The Megaflo Main 300 Litre Direct Unvented Hot Water Cylinder (7912288) is a UK-manufactured stainless steel hot water cylinder designed to provide reliable mains-pressure hot water for properties without access to mains gas. With a 300-litre capacity and two factory-fitted Incoloy 800 immersion heaters, it is well suited to very large homes, multiple-bathroom properties, off-grid installations and systems using solar PV or off-peak electricity tariffs.
Megaflo Main is the new name for the Main unvented cylinder range. This model replaces the Main 300 Litre Direct Unvented Hot Water Cylinder (720636401). Supplied as two boxes: cylinder plus fitting kit (90001992).
The cylinder features a high-grade stainless steel inner vessel, 50mm of factory-injected CFC/HCFC-free polyurethane foam insulation and a 24-litre expansion vessel. The adjustable thermostat, factory-fitted controls and supplied unvented safety components provide a complete solution for direct hot water storage.
300L Capacity
Direct Unvented
2 × 3kW Immersions
25-Year Vessel Warranty
300 Litre Storage
Large-capacity hot water storage designed for high-demand domestic applications.
Dual Immersion Heating
Two 3.0kW Incoloy 800 immersion heaters provide direct electric water heating.
50mm Insulation
Factory-injected CFC/HCFC-free polyurethane foam helps minimise standing heat loss.
High-Grade Stainless Steel
Pressure-tested stainless steel inner vessel designed for dependable hot water storage.
Applications & suitability
Large Homes
The 300-litre capacity is suited to properties with high domestic hot water demand.
Multiple Bathrooms
Provides substantial stored hot water capacity for properties with multiple bathrooms.
Off-Grid Properties
Direct electric heating makes the cylinder suitable for properties without access to mains gas.
Solar PV & Off-Peak Tariffs
Suitable for installations using solar PV generation or off-peak electricity tariffs.
Key specifications
| Product Code |
7912288 |
| Type |
Direct Unvented |
| Nominal Capacity |
300 Litres |
| Height (A) |
2065 mm |
| Diameter |
Ø 550 mm (cylinder) / 595 mm (base) |
| Weight (Empty) |
55 kg |
| Immersion Rating |
2 × 3.0 kW @ 240V |
| Heat-Up Time |
315 mins |
| Standing Heat Loss |
2.52 kWh/24h |
| ErP Energy Rating |
D |
| Operating Pressure |
3.5 bar |
| Expansion Vessel |
24 litre (supplied) |
| Connections |
22mm compression / ¾" BSP |
| Packaging |
Two boxes: cylinder plus fitting kit (90001992) |
Installation & compatibility
The Megaflo Main 300 Litre Direct Unvented Cylinder is designed for direct electric water heating using its two factory-fitted Incoloy 800 immersion heaters. It is supplied with a 24-litre expansion vessel, T&P relief valve, pressure reducing valve and factory-fitted controls. The cylinder is also suitable for installations using solar PV systems and off-peak electricity tariffs.
Design & performance benefits
Dual Immersion Heating
Two 3.0kW Incoloy 800 immersion heaters provide a combined 6.0kW direct heating capacity.
Stainless Steel Inner Vessel
The high-grade stainless steel inner vessel is pressure tested to 15 bar.
Factory-Injected Insulation
50mm CFC/HCFC-free polyurethane foam insulation helps reduce standing heat loss.
Adjustable Thermostat
Thermostat adjustment from 10–70°C with an 80°C high-limit cut-out.
Additional installation features
24L Expansion Vessel
A 24-litre expansion vessel is supplied as part of the cylinder package.
Factory-Fitted Controls
Factory-fitted controls help provide a ready-to-install unvented cylinder system.
KIWA & G3 Compliance
KIWA approved, Building Regulation G3 compliant and CE marked.
Ideal for
Very Large Homes
300 litres of stored hot water for properties with substantial domestic hot water requirements.
Multiple-Bathroom Properties
Large storage capacity for homes where hot water demand can be high.
Off-Grid Applications
Direct electric heating makes it suitable for properties without mains gas.
Solar PV & Off-Peak Systems
Designed for use with solar PV generation and off-peak electricity tariffs.
The Megaflo Main 300 Litre Direct Unvented Hot Water Cylinder combines high-capacity 300-litre storage, dual Incoloy 800 immersion heating, stainless steel construction and comprehensive unvented components. With its 25-year stainless steel inner vessel warranty and 1-year parts and labour warranty, it provides a robust solution for high-demand domestic hot water installations. Order now for a complete direct unvented hot water storage solution.
At GetPlumb, we strive to provide reliable and cost-effective delivery options to our customers. Please review our shipping policy below.
🆓 Free Local Delivery (Orders £100 & above)
We offer FREE delivery on orders £100 or more
for selected local areas.
Eligible Postcodes Include:
- RG*
- SL*
- OX10*, OX11*, OX49*
- HP1*, HP3*, HP8*, HP9*, HP10*, HP11*, HP12*, HP13*, HP14*
- WD*, HA*, UB*, TW*, KT*
- W1* – W9*
- NW*, SW*
Delivery Time: 2–4 working days
Shipping Cost: £0.00
📦 Standard Shipping (Weight-Based Rates)
For orders that do not qualify for free delivery, standard
shipping rates apply based on total cart weight.
- For cart weight between 0–2 kg, the shipping cost is £4.50 with a delivery time of 2–4 working days.
- For cart weight between 2–24 kg, the shipping cost is £9.99 with a delivery time of 2–4 working days.
- For cart weight between 24 kg and above, the shipping cost is £60 with a delivery time of 2–4 working days.
🧱 Block Salt (Harvey’s) – Unit-Based Shipping
This rate applies only to Harvey’s block salt products.
- £7.99 is charged for every 3 items.
- The charge increases by £7.99 for each additional set of 3 items.
Examples:
- 1–3 items → £7.99
- 4–6 items → £15.98
- 7–9 items → £23.97
Delivery Time: 2–4 working days
📏 Large / Long Items (Length-Based Shipping)
For oversized items where the product length is 1.5 metres or more:
Conditions:
- Product length ≥ 1.5 m
- Cart weight ≤ 40 kg
Shipping Cost: £18.00 (flat rate)
Delivery Time: 2–4 working days
Collection from Store
Customers can also choose to collect their order from our store in
Reading, UK, at no additional charge. For any questions regarding shipping, please contact our support team at online@getplumb.co.uk.
