What is the recommended action regarding the venting of a fan assisted Category 1 appliance with an input rating of 55,000 Btu/h into a 20-foot high chimney?

For a fan-assisted Category 1 appliance with an input rating of 55,000 Btu/h, venting into a 20-foot high chimney is generally not recommended due to potential issues related to venting design and the performance of the appliance.

Category 1 appliances are designed for use with a vertical venting system, but they require certain conditions to operate efficiently and safely. The height and design of the chimney can impact the needed draft; a 20-foot chimney could create excessive draft, which might cause negative pressure within the appliance, leading to problems such as backdrafting or inefficiencies in combustion.

Moreover, fan-assisted appliances are intended to overcome some drafting issues, but when combined with a very tall chimney, this can complicate the balance of airflow. The recommendation typically leans towards ensuring that appliances are vented in accordance with manufacturer specifications and local building codes, suggesting that alternative venting methods may be more appropriate for appliances like this.

In summary, not venting a fan-assisted Category 1 appliance into a high chimney prevents potential safety and performance issues related to improper drafting, making this the advisable action in a general sense.