Should I insulate vent pipes in loft (from DHW cylinder and central heating)

[Plumb Line]

Hi

I recently did some pipe insulating in my loft.

The only two I didn't do were the vent pipes. Not sure if that is the right term for them? They are the pipes that feed water back into the top of the tanks when there is excess, presumably from steam, expansion, etc. The one going to the cold water tank is 22mm. The one going to the F+E tank is 28mm.

I didn't insulate them because...

1. The water has to rise from the airing cupboard into the loft, UP the pipes until the very end where the pipes bend down through the tank lids. As such, water can never be sat in the pipes can it? And if so, it cannot freeze if not sat in it.

2. If both are used for excess, steam, expansion etc, then won't any water travelling through always be hot?

Or have I missed something? If anyone could confirm whether they need insulating or not that would be great.

Many thanks

 

[Ben-gee]

There will always be water in them up to the level of the water in the associated tank that they are connected to - water finds its own level and all open ended components on a given system will have water at that same level, isn’t that cool!

So yes, insulate them to the water level in their tanks.

 

[Bogart]

For what it costs insulate them if only for peace of mind in a cold snap.