Underfloor Heating vs Radiators

Even when BTL Property are working on the smallest of refurbishment jobs there is always the requirement to consider how the client would like to heat the newly refurbished or constructed space. Now there are many options available to us these days but for most of our clients, the choice comes down to whether to go for the trusty radiator, underfloor heating or a combination of the two.

So in this blog article let’s try and work out the pros and cons of these two systems.

Underfloor heating is a hugely popular way of heating the home that gained popularity with self-builders and eco-homes.

Underfloor heating is split into 2 types: wet and electric. Wet underfloor heating works by pumping warm water that is heated by the boiler or another heat source around plastic pipe loops that are often laid within a screed below the finished floor whereas electric underfloor heating uses thin heating cables much like an electric blanket that are laid again under the finished floor. Electric underfloor heating is ideal in small areas like bathrooms as it is cheaper to install but has higher running costs so we will focus on the wet underfloor heating option in this discussion as it is what we recommend for kitchens and basements.

Wet underfloor heating floor build-up shown with a timber floor finish

Wet underfloor heating floor build-up shown with a timber floor finish

To make a decision on which option to take it is probably wise to understand the fundamental difference between radiators and wet underfloor heating.

Whereas radiators heat the air through convection by drawing cool air onto the bottom of the radiator and warming it as it passes through and over the radiator, underfloor heating produces radiant heat that warms the fabric of the house from the floor up and makes you feel warm by turning the entire floor into a large radiator. Radiators require water to be pumped through them at around 65-80C and even then, because of the convection currents they create, you can end up with a warm room but cold tiled floor. You even hear of people who sleep near radiators having to have a window open to encourage ventilation in the winter months as the radiators are over-heating the space. Alternatively the water running through an underfloor heating system is set at a much lower temperature of around 45C and slowly heats the entire floor area thus eliminating cold spots and leads to an even and more comfortable heat.

Convection of radiators vs radiant heat from underfloor heating

Convection of radiators vs radiant heat from underfloor heating

One drawback of wet underfloor heating is that it should be run for extended periods and manufacturers often suggest it is run 24/7 in the winter months for optimum performance. This is because underfloor heating is less responsive at providing heat and works best at a constant lower temperature. The simple answer to this is to programme your heating correctly and follow the guidance so that you are not returning from work to a cold house and then unhappy with a slow heating response from the underfloor system. One might therefore conclude that this means higher running costs than radiators as the boiler is working more often but because the water is running at a significantly lower temperature in the underfloor heating pipes it works out as more efficient when used across an entire basement and ground floor for example.

The floor finish of each room is key when considering underfloor heating. We have already established that underfloor heating works by radiating heat through the floor so the material finish matters enormously as different materials conduct heat at different rates. Tiled stone floors and polished concrete work fantastically with underfloor heating. Timber floors work less effectively but still work if the system is run for prolonged periods. It should also be noted that engineered boards or laminated floors can be used with underfloor heating but solid timber floors are heavily advised against as the boards will move and warp with the heat below and can become an expensive floor to replace. Carpets are the worst performing conductors of heat and therefore generally advised against. It is often the case therefore that our clients choose underfloor heating in their basement and ground floor areas and then move to radiators on the upper levels to heat the carpeted bedrooms as radiators work with any floor finish. This decision is also helped by the fact that upper floors are normally constructed as suspended timber floors which are more expensive to prepare for underfloor heating when compared to an insulated reinforced concrete slab.

From an interior design point of view there are many types of radiators from the standard white panel radiator to sleek column radiators and traditional cast iron radiators whereas underfloor heating is by its nature unseen, freeing up space along the walls. Depending on your design preference this can be taken as either an advantage or disadvantage but on the whole we find that our clients prefer the flexibility underfloor heating affords them in their basement and open plan kitchen and means no more lost socks down the back of the radiator! It also means when Farrow and Ball French Grey goes out of fashion you don’t have to remove the radiator to paint behind it.

The underfloor heating manifold manages the flow of hot water into the system

The underfloor heating manifold manages the flow of hot water into the system and cold water out of the system and can be programmed from a thermostat much like a central heating system.

What we haven’t discussed so far is cost. There are many factors to consider though before you can make a straight comparison. For this example let’s assume that we are constructing a side return extension for an enlarged 450 sq ft kitchen-dining room with a new reinforced concrete slab, insulation and a sand/cement screed over already costed for separately. The cost to run copper pipes and fit 2 large designer style radiators for this space will be around £2000. Alternatively the cost for underfloor heating will be around £4000. This is a significant uplift in cost but over larger areas the increase becomes more even as the initial outlay for underfloor heating systems is high but thereafter, increases in the size of the system are relatively cheap to cater for. Radiators therefore win hands down on installation costs but as discussed earlier the running costs for underfloor heating are less so over 10 years the systems become much the same on overall spend.

Let’s put this all into a simple diagram below but in our opinion as builders: Underfloor heating wins hands down for a basement and ground floor extension but leave the radiators to handle the carpeted bedrooms.


If you have any questions relating to this article, why not ask our Build team?

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