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RM Stelflow Unvented Indirect Slimline Twin Coil

From £1,175.80 inc. VAT

Space Saving Gas Boiler & Solar Heated Hot Water Storage

  • 25-year guarantee on the vessel
  • 2 years guarantee on components
  • 50mm High-density insulation
  • Full unvented kit supplied, including remote expansion vessel
  • Treated to protect against corrosion


SKU: Stelflow Unvented Indirect Slimline Twin Coil Categories: ,


RM Stelflow Unvented Indirect Slimline Twin Coil Cylinder

The RM Stelflow Slimline Twin Coil unit, measuring just 475mm in diameter, has been developed to give homeowners with gas boilers the opportunity to capitalise on Solar Thermal technologies. In the age of growing fuel bills, the RM Stainless Twin Coil presents a real option to help save homeowners money and reduce their carbon footprint, thus safeguarding the future of the planet. Built to RM’s usual exacting standards the Slimline Solar Twin Coil is a perfect compliment to your gas boiler and solar needs.

RM Stelflow hot water cylinders have been constructed using high-quality components. A manufacturer guarantee of 25-year guarantee on the vessel and 2 years on parts, will give you a well-deserved peace of mind.


  • Working pressures Min: 1bar, Max: 3bar
  • 22mm compression fittings throughout
  • Minimum water supply 1.5bar, 20 Litres/min
  • 50mm insulation
  • New flat base for stability
  • 3kW Incoloy Immersion heater as standard
  • Clearly labelled unit connections
  • Butt welding for long life
  • 25-year guarantee on the vessel, 2 years on parts
  • High-efficiency Heat Exchanger


Kit Included



Technical Specification


Product IH-RM055 IH-RM056 IH-RM057
Capacity 150L 180L 210L
Height (mm) 1430 1710 1920
Diameter (mm) 475 475 475
Weight Empty (kg) 49 55 58
Weight Full (kg) 194 230 264
Indirect Reheat (mins) 18 22 24
Immersion Reheat (mins) 59 81 95
Heat Exchanger (kW) 16.2 18.4 21
Solar Volume (L) 77 95 101
Standing Loss (kWh/day) 1.6 1.9 2.16
ErP Band C C C

Tapping Heights


Product IH-RM055 IH-RM056 IH-RM057
Cold Inlet 162 162 162
Bottom Coil 269 269 344
Stat Pocket 324 324 399
Top Coil 621 665 759
Immersion 672 704 809
Stat Pocket 676 708 813
Secondary Return 1552
T&P Valve 1262 1527 1739


Additional information


150 Litre, 180 Litre, 210 Litre


RM Cylinders




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