Main 250 Litre Direct Unvented Hot Water Cylinder - 720636301
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The Main 250 Litre Direct Unvented Hot Water Cylinder (720636301) is a UK-manufactured stainless steel cylinder designed to provide reliable mains-pressure hot water for larger domestic properties. With a 250 litre capacity and two factory-fitted Incoloy 800 immersion heaters, it is well suited to large homes with multiple bathrooms, off-grid properties, solar PV installations and off-peak electricity tariffs.
Applications & suitability
The 250 litre capacity provides substantial hot water storage for larger homes with higher domestic hot water requirements.
Designed for properties where multiple bathrooms and simultaneous hot water demand require a larger stored water capacity.
Suitable for installations using solar PV-generated electricity to heat stored domestic hot water.
The direct immersion heating arrangement makes the cylinder suitable for use with off-peak electricity tariffs.
Key specifications
| Product Code | 720636301 |
| Type | Direct Unvented |
| Nominal Capacity | 250 Litres |
| Height (A) | 1752 mm |
| Diameter | Ø 550 mm cylinder / 595 mm base |
| Weight (Empty) | 47 kg |
| Immersion Rating | 2 × 3.0 kW @ 240V |
| Heat-Up Time | 260 mins |
| Standing Heat Loss | 2.22 kWh/24h |
| ErP Energy Rating | D |
| Operating Pressure | 3.5 bar |
| Maximum Flow Rate | Up to 55 l/min @ 6 bar |
| Inner Vessel | High-grade stainless steel, 15 bar pressure tested |
| Insulation | 50mm CFC/HCFC-free polyurethane foam |
| Thermostat | Adjustable 10–70°C with 80°C high-limit cut-out |
| Expansion Vessel | 24 litre, supplied |
| Connections | 22mm compression / ¾" BSP |
| Immersion Heater Material | Incoloy 800 alloy |
| Approvals | KIWA approved, Building Regulation G3 compliant, CE marked |
| Manufactured | UK by Baxi (Main Heating) |
| Warranty | 25 years on stainless steel inner vessel; 1 year parts & labour |
Installation & compatibility
Factory-supplied components: The cylinder is supplied with a 24 litre expansion vessel, T&P relief valve, pressure reducing valve and factory-fitted controls. Connections are provided as 22mm compression / ¾" BSP. The unit is KIWA approved and compliant with Building Regulation G3 requirements.
Design & performance benefits
Direct unvented operation provides stored hot water supplied from the mains-pressure system.
Two 3.0kW Incoloy 800 immersion heaters provide direct electrical heating for the 250 litre cylinder.
Factory-injected 50mm CFC/HCFC-free polyurethane foam helps minimise standing heat loss.
The 250 litre capacity is suited to properties requiring a substantial stored domestic hot water supply.
Additional installation features
Supplied with a 24 litre expansion vessel as part of the unvented cylinder package.
Supplied with factory-fitted controls, pressure reducing valve and T&P relief valve.
Temperature can be adjusted from 10–70°C with an 80°C high-limit cut-out.
Ideal for
The Main 250 Litre Direct Unvented Hot Water Cylinder is ideal for large homes, properties with multiple bathrooms, off-grid installations, solar PV systems and off-peak electricity tariffs. It can also be paired with the Main Eco Compact System or Main Eco Elite System boilers as part of a complete domestic hot water solution.
Manufactured in the UK by Baxi (Main Heating), this 250 litre unvented cylinder combines stainless steel construction, direct immersion heating, 50mm polyurethane insulation and factory-supplied controls. It is KIWA approved, G3 compliant and backed by a 25-year stainless steel inner vessel warranty plus a one-year parts and labour warranty.
