Can cold water be used to melt frozen water pipes in your home?

Yes. As long as the water is above freezing it will tend to melt the ice, but could itself freeze if the ice and pipe are very cold.

No, use warm water instead. Using cold water won't help melt frozen pipes in your home. Instead, try using warm water. Warm water can help thaw them and get the water flowing again. 

1 hour ago, Ammaniya said:

No, use warm water instead. Using cold water won't help melt frozen pipes in your home. Instead, try using warm water. Warm water can help thaw them and get the water flowing again. 

Yes. And warm water is even better. Warm water can help unfreeze freeze water in your pipes. Because it's warm, you see. 🤪 

18 minutes ago, exchemist said:

Yes. And warm water is even better. Warm water can help unfreeze freeze water in your pipes. Because it's warm, you see. 🤪 

You could also use hot water. Hot water is better than warm water.  🤪 

 

Thawing pipes containing frozen water can have unwanted consequences; how to go aout the job needs careful consideration.

Also a hair drier or other hot air blower is better since you won't have wet pipes to cope with.

If you must use hot water, soak a cloth in the water and wrap it round the pipe. Rinse and repeat.

 

Of course the water freezing itself is not as much of a trouble; the bursting of pipes is the major concern.

For the burst prevention, once I was building the plumbing in a remote cabin in the woods and inserted 6mm foam rods as used in filling cracks inside every pipe length in the dwelling.   The expansion of ice compressing the closed-cell air bubbles in the foam to prevent burst.

The building inspector did not like it only because had never seen such before. 

 

More entered to the subject; there is pipe heaters:

 

 

Just now, Externet said:

For the burst prevention, once I was building the plumbing in a remote cabin in the woods and inserted 6mm foam rods as used in filling cracks inside every pipe length in the dwelling.   The expansion of ice compressing the closed-cell air bubbles in the foam to prevent burst.

Interesting, you have taught me something.  +1

 

Just now, Externet said:

Of course the water freezing itself is not as much of a trouble; the bursting of pipes is the major concern.

It the dangers rather depend on where the freeze up is.

Some years ago, when we had colder winters, we were away for a holiday and when we came back there was no water coming out of the hot taps, except for an initial flow.

These taps were fed from a DHW copper cylinder, with an attic header tank and gravity inlet feed.

The attic tank had frozen, blocking its outlet to the DHW tank, causing a vacuum to prevent water exiting the hot tank.

I found this when I heard a crumpling sound and investigated.

The DHW tank had crumpled inwards because of the vacuum.

I was so relieved when the soft copper popped back to shape, but remained watertight. after the attic tank was thawed.

 

In very cold climates, PEX eases a lot of suffering.  Though now it's being considered for the eco-villain list because it is plastic.  

Those semi-slit foam insulation tubes with the self adhesive closures are also handy, on the outside of pipes.  You can buy them with the little T and L junctions and get thorough coverage of a water line.  Another help for sink water lines (because counter/sink are often along an exterior wall) is to open the cabinet space under the sink at night, so warmer room air infiltrates that space better.  (just be sure you don't have chemicals under there a pet or toddler could get at)

Putting thin foam rods inside pipes seems like a recipe for a future clog - never heard of that.  But I see the principle.  

6 hours ago, studiot said:

Interesting, you have taught me something.  +1

 

It the dangers rather depend on where the freeze up is.

Some years ago, when we had colder winters, we were away for a holiday and when we came back there was no water coming out of the hot taps, except for an initial flow.

These taps were fed from a DHW copper cylinder, with an attic header tank and gravity inlet feed.

The attic tank had frozen, blocking its outlet to the DHW tank, causing a vacuum to prevent water exiting the hot tank.

I found this when I heard a crumpling sound and investigated.

The DHW tank had crumpled inwards because of the vacuum.

I was so relieved when the soft copper popped back to shape, but remained watertight. after the attic tank was thawed.

 

That’s odd. Was the hot water cylinder not vented? I thought that was a requirement, e.g. a riser off the main hot water exit at the top of the cylinder.  If it had been, there would have been no vacuum created. 
 

(I went into this once, worrying about whether I could change a tap washer on a hot tap in my house, after turning off the cold water feed to the cylinder. I eventually convinced myself I could not collapse the cylinder, because of the vent pipe.) 

Edited January 16Jan 16 by exchemist

Just now, exchemist said:

That’s odd. Was the hot water cylinder not vented? I thought that was a requirement, e.g. a riser off the main hot water exit at the top of the cylinder.  If it had been, there would have been no vacuum created. 
 

(I went into this once, worrying about whether I could change a tap washer on a hot tap in my house, after turning off the cold water feed to the cylinder. I eventually convinced myself I could not collapse the cylinder, because of the vent pipe.) 

The discharge pipe went straight up from the airing cupboard containing the tank into the attic and curved over the header tank to discharge into it.

Straight into the block of ice at the top of that tank.

9 hours ago, Externet said:

For the burst prevention, once I was building the plumbing in a remote cabin in the woods and inserted 6mm foam rods as used in filling cracks inside every pipe length in the dwelling. 

Mmm. Sounds tasty! Any impact on your health from consuming foam rods as they break down?

Allowing a slow drip from a faucet also helps prevent pipe rupture if ice forms.

1 hour ago, studiot said:

The discharge pipe went straight up from the airing cupboard containing the tank into the attic and curved over the header tank to discharge into it.

Straight into the block of ice at the top of that tank.

Blimey! So the vent pipe was dipping into the water in the header tank. How weird. So you would have had cold water being sucked down the vent pipe when you ran hot water off. Not a great piece of plumbing, by the sound of it. But now I see why it had the effect it had. 
 

Comforting to know the cylinder can pop back into shape rather than splitting at the seams, at any rate. 🙂