Underfloor Heating FAQ

We know there is a lot to consider when installing underfloor heating. The team at Arcus have noticed a number of frequently asked questions which we have answered below.

If we do not answer your query below, please do not hesitate to Contact Us and we will be happy to help.


What type of floor coverings can I use with Underfloor Heating?

Underfloor heating will work with most floor coverings; however, some floors work better than others. You can use engineered board, laminate, ceramic tiles, carpet, vinyl, marble, stone, slate. Always check with the floor manufacturer before installing underfloor heating and follow our guidelines.

Can I use carpet with Underfloor Heating?

The maximum tog rating you can have with underfloor heating is 2.5 tog including the underlay; however, we recommend going for around 1.5 tog to achieve better heat outputs.

Where is the best place to position my underfloor Manifold?

Manifolds need to be located as centrally as possible. This reduces the amount and length of pipe runs, it also reduces the number of pipes passing through heated areas on route to other rooms.

Can I control my thermostats from my smart phone?

Yes, we can offer a range of thermostats that allow app control. If you are unsure which thermostats to choose please contact us.

Can I have different rooms at different temperatures?

Yes, we would recommend that each room has a separate thermostat.

How do I restrict the temperature of the floor?

You can install a floor sensing thermostat that will allow you to limit the floor temperature, this requires a small probe being installed into the floor.

Should I lay underfloor heating under my kitchen units and sanitaryware?

It is recommended that you should avoid heating underneath kitchen units and sanitary ware. Although, this is sometimes possible if it’s an extending breakfast bar or wall-hung basin / WC.

Do I need to lay insulation?

Yes, this is highly recommended. It is important to prevent any downward heat loss into the ground or the floor below. Please ensure you comply with building regulations.

Do I need I need edge Insulation?

Yes, Edge insulation forms a barrier around the floor slab and prevents any heat loss to surrounding walls. It also fills the expansion gap around the slab allowing the floor to expand and contract.

How do I know the underfloor heating will heat the room?

Generally, heat loss calculations should be carried out to determine what pipe centres should be installed. There are a number of factors that can have an influence over the performance of the system for example - glazing, insulation levels, flow temperatures. A boiler system would generally run at higher temperatures than a Heat pump system therefore this needs to be taken into consideration when designing the system.

Do I need a Mixing valve on the system?

If a boiler is being used then you do need to install a mixing valve, this allows the flow temperatures to be reduced going into the underfloor system. If a heat Pump is being installed then a mixing valve is not needed because the flow temperatures are much lower.

Can I connect radiators to my underfloor manifold?

This is not recommended. A separate radiator circuit should be installed, this makes it easier to balance the system and also allows separate control.

How much Screed do I need?

The optimum depth of a standard dry screed is 75mm. A much thinner flow screed can be installed but it is recommended that any screed is discussed with a specialist screed supplier.

How much height do I need to install underfloor heating?

There are many different systems that can be installed, if height is an issue a retro-fit system could be installed. This would require less height than a standard screed or plate system. Please contact us for more information.

What is the maximum length for each pipe loop?

Generally, as a rule we would suggest a maximum of 100 meters of pipe per loop. Some rooms may require more than one loop depending on the size, if this is the case it is recommended that the all the loops within the room should be approximately the same length.

How many loops do I need?

This depended on the size of the room and the pipe centres being installed, in some instances you can have go up to 20sqm with one loop at 200mm centres, however you need to take into consideration the distance to and from the manifold. If you are still unsure please contact us for assistance. It is important that the pipe loop does not exceed the maximum recommended length.

What is more efficient Screed or Plate?

A screed system will give higher outputs and hold the heat for longer periods of time, therefore requires less energy to maintain the desired temperatures. However, a plate system can have a faster response time.

Do I need to pressure test the system before I screed or lay the flooring?

Yes, this is very important. If damage occurs during the process the system will lose pressure, you can then repair the pipe before it is covered.

How long does Screed take to dry?

The screed should be allowed to cure and dry naturally until full strength is achieved. Heat commissioning of the system should not be carried out for at least 21 days and should only be run at 20-25degrees for at least 3 days and subsequently increased by 5 degrees every day until design temperature has been achieved. Please discuss this with a specialist screeding company as different screeds can have different drying times.

What happens if I damage a pipe?

We can supply repair kits for all our underfloor pipes, please contact us for more information.