Underfloor Heating with a Combi Boiler: Our Guide

Underfloor heating is a great way to keep your home warm throughout the winter, and many homeowners are opting for this kind of heating system during their home renovations. 

However, many homeowners also question whether underfloor heating will work with their current combi boiler. Thankfully, it works well and in this guide, we’ll explain how. 

Can you run underfloor heating off a combi boiler?

Yes, you can run underfloor heating off a combi boiler. If you haven’t already, you may need a two-port valve installed to ensure your combi boiler can run the central heating and underfloor heating separately. 

Without the valve, your boiler may overheat when running both systems at the same time. 

What type of boiler is best for underfloor heating?

A condensing boiler is usually the best for underfloor heating as it is great at recycling any excess heat. This lends itself better to underfloor heating than other traditional boilers.

However, any modern boiler would be highly effective at making underfloor heating run efficiently. Every house has its own needs, meaning each one may need a different type of boiler for its underfloor heating.

What temperature should a combi boiler be for underfloor heating?

In general, underfloor heating needs a maximum flow temperature of 55°C, with temperatures sitting in between 40 – 50°C being the most common. 

Our team will help to determine the best temperature for your underfloor heating by assessing your home and heating needs. 

Pros and cons of underfloor heating with a combi boiler

Before you decide whether underfloor heating with a combi boiler is right for you, it’s worth establishing the pros and cons. 

Pros of underfloor heating with a combi boiler:

• Keeping a combi boiler will save you money up front since you don’t need to have a heat pump installed 
• Great for compact spaces that don’t have much room for radiators 
• Provides consistent and comfortable heating
• Lowers your energy bills 

Cons of underfloor heating with a combi boiler:

• Underfloor heating needs to operate at a lower running temperature 
• Upfront installation costs can be pricey
• You may need to have a two-port valve installed on your boiler, which can cost you in additional work

Will you need to upgrade your combi boiler to have underfloor heating?

When you inquire about installing underfloor heating, your heating installer will discuss your current boiler with you. Your current boiler may be sufficient, but this will depend on the area you want covered. 

In some cases, your current boiler may not have a high enough power output. If this is the case, then it is likely that your combi boiler will need to be upgraded to one of a higher output. 

Are there risks with using a combi boiler for underfloor heating?

If your heating system is not adapted appropriately, there are some risks that could occur. 

Combi boilers are high temperature boilers and will likely need a blending valve to be fitted to the underfloor heating manifold. If this isn’t fitted, there is a risk of the pipes cracking and becoming damaged, as well as the floor overheating.