Re Xmas: Chauffe-eau left on or ....

[suein56]

Hi

We are going back to the UK for Xmas leaving our rented house for about 12/13 days. We cannot decide whether to leave the 200 L chauffe-eau switched on, or switch it and the water-supply off. I am told the chauffe-eau is 10 years old, and it is in the garage. I think the groupe de securite (sp?) might be starting to wear as it drips occasionally outside of the heures creuses when  the CE comes on automatically. Not having had a CE before we are unsure what is the best action to take. I am not overly worried about frost as we live in a mild climate by the sea.

Has anybody any thoughts on this?

Sue

[Liz]

A chauffe eau does seem to retain its heat for an amazing amount of time so from the economy point of view I wouldn't normally bother to turn it off for a few days absence.  But, particularly if it is in a garage, I would not take the risk and I would turn everything off.  We live in a pretty mild area too but we had one occasion a few years ago when we had a bust pipe, in our absence, due to an exceptional frost.

Liz

[Ty Korrigan]

Hello, Sorry to but-in, does any-one know how long a 100litre tank takes to heat up?

 Ta, Ty

[Loiseau]

My tank (sorry, I don't know the capacity, but it's as tall as I am - about 5'4" in old measurements) takes about 4 hours to heat right up.  It's distinctly feeling warm after an hour or two, when you wash your hands though.
When it's already full of hot water, the tank seems to hold its heat for a couple of days.

I would always turn my water supply off at the mains before leaving for a week or more.  Our hot-water tank sprung a leak one night for absolutely no reason at all (only about 10 years old).  Fortunately (a) we were in residence; and (b) I was still up (probably on the LF forum!) and wondered what the strange noise was.  Could have been a very nasty discovery otherwise...

Angela (UK and 85)

[suein56]

Many thanks to those who replied - and for confirming my gut instinct which was to switch off the chauffe-eau and the water at the mains.

Thanks again and

[*][*] Happy Christmas [*][*] 

to everyone

Sue

[Anton Redman]

[quote user="Ty Korrigan"]

Hello, Sorry to but-in, does any-one know how long a 100litre tank takes to heat up?

 Ta, Ty

[/quote]

From memory a kilowatt is 1000 watts and is the amount of heat  required to increase the temperature of 100 litres of water by 10 degrees.  Therefore assuming heater is rated at 1 Kilowatts and you need 20 degrees above ambient about two hous.

[Nick Trollope]

[quote user="Anton Redman"][quote user="Ty Korrigan"]

Hello, Sorry to but-in, does any-one know how long a 100litre tank takes to heat up?

 Ta, Ty

[/quote]

From memory a kilowatt is 1000 watts and is the amount of heat  required to increase the temperature of 100 litres of water by 10 degrees.  Therefore assuming heater is rated at 1 Kilowatts and you need 20 degrees above ambient about two hous.

[/quote]

I thought it was 4.2 Joules to heat 1cc of water by 1 degree. Isn't 1J 1Watt for 1 second? ie. 4.2W for 1second = 1 degree rise in temp.

Therefore, to heat 200L by 50 degrees with a 2400 Watt heater you would need (50degrees x (200 x 1000)cc x 4.2) / 2400 seconds?

Give or take the thermal & electrical efficiency of the heater and assuming no losses in the system....

About 6 hours according to the manual for my 200L Sauter.

I got my physics A level a long time ago....