Specifications & Sizing

The following POWERflow sizing guide is designed to act as a quick reference. However we would recommend that you contact our technical sales team who can discuss your project in more detail and provide the right size and specification for your requirements. 

POWERflow Sizing Guide
1 Bedroom + Bath/Shower75/120120/150
2 Bedroom + Bath/Shower150180
3 Bedroom + 2 Baths/Shower180210
4 Bedroom + 2 Baths/Shower210/250250/300

Larger Properties


If you are planning on incorporating solar energy, we would normally recommend you step up to the next size, however please contact our technical sales team on 01592 611123 to discuss your requirements.

  75 litre120 litre150 litre180 litre210 litre250 litre300 litre
Energy Efficiency ClassIndirectBBBCCCC
Energy Efficiency ClassDirectCCCCCCC
Heat LossWatts41495259657280
Overall Diametermm450550550550550600600
Ind. Weight (empty)kg26374455617086
Ind. Weight (full)kg101157194235271320386
Pressure Regulatorbar2.
Expansion Vessellitres8121218182424
Primary CoilkW12192428333947
Heat Up Time (indirect only)min20202020202020
  1. Isolating Valve
  2. Pressure Reducing Valve
  3. Balanced Cold Outlet
  4. Check Valve
  5. Cold Feed
  6. Immersion Heater
  7. Immersion Heater (only standard on 150 litre Direct upward)
  8. Expansion Relief Valve
  9. Pressure & Temperature Relief Valve
  10. 15x22mm Visible Discharge Tundish
  11. To waste in 22mm
  12. Hot Draw Off
  13. Expansion Vessel
  14. Drain Cock

POWERflow Indirect Hot Water Cylinder

  1. Primary Flow
  2. Primary Return
  3. Thermostat c/w Non Self Resetting Thermal Cut-out
  4. 2 Port Motorised Zone Valve

Call us now on 01592 611123 or contact us now.

  • Specially manufactured cylinders to fit awkward spaces
  • Units suitable for Solar input
  • Cased White Goods finish
  • Super Fast Recovery Finned Coils
  • Larger Diameter Valves
  • 28mm Coil Connections (for Gravity)
  • Secondary Return

Call our Technical Helpline (01592 611123) with any queries on the POWERflow mains pressure cylinder range. We are happy to help size units, detail specifications and answer any questions you have on the units.

POWERflow Unvented mains pressure cylinders from McDonald Water Storage. 


CPD Enquiry

Enter your details below...

Register Your Product

Please enter your details below to register your product.

Product Details
Homeowner Details
Installer Details
For more information on the warranty details, click here

Installation Service Quote

Please enter your details below to request a quotation for our installation service.

Technical Assistance Form

If you require Technical Assistance from our online cylinder site, please fill in the form below.

Product Request Form

If you cannot find a product or part in our store you can request it below and we will try to source it direct for you.

Product Enquiry

Enter your details below...

Join The Club!

Claim 10% off
mcdonald water storage
spare parts

To celebrate the launch of our online store with genuine McDonald Water Storage spares and free next day delivery (orders over £50), we want you to enjoy a 10% discount on your first order.
To claim your offer simply enter your email address below

By Entering your email address and pressing send, you agree to be happy to receive offers and updates from McDonald Water Storage.