Indirect Unvented

Available in six sizes from 120 to 300 litres to suit the vast majority of domestic installations, our Indirect models are the core of our cylinder range. Thanks to our large surface area, high performance heat exchanger coils the Indirect models boast impressive heat up times - the 180 litre model taking just 25 minutes to reach 60ºC from cold.

Our Indirect models, like the rest of the range, are designed to be fed directly from the mains water supply via the inlet group supplied, which is capable of receiving incoming water at pressures up to a maximum of 12 bar.

In order to achieve the best performance from our unvented cylinders the mains water supply must be capable of supplying a flow rate of at least 20 litres per minute with a dynamic pressure of at least 1.5 bar. Should the supply performance be less than this the hot water flow rates will be reduced, however a Warmflow unvented cylinder may still be installed and the benefits of a fast heat up time and minimal heat losses can still be enjoyed.

Purchase Info
Warmflow Hot Water Cylinders, Indirect Direct Unvented hot water cylinder UK, Ireland, Northern Ireland Product

Key features

  • 1 of the top 3 performing cylinders in the UK
  • Efficient coil-in-coil design
  • Duplex Stainless Steel
  • Part L Approved
  • Seamless Welding
  • WRAS Approved
  • KIWA Approved
  • Recycled materials used in construction
  • Honeywell Diverter Valve

Good to know

Because we use a thicker layer of high quality polyurethane insulation our cylinder range has amongst the lowest fully certified heat loss levels currently on the market, saving precious fuel and reducing carbon dioxide emissions.

Our insulation is also CFC/HCFC-free, has a zero Ozone Depletion Potential (ODP) and a Global Warming Potential of only 2. Due to the large surface areas of our coil-in-coil heat exchangers it is also possible for a condensing boiler to work in condensing mode for longer, and cycle less frequently when heating the hot water, thereby helping to further reduce fuel use and emissions.

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Cylinder Stats

  • IN120UV (120l)
    IN150UV (150l)
    IN180UV (180l)
    IN210UV (210l)
    IN250UV (250l)
    IN300UV (300l)
  • Overall height (mm)
    952
    1142
    1327
    1517
    1767
    2077
  • Secondary return connection (mm)
    n/a
    n/a
    n/a
    1223
    1473
    1783
  • Primary coil upper connection (mm)
    462
    462
    532
    532
    532
    532
  • Cold inlet connection (mm)
    412
    412
    482
    482
    482
    482
  • Primary coil lower connection (mm)
    362
    362
    432
    432
    432
    432
  • Cold water capacity (litres)
    115
    146
    175
    205
    245
    295
  • Weight when full (kg)
    142
    175
    207
    243
    286
    340
  • Standing heat loss (kWh/24h)
    1.16
    1.36
    1.55
    1.74
    1.99
    2.32
  • Primary coil rating @ 15L/min (kW)
    17.5
    17.2
    21.3
    19.9
    22.2
    20.4
  • Heat up time (EN12897) (mins)
    13
    17
    17
    22
    24
    29
  • ErP Rating boiler icon

View our Cylinders range

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Thanks to our large surface area and high performance heat exchanger coils, the indirect models.

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The electrically heated Direct cylinders are designed for instances where the use of fossil fuels is impractical / unavailable.

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