Is Underfloor Heating only an Option for a Luxury Self Build? Interview with REHAU
Choosing the right heating system can be an overwhelming task, with a vast array of solutions available to the self-builder. With the significant increase in energy costs, the real prospect of fuel poverty and the Government’s changes in energy regulations, the self builder must make the right choice when it comes to an efficient heating solution for their family home.
In the past Under Floor Heating (UFH) was often seen as an expensive luxury, found only in modernist mansion houses. However when used in energy effiicient ‘fabric first’ homes with lower heat demands, UFH systems are becoming the norm. To find out how UFH compares to other heating systems, we decided to ask Drew Clough, Underfloor Heating & Plumbing Product Manager from REHAU.
REHAU Ltd is a global manufacturer of polymer solutions. In the UK, the head office is based in Ross-On-Wye, and focuses on windows, industrial (furniture), and building and services infrastructure solutions. This includes pre-insulated pipe, underfloor heating, plumbing and cable management. Most people come into contact with REHAU products in almost every part of their daily life. But the vast majority of REHAU products are part of other products and non-branded so you wouldn’t necessarily know it’s one of ours.
WHAT SERVICES DOES YOUR COMPANY OFFER?
REHAU is a manufacturer of polymer solutions, so we manufacture our own pipe which is the highest quality available on the market – PE-Xa. REHAU offers a full set of high quality underfloor heating solutions from floating floors to screed, along with manifolds, pumps and smart controls. REHAU also offers pre and post installation support including onsite support.
We have a design office to ensure the circuits are designed correctly, maximising heat output based on heat loss calculations. Our design office will also advise on whether the circuit can be installed in conjunction with other building services being installed on site. All REHAU approved installations have an insurance-back warranty for up to £100,000 claim per installation.
AT WHAT STAGE OF A SELF BUILD PROJECT, SHOULD UNDERFLOOR HEATING BE INTEGRATED INTO THE DESIGN? WHAT DOES THE DESIGN PROCESS LOOK LIKE?
As early as possible.
REHAU is provided with CAD drawings of the floor plans and if possible heat loss calculations by the architect. The design office then designs circuits and locations of manifolds with the required heat source (boiler, heat pump, etc). Out of the design comes a confirmed bill of materials for installation. One of most important outputs is the designed circuits with pipe spacing and layout for the installer to follow.
HOW DOES AN UNDERFLOOR HEATING SYSTEM WORK?
In the simplest terms, underfloor heating provides heat similar to radiators but at a lower temperature and across the entire floor space; avoiding cold spots. Hot water (approx 35-55 degrees) from a heat source, such as a boiler, passes around circuits laid beneath the floor and gently heats the floor, which then becomes a heat emitter itself which in turn heats the room.
WHAT KINDS OF FLOORING CAN YOU USE WHEN INSTALLING AN UNDERFLOOR HEATING SYSTEM TO ENSURE IT IS MOST EFFECTIVE?
The only real limitation in type of flooring is the tog value of the flooring. If there is a thick carpet and/or rug, this can limit the effectiveness of the underfloor heating. Otherwise it is suitable for nearly all kinds of flooring. It is usually used in combination with a hard floor, such as tiles, engineered wood or real wood. Be sure that the floor temperature doesn’t exceed 29 degrees as this can be detrimental to some types of flooring. If in doubt speak to your contractor or installer.
WHAT ARE THE BENEFITS OF INSTALLING UNDERFLOOR HEATING IN A SELF BUILD HOME?
There are big advantages of underfloor heating, in that it is usually more economical to run, eliminates the need for radiators, avoids cold spots and provides a constant and ambient heat. Rather than the radiators burning hot and cold throughout the day, underfloor heating is designed to remain at a constant low level temperature. And as the floor can act as thermal storage, heat can still be emitted even when the heat source is off.
HOW DOES AN UNDERFLOOR HEATING SYSTEM COMPARE TO OTHER HEATING SOLUTIONS? SHOULD IT BE USED IN CONJUNCTION WITH OTHER HEATING SOLUTIONS OR IS IT SELF-SUFFICIENT?
Underfloor heating can work with pretty much any heat source, but it is especially useful when used with heat pumps. This is because heat pumps work more efficiently with lower water temperatures compared to boilers, so they need large heat emitters to be effective. Underfloor heating maximises the benefits of heat pumps by providing large surface areas working as heat emitters. But they can also be used with conventional gas boilers.
It is typical for many Self Builds to have underfloor heating downstairs and radiators upstairs. However, there are options if the owner wants to have underfloor heating throughout.
REHAU has a solution called EasyHeat panels. This is a pre-grooved tongue and groove chip board panel with a foil top, ideal for the first floor. EasyHeat means you can have structural flooring and heating all in one – and it heats up as quickly as radiators too. So do not think underfloor heating is only restricted to the ground floor.
FOR AN AVERAGE DOMESTIC HOUSE, HOW MUCH MIGHT IT COST TO INSTALL UNDERFLOOR HEATING? HOW DOES THE PRICE COMPARE TO OTHER HEATING SOLUTIONS?
The million dollar question! It is hard to put an exact price on it, as prices vary depending on manufacturer and installer. Prices also vary depending on the type of flooring solution installed. Retrofit or low profile solutions are typically more expensive than new build screed solutions. However, overall underfloor heating is more expensive than conventional radiators to install, but it should be pointed out that REHAU’s PE-Xa pipe has a life expectancy in excess of 50 years. With a long life expectancy, there isn’t a need to replace pipes, whereas you’ll likely have to replace a leaky radiator in the lifetime of a heating system. Once the pipe is in, it’s in, and should last a life time.
AT WHAT POINT DURING CONSTRUCTION SHOULD THE SYSTEM BE INSTALLED?
Ideally once the building is water tight. Remember that underfloor heating isn’t installed and operational within a day. The pipes need to be installed, then commissioned and then the screed has to cure. This can take 21 days. There are faster drying screeds but these come at an additional cost.
WHAT WOULD BE YOUR TOP TIPS TO SELF BUILDERS INTERESTED IN DESIGNING AN ENERGY EFFICIENT HEATING SYSTEM?
If possible, do your homework. If you can, speak to other home owners that have underfloor heating. See what they like and what they would change about their systems. Ask to see reviews and recommendations from your installer on their previous installations. Installing underfloor heating is very different from installing radiators, so get an expert to install it.
Not all underfloor heating systems are the same. Pipe isn’t just pipe. There are huge differences in quality in the types of pipe and once it’s laid in screed, it’s incredibly expensive and time consuming to replace should it ever go wrong. So make sure you get a high quality pipe as it underpins the entire heating system. Any of the above ground part of the system (controls, manifolds, etc) are relatively easy to replace if they ever need replacing but pipe will remain in the floor for many, many years to come.