to the control is removed when the thermostat’s
call for heat ends.
This system is suitable for a wide range of
fan-assisted, combustion, gas-fired appliances
including furnaces, rooftop furnaces, boilers, unit
heaters, infrared heaters, water heaters and commercial
cooking appliances.
The specific application of the SmartValve™
System is the responsibility of the appliance manufacturer.
See Table 2 for temperature ranges
and regulator types.
26 ICM/September/October 2022