hot water heaters and winter draining

[londoneye]

Hi

We have a couple of buildings which are not heated in winter, and which have hot water tanks in - the standard french chauffe-eau electrique.

I have no doubt that the temperature in the buildings goes below zero in mid-winter.

Last year we drained down the water tanks, but recently someone told me you are not meant to do this.

Does anyone know if it is best to drain them down or leave them please ?

[tonyv]

I've always drained mine (in the unheated attic) down, but it's a pig of a job and I'd rather not do so. I'm hoping to leave my central heating running at a low setting over the winter.

[Northender]

They are very well insulated so I don't think they would freeze up.

However the problem is if you don't drain off its difficult to ensure that the feed-in and feed-off pipes are completely drained and it would be these that would be most at risk.

I have drained ours for the last 10 years with no apparant ill effects.

Its a waste of 200l of water , I know , but we do have peace of mind.

[DerekJ]

We've done it for the last two years and will do again when we leave at the end of October after our next three week stay.  A real pain but no problems in doing it so far.  I tend to agree with Northender, it's probably the adjacent pipework that is more at risk.

[londoneye]

thanks - we are talking 700 litres of water, which sort of riddles me with guilt actually (not the cost, because water not terribly expensive in this area) but the waste thing.

Ok - will probably continue as before then, draining down, unless someone suggests otherwise !

[Alpinemist]

We drain our pipes down to the lowest faucet, flush all the W.C's so no water in the tanks but leave the water heaters. Been OK so far.

[Araucaria]

We can (and do) drain the water out of all the supply pipes - yes, remembering to flush the loo and get as much water out of it as possible - but we leave the hot water cylinder as is, full, and turned on. The supply and flow pipes to/from the hot cylinder will be empty, so there's nothing to freeze. As the cylinder both fills from the top and supplies hot water from the top (and the heater element is at the bottom) I can't see that there will be any problems. There haven't be so far, and we've had some very cold winters.

[Cacknanty]

We have a 150 ltr and 200 ltr hot water tanks. Since 2003 we have never drained them after our final visit of the year at the end of October.

Grasping some wood, we have not had a problem with the tanks. We only get problems with pipework and that is after blowing compressed air through the hot & cold systems.

I guess residual water drains down to the lowest point and then freezes.

We also put some sticks and salt in the water of the loo pan as we did have a cracked toilet once on our return in the spring.

I understand that temperatures can get down to -12 to -15 in the winter. We went once in February - never again, bleedin freezin!!!

Cheers

Nig

[andyh4]

[quote user="Northender"]They are very well insulated so I don't think they would freeze up. .[/quote]

 

A common misconception or misunderstanding.

Insulation only changes the speed at which things get colder or hotter from the outside.  It does not stop them getting cold and freezing.

No matter how good the insulation is, in reality if the temperatures have a prolonged period below freezing, the temperature of your tank will go down and down and down and will eventually go below freezing point.  The only positive thing to say is that the reverse is true when warming up and gentle warming might just stop a frozen tank from bursting.

 

FWIW before we moved permenantly we had a tank that was powered via a normal electric plug and put this on a suitably sized timer (3KW) to come on for half an hour morning and evening to ensure that heat was always put back into the tank.

[BIG MAC]

We switch the water off and drain down taps (Leaving them open)

By taking the pressure off we effectively leave a full tank but room for expansion via the ballon.