WOOD-BURNING FIREPLACES – Draft

WOOD-BURNING FIREPLACES – THE DRAFT

Technical guidelines and regulatory references for installers and CAT

All Moretti Design wood-burning fireplace models come with a specific installation manual, which serves as the primary reference for the correct installation of the product.

It is essential to emphasize that “professional” installation remains the responsibility of the installing technician, who must adhere to the manufacturer's instructions and current regulations, issuing the declaration of conformity.

▿ Fireplace draft

Proper draft is fundamental to ensure that combustion is:
• efficient
• safe
• compliant with regulatory requirements

In the case of Monodesign wood-burning fireplaces, the correct evacuation of smoke is an essential condition for the proper functioning of the system.

The monoblock is equipped with a top smoke outlet, designed for connection to the chimney flue. However, overall performance does not depend solely on the product.

👉 Draft is not a product parameter, but a system parameter.

It depends on the combination of:
• fireplace
• chimney flue
• building configuration
• environmental conditions

▿ Chimney flue

The chimney flue is a determining element for the correct functioning of the fireplace.

An optimal draft, approximately equal to 10 Pa, is necessary to guarantee stable and efficient combustion. The sizing must be carried out according to UNI EN 13384.

The product technical manual provides connection guidelines, but the design of the flue system remains the technician's responsibility.

▿ Main technical requirements

Chimney flue section
It must be properly sized according to the generator and maintain a constant internal section along the entire path, as required by UNI 10683.

Smoke connection inclination
Any non-vertical sections must have an inclination not exceeding 45°, to limit pressure losses and backflow phenomena.

▿ Chimney flue height

The terminal must exceed the roof ridge by at least 50 cm, to ensure adequate depression and correct smoke dispersion.

▿ Adjacent chimney flues

In the presence of multiple chimney flues, it is necessary that one chimney cap exceeds the other by at least 50 cm, avoiding interference between flows.

▿ Combustion air

An external combustion air intake is mandatory, as required by UNI 10683, to guarantee an adequate oxygen supply for combustion.

A lack of air can compromise:
• the draft
• the quality of combustion
• the safety of the system

▿ Practical points to verify during installation

To ensure proper draft, the technician must verify that:

Chimney flue section
It is internally constant, free of constrictions, narrowings, or sharp edges that could obstruct smoke flow.

Height and terminal outlet
The chimney cap must exceed the roof ridge as provided by UNI 7129 (by analogy for terminals) and local regulations, to ensure adequate depression.

External positioning
The terminal must be installed in an area free of obstacles (buildings, trees) and not subject to dominant wind effects that could cause backflows.

▿ Maintenance and draft preservation

Maintaining performance over time depends on proper maintenance.

Chimney flue cleaning
The accumulation of soot and creosote reduces the effective section and compromises the draft.
• Minimum frequency: annual
• In case of intensive use: semiannual

Interventions to be carried out according to UNI 10847.

Monoblock sealing
Periodically check:
• integrity of gaskets
• proper door closure

Uncontrolled air intakes alter the system's operation.

▿ Flue system verification over time

Any structural changes (roof renovation, elevations, new buildings) can influence the draft.

It is good practice to:
• reassess performance
• verify terminal compliance

▿ Responsibilities and warranties

MORETTI DESIGN guarantees exclusively the materials of its own production and declines all responsibility in cases where:
• the technical manual instructions are not followed
• the installation is not carried out professionally
• current regulations are not observed

The installer is responsible for the correct realization of the system and its compliance.

▿ Conclusions

Proper draft does not depend solely on the product, but on the entire fireplace–chimney flue–environment system.

Compliance with technical standards and correct installation are essential conditions to guarantee:
• system safety
• energy efficiency
• product durability

A well-designed and constructed system is the foundation for stable performance, comfort, and reliability over time.