Pipe Insulation - What Size (thickness) ?

ibz75

Hi all,

Following on from a repaired leak (2 frozen pipes burst) I am going to insulate the pipes as far as possible.

There are 3 pipes to insulate: Cold water from mains to storage tank (15mm), Cold water from storage tank to hot water cylinder (22mm), and a hot water pipe (15mm) - think its hot water return to storage tank.

All pipes are inside a partition wall, which will now be vented from the ceiling below to allow some circulation.

I have looked at sizes (thickness) and most are available in 13mm, 19mm and 25mm. What would you recommend for this location - is thicker generally better?

Thanks

P.S. popped into the large B&Q 'Extra' in Leeds yesterday and was told all insulation was sold out - wonder why???

suisidevw

15mm is widely available too as it's extremely common, Ours are wrapped in this.

ibz75

suisidevw wrote: »

15mm is widely available too as it's extremely common, Ours are wrapped in this.

I think 15mm is the size of the pipe (bore) - but I could be wrong.

A.Penny.Saved

You might have some problems pushing the insulation up there if there are pipe mounts fitted. Pipe insulation should be taped closed or it loses it's effectiveness.

Anything you put up there will lessen the effectiveness of the venting I would think.

I have some pipes that run up the corner of my kitchen which I want to insulate but it will mean removing the box section they go up inside and that is behind the kitchen sink unit so isn't something I am looking forward to. The pipes do need moving so that insulation can be fitted in the bathroom which is immediately above the kitchen.

Is there no way that you could get in to the pipes even if it means replacing part of the partition wall so they could be insulated properly? Or would this be too big a job? Did the pipes burst outside of this?

If you could get into it to insulate properly then maybe some silver coated bubble wrap insulation around the pipes and then some felt pipe wrap around that as much as space allows. Wickes sell that stuff fairly cheaply and the silver bulb pipe wrap is very cheap at Toolstation in their insulation section.

Changing the pipe supports might help too so that the pipes could be insulated more fully.

27col

If you are serious about insulation use the thickest for which you have room. The thicker the insulation the better the protection.

ibz75

After some research, I have discovered that the recommended minimum thickness is:

15mm pipe : 25mm

22-28mm pipe : 19mm

35mm and over : 9mm


The smaller pipes require a relatively larger thickness as the water has less heat energy and will therefore cool much more quickly.

However, these insulation measures seem to only protect pipes for around 12 hours of constant exposure to sub zero temperatures, after which the pipes will most likely freeze no matter what thickness of insulation is used.

So I guess a combination of insulation and some form of heating is essential to avoid pipes freezing (but not guaranteed!!!).

Hope this info helps others who are/were clueless about all this lagging lark.

ListysDad

Hi IBZ

Just need to add to your knowledge.

The grey polyethylene (slightly slimy) lagging CAN NOT protect you against freezing. The reason is that at 4 degrees C (that's ABOVE freezing) it begins to SHRINK. This means that no matter how you install it gaps will appear and make it useless. Sorry! NO manufacturer of this type of lagging will say it is suitable for protection against freezing.

If you wish to protect the best you can then fit a nitrile based product (like Armaflex or Tuflex) and install it correctly. By that I mean make 100% sure every joint/gap is glued and NO pipework or valve or whatever is exposed.

Lastly, the standard you found (Byelaw 49) is unfortunately a committee based standard built upon flawed data. For a start is says the water temp entering a house is at 7degs C. For the last two years water temp has been tween 3.5 and 4 degs C. It also assumes that the outside temp only goes as low as -6 degs C. We all know that is nonsense with -15 degs C common and -22 the lowest. What this all means is that the thicknesses they quote are inadequate even for a few hours. So, a minimum of 25mm wall thickness is a must regardless of pipe diameter BUT it MUST be fitted as Ive described or simply don't bother.

If you have a well insulated loft then go to 32mm wall thickness or fit trace heating.

HTH.