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What Is The Best Combi Boiler Flow Rate

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Let's take a look at some of the best

Whilst having optimum hot water flow rate from your combi boiler adds great benefits, such as increased (thermostatic or mixer only) shower performance, decreased wait times to fill your bath tub. We always recommend water flow rates to be tested first with a Weir Water Flow Cup to ensure you have sufficient flow rate incoming from your mains supply. If you have poor incoming flow rate from the supply, unfortunately, you will never reap the DHW benefits from a higher performing combi boiler. The boiler is unable to deliver flow rates specified by the manufacturer, if there is insufficient flow rate from the main supply. 

Always ask your installer to test this prior to choosing your new combi boiler.

That being said, we took a closer look into 3 of the UK’s leading boiler manufacturers to see which of their combi boiler range had the best combi boiler flow rate.

1. Vaillant ecoTEC Plus Combination Store 938 - 20.1 (l/min) DHW flow rate

The Vaillant ecoTEC Plus Combination Store 938 is designed with larger homes in mind and will deliver a whopping 20.1 (l/min).

If you have a large home with high hot water demands, but you’d prefer not to install a hot-water cylinder or cold-water tank, the ecoTEC plus 38kW combination store is the boiler solution for you.

Bare in mind though, although this particular model is a wall-hung boiler, because it’s a combination store, it contains a pressurised storage tank inside, which does increase the depth of the boiler to 440mm. So if you are planning on installing your new boiler inside your kitchen cupboard or any other tight space. This boiler may not be for you.



2. Ideal Vogue MAX C40 - 16.4 (l/min) DHW flow rate


The Ideal Vogue MAX C40 will provide you with an excellent flow rate of 16.4 (l/min) which is more than enough to provide a larger home with excellent hot water performance.

If you don’t have the room for the Vaillant, then we feel the Ideal is an excellent choice for your new combi boiler. Not only is the Ideal compact and delivers exceptional DHW performance, Ideal are offering a jaw dropping 12 Year Parts & Labour Warranty across the Vogue MAX range.

We have installed 100’s of the Ideal Vogue combi’s and we can assure you, you will not be disappointed.



3. Worcester Bosch 42CDi Classic - 15 (l/min) DHW flow rate


The Worcester Bosch 42CDi Classic is another fantastic boiler that delivers great performance for hot water. With a flow rate of 15 (l/min), this boiler is powerful enough to cope in larger homes with high hot water demands.

Worcester Boilers are industry renowned for their superior quality, and have been awarded Which? Best Buy Award for the seventh consecutive year and receive a high Trustpilot rating of 9.1 from over 7,000 reviews.



Other combi boilers worth a mention

Ideal Logic MAX C35

The Logic C35 will provide 14.5 DHW flow rate I/min. 35°C rise

The Logic MAX boilers are the flagship range and come complete with a 10-year warranty for total peace of mind. The entire range received the Queen’s Award in 2013 and the Good Housekeeping Reader Recommended status in 2013 and 2017.

Our thoughts

We have installed many of the boilers we have listed, and we can tell you first hand, you will not be disappointed with any of them. 

We have found all to be superior quality, robust, reliable and deliver exceptional performance on both hot water and central heating. They’re also all ‘A’ rated High Efficiency Condensing Boilers so hopefully you could save on your energy bills too, if you’ve considered the costs of your new combi boiler, then don’t hesitate to contact us for a free quote..