Outside pipe insulation

[transatlantic]

Ok - sorry for another piping thread!

My hot water pipes froze during the cold period and so my hot water taps didn't work until only recently. Luckily I have an electric shower. The central heating was fine, as it is on a frost timer. My boiler is located in my garage and there is about a meter or so of pipe work between the garage and the house that isn't contained within either building. I'm guessing this is where it froze, or it might of course be some of the pipework inside the garage.

All the pipe work inside the garage is insulated with that grey foam stuff. The outdoor pipework I'm not sure, as it's wrapped in something, so can't see. Either way - I plan on redoing the lot as something along the line isn't sufficient.

So am looking for recommendations for what I should use? a lot of the local places do the grey foam (which clearly isn't working for me), so I need to upgrade to something better?

 

[Rorschach]

How regularly has this happened?

I am seeing a lot of people going crazy over their pipe work at the moment, this was freak weather, we had the first pipe freeze of any kind in probably 15 years, maybe more. I am not going to go crazy preventing something that might not happen again for a few decades.

 

[transatlantic]

Does is matter? As has already been reported, it can cause a lot of damage. I'd rather spend a day or two trying to prevent that.

 

[lurker]

Having spent 2 days dumping my F in L's home into a skip, I think a few hours on precautions is time well spent. We could easily have another "freak event" at anytime.

 

[Sheffield Tony]

Worth remembering that insulation only reduces the rate of loss of heat. If a pipe is in freezing surroundings, with no flow through it, it will eventually freeze whatever.

When I did my CH, the grey foam stuff came in a cheap, thinnish sort of stuff and a much thicker - inconveniently thicker than the standoff of most pipe clips - version. I presume you have the latter ?

 

[transatlantic]

When I did my CH, the grey foam stuff came in a cheap, thinnish sort of stuff and a much thicker - inconveniently thicker than the standoff of most pipe clips - version. I presume you have the latter ?

Mine is the grey stuff yes, about an inch or so thick. But having done a little reasearch, it appears that the grey stuff is not for protecting against frost. For outdoor piping (I'd class a garage as outdoor temps) you need something like Armaflex, which is about 6 times the price

https://www.pipelagging.com/22mm-pipe-l ... black-foam

Still though, not hugely expensive as I don't have that much of a run. Still not sure what thickness to get though (9, 13, 19, 25mm) - figured I'll just go with the thickest and call it done?

 

[powertools]

Personally I would install a frost protection cable around all suspect pipes and then insulate.

 

[julianf]

Tony makes a valid point above. Insulation only slows heat loss. Go sub zero for days, and insulation is not going to keep a pipe warm.

Trace heating if you're really worried, I guess.

 

[transatlantic]

It's not about keeping the pipe warm, it's about preventing it from freezing

 

[Halo Jones]

It's not about keeping the pipe warm, it's about preventing it from freezing

Read your reply carefully. To keep something from freezing you.....

keep it warm!!

 

[transatlantic]

It's not about keeping the pipe warm, it's about preventing it from freezing

Read your reply carefully. To keep something from freezing you.....

keep it warm!!

Not sure I'd say keeping something above 0 °C is keeping it warm, but ok ... :roll: :roll: :roll:

warm : of or at a fairly or comfortably high temperature

 

[novocaine]

I wrote a whole reply with the calculation for heat loss from an insulated pipe and some typical values, but then I realised it is probably pointless.
so I'll write this instead. warm is a comparative term, 0c is warmer than -10c.
insulation wont hold something that is 0c at 0c for ever in -10c, the stuff you posted that is expensive (and so it should be, it's for industry) will give you a few hours of protection but it's heat loss is in the region of 8 watts per metre for 22mm pipe so if the water isn't moving it will freeze in a day or so assuming there is no moisture at the surface of the pipe or on the lagging, which is unlikely and will reduce that time.
is the water sat still though? nope, so this changes things a bit. if your really worried about it, box it in and insulated with normal lagging and something that retains heat like mineral wool. then flow the pipe every 1/2 day or so. insulation on it's own will not stop the pipe from freezing if it doesn't have any heat to retain.

what I'd really want to know though is who thought running a hot water pipe externally was a good idea? the outside pipework is most likely wrapped in insulation already, still a crap design.

 

[transatlantic]

I wrote a whole reply with the calculation for heat loss from an insulated pipe and some typical values, but then I realised it is probably pointless.
so I'll write this instead. warm is a comparative term, 0c is warmer than -10c.
insulation wont hold something that is 0c at 0c for ever in -10c, the stuff you posted that is expensive (and so it should be, it's for industry) will give you a few hours of protection but it's heat loss is in the region of 8 watts per metre for 22mm pipe so if the water isn't moving it will freeze in a day or so assuming there is no moisture at the surface of the pipe or on the lagging, which is unlikely and will reduce that time.
is the water sat still though? nope, so this changes things a bit. if your really worried about it, box it in and insulated with normal lagging and something that retains heat like mineral wool. then flow the pipe every 1/2 day or so. insulation on it's own will not stop the pipe from freezing if it doesn't have any heat to retain.

what I'd really want to know though is who thought running a hot water pipe externally was a good idea? the outside pipework is most likely wrapped in insulation already, still a rubbish design.

Thanks for the info, food for thought. Yes - it's not great having it outside, but that's what I have (it was there when I moved in). As for the water being sat still, it will be like that most of the time to be honest as I only use it for a bath in the morning and the odd washing up.

I came across this document which sums it up - similar to your analysis.

http://www.tidl.ie/files/Armacell_Freez ... le_-6C.pdf

-6c ambient temp, 7c initial water temp.
[Copper pipe, 22mm, with 25mm of Armacell,]
about ~15 hours before it freezes

 

[novocaine]

here you go, enjoy. I can't be bothered to type it all out from the book so went and found it online.

https://www.engineeringtoolbox.com/cond ... _1487.html

 

[AES]

We have 2 "outside outside" pipe runs to outside taps here. They start in the cellar and end up with short (less than a foot) bare-ish runs to taps mounted on the wall.

Standard procedure every year when Winter starts is to close the in cellar stop cock, drain at the taps until no water left, then leave all turned off until spring time. "Everyone" does so.

We've never had a freezing problem so far (touch wood), despite pretty regular below minus 10C overnight temps in Winter. The lowest this year (so far) was minus 17C, though we have had that once in a while in previous hard Winter years.

The runs (iron pipe) are not insulated at all, though as said, 99% of the runs are inside the cellar, in which air temp never gets below about plus 7 or 8 C. Also no running water at all (I doubt that the above draining procedure gets every last drop out of the system).

I don't know if that info helps, or is relevant to UK, but anyway, FWIW.

AES

 

[transatlantic]

We have 2 "outside outside" pipe runs to outside taps here. They start in the cellar and end up with short (less than a foot) bare-ish runs to taps mounted on the wall.

Standard procedure every year when Winter starts is to close the in cellar stop cock, drain at the taps until no water left, then leave all turned off until spring time. "Everyone" does so.

We've never had a freezing problem so far (touch wood), despite pretty regular below minus 10C overnight temps in Winter. The lowest this year (so far) was minus 17C, though we have had that once in a while in previous hard Winter years.

The runs (iron pipe) are not insulated at all, though as said, 99% of the runs are inside the cellar, in which air temp never gets below about plus 7 or 8 C. Also no running water at all (I doubt that the above draining procedure gets every last drop out of the system).

I don't know if that info helps, or is relevant to UK, but anyway, FWIW.

AES

Thanks - unfortunately, this is my hot water supply, so not really something I want to have drained/disabled.

 

[AES]

Ah, Ok, understood. I wouldn't want to drain the hot water either! ;-)

AES

 

[Brandlin]

what you describe is basically the same situation and procedure that I have AES. Although my winter temperatures are not as bad.

Remember the only reason that a frozen pipe bursts is because water expands when it freezes until it gets to around -4C (from memory). So you dont need to drain the pipe completely - just enough to allow expansion.

 

[transatlantic]

what you describe is basically the same situation and procedure that I have AES. Although my winter temperatures are not as bad.

Remember the only reason that a frozen pipe bursts is because water expands when it freezes until it gets to around -4C (from memory). So you dont need to drain the pipe completely - just remove enough to allow enough expansion.

As mentioned it's my hot water supply, so how could I do that?

 

[AES]

I'm definitely NOT expert in this stuff transatlantic, but the only way I can think of is to drain the hot water (tank?) completely, and shut off the complete system so the tank (or whatever) doesn't refill. And of course shut off whatever it is that heats the water.

As said, assuming you'll still live there at least sometimes (!) then I wouldn't want to try that! Maybe if the house is going to be completely unoccupied over the Winter?

There must be other members here who ARE experts on all this. I strongly suggest you wait until one of them comes along - me, I'm just guessing!

AES