In Condensing Boilers, this component is placed between the primary heat exchanger and the drain line, and it prevents the exhaust gases from discharging into the condensate drain pipe.

Introduction to Condensing Boilers

During the heat production phase, the condensing boiler produces many liters of condensate; in winter, it is estimated to produce more than 12 liters per day. In the summer period, however, this component is less irrigated by condensate water. For this reason, many condensate drain traps have narrow passages so that they fill quickly at the first opportunity and block the gases from passing into the drain pipe.

Alternative Types of Drain Traps

Other types of drain traps block the passage of gases in the drain through different mechanisms, such as a condensate trap with a "ball". The ball inside this trap falls in dry conditions, blocking the passage in the drain.

Maintenance and Cleaning of the Trap

The condensate trap of the boiler should be cleaned regularly on an annual basis. The dirt coming from the primary heat exchanger could:

  • Block the trap and cause loud noises: This happens because the accumulated dirt prevents the condensate water from evacuating. In the winter season, this causes the heat exchanger to fill with condensate water, and as soon as the level exceeds the flue pipe, the boiler starts to gurgle. This is mainly due to:
    • The fan must push the gases through an increasingly smaller opening and overcome the resistance of the water
    • The combustion chamber fills with CO2, and the flame extinguishes.

Comparison with Other Types of Boilers

The condensate trap can come in different forms; the goal of all manufacturers is to exclude the possibility that the gases, during the summer or the first ignition, find it more convenient to pass through the drain pipe.

For this reason, the traps:

  • Are equipped with a closing ball: This, when the trap is empty, closes the drain passage, excluding the possibility of gases exiting through the condensate drain.
  • Are made with narrow and tortuous passages: This allows the trap to fill very quickly and perform its function.

Each design has its drawbacks if not properly maintained.

Frequently Asked Questions and Troubleshooting

To resolve the main problems with the trap, proper maintenance is required.

The condensate trap leaks

Ensure that the rubber seals are always present. Some condensate traps have plastic rings; they should not be too tight or too loose, which allows the rubber seal to remain in place. Also, check that:

  • The trap has no cracks
  • The ring is correctly screwed and not stripped

Use PTFE tape if needed (Teflon)

The boiler gurgles or makes rhythmic noises

This can happen if the trap is clogged, the accumulated condensate is too much, and it extinguishes the flame.

With the help of an expert technician, free the trap and the condensate from the primary heat exchanger.

If everything is clear, it is necessary to adjust the flame with the help of a combustion analyzer.

The boiler shows a flame presence error with the burner off

This happens when the combustion chamber fills with condensate. If the trap is dirty, it rises in level in the primary heat exchanger, wetting the ignition and detection electrodes.

At that point, the water conducts the electrode to the boiler body, transmitting a flame value to the board.

It is necessary, with the help of a qualified technician, to free the trap and dry the ignition and detection electrodes.