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Insulating Heating and Hot Water Pipes

We're all feeling the pinch at present with energy bills rising, so it is worth taking some time to look at insulating your heating and hot water pipes, which if left bare are not only letting out heat, but your money too. Insulating your pipes shouldn't cost a great deal and will save you money for years to come.



Insulating hot water pipes is not a complicated job, most people who are experienced at DIY will be able to install it without much difficulty. In this blog we will assume that the pipes are running at 60ºC with an ambient temperature of 15ºC. These are the parameters set out in the TIMSA HVAC Compliance Guide, a copy of which can be found here: TIMSA HVAC Compliance Guide.The guide is written to help comply with Part L of the Building Regulations, we will be concentrating here on domestic dwellings.

The first questions we ought to address is what kind of material out to be used? Climaflex would certainly be one of the simplest and most cost effective options. It is a grey polyethylene material and has a good thermal conductivity, comes pre split and is easy to work with. You can fix it in place with clipsadhesive, or pvc tape; a good installation is always one without any gaps in the insulation where heat can escape.

You could also use a nitrile rubber such as Eurobatex or Armaflex Self-Seal, these materials have the same thermal conductivity as the Climaflex but are more flexible and easier to work wit around corners and bends. These materials are more expensive than polyethylene materials such as Climaflex though as they have a
Class 0 fire rating which may be required in certain cases, such as work for housing associations or council owned properties. More often than not though, this rating will not be required so the choice would come down to personal preference.

The following table, taken from the TIMSA HVAC Compliance Guide, indicates the correct thickness to use for the insulation of heating and hot water pipes in a dwelling:


Outside diameter on which insulation has been based
mm
Water temperature of 60ºC for hot water with ambient still air temperature of 15ºC (high emissivity facing: 0.95)


Thermal Conductivity at 40ºC W/m.K

Maximum permissible heat loss
0.025
0.030
0.035
0.040
0.045
Thickness of insulation (mm)
W/m
8
5
7
9
12
16
7.06
10
6
8
11
15
20
7.23
12
7
10
14
18
23
7.35
15
9
12
15
20
26
7.89
22
11
14
18
23
29
9.12
28
12
16
20
25
31
10.07
35
13
17
22
27
33
11.08
42
14
18
23
28
34
12.19
54
15
19
24
29
35
14.12


So, using this table, Climaflex, Eurobatex and Armaflex would all fall under the 0.040 W/m.K bracket (as the mean temperature is taken at 40ºC). All 3 three products would commonly be available in thicknesses of 9mm, 13mm, 19mm and 25mm, with Eurobatex and Armaflex additionally being available in 6mm wall and 32mm Wall (though neither thickness would apply to this table, unless you wished to gain extra efficiency with a 32mm Wall thickness).

If we were to take an example of the three common pipe sizes in most peoples homes (15mm, 22mm & 28mm) then the appropriate thickness of insulation to use would be 20mm, 23mm & 25mm respectively meaning that you would need to use 25mm Thick for each; You would usually scale up to the next available wall thickness in order to comply with these guide lines.

Where the pipe size is greater than 54mm then you would assume it to be 54mm for calculation purposes. These heat loss figures apply to steel, copper and plastic pipes as well as other kinds less commonly used.

Special attention ought to be paid to pipes laid in unheated areas of the house to allow against freezing. In these cases you would refer to the frost protection table in Water Bylaw 49 (where the mean temperature is taken at 0ºC), given below:


Pipe Size
(mm)
Thermal Conductivity of Pipe Insulation (W/m.K)
0.020
0.025
0.030
0.035
0.040
0.045
15
20
30 (30)
25
25 (62)
32
(124)
22
15
15 (12)
19
19 (20)
25
(30)
28
15
15 (8)
13
19 (12)
22
(17)
35
15
15 (6)
9
9 (9)
13
(12)
42
15
15 (5)
9
9 (7)
9
(9)
Note: Figures shown in brackets are calculated values shown in BS 6700


For more information on this area refer to our blog on Frost Protection for Domestic Pipes.

Where two thicknesses are given, you should always defer to the thicker wall pipe insulation. For example for a 15mm pipe you would apply 19mm of insulation for heat loss prevention, or 25mm for frost protection. In this case you would allow 25mm of insulation to cover both eventualities.

A general rule of thumb for frost protection is that the thinner the pipe, the thicker the insulation, but for heat loss it is the other way around; the thicker the pipe the thicker the insulation. 

For more information on the range of insulation products available, please visit our website via the link below

Pipe Insulation Products



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  1. I read your post and I really like it, Thanks for sharing this useful information..

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