SOLFEX Unvented Indirect Solar Cylinders

Last Updated: March 16, 2017 12:41

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Product Details

SOLFEX's unvented cylinders were specifically designed with solar applications in mind, therefore providing an efficient way of providing domestic hot water. Each model features a dedicated high performance solar coil, transferring the maximum amount of heat from the solar circuit to the stored water.

The indirect cylinders are heated by a conventional boiler (either gas or oil) through a second high performance coil.

Features & Benefits

Duplex Stainless Steel

Using the latest high specification Duplex stainless steel to resist all forms of corrosion including crevice and stress whilst its high mechanical strength gives it durability.

The very latest automated welding procedures along with full post weld treatments guarantee welds that are as strong as the metal.

All cylinders are factory pressure tested to a full 12 bar which is four times the normal working pressure.

Corrugated Stainless Steel Coil

The high heat transfer corrugated tube heat exchanger to gives a 20% faster recovery than plain tube heat exchangers, it is also lighter & stronger than plain tube making the storage cylinder the lightest and easiest to handle on site.

Maximum Capacity

An inbuilt diffuser reduces turbulence when cold water enters the storage by baffling the flow, the end result is that the hot water output is equal to the capacity, a 180 litre cylinder will produce 180 litres of hot water!

Heat Loss

Manufactured using the latest HCFC free Enviro-foam insulation, tests show that 50mm of Enviro-foam injected into the case and covering both domes achieves astonishingly low levels of heat loss which ensures it fully complies with the 2010 Part L requirements for both new build and replacement cylinders.

Quality Standard

All SOLFEX unvented stainless cylinders are manufactured in accordance with BS EN 12897 the specification for unvented water storage vessels. The cylinders have been tested by Kiwa which is a member of the European Organisation for Technical Approvals and comply with current UK Building Regulations G3 and Water Regulations, in performance it complies with the requirements of BS 6700 and meets the NHBC criteria for domestic properties.

Cylinders are supplied with:

  • Immersion heater (s)

  • Wiring centre (indirect)

  • Inlet control set

  • Expansion vessel kit

  • Temperature and pressure relief valve

  • Control thermostat and drain valve

  • 2 port zone valve (indirect)

  • Dual thermostat (indirect)

  • Tundish

  • Installation manual & benchmark log book

Technical Specification

Height (mm)12951483173320202040
Diameter (mm)550550550550630
Weight empty (kg)3030404659
Weight full (kg)210245290346459
Capacity (l)180210250300400
Pressure regulator (bar)33333
Expansion vessel size (l)182424352 x 24
kW rating of primary coil18.018.519.020.522.0
Recovery time after 70% draw off (min)1616192024
Standing losses (kWhr/24hr)1.401.601.751.933.33
Surface area of solar coil (m²)0.6800.6800.9700.9701.270
Dedicated solar volume (l)96101107125165

Model Selection Guide

Maximum hot water demandMaximum solar panel area (m²)BedroomsModel
1 bathroom2.81-3SOL180i
1 bathroom & separate shower room3.61-3SOL210i
1 bathroom & 2 separate shower rooms4.82-4SOL250i
2 bathrooms & separate shower room5.03-4SOL300i
2 bathrooms & 2 separate shower rooms6.64-5SOL400i


  1. Recovery time is based on primary coil/immersion heater duty (ie. assumes the boiler outputt is adequate)
  2. All connections are supplied with compression fittings for direct connection to copper pipework
  3. When selecting a solar model, it is important to check the dedicated solar volume is suitable for either the total floor area of the dwelling or the total net area of the solar panel to ensure compliance with Building Regulations
  4. Maximum solar panel area is calculated based on 25l/m² of net solar panel area

Specification & Product Codes



939984 - SOLFEX 180l Cased Indirect Solar Unvented Cylinder

163712 - SOLFEX 210l Cased Indirect Solar Unvented Cylinder

745924 - SOLFEX 250l Cased Indirect Solar Unvented Cylinder

745932 - SOLFEX 300l Cased Indirect Solar Unvented Cylinder

745946 - SOLFEX 400l Cased Indirect Solar Unvented Cylinder