condensing combi boiler

Storage Combi Boiler

Storage Combi Boiler?  Isn’t a combi boiler supposed to not need storage tanks or cylinders?  Isn’t that the whole point of a “combination” boiler?  Calm down.  You are right.  However, if you have a larger family home with more than 2 bathrooms, or need efficient heating combined with larger volumes of hot water, this is a great idea to simplify installation and save space.


If you’ve recently suffered a boiler breakdown when your 20 year old boiler suddenly ceased, and are new to the combi boiler world, we don’t blame you for being a little confused.  Which is why we’ve created articles like What is a Combi boiler and How a Combi Boiler Works on our website earlier.  If you can’t be bothered reading those full articles, let us explain to you why combi boilers are so popular in the UK at the moment:

  • Combi boilers are cheaper than Open Vent or System Boilers.
  • Great for saving space: no need for attic tanks or hot water cylinders.
  • Easy to install and set up for the installer.
  • Compact Size; some models can fit inside a kitchen cabinet.
  • Combi boilers may be more energy efficient.

What is a Storage Combi Boiler?

In simple terms, a storage combi boiler has a hot water cylinder housed within the boiler unit itself.  Storage combi boilers used to be floor standing larger boilers, but lately some companies have pioneered wall-mounted, compact storage combi boilers.  Smaller sized storage combi boilers are well suited to larger apartments or flats with a family where there is no space for Open Vent or System Boilers, but the residents have high hot water demands.  For ex. if everyone in your home has to get ready and leave the house at around the same time, whether they’re going to work or to school, it helps to have a boiler capable enough to deliver hot water for bathrooms and sinks and washbasins simultaneously.

The cross section diagram of the Viessmann Vitodens 111-W in the banner below shows a 46 litre thermal store inside.

Best Storage Combi Boilers in the UK in 2018

1. Viessmann 111-W Storage Combination Boiler

46 Litre Integrated Thermal Store

storage combi boiler, viessmann 111-w

This is a high performance storage combi boiler, perfect for a larger flat or a family home with high demand for hot water on a daily basis.  With its CLS technology (Cylinder Loading System) and 46 litre integrated stainless steel storage tank, this storage combi boiler produces 18 litres of hot water per minute, and can fill a standard bath in 8 minutes, while simultaneously also supplying a sink or washbasin.  All Viessmann boilers modulate energy usage between 5kw and 30kw when not in use, so energy efficiency is always high on their agenda, saving you money on your energy bills.  The advanced sensor technology allows constant output temperatures to be maintained even under high demand.  This storage combi boiler can also be controlled with a tado° thermostat and smartphone app.  Some more of its features:

  • Measurements (H x W x D): 900mm x 600mm x 480mm
  • Cylinder loading system (CLS) and integrated stainless steel storage tank.
  • User friendly control via backlit LCD touchscreen.
  • High hot water capability of >18 l/min.
  • Available in outputs from 4.7 to 35.0 kW.
  • Hot water performance equivalent to a separate installed 150L cylinder.
  • User-friendly dials for rapid adjustment of heating and hot water.
  • Energy efficiency class: A.
  • Optional wireless remote control available.
  • Optional solar thermal back up.
  • Up to 10 year extended warranty available with Boilerhut.

Price (Boiler-Only, NOT including installation and extras):

26kW – £1,516.17 inc. VAT

35kW – £1,630.02 inc. VAT

If you want to find out how much a 111-W storage combi boiler installation will cost, please get an online boiler quote by entering your postcode below and hitting the green button.


2. Vaillant ecoTEC plus Combination Store

15 Litre “actoSTOR” Hot Water Cylinder

storage combi boiler, Vaillant ecoTEC plus combination store

This storage combi boiler from Vaillant delivers great performance at lower energy consumption.  It produces 20 litres per minute of hot water when needed, and then modulates to using only 16% power, saving you fuel and money.

  • ErP A rated for both hot water and heating efficiency.
  • Dimensions in mm: H 720 x W 440 x D 600
  • Integrated hot water storage device at the back of the boiler.
  • Hot water within 5 seconds. A wide range of heating control options.
  • 5-year guarantee as standard, with 7 to 10 years available when you book a Vaillant Advance installer

Vaillant have gone a different route compared to Viessmann for their storage combi boiler.  When we look at measurements; H (Height) x W (Width) x D (Depth) in mm (millimeters):

Viessmann 111-W: 900 x 600 x 480

Vaillant ecoTEC plus combination store: 720 x 440 x 600

So, the Vaillant is a much thicker boiler compared to the wider Viessmann.  The good thing about today’s boiler market in the UK is you have abundance of choices, and you can go in any direction you want.

Price (Boiler-Only, NOT including installation and extras):  38kW: £1,530.98 inc VAT

3. Glow Worm Energy 35 Store Combi Boiler

Two 21 Litre Integrated Tanks Totaling 42 Litres Thermal Storage

storage combi boiler, glow worm

The Energy 35 Store is a wall mounted storage combi boiler.  Glow Worm may not be a premium brand like Viessmann, or Vaillant for that matter, (psst, even though they are owned by Vaillant).  Glow Worm have gone the Vaillant route (surprise, surprise) by making their storage combi boiler thicker rather than wider, and it’s also got two 21 litre insulated tanks housed inside the unit, providing a re-heat time of less than 5 minutes.

Features & Benefits:

  • Two highly insulated 21 litre integrated tanks.
  • DHW flow rate of 19.7 litres/minute.
  • High efficiency modulating Grundfos pump – Lower running costs as pump adapts to actual heating and hot water demand.
  • LPG compatible – Providing greater siting options for off-grid properties.
  • 7 year guarantee.

Price (Boiler-Only, NOT including installation and extras):  35kW: £1,547.64 Incl. Tax

Larger Storage Combi Boiler – For Larger Homes


Viessmann Vitodens 222-F

Floorstanding Gas Condensing Storage Combi Boiler – 100 Litres Integrated Tank

Integral enamelled loading cylinder or DHW cylinder with internal indirect coil.

storage combi boiler, viessmann vitodens 222-F

  • Colour touch-screen with plain text and graphic display, commissioning assistant and displays for energy consumption.
  • Alternative operation from a mobile end device.
  • Connect to your home or local wireless network for Web enabled capability for operation and service via Viessmann apps.
  • Modulating Matrix cylinder burner.
  • Inox-Radial Stainless Steel Heat Exchanger.  (10 year warranty)
  • Cylinder size 100 litres with thermal insulation.
  • Dynamic burner cycling reduces the number of burner starts over the year by a third.
  • Power saving, high efficiency pump.
  • Wide modulation 1:19 (35kW).
  • No LPG conversion kit needed.
  • Includes unvented safety kit and DHW expansion vessel.
  • Flow rate 23 l/min.
  • Constant temperature mode.
  • Easy installation.
  • Automatic flue gas route adaption.
  • Fully assembled and wired.
  • Free Delivery

Viessmann Vitodens 242-F

Floorstanding Gas Condensing Storage Combi Boiler – 170 Litres Integrated Tank

State of the art heating with condensing and solar technology in detached houses.  This storage combined floor standing condensing boiler is designed specifically for direct connection to a solar thermal system.  Incorporating three technologies in one; gas condensing boiler, DHW cylinder and solar control package, for where space is at a premium.

storage combi boiler, Viessmann Vitodens 242-F

  • Gas condensing storage combination boiler with integral solar cylinder
  • Colour touch-screen with plain text and graphic display, commissioning assistant and displays for energy consumption, as well as alternative operation from a mobile end device
  • Inox-Radial stainless steel heat exchanger. (10 year warranty)
  • Can reduce your hot water energy usage by 60%
  • Power saving, high efficiency circulation pumps for heating circuit and solar circuit
  • Unvented cylinder with 170 litre capacity and solar indirect coil.
  • Up to 19 Litres per minute flow rate.
  • DHW secondary circulation pump can be integrated inside the appliance (see accessories).
  • Matrix cylinder burner with Lambda Pro Control Plus combustion controller for permanently high efficiency and clean combustion.
  • Modulation range up to 1:10.
  • For natural gas and LPG.
  • Automatic flue gas adaption.
  • Factory fitted cylinder solar pump.
  • Unvented safety kit and DHW expansion vessel included.
  • Solar ready, solar pump and control built in.

large storage combi boiler


These larger storage combi boilers are top of the line.  While they may be expensive compared to a system boiler, what you get are two of the most technologically advanced, highest efficiency (close to 98% and above), highest quality premium boilers in the UK market.  Space saving is one of the most important requirements of a storage combi boiler, which is why using CLS (Cylinder Loading System) technology, with integral loading cylinders with 100-170 litres capacity, a storage combi boiler like these two offer the domestic hot water convenience of an unvented cylinder with twice the capacity (200 to 300 litres).

Smart Controls with Colour Touchscreen and Precise Indicators

storage combi boiler smart controls

The Vitotronic 200 is a user friendly control until that both you and the installers can benefit equally from.  It’s got a bright 5 inch colour touchscreen that is intuitive, easy to understand and has a logical menu interface.  The wizard simplifies commissioning of the boilers after installation.  It saves time for the installers setting up a storage combi boiler.

storage combi boiler consumption indicator

The energy cockpit indicates gas and electricity consumption of the heat source directly on the display of the storage combi boiler.  It also provides information on solar yield for an energy statement, on the cylinder loading status and temperature curve as well as temperature stratification in the cylinder for the storage combi boiler.

What is CLS (Cylinder Loading System) Technology?

Most unvented cylinders use a heating coil to heat up the cylinder.  The CLS technology replaces the coil with a plate heat exchanger.  A DHW pump circulates the cold water from the bottom of the cylinder, through the plate heat exchanger and puts the hot water back to the top of the cylinder.

Why Viessmann and Boilerhut?

Inox-Radial Stainless Steel Heat Exchanger

storage combi boiler, viessmann heat exchanger

This patented heat exchanger is at the heart of every Viessmann boiler.  It is one of the most durable and efficient and highest quality internal components found inside any domestic boiler in the UK market.  And because Viessmann manufacture it in-house, they are able to compete on price.

98% Energy Efficiency and Above!

The Vitodens 200 range, which includes the 200-W, 222-F and 242-F, operate at a mind boggling 98% efficiency, which is the highest by far in the UK market for any storage combi boiler.  All the boiler offerings from rival manufacturers are between 89% and 92% efficiency.  The Viessmann 200-W may even be above 100% efficiency in some cases with the help of weather compensation and smart controls, where it’s recycling outside air and is always condensing.  98% efficiency means gigantic savings on energy bills, because you’re wasting only 2% of the fuel  going into your storage combi boiler.  It sounds even more impressive considering your older non-condensing boiler (older than 12 years) may be between 50% to 70% efficient depending on wear and tear and corrosion on internal components.

High energy efficiency not only helps you save money on your energy bills (between £300 to £600 per annum), gives more consistent heating and water, but also leaves a cleaner, greener planet behind for future generations by reducing your carbon footprint.

Amazing Reviews

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Read Boilerhut Reviews

Read our reviews by clicking the link above and see exactly why our customers love us.  To get the same high quality installation, free advice on heating, and excellent after-sales customer service, start by getting an online boiler quote.  Simply enter your postcode below and hit the green button.


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