The Megaflo Eco Slimline Indirect is a compact-diameter version of the Megaflo Eco cylinder, designed for homes where floor space for a hot water storage cylinder is limited — narrow airing cupboards, flats, or properties with restricted plant-room dimensions. At just 491 mm in diameter (vs 579 mm on the standard Megaflo Eco), the Slimline Indirect trades a taller footprint for a significantly narrower one, without compromising on the internal expansion system, duplex stainless steel construction, or 30-year tank warranty that define the wider Megaflo Eco range. Boiler-fed via an internal coil with a single 3 kW backup immersion, it's available in five sizes from 100 to 200 litres.
491 mm
Diameter (all models)
Safety / Regulatory — G3 Competent Person Required
Slimline Indirect cylinders must be installed and commissioned by a G3 accredited competent person. All electrical connections must be made by a qualified electrician to current IET Wiring Regulations, with the Benchmark commissioning checklist completed at handover.
Info — Why choose Slimline over the standard Megaflo Eco?
The Slimline's 491 mm diameter is 88 mm narrower than the standard Megaflo Eco's 579 mm — a meaningful difference in a tight airing cupboard or a flat with restricted floor space. The trade-off is height: for a given capacity, the Slimline is taller than the standard-diameter equivalent, so ceiling height needs checking before specifying.
Compatibility — Boiler-fed with electric backup
Slimline Indirect models are heated primarily by a gas, oil, or heat-pump boiler via the internal coil, with a single 3 kW backup immersion for off-peak charging or when the boiler is unavailable. If you have no boiler and want the cylinder heated purely by immersion, the Slimline Direct range is the correct choice instead. Neither Slimline range includes a secondary return connection as standard.
KEY FEATURES
Narrow 491 mm Diameter — Fits Restricted Spaces
At 491 mm diameter, the Slimline Indirect is specifically sized for homes where floor space for a hot water storage cylinder is limited — narrow airing cupboards, flats, or properties with restricted plant-room dimensions where the standard 579 mm Megaflo Eco body won't fit.
Fast Coil Heat-Up
Despite the compact diameter, the internal coil achieves a full heat-up in 19-35 minutes depending on cylinder size, with a consistent 16.9 kW coil rating across the range — fast recovery even in the narrower body.
Internal Expansion System
Like the wider Megaflo Eco range, the Slimline Indirect uses an internal expansion system to accommodate thermal expansion within the cylinder body — reducing installation time and the space needed for an external expansion vessel, which matters even more in an already-tight installation location.
Duplex Stainless Steel — 30-Year Warranty
Every Slimline Indirect is fabricated from high-grade duplex stainless steel for excellent corrosion resistance, with a 30-year warranty on the inner stainless-steel tank matching the rest of the Megaflo Eco range. KIWA approved, complying with Water Regulation 4 and Building Regulations Part G3.
Consistent Insulation Performance
Despite the narrower body, standing heat loss figures remain competitive across the range — from 1.13 kWh/24h (100L) up to 1.88 kWh/24h (200L) — thanks to the polyurethane foam insulation applied around the taller, narrower vessel shape.
Standard 22 mm Connections
All connections accept 22 mm outside-diameter pipe (compression nuts and olives supplied), with a ¾" BSP male parallel thread to accept standard ¾" BSP female fittings — no special fittings required, keeping the Slimline installer-friendly despite the space-saving body.
TECHNICAL SPECIFICATIONS — SLIMLINE INDIRECT
Parameter
100i
125i
150i
170i
200i
Product code
7034087
7034088
7034089
7034090
7034091
Volume (L)
100
126
146
174
195
Height (mm)
1194
1440
1622
1883
2079
Diameter (mm)
491
491
491
491
491
Empty weight (kg)
31
36
40
45
48
Full weight (kg)
131
162
186
219
243
Standing heat loss (kWh/24h)
1.13
1.38
1.46
1.72
1.88
Coil surface area (m²)
0.78
0.78
0.78
0.78
0.78
Coil heat-up time (min)
19
26
27
31
35
Coil rating (kW)
16.9
16.9
16.9
16.9
16.9
Coil pressure drop (bar)
0.02
0.02
0.02
0.02
0.02
Backup immersion
1 x 3 kW
1 x 3 kW
1 x 3 kW
1 x 3 kW
1 x 3 kW
Secondary return
No
No
No
No
No
All connections accept 22mm outside-diameter pipe (compression nuts and olives supplied); thread rate ¾" BSP male parallel to accept standard ¾" BSP female fittings if required.
FREQUENTLY ASKED QUESTIONS
How much narrower is the Slimline than the standard Megaflo Eco?
The Slimline is 491 mm in diameter across every model, compared to 579 mm on the standard Megaflo Eco Indirect range — an 88 mm reduction. This comes at the cost of extra height: for example, the 170i Slimline is 1883 mm tall vs 1384 mm for the standard 170i. Always check both diameter and height clearance before specifying.
Does the Slimline Indirect include a secondary return connection?
No — the Slimline Indirect range does not include a secondary return connection as standard, across any capacity. If a secondary return circuit is required, please contact us before ordering to discuss options.
Which Slimline Indirect model should I choose for my property?
Size (100-200L) should be matched to occupancy and hot water demand in the usual way — smaller flats and 1-2 bedroom properties typically suit the 100-150L models, with 170-200L for larger households where floor space remains restricted. Slimline Indirect is the right choice where a gas, oil, or heat-pump boiler is available to provide the primary heat source; if no boiler is present, see the Slimline Direct range instead.
What warranty does the Slimline Indirect carry?
Heatrae Sadia provide a 30-year warranty on the inner stainless-steel tank, matching the standard Megaflo Eco. All other components carry a standard component warranty. Warranty validity requires correct G3 installation, annual servicing, and a completed Benchmark commissioning checklist.
