Insulating plastic CH pipes

[VAG_dude]

Hi there,

We have around 4-5 metres of plastic CH pipe in the loft space, I was wondering if there should be insulated?

Can I use 15mm bore Armaflex to lag them?

[The Natural Philosopher]

yes

yes

[Tabby]

it would eliminate a little heat loss

you can use just about anything, pipe insulation, loft insulation, rags, whatever

NT

[VAG_dude]

Thanks guys, also in the boiler cupboard on the second floor bathroom there are quite a few CH pipes in there, about 3 metres of 22mm flow and return pipes and around 4 metres of 15mm pipe leading in to the loft, I presume these could also do with a little insulation even though there are in a heated room? Only thing is the 15mm pipes are quite close together and clipped to the wall so not sure how I will insulate them.

One more thing too actually; I have heard you should insulate pipes under the floor downstairs? There is only one drop to downstairs of CH pipes in our house and all the pipes are run under the floor boards and up in to the rads, the extension has the pipes channelled in and wrapped with denso tape. I haven't really seen under the floor boards though. In case it helps the house is an old 1930's (maybe older?!) semi, it has 9" solid walls.

[Roger Mills]

The answer is almost certainly yes and yes, but I'm puzzled as to what the pipes are doing there. Is there any heated living space in the loft? Are the pipes carrying hot water, or are they simply the connections to a F&E tank (assuming a vented system)?

[Roger Mills]

Is it also an airing cupboard? If so, a bit of escaping heat is good for airing your clothes.

You should certainly insulate any CH pipes running in the void under a suspended downstairs floor - for two reasons. Firstly, to avoid wasting energy heating up the neighbourhood when your CH is running and secondly to reduce the possibility of freezing up when the CH *isn't* running. Is there enough space to crawl around under the floor? If so, get in there [1] and see what's what - and fit foam insulation round the pipes if they're not already insulated.

[1] You'll probably wish to wait for the weather to warm up a bit before undertaking this job!

[VAG_dude]

The loft has a 1.7kw radiator on the plasterboard wall and is fed by the plastic pipe behind the board. It's a sealed system running at around 70=BA when on full tilt and 55=BA when maintaining the set temp.

[VAG_dude]

Used to be but now there is next to no heat in there really, the new boiler seems to give off virtually no heat which I believe is a good thing. No space for clothes in there.

Thanks Roger, makes sense now :)

[fred]

In article , VAG_dude writes

Climaflex is cheaper and easier to cut about that armaflex and fine for this job. For pipes close to walls or close together a bit shaved off the sides of each length of insulation so they don't foul but butt together neatly would be my suggestion. The lengths will come slit these days, tape seams and joints with duct tape to make sure the gaps don't open up and lose heat.

IMV it's better to pay a little more and get 25mm wall insulation for CH pipes and all my (plastic) CH pipes in floor voids have this on them. It's about a quid a metre.

Someone asked this recently and I looked it up, IIRC heat loss was of the order of 20W/m on both flow and return so it's worth doing.

[VAG_dude]

Thanks for the suggestion

Is the Bylaw 49 approved stuff you get in a lot of places?

Like this?

did think about getting this type but for the pipes coming from the boiler there would be a lot of cutting/shaving etc to do, I was under the impression that Armaflex gives the same performance but the wall is not as big?

Definitely worth it then.

Thanks

[Toby]

Do you ever turn this radiator totally off?

If so, do you have insulation in the roof of the loft, and do you have insulation in the floor of the loft?

[fred]

and not particularly compressible. Cheaper here:

I did think about getting this type but for the pipes coming from the

AFAIAA, armaflex is no better ins wise but is closed cell and so is suitable for use on air-con on moisture attracting chilled pipes, no gain for heated pipes. As a general rule I wouldn't expect better performance from a foam insulator unless it was the same stuff as Celtotex etc ie PIR foam which I'm sure it's not. Happy to be corrected though.

Forgot to say that a hand held hacksaw blade makes short work of cutting this stuff to fit, I've done some quite complex sculpting when installing mine and it it pretty quick and easy. On a bend you can keep the side opposite the slit uncut and just cut out a V to take it round a knuckle bend or a few small Vs to take it round a swept bend.

Good quality duct tape is best for sealing up joints/slit as gaps can open up with time. The adhesive on cheap tape may harden with time and it falls off.

You're welcome

[BartC]

By the time I've finished, I'll have used up 30-35m of the stuff to lag copper CH pipes in unheated loft areas.

A lot of it had been/will be under a few inches of loft insulation, but a quarter wasn't covered at all (mostly 10mm pipe though).

Good tip.

[Tabby]

in a heated place the pipes act like a bit more radiator area, there's really no point insulating the heating ones, but insulating the hot water only ones is of use in summer.

Yes, or you're heating the outdoors and they can freeze.

NT

[VAG_dude]

Loft is used as a bedroom, it's completely off at night and the temperature drops to about 12=BA then, when occupied in the day or evening it's on, maintaining about 16=BA=A0- 18=BA.

Floor is insulated, boarded over with carpet on top. I believe the roof SHOULD have been insulated but whoever done the loft conversion unfortunately didn't do it, it's all painted and plasterboarded over now so I can imagine it being quite hard and messy to remove everything to put some insulation. Whenever it snows and the heating has been on in the loft the snow melts quicker than all the other houses in the area.

Thanks

[Toby]

In that case it isn't really worth bothering with insulation as it is acting as extra heat output to the bedroom ( and will do ony when the radiator up there is on) - if you said it was a bedroom to start with and not a loft, I expect others would have said the same!

If there isn't insulation in the roof and there is in the floor then you need to make sure that room never gets below zero or your radiator will froze and probably burst.

If you want to be able to shut off the heating in this space totally I would recommend installing some isolation valves in the pipework to the loft (in the room below) and also include drain points above the two vales so you can drain all the water out of this bit.

[VAG_dude]

The pipes are not in the actual bedroom and neither are there under the floor space of the room, they are behind the plasterboard wall which is used for storage.

That particular radiator is on a separate zone with a programmable stat so I expect I could just set the stat to around 7=BA.