The Heatrae Sadia Megaflo Eco Indirect is the UK's market-leading indirectly heated unvented hot water cylinder — designed to be fed by a gas, oil, or heat-pump boiler as the primary heat source, with a single 3 kW backup immersion heater for off-peak or emergency use. Built in the UK from high-grade duplex stainless steel, the Megaflo Eco Indirect features a unique coil-in-coil heat exchanger for exceptionally fast recovery, internal expansion (no external vessel required), and delivers mains-pressure hot water at up to 76 litres per minute — with a 30-year guarantee on the inner tank.
76 l/min
Max flow at 3 bar
60 mm
CFC-free insulation
17–39 min
Coil reheat time
30-year
Inner-tank guarantee
⚠ Important Safety Information
Megaflo Eco Indirect cylinders must be installed and commissioned by a G3 competent person (or equivalent under Scottish / Northern Irish Building Regulations). All electrical connections must be made by a qualified electrician in line with current IET Wiring Regulations. The Benchmark commissioning checklist must be completed and left with the householder.
🔄 Please Note
Heatrae Sadia has updated the 170i, 210i, 250i, and 300i models to a new generation (sometimes listed as "Megaflo Eco 2") with new 7-digit order codes, replacing the older 950504XX codes. The 70i, 125i, and 145i product codes are unchanged. The updated models also carry a revised 30-year inner-tank guarantee (up from lifetime/first-owner wording on the previous generation) and slightly revised coil ratings.
ℹ Good to Know
These cylinders are heated primarily by your gas, oil, or heat-pump boiler via the internal coil. A single 3 kW backup immersion heater is included for off-peak electricity tariffs or when the boiler is unavailable. They are not suitable for use with solid-fuel boilers or gravity-circulation primaries unless additional safety measures are fitted. If you need electric-only heating, please see our Megaflo Eco Direct range.
Coil-in-Coil Heat Exchanger
The Megaflo Eco Indirect's unique coil-in-coil heat exchanger maximises contact surface area between the primary circuit and stored water, delivering exceptionally fast heat-up and recovery times — as quick as 17 minutes for the 70i at 15 l/min primary flow — without the need for a high-volume boiler output.
Internal Expansion — No External Vessel
An internal floating-baffle air-gap system accommodates all domestic hot water expansion within the cylinder itself. No external expansion vessel is required for the DHW circuit, reducing pipework complexity and saving installation space — note that the primary heating circuit will still require its own expansion vessel if running a sealed system.
Duplex Stainless Steel Construction
Every Megaflo Eco Indirect is fabricated from high-grade duplex stainless steel, pressure-tested to 15 bar. The alloy combines superior corrosion resistance with a high strength-to-weight ratio — the basis for Heatrae Sadia's 30-year guarantee on the inner tank.
Mains-Pressure Delivery — No Pump Needed
Fed directly from the cold-water mains, the Megaflo Eco Indirect delivers up to 76 litres per minute at 3 bar and 45 litres per minute at 1 bar — providing powerful, simultaneous hot water to multiple outlets without shower pumps or loft tanks.
60 mm CFC/HCFC-Free Insulation
60 mm of fire-retardant polyurethane foam (zero ozone depletion) with an insulated T&P valve delivers excellent standing heat-loss performance — from 0.91 kWh/24h (70i) to 1.69 kWh/24h (300i) — exceeding Building Regulations Part L requirements across the range.
Backup Immersion & Full Control Pack
A factory-fitted single 3 kW Incoloy 825 alloy-sheathed immersion heater with manual-reset thermal cut-out provides electric backup. The cylinder ships complete with an additional thermostat and thermal cut-out, 22 mm 2-port motorised valve, and wiring centre.
Full Safety Kit Supplied as Standard
Every model includes a complete cold-water inlet control kit (3 bar PRV · 8 bar pressure relief valve · ¼-turn isolator · line strainer · non-return valve · drain cock), a factory-fitted 90°C / 10 bar T&P relief valve, tundish, and T&P insulation kit.
ErP-Rated & Regulation-Compliant
The Megaflo Eco Indirect range achieves an ErP Energy Efficiency Class B (70i–210i) or Class C (250i–300i), complies with Building Regulations Parts G and L, and holds Kiwa certification.
| Construction & Insulation |
| Inner vessel material |
High-grade duplex stainless steel — pressure tested to 15 bar |
| Thermal insulation |
60 mm CFC/HCFC-free fire-retardant polyurethane foam |
| Outer casing |
White textured plastic-coated corrosion-resistant steel |
| Country of manufacture |
United Kingdom |
| Pressure & Flow |
| Operating pressure (DHW) |
0.3 MPa (3 bar) |
| Max incoming mains pressure (to PRV) |
1.6 MPa (16 bar) |
| Min recommended supply pressure / flow |
0.15 MPa (1.5 bar) — 20 litres/min |
| Pressure relief valve |
0.8 MPa (8 bar) |
| T&P relief valve setting |
90°C / 1 MPa (10 bar) |
| Max flow at 3 bar |
76 litres/min |
| Electrical & Connections |
| Immersion heater (backup) |
Single 3 kW @ 240V / 2.8 kW @ 230V (AC only) — Incoloy 825 alloy sheathed |
| DHW connections |
22 mm compression / ¾" BSP male |
| Secondary return connection |
½" BSP female (125i and above) |
| Thermostat setting (factory) |
60°C |
| Compliance & Warranty |
| Diameter (all models) |
579 mm (Ø) |
| Certification |
Kiwa certified |
| Tank guarantee |
30 years (inner tank) · 2 years (components) |
Current Product Codes & Core Specification — All Indirect Variants
| Model |
Product code |
Capacity (L) |
Immersion (kW) |
Coil rating (kW) |
ErP class |
Height (mm) |
| 70i |
95050461 |
70 |
1 × 3 |
20.1 |
B |
802 |
| 125i |
95050463 |
125 |
1 × 3 |
19.5 |
B |
1102 |
| 145i |
95050465 |
145 |
1 × 3 |
20.9 |
B |
1229 |
| 170i |
7817127 |
170 |
1 × 3 |
19.9 |
B |
1384 |
| 210i |
7817128 |
210 |
1 × 3 |
18.4 |
B |
1486 |
| 250i |
7817129 |
250 |
1 × 3 |
19.4 |
C |
1738 |
| 300i |
7817130 |
300 |
1 × 3 |
19.7 |
C |
2053 |
Performance & Weight — All Indirect Variants
| Model |
Storage vol. @ 3 bar (L) |
Coil heat-up @ 15 l/min 80°C (min) |
Recovery 70% draw-off (min) |
Standing heat loss (kWh/24h) |
Weight empty (kg) |
Weight full (kg) |
| 70i |
92 |
17 |
10 |
0.91 |
25 |
125 |
| 125i |
137 |
23 |
15 |
1.05 |
31 |
180 |
| 145i |
155 |
24 |
17 |
1.18 |
35 |
204 |
| 170i |
178 |
22 |
16 |
1.20 |
39 |
233 |
| 210i |
195 |
28 |
19 |
1.42 |
45 |
253 |
| 250i |
233 |
34 |
23 |
1.61 |
50 |
300 |
| 300i |
283 |
39 |
27 |
1.69 |
58 |
358 |
What is the difference between the Megaflo Eco Indirect and the Megaflo Eco Direct?
The Indirect models (70i–300i) are heated primarily by a boiler via an internal coil, with a single 3 kW backup immersion heater. They are the right choice if you have a gas, oil, or heat-pump boiler and want faster recovery times and lower running costs. The Direct models rely exclusively on electric immersion heaters and suit all-electric homes or properties without a boiler.
Has the product code for the 210i changed?
Yes. Heatrae Sadia has updated the 170i, 210i, 250i, and 300i models to a new generation with new order codes. The 210i now carries the code 7817128, replacing the older code 95050469. The 70i, 125i, and 145i codes are unchanged. Always check the code on your confirmation before ordering replacement parts to ensure compatibility with your installed unit.
Is a separate expansion vessel needed for the DHW circuit?
No — the Megaflo Eco Indirect's internal floating-baffle air-gap system accommodates domestic hot water expansion within the cylinder, so no external DHW expansion vessel is required. However, if you are running a sealed primary heating circuit, you must fit a separate primary-circuit expansion vessel governed by your boiler manufacturer's instructions.
What boilers is the Megaflo Eco Indirect compatible with?
The Megaflo Eco Indirect is designed for use with heat-only (regular) boilers and system boilers. It is not suitable for use with solid-fuel boilers or any boiler without effective thermostatic energy-input control, or with gravity-circulation primaries, unless additional safety measures are installed. It is also incompatible with combination (combi) boilers.
Who must install a Megaflo Eco Indirect, and what regulations apply?
Installation must be carried out by a G3 Competent Person (England & Wales), under Building Warrant (Scotland), or to Building Regulation P5 (Northern Ireland). Electrical connections must be made by a qualified electrician to IET Wiring Regulations. The installer must complete the Benchmark commissioning checklist and leave the product guide with the householder.
What is the guarantee on the Megaflo Eco Indirect?
Heatrae Sadia provide a 30-year guarantee on the inner duplex stainless steel tank. All other components — immersion heater, valves, motorised valve, wiring centre — carry a 2-year warranty. Warranty validity requires correct installation, annual servicing, and a completed Benchmark checklist.
