# Panic - heat not turned on in empty house



## HMC (30 Nov 2010)

I'm a total panic since this cold snap began.  My house in Cork is unoccupied, currently with a full tank of water (!) and the heating turned off, and my keyholder friend cannot reach the house to turn on the heating because of road conditions.  

What kind of temperatures can pipes endure before they burst?  The house is a semi-d, about 10 years old.  I've been thinking of nothing else for the last 24 hours.

Hopefully someone can put my mind at ease.


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## aristotle (30 Nov 2010)

Its not the temperature that causes pipes to burst, its the way water expands when freezing and that obviously happens at 0c degrees.

You may not have burst pipes, sometimes it happens and sometimes it doesn't. Only way to know is to go to the house.


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## jpd (30 Nov 2010)

after the thaw - if the water in the pipes is still frozen, there will be no leaks


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## roker (1 Dec 2010)

I am in a 10 year old semi and I am just back from holiday. Before I left the house I turned off the stop cock and drained the header tank through the bath, I know there is still about 6 gallons in the primary circuit but I did not drain the heating system because I have chemicals in to stop rot.
The tanks should be over the hot press and lagged which will give them a chance in a freeze. The idiot plumber that constructed our system put the tanks 6 foot high up in the loft making them impossible to lag. I monitor the temperature in my loft and it is approx 4 deg higher than the outside temperature, if the temperature goes negative I have a small electric oil filled radiator under the tanks that I switch on.


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## villa 1 (1 Dec 2010)

The 'idiot plumber' may have installed your tanks 6 ft up in the attic so as to increase water pressure in your domestic hot and cold water system
In severe cold conditions pipes and tanks will freeze but leaks will not occur until there is a thaw.
It is good practice to completly drain both heating and plumbing systems during times of freezing weather conditions in unoccupied houses/buildings. This includes hot water cylinders that are known to collapse with catastrophic leaking during extreme cold weather conditions (frozen cold feeds and vent - vacuum - leak)


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## roker (1 Dec 2010)

If the house is being left regularly, anti-freeze can be added to the primary circuit,
My last house had plenty of pressure in the shower without the header tank being raised. This house did not have a shower installed that works from the header tank.
Water pressure is aprox 0.5 psi for every foot in height


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## villa 1 (1 Dec 2010)

You can add anti-freeze to heating systems but not the domestic hot and cold.
In a typical house if you site your storage tank on the ceiling joists and put in a gravity fed shower you will end up with approx 4ft head which translates into a miserable pressure of approx. 2lbs/inch,.15 bar  and that's not taking into account frictional losses from pipes and fittings.


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