4 Central Heating Pipework: Materials & Installation

• Materials used to install domestic central heating pipework
• Learners should be able to identify materials in plumbing, describe materials for insulation, and look at specific tools used in installations.

Copper

• Grades R220 and R250 are commonly used in domestic heating systems.
• R220 is soft coiled microbore pipe, available in 8mm and 10mm sizes and sold in 10 and 25 meter coils.
• R250 is half hard straight lengths, available in 15mm, 22mm, and 28mm sizes, and sold in 1, 2, 3, and 6 meter lengths.

Copper: Microbore

• R220 is commonly used as soft coiled microbore pipe in 8mm and 10mm.
• In fully pumped systems, 22mm and 15mm small bore pipe is often used.
• Microbore systems utilizing 12mm, 10mm, 8mm, and 6mm pipe are an alternative.
• 28mm or 22mm flow and return pipes are fitted with a manifold, which accommodates several radiators.
• Manifolds are adaptors with numerous small outlets allowing runs to individual radiators.
• Microbore systems contain less water, resulting in faster heating.
• Manifolds can be side entry or linear.
• Microbore pipes come in coils and are clipped to joists to avoid multiple joints.
• Connections are soldered, push fit, or compression.

Low Carbon Steel

• Low carbon steel (LCS) is rarely used in domestic installations but can be found in larger and older properties.
• LCS is commonly used in commercial and industrial installations.
• Heavy-grade LCS is red and used for steam and fire systems.
• Medium-grade LCS is blue and used for heating and oil lines.
• Light-grade LCS is brown and used for gas.
• Systems with LCS must have an inhibitor to prevent corrosion.

Polybutylene

• Plastic pipe is becoming increasingly popular for installations due to its ease of installation and ability to have long lengths without connections.
• Connections to boilers typically need to be made in copper.
• Heat emitter tails are often made of copper, with the carcass under the floor made of plastic.
• Polybutylene has high temperature and pressure resistance with a low noise transmission and thermal expansion.
• Polybutylene has a smooth internal bore, allowing for good flow rates, and it does not corrode like copper and LCS.
• Polybutylene is microporous, but newer pipes have an impermeable barrier for use in hot and cold water installations.
• Polybutylene pipes are available in 10mm, 15mm, 22mm, and 28mm diameters, with lengths of 3 meters, and coils of 25, 50, and 100 meters.

Materials: Insulation

• Insulation does not fully prevent freezing but delays the cooling process.
• Insulation stops cold from getting to the pipe and heat from leaving it.
• It is made up of pockets of still air.
• Commercial insulation uses foil to deflect heat or cold.
• Flexible polyethylene pipe insulation is commonly used, conserves fuel and power, and protects pipes from freezing for standard domestic installations.
• It complies with part L Building Regulations and meets water regulations.
• Traditional stitched felt pipe insulation is an economical and effective protection for pipework under floors.
• Stitched felt is not flammable, but original horsehair lagging is flammable, requiring caution when soldering in older properties.
• Stitch felt, polyethylene foam, phenolic foam, polyisocyanurate foam, PVC foam, polystyrene, nitrile rubber (expanded), and cellular glass foam are used to make insulation.

Insulation Guidelines

• The primary circuit for heating and hot water should be insulated whenever it passes outside the heated living space.
• The primary circuit for hot water should be insulated throughout its entire length.
• Pipes connected to the hot water vessel, including the vent, should be insulated for at least 1 meter from the point of connection to the vessel, or to where it becomes concealed.
• Secondary circulation should be insulated for the entire circuit.
• Insulation saves energy, reduces fuel bills and CO2 emissions, improves draw-off temperatures, keeps water warmer for longer, retains heat in the system, and provides frost protection.