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UNDERFLOOR HEATING GUIDE

 

FOR ARCHITECTS AND NEW HOUSE BUILDERS

1. Introduction     

 

The Romans brought underfloor heating to this country 2000 years ago to heat their homes and bathhouses.

 

Certainly heating the floor of a living space gives a most comfortable environment leaving all the walls free of appliances and complete freedom for the interior designer.

 

 

2. Floor heating  The Pros and Cons

 

With modern well insulated buildings, underfloor heating gives significant energy savings over a conventional radiator system.  Couple this with a condensing boiler and a very economical heating system can be achieved.

 

The ideal living space has a warm floor for warm feet and a slightly cooler ceiling for a cool head.  Underfloor heating in a well insulated house can provide this ideal in a very economical manner.

 

Floor heating must be designed carefully as it is not suitable for all buildings.  For example if the floors are uninsulated then floor heating would  waste a significant proportion of the energy.  Walls and ceilings should also be well insulated, as is the modern trend, to cut down on wasteful convection currents (cooling draughts) within the building.

 

Radiators and particularly forced air heaters set up convection currents which make the room feel slightly draughty.   Floor heating is a radiant heat minimising convection currents and is therefore much more comfortable, and one can reduce the thermostat setting.

 

A poorly insulated building would require so much heat output from the underfloor heaters that the floor would feel uncomfortably hot.  In cases such as this underfloor heating alone is not adequate and extra heating would be recommended for colder weather.

 

Floor heating installation costs are comparable with but slightly more expensive than conventional radiators.

 

 

3. What is involved with a Floor Heating System?

 

Materials

 

All materials are readily available either from plumbers merchants or from ourselves.  Plastic barrier pipe used extensively in Europe for underfloor heating is recommended.

 

The Floor

 

The ground floor must be well insulated and at least 60mm of high value polyurethane floor insulation is recommended.  If the floor is to be screeded then a further 75mm of screed is required.  The pipes are laid in the screed.

 

The heating pipes can also be laid below a timber floor or routed within chipboard flooring.  Foil backed insulation firmly secures the pipes beneath, and in contact with the wooden floor.

 

First Fix

 

Simply lay the barrier pipe onto the floor insulation using clips or onto thin weld mesh over the floor insulation and tie into place.  Bring all the tails to the chosen manifold position.

 

After pressure testing screed is laid over the pipes to depth of 65-75mm.

 

 

Installation

 

All the tails are brought to the manifold, which consists of balancing valves and control valves controlled either by electric heads or by thermostatic radiator valves.

 

Manifolds may bought, or be made up from fittings. The smaller manifold types may be mounted in a floor well.

 

Manifolds are connected via flow and return pipes to the underfloor heating controller, 3 port mixing valve and pump.

 

 

 

4. The Boiler and Domestic Hot Water System

 

The boiler should be a condensing boiler to take advantage of the low return temperatures from the underfloor heating system but otherwise all boiler and domestic hot water connections are standard.  A sealed or open vented system can be used.

Control

 

A temperature controlled mixing valve provides the correct underfloor water temperature to the floors.

 

The ambience is controlled by optimum start timer thermostats which can be programmed for different temperatures throughout the day, interlinked with the boiler. 

 

The individual rooms may be controlled by room-stat or by temperature sensors.

 

 

 

 

 

5. Design

 

Conservation Engineering provide a Floor Heating Design Service for architects and builders of both domestic and commercial buildings.

 

Just send the building plans including proposed `U' values for floors, walls, roofs and windows to us for a carefully balanced floor heating design.

 

We provide the design service in two parts:-

 

Firstly we will discuss all your options and provide initially, heat loss calculations room by room, proposals and outline costs to enable you to choose the system you require.  We will also sort out details of floor insulation required for your choice of flooring.

 

The detailed design will include a comprehensive parts list;  layout of underfloor pipework room by room, and details of manifolds and control system.  Schematic diagrams of pipework, pump and boiler with domestic hot water system and wiring diagrams are also provided with detailed instructions so that any competent person can install the underfloor system.

 

We particularly recommend that heat recovery and /or solar water heating  is included in your energy efficient building.

 

6. Helpline

 

A helpline for all technical queries on 01359 268340 is available.

 

7. Supply of Parts

 

Our service provides a list of parts for purchase by the installer, but if required the complete kit of parts can be supplied by ourselves.   We also supply a range of very reasonably priced pipe, manifolds and valves.

 

8. Installation

 

Our service is designed for installation by plumber or client, and we are happy to help via a phonecall.  In emergency we can come to site to sort out any problems

9. Quotation

Just send the building plans including proposed `U' values for floors, walls, roofs and windows to us for the quotation to prepare a carefully balanced floor heating design.

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