Honeywell 3-Molex Plug Upgraded Smart Gas Valve.
GAS VALVE TROUBLE:
TO DISCUSS SMART VALVE II COMBINATION GAS VALVE/IGNITION CONTROL ISSUES.
Recently we have been receiving calls regarding failures of the Smart Valve II product.
Analysis of the Smart Valve II has been ongoing and will continue. Several generations of the Smart Valve II exist in the Armstrong Product Family.
Symptoms generally consist of the induced draft blower motor not energizing, or the inducer motor cycling on and off frequently and inconsistently. Another symptom that has been observed consists of the gas valve failing to operate yet incorrectly displaying either no diagnostic lights, or erratic diagnostic lights.
An analysis of returned valves has determined the cause of these problems. This situation is a direct result of water coming in contact with the internal circuit board of the Smart Valve II control. Further analysis showed that 97% of the incidents have occurred specifically on single stage 80% non-direct vent 50-75,000 BTU units installed in the upflow position.
Our analysis has determined the source of the water. The moisture is the result of the condensation of flue gases leaking out of the vent connector directly over the Smart Valve molex connections. As was stated above, this condensate problem has been found only on single stage 80% non-direct vent 50-75,000 BTU units installed in the upflow position.
Several factors have been determined to be contributing to this situation:
Vent Connector Type: Due to their low volume of flue gases, 50-75,000 BTU units tend to run with flue temperatures in the 350
•F range and many things can quickly reduce this flue temperature, causing it to get closer to its dew point, resulting in condensation. Category 1 units require a vent connector and a vent. A vent connector is defined as "the pipe or duct which connects a fuel-gas burning appliance to a vent or chimney". A vent is defined as "a passageway used to convey flue gases from gas utilization equipment, or their vent connectors, to the outside atmosphere". Category 1 vent tables may allow a single wall vent connector, or may require a double wall (B-vent) connector. Factors such as vent height, lateral length, and input size of furnace all play a roll in this determination. 50-75,000 BTU units generally will need a B-vent connector to reduce any possibility of condensation.
Low Temperature Rise: Short run times will also contribute to low flue temperatures. Temperature rise should be at the mid-point range as printed on the rating plate. A 20
•F difference in temperature rise can sometimes add as much as 50
•F to the gross flue temperature. Slowing down the circulating air blower speed will result in a higher temperature rise.
Introduction of Outside Air: The introduction of outside air into the return air can cause flue temperatures to decrease dramatically. Return air temperatures dipping into the 55
•F range will have an impact on the flue gas temperatures. Temperature rise will stay the same but the supply and return air will lower proportionally, which will lower the flue temperature. Note: Introduction of outside air is not the same as external combustion air.
Furnace Rate: Manifold pressure should be properly set to ensure the rate is correct for the system. Single stage units using natural gas require a 3.5" W.C. manifold pressure. Single stage units using LP gas require a 10" W.C. manifold pressure. Low manifold pressure will result in a decrease in flue temperature.
In the unlikely event that this condensation problem occurs, a protector shield can be installed to prevent the condensate from contacting the gas valve assembly.
This protector shield mounts to the inducer to divert any condensate that may develop during a short run time, or in cold ambient conditions. The part number for this shield is 46006-001.
FACTORY CORRECTIVE ACTION:
All single stage 80% 50-75,000 BTU upflow capable non-direct vent units will have the protector shield installed beginning with serial number 8400M23586.
Intermittent Hot Surface Pilot Ignition SmartValve
• Control with slow opening and 3.2 in. wc pressure regulator setting.
• System Controls provide easy field replacement of a wide range of SV9500, SV9501, SV9502 and SV9602 SmartValve
• System models. Gas appliance manufacturers use these models in many types of gas fired heating appliances including central furnaces, residential boilers, rooftop
•furnaces, commercial cooking appliances, and unit
•heaters. These controls provide intermittent pilot gas ignition sequencing, pilot flame sensing, and both pilot and main gas control functions in
•a single control. They are directly compatible with the Q3450 or Q3480 Intermittent Pilot burners used with the original controls on the appliance.
Suitable for a wide range of gas-fired appliances including residential furnaces, roof-top furnaces, residential boilers, unit heaters, infrared heaters, space heaters and commercial cooking units.
Replaces SV9500, SV9501 and SV9502 controls as noted below.
Ignition sequence includes timed trial for ignition.
Testing and servicing the Honeywell SmartValve II SV9520H
The SV9520H valve is used with ST9160B electronic fan timer board and a Norton Model 601, 120 volt.
hot surface ignitor. The SV9520H controls the inducer motor, the Hot Surface Ignitor (HSI) and moniters.
the pressure switch and limit controls. The ST9160B control board privides a central place for wiring.
connections, adjustable fan delays and connection points for accessories.
The SV9520H provides an LED diagnostic indicator to assist in troubleshooting the system.
In the event of abnormal situations this unit will reset itself after a one hour delay to minimize nuisance shutdowns.
The following specifications on the SV9520H will provide helpful when servicing the system:
120 volt hot surface direct ignition.
Remote flame sence.
15 second pre purge.
Pressure switch check during pre purge.
7 second ignitor warm up.
slow opening valve.
7 second trial for main burner.
4 trials for ignition with 30 seconds between each ignition.
Lockout after 4 trials.
1 hour reset from lockout.
5 second post purge.
Gas Pipe Inlet Size: 1/2"
Gas Pipe Outlet Size: 1/2"
The following specifications will apply to the ST9120H electronic fan timer board:.
Non adjustable fan on delay of 6 seconds on a call for cooling.
Non adjustable fan off delay of 30 seconds at the end of a cooling call.
Non adjustable heating on delay of 30 seconds.
Adjustable heating off delay 60, 90, 120 or 150 seconds (field selectable by dip switches)
HUM terminal 120 volt output on with heat speed for humidifer connection.
EAC terminal 120 volt output on with heat or cool speed.
5 amp fuse protection
Room thermostat anticipator setting of 0/1 amp at 24 vac.
Flame sense information:
Line input must be connected to correct polarity.
unit must be connected to earth ground.
flame sence must be sensed at end of ignition trial for unit to run.
flame sence levels:
1. will detect 1.1 u amp
2. flame lost at 0.4 amp
3. flame out sequence 0.1 u amp
4. Recommended 2 + u amp for operation
Flame Sense Electrode.
Type of Gas Natural.
Ignition System Type Intermittent Hot Surface Pilot Ignition.
Ignition Sequence Intermittent Pilot.
Ignition Source Pilot.
Ignition Trials To Lockout continuous retry.
PrePurge 15 sec.
Body Pattern Straight-through.
Opening Characteristics (standard, step) Slow Opening.
Ignition Trial Time (sec) 90 sec.
Electrical Ratings 24 Vac.
Frequency 60 Hz;50Hz.
Flame Failure Response Time (sec) 1.6 sec @ 3
Ambient Temperature Range (F) -40 F to +175 F.
Ambient Temperature Range (C) -40 C to +79 C.
Pressure Regulator Setting (psi) 3.2 in. wc.
Pressure Regulator Setting (kPa) 0.80 kPa.
Pressure Ratings (psi) 1/2 psi.
Pressure Ratings (kPa) 3.45 kPa
Inlet/Outlet Size (in.) 1/2 in. NPT x 1/2 in. NPT.
Maximum Capacity (ft
•/hr) 200 ft
Maximum Capacity (m
•/hr) 5.7 m
Minimum Capacity (m
•/hr) 0.6 m
Maximum Capacity at 1 in. P.D. (ft
•/hr) 150 ft
Maximum Capacity at 1 in. P.D. (m
•/hr) 20 ft
Pilot Gas Outlet Yes.
Typical Ignition Hardware Q3450.
Used in Armstrong, Consolidated, Hamilton, Concord Furnace Models:
MBA 060 NH3RX
G1D80, G1D91, G1N801, G1D801, G1D93, G1D91AU075D12B-1
Replaces Gas Valve Part Numbers:
CARSV9520H8067, CARRS45390002, CARSV9520H8067,CAR28M95.CARSV9520H8513.