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Under floor heating by Heatec

Floor heating pages:                                                               Other pages:

 FAQ   Under tile   In-concrete   Under timber    Control                                Coldroom/freezer door heaters,  frost heave protection and condensation prevention.  Pipe tracing

 

  Under carpet mats   Running cost   Floor heating kits                                 Heated towel rails   Drying equipment   Drying/freezing trays  Propagation bed heating  Animal pen heating

 

 

 

Floor heating features
Heating tiled floors
Slab floor heating methods
Floor heating for timber floors
Programmable thermostat control
Underfloor heating FAQ
Running cost
Floor heating kits
Door heating for cold room and freezer doors
Sub-floor heating for freezers
Condensation prevention
Pipe tracing
Towel warmers
Drying of fruit and other products
Plant propagation bed heating
Heating for enclosed animals

Freezer sub-floor heating

Frost-heave prevention for freezer floors on-ground.

 

The earth beneath freezer floors more than a couple of metres wide will slowly freeze, causing lifting of the floor.

Moisture beneath the floor will slowly freeze, lifting the floor.

Beneath larger rooms without frost heave protection, the earth has been known to gradually freeze to a depth of at least 3 metres, despite the floor insulation. This causes a dome-shape upward heave to the freezer floor of more than 400mm at the centre. Although this can take years to become apparent, the structural failure of the floor is serious.

 

Will this happen to all freezers on ground?

Provided that the floor incorporates 150 - 200 mm of polystyrene floor insulation or an equivalent, and the room is no more than 3 m wide, frost heave is unlikely. This may be increased to rooms up to 4 m wide provided that the sub base to the room is well drained to a depth of 600mm and even further if the floor is well elevated above the surrounding ground level.

 

How is frost heave prevented?

Three different methods of prevention are employed. The first is the use of a system of vented pipes laid at around 500mm spacing to provide for cross flow ventilation beneath the room. This method is not common because it requires unobstructed airflow across opposite sides of the room, free from other external obstructions or buildings.

The second and most common method of prevention requires heating cables run at around 400 - 600 mm spacing. Heatec can design the layout and either supply the cable with layout plan, or complete the installation. The electrical loading depends on floor insulation and room temperature, but is usually very low - around 15 - 20 W/sq.m. Dual circuits with one cable not connected are usually employed. The cable loading is very low, preventing any form of  cable deterioration, however most clients request dual circuits for the added peace of mind.

Mains voltage (234-240V) cable circuits are normally used, as there is no advantage or justification for using lower voltages.

 

Heating cable method for preventing frost-heave

A third method is the installation of polyethylene pipework either in or below the base concrete slab. A closed circuit of warm water is circulated through the pipe work runs at 600mm centres, using condenser heat captured from the refrigeration plant. This is more expensive to set up, but is justified for very large rooms eg. 400sq.m or larger.

 

The integrity of the vapour barrier below the insulation is very important. Failure can lead to water soaking into the insulation, dramatically reducing it’s thermal resistance. Sub-floor heating is installed at a low rate to balance the small rate of heat movement up into the room and is not designed to cope with insulation failure.

 

 

Information required for quotation:

Inside floor area

Room temp

Type and thickness of floor insulation.