The Megaflo Main 120 Litre Indirect Unvented Hot Water Cylinder (7912277) is a UK-manufactured stainless steel cylinder designed to provide reliable mains-pressure hot water heated indirectly by a gas, oil or system boiler. With a factory-fitted 3.0kW Incoloy 800 immersion heater for backup heating, it provides dependable hot water for homes with one or two bathrooms.
The Megaflo Main is the new name for the Main unvented cylinder range and replaces the previous Main 120 Litre Indirect Unvented Hot Water Cylinder (5133561). Featuring a unique coil-in-coil heat exchanger, 50mm factory-injected polyurethane insulation and a comprehensive set of factory-fitted controls and safety components, this 120-litre cylinder is designed for fast heat recovery and reduced standing heat loss.
120L Capacity
Indirect Unvented
12.5kW Coil
Incoloy 800 Immersion
25-Year Vessel Warranty
Key Benefits at a Glance
12.5kW
Primary Coil Rating
55L/min
Maximum Flow Rate
25 Years
Inner Vessel Warranty
Applications & Suitability
- Domestic hot water systems requiring 120 litres of mains-pressure hot water storage.
- Homes with one or two bathrooms requiring reliable hot water delivery.
- Installations using a gas, oil or system boiler as the primary heat source.
- Domestic systems requiring an indirect unvented cylinder with backup immersion heating.
- Projects using Main Eco Compact System or Main Eco Elite System boilers.
- Installations requiring KIWA approval and compliance with Building Regulation G3.
Key Specifications
| Product Code |
7912277 |
| Type |
Indirect Unvented |
| Nominal Capacity |
120 Litres |
| Height (A) |
931 mm |
| Diameter |
Ø 550 mm cylinder / 595 mm base |
| Weight (Empty) |
27 kg |
| Primary Coil |
22mm stainless steel coil-in-coil heat exchanger |
| Coil Rating |
12.5 kW |
| Coil Heat-Up Time |
27 minutes |
| Recovery Time |
23 minutes |
| Immersion Heater |
1 × 3.0kW Incoloy 800 @ 240V |
| Inner Vessel |
High-grade stainless steel |
| Pressure Tested |
15 bar |
| Operating Pressure |
3.5 bar |
| Maximum Flow Rate |
Up to 55 l/min @ 6 bar |
| Insulation |
50mm CFC/HCFC-free polyurethane foam |
| Standing Heat Loss |
1.47 kWh/24h |
| ErP Energy Rating |
B |
| Thermostat |
Adjustable 10–70°C with 80°C high-limit |
| Connections |
22mm compression / ¾" BSP |
| Expansion Vessel |
12 litre, supplied |
| Manufacturer |
Baxi, UK manufactured |
| Warranty |
25 years stainless steel inner vessel; 1 year parts & labour |
Indirect Heating & Rapid Heat Recovery
The Megaflo Main 120 Litre uses a 22mm stainless steel coil-in-coil heat exchanger with a 12.5kW rating to heat the stored domestic hot water indirectly from a compatible gas, oil or system boiler. The design provides a stated 27-minute coil heat-up time and 23-minute recovery time.
A factory-fitted 3.0kW Incoloy 800 immersion heater provides backup heating, helping maintain hot water availability when required. The immersion element is rated at 240V.
Insulation, Safety & Factory-Fitted Components
50mm Insulation
Factory-injected 50mm CFC/HCFC-free polyurethane foam helps minimise standing heat loss, specified at 1.47 kWh/24h.
Safety Protection
Supplied with a T&P relief valve, pressure reducing valve and 2-port motorised valve for primary over-temperature protection.
Expansion Vessel
A 12-litre expansion vessel is supplied as part of the cylinder package.
Factory-Fitted Controls
Supplied with factory-fitted controls alongside the required safety components for the cylinder system.
Approvals & Compliance
The Megaflo Main 120 Litre Indirect Unvented Cylinder is KIWA approved for compliance with Water Regulations and is compliant with Building Regulation G3. The cylinder is also CE marked.
The stainless steel inner vessel is pressure tested to 15 bar, with a stated operating pressure of 3.5 bar. The thermostat is adjustable from 10–70°C with an 80°C high-limit.
Supplied Components
- 12 litre expansion vessel
- T&P relief valve
- 2-port motorised valve
- Pressure reducing valve
- Factory-fitted controls
- Factory-fitted 3.0kW Incoloy 800 immersion heater
Ideal For
- Homes with one or two bathrooms.
- Domestic hot water systems using gas, oil or system boilers.
- Installations requiring 120-litre mains-pressure hot water storage.
- Heating upgrades using Main Eco Compact System boilers.
- Heating upgrades using Main Eco Elite System boilers.
- Domestic installations requiring backup immersion heating.
Frequently Asked Questions
What is the capacity of the Megaflo Main 120 Litre cylinder?
The cylinder has a 120-litre nominal capacity and is designed to provide mains-pressure domestic hot water.
Is the Megaflo Main 120 Litre cylinder indirect?
Yes. It is an indirect unvented hot water cylinder that uses a 12.5kW coil-in-coil heat exchanger to heat the stored water from a compatible boiler.
What backup heating does this cylinder have?
It is supplied with one factory-fitted 3.0kW Incoloy 800 immersion heater rated at 240V.
What is the operating pressure?
The stated operating pressure is 3.5 bar, with the inner vessel pressure tested to 15 bar.
What warranty is included?
The stainless steel inner vessel is covered by a 25-year warranty, with a separate 1-year parts and labour warranty.
What boilers can the Megaflo Main cylinder work with?
The cylinder is designed to be heated indirectly by a gas, oil or system boiler. It pairs with the Main Eco Compact System and Main Eco Elite System boilers for a complete domestic hot water solution.
What are the dimensions of the cylinder?
The stated height is 931mm. The cylinder diameter is 550mm, with a base diameter of 595mm. The empty weight is 27kg.
Megaflo Main 120 Litre Indirect Unvented Cylinder – Reliable Mains-Pressure Hot Water
The Megaflo Main 120 Litre Indirect Unvented Hot Water Cylinder (7912277) combines a 12.5kW coil-in-coil heat exchanger, 3.0kW Incoloy 800 backup immersion heater, 50mm polyurethane insulation and factory-fitted safety components. With a 25-year stainless steel inner vessel warranty, KIWA approval and Building Regulation G3 compliance, it is a practical choice for domestic hot water systems serving one or two bathrooms. Order online from GetPlumb for UK delivery or collect from the Reading trade counter.
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