The pilot flame in your fireplace/log set is located just beside the main burner to ignite the gas when the unit is turned on. This usually happens within seconds of the main valve opening inside a sealed (Direct Vent fireplace) or within 10-20 seconds in an open (Natural vent, Vented gas logs, Vent-free fireplace or logs) system. If the ignition is delayed, more gas accumulates and once it ignites it happens with a “PUFF” that can be scarry. Most fireplaces (except power vented units) rely on a natural draft to operate and are subject to NATURAL INTERFERENCES such as wind and temperatures which will affect the lighting process and the operation. Some delayed ignition can happen on occasion but it should not be the rule and if it is “getting worse” it is definitely the time to call an expert.
NOTE: Gas hearth products use many different systems for a safe and convenient operation and the symptoms and resolutions are not always the same. However, most issues relate to either outside influences (weather or environment) or internal factors that relate to the pilot operation. There are different pilot designs but they all rely on the pilot flame to be in specific contact with another part (thermopile/coupler or flame rectification rod). If this contact is disturbed or non existent, the fireplace will shut down. These can be “nuisance” shut downs (flickering of pilot due to high winds) or caused by old age (deteriorating thermopile/coupler). This function may seem scary, but it always happens on the side of caution. Ask your fireplace experts at Alber’s whether your shutdown was a nuisance or if it should be investigated by a fireplace service professional.

Wind related delayed ignition

• The wind may directly affect the ignition and blow the gas away from the pilot flame long enough for more gas to acculate inside the firebox to finally reach the pilot.
  • Depending on the unit, the installation of a wind shield may be required. Sometimes a repositioning of the logs (not possible in DV or VF units) or burn media may resolve this situation
• Excessive draft
  • The natural draft in the chimney may be so strong that the pilot flame is distorted away from the burner or the gas get’s “sucked” away from the pilot. Depending on your unit, this may also be resolved with wind shields or in DV units, a restrictor may be installed. The correct diagnosis and rectification will most likely require a professional service.

Burn media/log related issues

• Too much or too little burn media The burn media (ember materials, sand, glass, etc.) may need to be shifted or adjusted. Over time it may have deteriorated and needs to be replenished. Some of this can be experimented with by a homeowner but it may be a good time to call for service.
• Pilot placement/adjustment Factory set pilot flames may need to be adjusted (NOT possible on VF units) for the right flame height. The pilot bracket may have bent away from the burner or just needs to be in better contact. This may require a professional service for the correct setting and adjustment.

Other causes

• Propane units
  • Propane is heavier than air and has different burn characteristics than natural gas. Propane is more likely to have delayed ignition and the above symptoms are usually more pronounced with it.
• Blocked burner ports
  • Blockages in burner ports can occur for different reasons, causes and time frames. Here are some of the possible causes:
    • Blocked burner ports due to corrosion or debris. The result may be partial flame patterns (the unit lights normally but parts of the flame pattern are slow to ignite or don’t work at all) or a delayed ignition due to wrong gas pattern or not enough gas at the pilot location. Metal burners tend to corrode around the burn ports and “flaking” material can clog the prts. Annual service calls can maintain the burners by brushing off the burner and remove rust to keep all the ports open
    • Blocked burners due to spider webs. These blockages may happen overnight (fireplace works fine one day, not flames the next) but most likely they happen over the summer when the fireplace sit’s idle. This is the work for a professional. Depending where the blockage is, the burner, gas tubes or the pilot may have to be removed and cleaned to clear this blockage.
    • Multi burner systems may have “crossover” tubes that are blocked or separate controls (solenoid valves) that may be blocked or not working.

Turning the fireplace on but it takes minutes to actually light.

• This type of delayed ignition does not create the big “puff” situation but it is a reason for a service call. The delay is caused due to a defective or badly placed thermopile on the pilot assembly. The thermopile has to generate a minimum amount of electricity (usually around 325mv) to activate the electromagnet that open the gas valve. If the thermopile is damaged/corroded or broken it may only barely get to this threshold and thus the delay in the fireplace igniting. A cleaning of the thermopile (in case of corrosion or debris) may bring the production over the threshold or the TP should be replaced. The mormal production is between 500-750mv. NOTE: Not all fireplaces use a millivolt system with a thermopile.
• What is the difference between a thermo-coupler and thermo-pile?
  • A thermo coupler produces a small flow of electricity based on the temperature difference between two dissimilar conductors. This small amount of electricity is measured in MilliVolt. Thermo couplers in fireplaces usually produce around 20-30 mv which is enough to activate a small electo magnetic plunger inside a gas valve to allow gas to flow thru.
  • A thermo pile is a bundle of thermo couplers that produce a larger amount of electricity (usually between 500-750mv) to operate more complex systems and valves. The thermopile is a larger diameter device than a thermocoupler. Many systems use both a (smaller) thermocoupler which opens the valve for standby operation and the thermo pile which opens for the main burner and allows safety systems to operate.
• Bad electrical connections or components. Similarly to the proper communication between pilot flame and thermopile/coupler
• Vent free fireplaces use a special ODS pilot assembly that is more sensitive to nuisance shut downs. Vent free appliances are equipped with an “Oxygen Depletion Sensor) which shuts the appliance down should the oxygen level in a room fall below a safe limit.
  • The design of this device includes a small air hole that creates a very specific pilot flame shape. A small change in the oxygen level OR a small particle of dust/hair etc. can change this pattern and cause a shut down. Obviously we want the system to shut down if the oxygen level is unhealthy but more often the cause is some hair or dust. Simply cleaning the ODS assembly clears this issue 9 out of 10 times. NOTE: ODS pilot assemblies are NOT SERVICEABLE AND CANNOT BE FIXED by law. If any part of the ODS assembly failed, the whole assembly has to be replaced for safety. The components are either welded together or are attached in a way that they cannot be removed without damage to the assembly. https://www.gaslogpro.com/what_is_ODS.htm