quality pipe lagging

bockster

calling all plumbers/heating engineers,
i am currently planning the installation of new combi boiler in the loft which will have many advantages. however one disadvantage is that the distance to the kitchen sink will be some 15 - 20m. i therefore want the very best pipe insulation possible for dhw. i'm currently looking at armacell, but woundered if you guys recomend anything else over this?, or do you know of any comparison tables?
would also love to here of your experiances with long dhw runs and whether the water can actually be kept hot in the pipe for some time?

thanks in advance


ps. away for a few days, so sorry if no replies from me till after w/e

Canucklehead

Hi

You'll wait quite a while for hot water over that distance! Avoid if at all possible.
Armacell (Armaflex) is the best AFAIK. The seam/joint is sealed shut with contact adhesive. 15mm x 32mm wall thickness is available.
Corgi Guy.

bockster

cheers corgi guy.

i think i will experiment in the garage with meter lengths of pipe filled with hot water and insulated to different degrees, to see for myself the heat loss.

my theory is, that my current hot water tank is only insulated to 25-30mm, and this keeps the water hot all day! if i insulate the 15mm pipework to a high standard, maybe this will be ok. the floor in my theory could be, though, that the larger volume of water in the tank may keep itself warmer by insulating itself, if you know what i mean. we shall see.

cheers, bockster

TimBuckTeeth

With a combi boiler when a hot tap is switched on a flow sensor detects this and starts up the boiler, it takes about 1 second to ignite and about 2 seconds to get up to temperature, during this time cold/luke warm water passes into the pipe.

It is good to have well insulated pipes, but it is difficult to keep static hot water in pipes hot due to the large surface area of the pipes. Even if you manage to keep the water hot enough in the pipe from the previous time the hot tap was on, the water temperature will drop, after the hot water in the pipes has passed through, while the boiler fires up.

With short length of pipe this is not a problem but with a long length of pipe the cold water could arrive around 20 seconds after the tap is switched on, or you could be waiting that long for hot water if the pipes have cooled.

If the boiler can't be resited then have a look at boilers with a small pressurized storage tank.