Conversion, Commissioning, and Documentation

Chapter Introduction

This chapter covers the operations of converting gas appliances and installations, commissioning systems, and mandatory documentation. For the Red Seal exam, you must master the precise procedures, pressure calculations, regulatory requirements, and common pitfalls. This chapter covers the requirements of the Canadian Electrical Code, Part I (CE Code) (for electrical connections of gas appliances) and CSA B149.1 (Natural Gas and Propane Installation Code). No provincial content is included; refer to national standards only.

1. Appliance Conversion: Fundamental Principles

1.1 Definition and Scope

Conversion consists of modifying a gas appliance so that it operates with a different gas than the one for which it was manufactured. The two commonly used gases are natural gas (NG) and propane (LP) . Conversion involves:

Replacing the orifices (nozzles);

Adjusting the supply pressure at the regulator;

Adjusting the primary air flow (air shutters);

Sometimes, replacing the burner or heat exchanger.

Key CSA B149.1 Rule, Article 7.2.1: Any conversion must be performed in accordance with the manufacturer's instructions. If no instructions exist, the installation must be evaluated by a qualified professional, and the conversion must comply with the requirements of the code.

1.2 Heating Value and Relative Density

The higher heating value (HHV) and relative density determine the sizing of orifices.

Parameter	Natural Gas (NG)	Propane (LP)
HHV (MJ/m³)	37.5 to 39.0	93.0 to 96.0
Relative density (air = 1)	0.60 to 0.65	1.50 to 1.55
Typical supply pressure (inches water column, iwc)	7 iwc (1.74 kPa)	11 iwc (2.74 kPa)
Manifold pressure (iwc)	3.5 iwc (0.87 kPa)	10 iwc (2.49 kPa)

Conversion Calculation: The volumetric flow rate required for the same heat input is inversely proportional to the HHV.

Formula: Q₂ = Q₁ × (HHV₁ / HHV₂)

Where:

Q₁ = volumetric flow rate with the original gas (m³/h)

Q₂ = volumetric flow rate with the new gas (m³/h)

HHV₁ = heating value of the original gas (MJ/m³)

HHV₂ = heating value of the new gas (MJ/m³)

Example: An appliance consumes 2.5 m³/h of NG (HHV = 38 MJ/m³). Converting to LP (HHV = 94 MJ/m³):

Q₂ = 2.5 × (38 / 94) = 2.5 × 0.404 = 1.01 m³/h of LP.

Exam Trap: Do not confuse HHV and LHV (lower heating value). Sizing calculations use HHV.

1.3 Orifice Sizing

The diameter of the orifice depends on:

The supply pressure;

The relative density of the gas;

The required mass flow rate.

Approximate Relationship: The flow through an orifice is proportional to √(ΔP / ρ), where ΔP is the pressure drop and ρ is the density.

Practical Formula: d₂ = d₁ × √(ρ₁ / ρ₂) × √(HHV₁ / HHV₂)

Where d₁ and d₂ are the orifice diameters (mm).

Example: NG orifice of 2.0 mm. Converting to LP:

d₂ = 2.0 × √(0.62 / 1.52) × √(38 / 94) = 2.0 × √0.408 × √0.404 = 2.0 × 0.639 × 0.636 = 0.81 mm.

CSA B149.1 Rule, Article 7.2.2: Orifices must be replaced, never enlarged or modified. A modified orifice invalidates the appliance certification.

1.4 Step-by-Step Conversion Procedure

38.Shut off the gas supply and lock out the shut-off valve (lockout/tagout procedure).

39.Consult the manufacturer's instructions: the conversion kit must be specific to the model.

40.Replace the orifices: use the orifices supplied in the kit, identified by their code or diameter.

41.Adjust the pressure regulator: set the manifold pressure according to the manufacturer's values (e.g., NG: 3.5 iwc; LP: 10 iwc).

42.Adjust the primary air shutter: to achieve a stable, blue flame, without yellowing or lifting.

43.Check for leaks: apply a leak-detection solution to all modified connections.

44.Light the appliance and verify combustion (CO₂, CO, temperature).

45.Affix the conversion label: indicate the gas type, date, technician's name, and certificate number.

CSA B149.1 Requirement, Article 7.2.3: A conversion label must be affixed near the appliance nameplate, indicating the new gas type and supply pressure.

2. Commissioning

2.1 Definition and Objectives

Commissioning is the set of verification, adjustment, and validation operations for a gas installation before it is put into final service. It includes:

Leak testing of the piping system;

Purging of the piping;

Pressure testing;

Verification of appliances (ignition, combustion, ventilation);

Verification of safety devices;

Documentation of results.

2.2 Leak Testing (Pressure Test)

CSA B149.1 Requirement, Article 5.7.1: Every installation must undergo a pressure test before being put into service.

Minimum Test Pressures:

System Type	Test Pressure	Minimum Duration
Low pressure (≤ 7 iwc)	15 iwc (3.7 kPa) or 1.5× the service pressure, whichever is greater	15 minutes
High pressure (> 7 iwc)	1.5× the service pressure, minimum 50 iwc (12.4 kPa)	30 minutes
System with regulator	Test upstream and downstream separately	—

Procedure:

62.Isolate the appliance or regulator if the test pressure exceeds its maximum allowable pressure.

63.Pressurize with air or an inert gas (nitrogen).

64.Stabilize the pressure (wait 5 minutes for thermal equilibrium).

65.Record the initial and final pressures. No pressure drop is tolerated.

66.If a drop occurs: locate the leak with a leak-detection solution, repair, and retest.

Exam Trap: The test must be performed before connecting the appliances, unless they are designed for the test pressure.

2.3 Purging of Piping

Purging consists of evacuating air or inert gas from the piping before putting it into service.

Methods:

Direct purge: open the shut-off valve and let the gas displace the air. Prohibited inside buildings (explosion risk).

Pump purge: use a vacuum pump to evacuate the air, then introduce the gas.

Inert gas purge: introduce nitrogen, then the gas.

CSA B149.1 Requirement, Article 5.8.1: Purging must be performed in a manner that avoids any gas discharge into a confined space. The purge point must be outdoors or in a well-ventilated location.

Purge Volume Calculation: V_purge = V_pipe × 1.5 (to ensure sufficient dilution).

Example: Pipe of 50 mm diameter, 30 m long.

V_pipe = π × (0.025)² × 30 = 0.0589 m³.

V_purge = 0.0589 × 1.5 = 0.088 m³ of gas.

2.4 Appliance Verification

Ignition and Combustion:

Verify the ignition of the pilot or electronic igniter.

Measure the flame temperature and colour (blue flame = good combustion).

Measure CO₂ and CO in the combustion products. CO must not exceed 100 ppm (for residential appliances).

Ventilation:

Verify that ventilation openings (air supply and exhaust) comply with CSA B149.1, Article 8.2.

Calculate the required ventilation area: 1 cm² per 4.2 kW (14,300 BTU/h) for air supply.

Safety Devices:

Thermocouple: verify that the pilot stays lit after 30 seconds of holding.

Flame detector: test gas shut-off in case of flame failure.

Pressure switch: verify operation at minimum and maximum pressure.

2.5 Commissioning of Control Systems

Thermostats and Valves:

Verify electrical wiring in accordance with the Canadian Electrical Code, Part I (CE Code) (Rule 8-200 for gas appliances).

Test the ignition sequence: heat call → valve opening → ignition → flame verification.

Verify the safety cycle: if the flame is not detected within 4 seconds, the valve must close.

Pressure Regulators:

Verify supply pressure and manifold pressure with a manometer.

Adjust if necessary, within the manufacturer's limits.

Verify regulator tightness (no leak at the vent).

3. Mandatory Documentation

3.1 Types of Documents

Documentation is essential for traceability and compliance. The following documents are required:

Document	Content	Reference
Installation Report	Description of the installation, tests performed, results	CSA B149.1, Article 4.1
Commissioning Certificate	Confirmation that the installation is compliant and safe	CSA B149.1, Article 4.2
Conversion Label	Gas type, date, technician	CSA B149.1, Article 7.2.3
Maintenance Log	History of interventions, repairs, replacements	CSA B149.1, Article 4.3
Installation Plan	Piping diagram, diameters, materials, locations	CSA B149.1, Article 4.4

3.2 Contents of the Installation Report

The report must include:

Site identification (address, owner);

System description (gas type, pressure, materials, diameters);

Test results (pressure, leak test, purge);

List of appliances (brand, model, serial number);

Adjustments made (manifold pressure, air flow);

Technician's name and signature, qualification certificate number.

CSA B149.1 Requirement, Article 4.1.1: The report must be given to the owner, and a copy must be kept by the installer for at least 5 years.

3.3 Labeling and Signage

Warning Label: Every installation must have a label indicating:

The gas type (NG or LP);

The supply pressure;

The manifold pressure;

The date of commissioning.

CSA B149.1 Requirement, Article 4.5: The label must be legible, durable, and affixed in a visible location near the main shut-off valve.

Exam Trap: A conversion label must be separate from the manufacturer's nameplate. It must not cover it.

3.4 Electrical Documentation

The Canadian Electrical Code, Part I (CE Code) (Rule 8-200) requires:

A wiring diagram for each gas appliance;

Verification of polarity and grounding;

Documentation of electrical tests (voltage, current, continuity).

Rule 8-202: Gas appliances must be connected to a dedicated circuit, with an appropriately sized breaker.

Example: A gas water heater of 30,000 BTU/h (8.8 kW) requires a 120 V, 15 A circuit. The documentation must include voltage measurement (120 V ± 10%) and current (≤ 12 A).

4. Conversion and Sizing Calculations

4.1 Pressure Conversion

Pressures are often expressed in inches of water column (iwc) , kPa, or PSI.

Conversion Factors:

1 iwc = 0.249 kPa

1 kPa = 4.02 iwc

1 PSI = 6.895 kPa = 27.7 iwc

Example: LP supply pressure = 11 iwc. Converting to kPa:

11 × 0.249 = 2.74 kPa.

4.2 Heat Load Calculation

The heat load of an appliance is given in BTU/h or kW.

Formula: Q = V × HHV

Where:

Q = heat load (kW)

V = volumetric flow rate (m³/h)

HHV = higher heating value (MJ/m³)

Example: An appliance consumes 1.5 m³/h of NG (HHV = 38 MJ/m³).

Q = 1.5 × 38 = 57 MJ/h = 15.8 kW (1 kW = 3.6 MJ/h).

4.3 Pipe Sizing

Pipe sizing depends on:

The equivalent length (actual length + fitting losses);

The required flow rate;

The allowable pressure drop (generally 0.5 iwc for low-pressure systems).

Sizing Table (excerpt, NG, 7 iwc pressure, 0.5 iwc drop) :

Diameter (mm)	Max Length (m) for 10 m³/h	Max Length (m) for 20 m³/h
15	5	2
20	15	6
25	30	12
32	60	25
40	100	40

CSA B149.1 Rule, Article 6.3.1: The total pressure drop must not exceed 0.5 iwc for low-pressure systems.

4.4 Ventilation Calculation

Ventilation must provide sufficient air for combustion and room ventilation.

Formula: A = Q / 4.2

Where:

A = opening area (cm²)

Q = total heat load (kW)

Example: Two appliances of 15 kW each.

Q = 30 kW.

A = 30 / 4.2 = 7.14 cm² (minimum).

CSA B149.1 Requirement, Article 8.2.2: Openings must be located within 300 mm of the ceiling for exhaust and within 300 mm of the floor for supply.

5. Pitfalls to Avoid

168.Confusing HHV and LHV: Always use HHV for sizing calculations.

169.Enlarging an orifice: Prohibited by CSA B149.1. Always replace the orifice.

170.Forgetting the conversion label: Mandatory, with the date and technician's name.

171.Pressure testing with the appliance connected: Risk of damaging the regulator. Isolate the appliance.

172.Purging indoors: Prohibited. Use an outdoor purge point.

173.Ignoring the pressure drop: Never exceed 0.5 iwc for low-pressure systems.

174.Not checking electrical polarity: Requirement of the Canadian Electrical Code, Part I, Rule 8-200.

175.Using incorrect pressures: NG = 7 iwc, LP = 11 iwc (supply); manifold NG = 3.5 iwc, LP = 10 iwc.

176.Not documenting adjustments: The installation report must include all adjustments made.

177.Forgetting the flame test: Check the colour (blue) and CO (≤ 100 ppm).

6. Summary

Appliance conversion requires replacing orifices, adjusting pressure, and adjusting primary air, in accordance with the manufacturer's instructions (CSA B149.1, Article 7.2).

Orifice sizing uses the formula d₂ = d₁ × √(ρ₁/ρ₂) × √(HHV₁/HHV₂).

Leak testing must be performed at 15 iwc (low pressure) or 1.5× the service pressure (high pressure), with no drop tolerated.

Purging must be performed outdoors or in a ventilated area, with a volume of 1.5× the pipe volume.

Commissioning includes verification of ignition, combustion (CO ≤ 100 ppm), ventilation, and safety devices.

Documentation must include the installation report, commissioning certificate, conversion label, and maintenance log.

Pressure calculations use the factors: 1 iwc = 0.249 kPa, 1 PSI = 6.895 kPa.

Ventilation requires 1 cm² per 4.2 kW of heat load.

The Canadian Electrical Code, Part I (CE Code) (Rule 8-200) requires a wiring diagram and verification of polarity and grounding.

7. Self-Assessment Questions

191.What is the typical supply pressure for propane (LP)?

Answer: 11 iwc (2.74 kPa).

193.A 2.5 mm NG orifice is converted to LP. What is the new diameter?

Answer: d₂ = 2.5 × √(0.62/1.52) × √(38/94) = 2.5 × 0.639 × 0.636 = 1.02 mm.

195.What is the minimum duration of a pressure test for a low-pressure system?

Answer: 15 minutes.

197.What is the purge volume for a pipe of 0.05 m³?

Answer: 0.05 × 1.5 = 0.075 m³.

199.What is the required ventilation area for a 20 kW appliance?

Answer: 20 / 4.2 = 4.76 cm².

201.Which article of CSA B149.1 requires the conversion label?

Answer: Article 7.2.3.

203.What is the maximum allowable pressure drop for a low-pressure system?

Answer: 0.5 iwc.

205.What is the maximum tolerated CO in combustion products?

Answer: 100 ppm.

This chapter prepares you for exam questions on conversion, commissioning, and documentation. Review the formulas, tables, and code articles. Good luck with your preparation!

Conversion, Commissioning, and Documentation