Underfloor Heating Technical FAQs

What type and depth of screed do I need?

In domestic properties we recommend a 65mm 4:1 sand/cement wet screed mix. If used in a commercial property this should be increased to 75mm. The screed should be laid for a minimum of 28 days prior to switching on the system. If is possible to get specialist screed supplements which will reduce the drying time and/or reinforce the screed. Please contact the specialist manufacture for further details on drying times and/or depths with regards to anhydrite screeds or screed supplements as the guidance does differ depending on the manufacturer.

How much insulation do I need?

Insulation within the ground floor of properties is required to comply with Part L of the building regulations regardless of whether UFH is being installed. A ground floor of a domestic property is to be insulated so that it has a U value of 0.25 or less (note the lower the U value the greater the resistance to heat transfer, the reciprocal to an R value). When calculating a U value the floor area and the exposed perimeter of the building need consideration as the building will lose more heat around the perimeter than in the centre. Generally 70mm of a PIR or PUR board (such as Kingspan or Celotex) will satisfy for ground floors however your architect should confirm the exact requirements with you.

On intermediate floors there is no requirement under building regulations to have thermal insulation. However, BS EN 1264 (the British and European Standard which applies to water based underfloor heating systems) requires that intermediate floors that have a heated area below are to be insulated and the insulation is to have a thermal resistance  of 0.75m2K/W or greater. (note, the thermal resistance (R Value) is the ability of a material to resist heat flow.  The greater the r value the more efficient the insulating material will be) 25mm of a PIR or PUR will suffice.
Please note in flats where there is a separate dwelling below acoustic insulation will be required to comply with Part E of the building regulations.

Where do I start with wiring up the controls for my Underfloor Heating system?

Talk to our technical team on 01455 555930, we have lots of schematics and information to help you wire up your system.
There is a full range of wiring schematics available for down load within the website. The matrix on the page [link]will direct you to the correct diagram that you require for your system. If you are unsure or wish to discuss the wiring of your system please don’t hesitate to contact a member of the Maincor Technical Team at the head office on 01455 555930.

Can I link Maincor Underfloor Heating into my own control systems?

At Maincor we offer various control systems including standard dial type thermostats, LCD programmable thermostats, radio thermostats, floor or wall sensors etc so there’s every chance we’ve got the ideal solution for you. However if you have a thermostat that you wish to use it’s very likely that it is compatible with our system. We supply 24V or 230V thermal actuators which can be connected via a wiring and relay centre to volt free thermostats or to 24 or 23V thermostats. Please call to discuss your requirements if you wish.

What is Weather compensation?

As the outside temperature decreases the heat loss of the building will increase hence the amount of energy that we have to put back into the building will also increase, if comfort conditions are to be maintained. This is the fundamental principal that weather compensation works upon. The Maincor weather compensation controller has a series of sensors including one to measure the external temperature. The information regarding the external temperature is fed back to the control unit which calculates the optimum flow temperature for the UFH system to work at. This method of control offers greater efficiency and decreases the amount of temperature swings thus creating a more comfortable environment whilst reducing carbon emissions.

How do heat pumps work with Underfloor heating?

UFH Systems will typically run with water temperatures of between 35-55°C depending on the floor structure, the floor finish, pipe diameter/pipe centres and the buildings energy requirement. The low temperatures are ideal for use with heat pump technology where greatest efficiency can be found at the lowest temperatures.
Heat pumps take low temperature energy from an ambient heat source (usually ground or air) and electrical energy is applied via a compressor which gives off heat energy and raises the temperature of the medium (water and brine/glycol mix). This water is then circulated around the UFH circuits that transfer the energy to the floor and ultimately to the room that requires the heating.
If you take a ground source heat pump as an example we are effectively moving the energy from the ground outside via the heat pump and the floor (being the heat emitter) and into the heated environment.

What size boiler do I need for Underfloor heating?

The size of boiler required will vary with each system, and we will give you assistance when we quote for your project.
The boiler will need to be sized in order to generate enough heat to satisfy the heating requirements and in most cases provide enough heat to supply warm water to a property. Care should be taken to ensure that the boiler is not over sized as a correctly sized boiler will work far more efficiently than an over sized one.

Where should I position the room stats?

Each room stat needs to be located in the room it is controlling, we recommend that they be positioned in a draft free place, out of direct sunlight and not near to any other heat sources such as cookers or towel rails.
A thermostat should ideally be positioned in way that it can take a fair reading of the environment that it is situated and it should be positioned away from any heat gains or heat losses which may offset the reading. In practical terms this means that it should be positioned in a draft free place and away from heat sources such as direct sunlight, fire places, cookers etc.