Frozen pipe in extension

Pineapple88

Hi, I'm wondering if you lovely people can help me to sort out a difficult to access frozen pipe? 

The cold water pipe in my kitchen (which is in an extension) has frozen overnight. All other taps in the house are ok (including the hot water tap in the kitchen). The heating has been on whilst I've been at home but the kitchen, with three external walls and questionable wall insulation, is always the coldest place in the house. 

I've tried to access the pipe but apart from a small section which runs to the tap, the rest of it is hidden behind the sink unit. No part of the pipe seems to be exposed outside apart from a small section which connects to the outside tap (which is also frozen). 

For the time being I'm running the hot water tap in the kitchen in the hope that the heat it generates it will help to heat the cold water pipe up slightly (doubtful, but not sure what else I can do), and have left the sink cupboard open and have turned on the heating and am running a fan heater in the kitchen to try and heat the room up. 

Is there anything else I could/should be doing to find the pipe and thaw it out? 

Thank you 

ThisIsWeird

You seem to have all areas covered Running the hot is a good idea, assuming the pipes will be close to each other for this to have an effect - good chance they are. Don't 'waste' hot water - just have it running at a trickle, as the hot pipe won't be any hotter if running at a fast lick.

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

Pineapple88

Thank you! Unfortunately the back panel has been slid in before the worktop and sink were put on top. There's a dishwasher next to the sink  but the kickboard and plinth at the bottom of the cupboard aren't coming out easily. I think long term I will need to saw through the back panel and lag the pipes

Section62

ThisIsWeird said:

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

No, the OP was correct to use a fan heater to gradually warm up the room as a whole.  The idea is to raise the temperature slowly so the ice melts gradually, avoiding a build up of pressure which could burst the pipe.

The worst thing to do with a frozen pipe is to "blast it" with heat - even if the blasting is in the general direction rather than directly on the pipe.  The key word here is 'slowly'.

If it is desperately urgent to get the pipe working again then call a plumber - as they will then be able to fix any burst or leak they caused by the rapid heating of the pipe.  Especially important where the pipes are inaccessible behind/under kitchen cupboards.

OP, once you've got the pipe flowing again, isolate the supply to the outside tap (if you can), then wrap it with insulating material (anything will do).  The chances are the cold outside was conducted into the pipes inside via the outside tap and connecting pipe.

Also, if you don't already know where it is, find the location of the main stopcock before you do anything else so you can turn the supply off if a pipe does burst.

FreeBear

Section62 said: OP, once you've got the pipe flowing again, isolate the supply to the outside tap (if you can), then wrap it with insulating material (anything will do).  The chances are the cold outside was conducted into the pipes inside via the outside tap and connecting pipe.

If this pipe is prone to freezing on a regular basis each winter, it might pay to add a heat trace under any lagging. Kits are not particularly cheap, and there is a running cost to consider (budget about 0.01KWh per metre). But it only needs to be powered up if/when temperatures plummet to zero or lower, so the annual running cost shouldn't be very much.

Section62

Pineapple88 said:

I think long term I will need to saw through the back panel and lag the pipes

If the pipes - including the one to the outside tap - are copper, then lagging them can sometimes make the problem worse.  The lagging can stop a cold pipe being warmed by the ambient air in the room, counterintuitively making it more likely to freeze than if it is left unlagged.

The most important thing to do is to either insulate the outside tap, or else create a 'thermal break' between the pipe outside and the pipes inside.  This could be done by having an isolating valve followed by a length of plastic pipe before the pipe goes through the wall to the outside.  In cold weather, turn off the isolating valve and open the outside tap to let the water drain off.

ThisIsWeird

Section62 said:

ThisIsWeird said:

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

No, the OP was correct to use a fan heater to gradually warm up the room as a whole.  The idea is to raise the temperature slowly so the ice melts gradually, avoiding a build up of pressure which could burst the pipe.

The worst thing to do with a frozen pipe is to "blast it" with heat - even if the blasting is in the general direction rather than directly on the pipe.  The key word here is 'slowly'.

If it is desperately urgent to get the pipe working again then call a plumber - as they will then be able to fix any burst or leak they caused by the rapid heating of the pipe.  Especially important where the pipes are inaccessible behind/under kitchen cupboards.

OP, once you've got the pipe flowing again, isolate the supply to the outside tap (if you can), then wrap it with insulating material (anything will do).  The chances are the cold outside was conducted into the pipes inside via the outside tap and connecting pipe.

Also, if you don't already know where it is, find the location of the main stopcock before you do anything else so you can turn the supply off if a pipe does burst.

I hadn't realised - I'd always assumed that the 'burst' would have occurred with the freezing, and thawing it out would only reveal the fact it had been burst.

ThisIsWeird

Pineapple88 said:

Thank you! Unfortunately the back panel has been slid in before the worktop and sink were put on top. There's a dishwasher next to the sink  but the kickboard and plinth at the bottom of the cupboard aren't coming out easily. I think long term I will need to saw through the back panel and lag the pipes

It will be the most awkward panel to redo because of all the pipes in the way, and some presumably passing through it, but it's quite doable with a bit of patience. Clearly worth doing, since this will be a recurring problem.

Any access holes through from the dishwasher recess - aren't there pipes and hoses going through to the kitchen base unit? A hair dryer gently... blown through there will very likely sort it.

And, yes, know where the mains stopcock is, and check that it operates smoothly. If it's a multi-turn type (the most common), then whenever you open it up fully, always back it closed a half-to-one turn. This won't affect the flow rate, but will make it far less likely to seize in the open position.

macman

ThisIsWeird said:

Section62 said:

ThisIsWeird said:

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

No, the OP was correct to use a fan heater to gradually warm up the room as a whole.  The idea is to raise the temperature slowly so the ice melts gradually, avoiding a build up of pressure which could burst the pipe.

The worst thing to do with a frozen pipe is to "blast it" with heat - even if the blasting is in the general direction rather than directly on the pipe.  The key word here is 'slowly'.

If it is desperately urgent to get the pipe working again then call a plumber - as they will then be able to fix any burst or leak they caused by the rapid heating of the pipe.  Especially important where the pipes are inaccessible behind/under kitchen cupboards.

OP, once you've got the pipe flowing again, isolate the supply to the outside tap (if you can), then wrap it with insulating material (anything will do).  The chances are the cold outside was conducted into the pipes inside via the outside tap and connecting pipe.

Also, if you don't already know where it is, find the location of the main stopcock before you do anything else so you can turn the supply off if a pipe does burst.

I hadn't realised - I'd always assumed that the 'burst' would have occurred with the freezing, and thawing it out would only reveal the fact it had been burst.

Solids, liquids and gases all expand when heated.

ThisIsWeird

And water expands when freezing, which is surely the primary cause of burst pipes?

Yes, water also expands due to heat, but in this case - using a fan-heater or hair dryer - any expansion will be minimal, because the actual temperature rise in the pipe will also be tiny.

grumbler

Section62 said:

ThisIsWeird said:

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

No, the OP was correct to use a fan heater to gradually warm up the room as a whole.  The idea is to raise the temperature slowly so the ice melts gradually, avoiding a build up of pressure which could burst the pipe.

The worst thing to do with a frozen pipe is to "blast it" with heat - even if the blasting is in the general direction rather than directly on the pipe.  The key word here is 'slowly'.

I don't think there is any physics behind this. Pipes burst because of water expanding when freezing, not because of some pressure 'building up'.

macman said:

ThisIsWeird said:

Section62 said:

ThisIsWeird said:

Your best bet is the fan heater, as this will likely get to the frozen area most quickly. Don;t try and warm the whole kitchen, but aim it at the frozen site. The best ways will be from under the sink base cupboard - can you unscrew the plinth? If so, aim it in there so it flows up behind the unit where there will be a gap. Or, is there a washing machine beside the sink base? Pull it out and look in there - any holes or gaps in to behind the sink base? If so, see if a hair dryer can fire a warm blast in there.

As with the running of the hot tap, I wouldn't necessarily have the heaters running full blast, but at a medium setting - give the pipe time to thaw. If that doesn't work in 30 minutes, then blast it!

No, the OP was correct to use a fan heater to gradually warm up the room as a whole.  The idea is to raise the temperature slowly so the ice melts gradually, avoiding a build up of pressure which could burst the pipe.

The worst thing to do with a frozen pipe is to "blast it" with heat - even if the blasting is in the general direction rather than directly on the pipe.  The key word here is 'slowly'.

If it is desperately urgent to get the pipe working again then call a plumber - as they will then be able to fix any burst or leak they caused by the rapid heating of the pipe.  Especially important where the pipes are inaccessible behind/under kitchen cupboards.

OP, once you've got the pipe flowing again, isolate the supply to the outside tap (if you can), then wrap it with insulating material (anything will do).  The chances are the cold outside was conducted into the pipes inside via the outside tap and connecting pipe.

Also, if you don't already know where it is, find the location of the main stopcock before you do anything else so you can turn the supply off if a pipe does burst.

I hadn't realised - I'd always assumed that the 'burst' would have occurred with the freezing, and thawing it out would only reveal the fact it had been burst.

Solids, liquids and gases all expand when heated.

 Ice is a solid, but it melts and contracts. At least when its temperature is just below freezing.