Is the Gas piping Installation and Supply Gas Pressure correct for startup?
- It is recommended to consult the most up to date IOM information on the Supply Gas pressure requirements for the assembly and configuration of the unit. The IPAK 1 Staged and Modulating Gas heat assemblies (Digit 9 of the Model number = H, K, L, M, P) require a steady 6.8 – 7.2” iwc at High Fire volumes, a Field Installed Supply Gas Regulator on the incoming gas piping is required to accomplish this, and is also specified in the IOM (Page 48 in “RT-SVX090C-EN”). If the unit has a Main Gas Regulator installed then a field installed one is not necessary (Units manufactured in 2025 or later should have a factory regulator installed).
The IPAK 1 Ultra Modulating (Digit 9 = K or T) and all IPAK 2 Gas heat assemblies have a Main Supply Gas Regulator factory installed from Midco and require the outlet pressure to be set for 5.8 – 6.2” iwc at High Fire Capacity (The inlet pressure is required to be adjusted to 7 – 12” for the regulator, but it is recommended to set closer to 8” as discussed in the next bullet).
- The reason for the lower Supply Gas Pressures than in past Trane Gas Heat assemblies is due to the Midco gas train design, the Ratio Regulator valve (the regulator downstream of the main Gas valves with the clear “poly” air pressure tubing connected to it) is a sensitive throttling component, it regulates the gas flow with a diaphragm operated on internal pressures (as the combustion fan increases the diaphragm is pushed open to allow more gas volume for high fire), and Midco has stated that if the gas pressure going to the Ratio Regulator is above 8” iwc incoming it can cause erratic and unpredictable flow due to the diaphragm being pushed open prematurely. Typically the incoming gas pressure to the main gas regulator (Factory or Field installed) is specified for 7-12”, the technical support team has observed that better results are when the incoming pressure to the main supply gas regulator is closer to 8” iwc. Then the outlet pressure can initially be set for the 5.8 – 6.2” or the 6.8 – 7.2” (configuration dependent), but even lower outlet pressures may result in more consistent and efficient operation.
Entering a Gas Heat Manual Override/Call for Heat
- IntelliPak/RAUK Symbio 800 - Manual Override Operation
- Once a call for heat has been established the Siemens controller should begin the Ignition sequence. The controller will begin displaying different phase numbers, the P21 confirms that the combustion fan is off by checking the fan proving input (it must be open during the P21 if it is closed you’ll get a “Loc 5” error), next is the P22 where the combustion fan energizes and the controller verifies the proving input closes (The 3KF31 module closes a relay on the J2 between pins 1 & 3, this is a 115Vac output from the 3KF31 to the X5-03.1 input, so if the combustion fan does not energize verify you have 115Vac on X5-03.1), P30 is the pre-purge and should last ~60 seconds, P40 is the trial for ignition, the Gas valves will energize (you should hear an audible click) and if the air/fuel mixture is sufficient the ignition should proceed and then the P42 flame detection will be the last Phase and flash an “OP” for operating. The controller should now be displaying a number with a decimal point on the left for example a “.51”, this represents the percentage of the combustion fan range (the display can be set for flame signal strength as well and details for that will be in the flame adjustment section). The Gas heat should ignite at the “P0” RPM setting, once the Flame is established then the Control is released to the Low or High Fire request. Refer to schematic “Sheet 12” for the heat wiring.
- For IPAK 1 Staged Heat configurations there will only be a “Stage 1” and “Stage 2” request in the Manual override menu and the Heat Status Report page. The Stage 1 and Stage 2 request will come from the 3KF31 module, Stage 1 will be a closure on J2 pins 1 & 3, and Stage 2 will be a closure on pins 4 & 6. The Stage 2 output from the 3KF31 will energize the ”Relay A” coil to close the Normally open contact, there should be 115Vac present on X5-03 terminals 1 and 3. Once the stage 2 request in received by the controller then the combustion fan will begin to ramp up and the display percentage should increase to “.99” for high fire.
- For IPAK 1 Modulating and Ultra Mod Heat/IPAK 2 configurations there will be the Stage 1 request to initiate the heat request to the controller as described above, but the combustion fan will then be controlled with a 0-10Vdc signal or 2- 10Vdc (IPAK 1 Ulra Mod and IPAK 2) from the 3KF40 module. The IPAK 1 Ultra Mod and the IPAK 2 configurations will have the Yellow “RTC SCEBM-2” Digital Signal Conditioner controller for the signal output.
Preparing the Burner for Ignition
- IPAK 1 Staged and Modulating Heat units do not have the main gas regulator, Pilot Valve/Solenoid, or a Manifold Gas shut off valve. Just ensure that the main manual gas valve is in the open position and the supply gas pressure inlet to the Main regulator is less than 10” preferably.
- The IPAK 1 Ultra Mod and IPAK 2 assemblies have a pilot Valve and regulator, so before beginning the ignition sequence make sure that the Manifold gas shut off valve is closed (when starting and establishing flame on startup or when troubleshooting the pilot gas flow will be sufficient to ignite and establish flame), the Pilot gas regulator should be set for 3-3.5” iwc. Once the Pilot flame is established (The Pilot Solenoid will remain energized from the P40 ignition trial phase until the OP1) slowly open the Manifold shutoff valve to allow flow from the Ratio Regulator into the combustion chamber.
Are there any Diagnostics on the Siemens Controller upon Heat Request or Ignition trial?
- The Diagnostics listed below are some of the more common diagnostics, but for full diagnostic details refer to the Siemens LME7 Burner control manual. (LME 7 Documentation and information).
- Loc 2 – No Flame on Startup: The most common occurrence that we see on this is due to an issue with the supply gas pressure being too high or pulling down too low when the main Gas valves energize. If you have a manometer monitoring the Supply, make sure it is not dropping below 5” when the Gas valves open and if the Inlet pressure is higher than 9” on the Main Gas regulator try backing down to ~8. If you’re monitoring the manifold pressure, ensure that you do see an increase from 0” indicating that the gas valves have energized/opened and the Ratio Regulator is passing through enough fuel for ignition (at ignition this is typically ~0.4 – 0.7” iwc). For the Ultra Mod and IPAK 2’s you’ll verify you have 3-3.5” iwc on the pilot line for ignition.
- Loc 3 – Air Pressure Switch Open: The air pressure switches connected to terminal X3-02.1 are open, causing a fault. The Combustion Fan Proving Switch in the Siemens Control box and the Supply Air Proving Switch (3S14) are wired in series…in most cases the 3S14 is the culprit of the diagnostic if it is happening at the beginning of the ignition sequence, it is a differential pressure switch so make sure the tubing is secure on the high port and the “Red Cap” has been removed from the low port. The sensitivity of the switch can be adjusted (just verify the switch is open when the fan is off and closed when the supply fan is at 22Hz or greater). Keep in mind that on Staged Gas configurations the Supply fan will ramp to 100% command for a call for heat and so high duct static pressure situations or vibrations on the mounting bracket could also be a cause.
- Loc 5 – Air Pressure Switch Closed: If the Combustion or Supply Air Pressure switch is closed before the “P22” phase this diagnostic is generated.
- Loc 7 – Loss of Flame: This is when the flame signal was established at the P40 and P42 phases and transitioned into the normal operation or OP1 and then sometime lost the flame signal, typically this is due to the manifold pressures being out of range or a possible issue with the flame sensing rod.
- Loc 20 – Gas Pressure Fault: There is a gas pressure switch on the Supply and one on the Manifold typically they are both set at ~4” iwc so if the Supply drops below 4” or the manifold goes above 4” the switches will change state.
- Clearing the Siemens diagnostics: Press and hold the “Info” button for 1-3 seconds, just pressing info will have no effect, if held for longer than 3 seconds the LME7 will enter a diagnostic mode.
Low and High Fire adjustments
- Once the Flame is established at high fire the burner can be adjusted for low and high fire manifold pressures and O2 readings.
- Low Fire: For Staged Gas heat this will be the Stage 1 request, for the Mod and Ultra Mod the request should be set for 1% from the Manual Override Menu. Refer to the IOM for the O2 range and manifold pressure at low fire. The Ratio Regulator controls the flow of gas to the manifold, but it will ONLY be adjusted for low fire, once the flame has been established at low fire for ~10 minutes measure the O2 readings from the flue if the readings are high adjust the regulator setting ½ turn CW, if the O2 is low adjust ½ turn CCW then recheck (On 235/350/500 MBH burners the brass ratio regulator cap protecting the plastic adjustment screw must be reinstalled for the adjustment to take effect).
- High Fire: For Staged Heat configs set the stage request for 2 stages, for Mod and Ultra mod set the Heat Request to100%. Allow the Combustion fan to ramp up (the Siemens controller should display “.99”) and wait another 10 minutes for the burner to stabilize. The O2/manifold pressure should be within the IOM specified range, the CO2 should be ~8 – 10%, and the CO less than 100PPM, if this is the state of the burner no adjustment is needed. For High fire the slide air damper will need to be adjusted (closing will increase the CO2), if the manifold pressure needs to be adjusted for the burner output you will adjust either the supply gas pressure or the P2 setting in the Siemens controller.
- Adjusting the P0, P1, and P2 settings in the Siemens controller: For the Staged Heat configurations remove the Relay A before entering this mode (Cannot Change P settings on LME 7 for Staged Gas Heat). While in the Manual Override mode set the Heat Stages Request to “0” and The Siemens controller should display “Off”. Press and hold the “A” and “+” buttons for more than five seconds (the “Off” display will begin to blink). Go to the TD7 and set the Heat Stage Request to “1”. The controller will begin the ignition sequence as described above and once the pre-purge stage is reached you’ll confirm/set the “P0” ignition RPM. At this point, the LME7 will alternately display P0 and a three-digit number. The three-digit number is the setting of the ignition speed P0 divided by 10. For example, if the display alternately displays P0 and 200, this means that the ignition speed is currently set for 2000 RPM. To adjust the ignition speed, press and hold the A button while simultaneously pressing the + or - button to increase or decrease the speed, once the desired value is set press “Info” once. The startup of the burner will continue. The burner will light off and establish flame. Once the burner has lit off, it will drive to the preset low fire speed (P1). It will be the same process for P1…press and hold “A” while using the + and – to increase or decrease the RPM setting then press info once the value is set, the burner will then ramp up to the P2/High fire speed, repeat the process (this is where you would fine tune the manifold pressure and O2 for high fire).
- Setting the Fhi for the IPAK 1 Ultra Mod and IPAK 2: For the IPAK 1 Ultras and IPAK 2 burners the Combustion fan is controlled by the RTC SCEBM-2 signal conditioner (You will NOT adjust the P0, P1, or P2 on the Siemens for high fire with this configuration). To enter the programming menu on the SCEBM controller press and hold the “ENT” button in the center while in normal operation/call for high fire until the displays shows “APP”. Press the DN arrow until the Fhi is displayed then press the RT arrow to see the value. Use the UP and DN arrows to set the desired value then press the ENT button to save the change (change 5% at a time and allow ~5 minutes for the burner to re-stabilize). The Flo setting should not be adjusted but you can verify that it is 10% for EBM motors and 15% for Fasco. RTC SCEBM programming Guide