Frozen pipe in extension

Section62

grumbler said:

Section62 said:

grumbler said:

Section62 said:

grumbler said:

Section62 said:

Thames Water (who ought to know what they are talking about)

Absolutely groundless assumption. I remember reading some E-on's guide (on energy) written by some absolutely clueless idiot(s).

I get the feeling you just want to have an argument here grumbler, rather than actually offering helpful advice to people who have frozen water pipes.

No, it's just my nature to find real sense in everything, and to understand instead of just believing in everything said.

Anything wrong with this?

There are far too many urban myths around to believe in everything you hear.

Water expanding in volume as it is heated, once it is warmer than 4C, is not an "urban myth" though. It is a scientific fact.

But you don't have to believe it if you don't want to.

Yes, it's a fact - absolutely isolated, not explaining anything. 

Before the water started expanding, it was frozen. When melted, it contracted significantly first.

Was it frozen?  How could we tell that by looking at an opaque pipe?

grumbler

Section62 said:

grumbler said:

Section62 said:

grumbler said:

Section62 said:

grumbler said:

Section62 said:

Thames Water (who ought to know what they are talking about)

Absolutely groundless assumption. I remember reading some E-on's guide (on energy) written by some absolutely clueless idiot(s).

I get the feeling you just want to have an argument here grumbler, rather than actually offering helpful advice to people who have frozen water pipes.

No, it's just my nature to find real sense in everything, and to understand instead of just believing in everything said.

Anything wrong with this?

There are far too many urban myths around to believe in everything you hear.

Water expanding in volume as it is heated, once it is warmer than 4C, is not an "urban myth" though. It is a scientific fact.

But you don't have to believe it if you don't want to.

Yes, it's a fact - absolutely isolated, not explaining anything. 

Before the water started expanding, it was frozen. When melted, it contracted significantly first.

Was it frozen?  How could we tell that by looking at an opaque pipe?

We talked about frozen pipes, didn't we?

Unless it's at the melting point, 0C, it's easy to tell if needed. Breathe on the pipe, and see what happens to the condensation. If the condensation doesn't freeze and you aren't sure that the pipe was frozen,  don't heat the pipe.

ThisIsWeird

Pinapple, if you'd like to post a photo of the inside of your base unit, we can hopefully suggest ways of getting access to the pipes behind it.

Section62

ThisIsWeird said:

Even for this, other variables would also need to be involved, such as the water expansion having to occur in a completely sealed side of the frozen plug. Most often, surely, at least one side will be available to accommodate such tiny expansions, either by pushing the water back down the 'mains' system, or up to a storage tank...

If that side is open or semi-open then yes, the water (subject to passing any check valves) could be 'pushed back'.  But how does someone with a suspected frozen pipe know which 'side' any given point on their pipework is?

Hence the advice to start with a 'known' - a tap which has been opened, and work back towards the supply side.

....or even just being swallowed by an elastic expansion of the rest of the pipework as occurs in normal use?

This "elastic expansion" is what engineers would talk about in terms of "stress".  Stress exceeding capacity (strength) is what causes things like pipes to burst. Pressurising a pipe causes it to be stressed.  Stress it too much and it will burst.

I do not think that what Section62 has brought to our attention is a myth, but I just wonder if it has been over-claimed in the cyber-ether, from a misinterpretation of what happens in reality - the pipes thaw out, and the leak is then revealed?

It was taught on degree-level hydraulic engineering courses before the internet was invented... so I'd be reasonably confident the BiB isn't the case.

elsien

Not a chance I was wanting to take when my landlord's dodgy handyman did approach my frozen pipes with a blow torch.  I erred on the side of playing safe. 

ThisIsWeird

Section62 said:

ThisIsWeird said:

Even for this, other variables would also need to be involved, such as the water expansion having to occur in a completely sealed side of the frozen plug. Most often, surely, at least one side will be available to accommodate such tiny expansions, either by pushing the water back down the 'mains' system, or up to a storage tank...

If that side is open or semi-open then yes, the water (subject to passing any check valves) could be 'pushed back'.  But how does someone with a suspected frozen pipe know which 'side' any given point on their pipework is?

Hence the advice to start with a 'known' - a tap which has been opened, and work back towards the supply side.

Good point - first step should be to open the kitchen cold tap, which hadn't occurred to me, so I didn't suggest it to the poster. It would also be a good guide as to how the unfreezing is getting on - as soon as a trickle begins, you can stop warming the pipes; the rest will occur naturally with the balmy incoming water.

....or even just being swallowed by an elastic expansion of the rest of the pipework as occurs in normal use?

This "elastic expansion" is what engineers would talk about in terms of "stress".  Stress exceeding capacity (strength) is what causes things like pipes to burst. Pressurising a pipe causes it to be stressed.  Stress it too much and it will burst.

I am talking purely about the 'elastic' part of the expansion, where pipes flex and expand naturally on a daily basis simply by taps being turned on and off. I would imagine that this would absorb a great deal - if not all in most cases - of the thawing-expanding water. Coupled with the at least 50% chance that any expansion will be accommodated simply by the water backing up from whence it came.

I do not think that what Section62 has brought to our attention is a myth, but I just wonder if it has been over-claimed in the cyber-ether, from a misinterpretation of what happens in reality - the pipes thaw out, and the leak is then revealed?

It was taught on degree-level hydraulic engineering courses before the internet was invented... so I'd be reasonably confident the BiB isn't the case.

I accept the science - I've already said that. And it was new to me, so thank you. (Did these degree-level engineering courses refer to 'freezing domestic pipes', I wonder, and make the claim that it was the cause of the majority of bursts?)

I am talking about practical situations such as this poster's. My point is simply that firing a fan heater under that base unit, or a hair dryer through a hole from the w/m space is extremely unlikely - in my practical, long-in-the-tooth-based view - to be the cause of a subsequent pipe burst. My critical faculties suggest to me that the vast majority of water pipes that burst due to cold conditions, will occur as the pipes freeze and not due to the subsequent thawing process. The evidence of the burst - a water leak - will manifest itself after the thaw, yes, but I cannot see it being commonplace that it was caused by it. But obviously I cannot demonstrate that in any realistic way.

Genuinely interesting topic.

ThisIsWeird

elsien said:

Not a chance I was wanting to take when my landlord's dodgy handyman did approach my frozen pipes with a blow torch.  I erred on the side of playing safe. 

Pfffft - I would have said, "Bring it on, pal!"

And then gone and fetched a towel :-(

Eldi_Dos

One observation I have noticed over the years is that bottles that are outside and have water in them during freezing weather seem to fracture when the cold spell is at the thawing stage rather than the coldest spell.

ThisIsWeird

Eldi_Dos said:

One observation I have noticed over the years is that bottles that are outside and have water in them during freezing weather seem to fracture when the cold spell is at the thawing stage rather than the coldest spell.

Or possibly the fractured bottles are being held together by the ice, and only fall apart when thawing out?!

I really don't know. If it is as you and Section 62 say, then I will certainly have learned something I had been completely unaware of.

Mutton_Geoff

grumbler said:

There are far too many urban myths around to believe in everything you hear.

I agree, including the widespread urban myth that pipes burst when they thaw 

https://www.youtube.com/watch?v=34QI8mLeOd0

About 6 mins in.