Tube Spacing Table Kits 6-15

The heat output from floor heating is governed mainly by the following criteria:-

(1) The spacing of the underfloor heating tubing

(2) The size of the underfloor heating tubing

(3) The temperature of the water in the underfloor heating tubing

(4) The velocity of the circulated water in the tubing

(5) The floor insulation and type and depth of screed

(6) The floor finish.

The most important of these at the time of installation is item (1) the tube spacing as this is very difficult to change after the floor is screeded.

The most common size of tubing used in underfloor heating is 16mm OD , this is the size we use in these kits as well as our bespoke systems.

Items (2) and (3) will offer some help if there isn’t enough tubing installed , however it is advisable to play safe with your tubing centres.

It is always better to use the best quality insulation available. The industry standard at the moment is to use 70mm Kingspan or similar , This should be tightly fitted and have perimeter insulation to the finished floor height. Screed is normally 4-1 sand and cement mix and is normally at a depth of 70mm , the screed should be well compacted.

The floor finish can vary from tiles or slate etc., which are ideal with little or no resistance to heat passing through, to carpet and underlay which can have quite a high resistance. It is important to select underlay that is suitable for underfloor heating and we would recommend a TOG value of no more than 1.5. This would also apply to timber floors.

We normally design to the worst case i.e TOG 1.5 as usually the final floor finish isn’t known at the time of the installation and even if people think they know they are liable to change their minds. We have prepared the table below with that in mind

A = Low-Moderate Heat Loss areas i.e. rooms with insulated walls and ceiling/roof and one – two outside walls.- Recommended Tube Spacing 200mm

B = Moderate – High Heat Loss areas – as A but with more than two outside walls or high ceilings or exposed locations – Recommended Tube spacing 175mm

C = High Heat Loss areas – As B but with high ceilings plus areas with additional glass like sun rooms or conservatories in secluded areas. Recommended Tube spacing 150mm

D = Higher Heat Loss Areas – More exposed conservatories Recomended Tube spacing 125mm

E = Very High heat loss Areas – Conservatories in areas of high exposure – seaside etc Recommended Tube 100mm

                                 A                   B                C                  D                  E

                           Area M2       Area M2       Area M2      AreaM2       Area M2

Kit 4 = 150 met      30                  26                23                 19                 15

Kit 7 = 300 met      60                  52                45                 37                 30

Kit 8 = 350 met      70                  61                52                 44                 35

Kit 9 = 400 met      80                  70                60                 50                 40

Kit 10 = 450 met    90                  78                67                 56                 45

Kit 11 = 500 met    100                 87               75                 63                 50

Kit 12 = 550 met    110                 96               82                 69                 55

Kit 13 = 600 met    120                 104             90                 75                 60

*Note if you are in doubt which kit you should use it is best to play safe and opt for the next biggest kit, remember your room thermostat will control the temperature of the room.

* For free advice on which kit to choose for your project please contact us on one of the contacts below or if you would like a free quotation for a fully designed bespoke underfloor heating system please click here

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