House unoccupied - complete drain down CH & DHW

Leaving house unoccupied Dec-Jan> Boiler a bit iffy and gas costs a lot so I am planning to drain everything. But normal draining doesn't get everything out does it? Queries

DHW: The loft tanks are grey asbestos type (1975 build). Will the water below the outlet crack the cistern if it froze?

DHW Likewise the water remaining in the DHW cylinder below the outlet will not be a worry as my airing cupboard is in the middle of the first floor and completely surrounded by other rooms?

WC cisterns. Assuming the house interior remains above zero no problem? Likewise sink and bath traps?

CH: The boiler will be separately drained so that just leaves the worst case of the CH copper pipes in the ground floor concrete screed. In 1975, these were just wrapped in hessian. However, I assume the concrete floor inside a relatively modern well insulated house in Cambridge will not go below zero even with a winter like last.

All comments,suggestions welcome

If you have no heat source then the inside will become the average of the outside temp.

The usual advice is to have the heating on low to keep the house at about 5-6 C and have someone come in to check the house every week or so!

Tony

mahogany said:

L I assume the concrete floor inside a relatively modern well insulated house in Cambridge will not go below zero even with a winter like last.

All comments,suggestions welcome

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Assume nowt. I went to many houses that had completely frozen up over he last winter, even if they had the heating on for a couple of hours morning+evening.

If the water is drained as best you can from tanks, pipes, boiler etc then you should be ok. Issue's arise when the water freezes and has nowhere to expand into.

Timiing the heating is where most people go wrong!

Its coldest overnight so thats when the heating is needed most.

Leaving a boiler on to keep it to 5-6 C is not very expensive and an save lots of damage.

Tony

mahogany said:

. However, I assume the concrete floor inside a relatively modern well insulated house in Cambridge will not go below zero even with a winter like last.

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IMHO, you assume wrong.

Check your insurance policy with regard to the requirements of leaving the house unoccupioed for more than 2 weeks and leaving the heating off.

I'd fit a frost thermostat, if the boiler were reliable. You could add anti-freeze, but it's costly and causes huge corrosion problems once it 'goes off'.

The tanks will split, put a plastic ball in.