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RM Unvented Cylinder 250ltr Direct Mega Flow Stainless Steel 25 Year Guarantee

In stock
  • Estimated Delivery
  • FREE

4 to 7 Working DaysOrders placed before 1pm are processed the same day, delivery times are between 8am & 6pm Monday to Friday, all deliveries require a signature, for delivery instructions please use the notes section during checkout. Please see below for Items you will also require for this product.

Was £1,254.47 Special Price £706.63 (inc VAT)

✝ Subject to stock availability. UK Mainland only. Delivery fees and times to Northern Ireland, Scottish Highlands & Isles, Isle of Man, Isle of Wight, Isles of Scilly, and the Channel Isles may vary. Deliveries are made during working days only.

More Information
SKU 8717
Manufacturer ID RMCYL250D
Estimate Delivery Time 4 to 7 Working Days
Cylinder Capacity 250 Litres
Cylinder Diameter 545mm
Cylinder Type Unvented
Cylinder Height 1728mm

25 Year Guarantee Unvented CylinderDirect Heated Unvented Cylinder250 Litre Capacity Unvented CylinderUnvented Cylinder

The RM Stelflow Direct cylinder is a mega flow type pressurised stainless steel hot water cylinder. This domestic hot water tank is made in Britain to exacting standards, featuring an efficient immersion element, giving high recovery rates, meaning you can run a bath upstairs and still wash up in warm water downstairs. A Direct cylinder heats water by electricity - ideal for homes without gas or oil-fired central heating. These cylinders come with two immersion heaters, a temperature and pressure relief valve, a 15mm x 22mm tundish, expansion vessel and an expansion vessel hose, meaning your fitter has everything they need to complete your installation. This Unvented hot water tank is Vertical and stands 1728mm high, giving you a capacity of 250 Litres stored hot water.


  • 25 Year vessel guarantee.
  • Cylinder components guaranteed for 2 years.
  • Available in a range of styles sizes 90 to 600 litres.
  • A range of horizontal cased units.
  • Coil in coil high effeciency coil - high recovery rates.
  • External expansion for reliability and flexible siting.
  • Full Kiwa Approval.
Addition Features:

  • Minimum recommended working pressure 1 bar.
  • Maximum working pressure 15 bar.
  • All cylinder connections are 22mm compression.
  • Units tested to 15 bar.
  • Minimum water supply 1.5 bar, 20 litres/min.
  • Primary coil circuit must be pumped.
  • Gravity coils available by special order.
  • Stainless steel stat pocket guaranteed against corrosion.


  • Capacity (L): 250
  • Height (F)(mm): 1728
  • Diameter (mm): 545
  • Cold Inlet (A)(mm): 250
  • Immersion 1 (B)(mm): 242
  • Immersion 2 (C)(mm): 959
  • Sec. Return (D)(mm): 1259
  • T&P Valve (E)(mm): 1516
  • Water Heating System: Direct
  • Vented or Unvented: Unvented
  • Vertical or Horizontal: Vertical

The RM Stelflow has carefully been brought together from quality components and has been designed with performance in mind.

Using our many years of involvement within the hot water industry and out knowledge of bringing unvented cylinders to the market we have created a new stanard in unvented water storage.


RM Cylinders have pushed the boundries even further leaving the competition to catch up once again. Using a state of the art production facility RM Cylinders can produce bespoke Stelflow cylinders, tapping sizes and heights can now be changed to suit your application giving you flexability without compromise.

When altering inlet and outlet connections we can even provide corresponding control kits meaning you still end up with a complete packaged solution, leaving nothing to chance.



Technical Information

Fitting Instructions

Here at TradePlumbing.co.uk we have voluntarily extended our returns period to 90 days, as we understand that sometimes there may be the odd item left over from a project or you may have an unexpected delay to a project meaning that you need the added peace of mind when ordering products in case a return is necessary.

We truly believe in being able to offer customers a flexible service and this extended period allows us to go that little extra to help you when in need, as long as goods are returned in the same condition as received we are happy to help.

To return any time initially please email your request to our Customer Support team at customerservice@tradeplumbing.co.uk along with your TP - Order Reference, please allow at least 1 working day for response and we will take it from there.

To View our complete Return Policy Click on Return and Refunds