Has Anyone Lagged Their HW Immersion Heater?

Just wondering is anyone has bothered to lag their immersion heater in France.

Ours was replaced in 2020, so it’s a very modern, well insulated one. However, it sits in the attic which has some insulation, but isn’t heated.

I’m just wondering if anyone’s lagged their immersion heater and did they notice any difference.

I guess you mean the ballon d’eau chaude? They are generally well insulated anyway, but a little more cant hurt. Word of warning about installing in the attic though. Had a friend who thought this was a good idea, unfortunately during a very cold snap, the safety valve on the incoming cold froze and split. Being in the attic it caused much water damage throughout the house. Also, being out of sight (and mind) its not so easy to keep an eye on it for leaks, checking safety valve etc.


our ballon d’eau chaude (200ltrs) is placed in a discrete corner of the bathroom/utility room and is heated automatically using the HC setting on our electric system.
There is sufficient hot water provided for the whole day and to insulate it further would make it look, well, ugly and unnecessary.
As @Mark suggests, placing this device in a loft was not perhaps the best option.
You might have more overall success bumping up the insulation in the whole loft perhaps using the high performance multi-foil insulation sheets available in the brico sheds at roof truss level.

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Alas, we inherited the location and to be brutally honest, putting it anywhere else would be an enormous PITA.

Pipes to and from have some ancient felt/fabric wrapping, but I will be replacing this with foam sleeves.

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Our tank is in the cellar, and lagged with 2 covers purchased from Screwfix.
It may have contributed to our electric consumption reducing last year - hard to tell as we had other changes carried out at the same time.

My view is for the marginal cost, its probably worth it.


They are incredible efficient unlike the Brit equivalents…would suggest adding extra insulation is a waste of time and money.

What do you mean?

quote=“Beerbiker, post:6, topic:41823”]
would suggest adding extra insulation is a waste of time and money.
No not really, mines in a corner of the room in a box with 60mm of reticel foiled pir insulation sealing it in where possible stays warm for days instead of 24 hours. That said I will replace it with a Sunamp heat battery at some point

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Ours is in our utility and we have lagged it, as the room is not heated. I know it works, because when I slide my hand inside the cover, the ballon is very warm. Without the cover, it feels cold. The ballon is a new one and well insulated, but it’s not 100% perfect. We run the ballon on creuse hours and never run out of hot water, even with guests, but it certainly stays a lot hotter, longer. Hope this helps.


We brought ours across from Screwfix UK as well, finding anything in France was next to impossible.

All heaters are not equivalent concerning insulation (have a look there https://www.leroymerlin.fr/produits/chauffage-plomberie/chauffe-eau-et-ballon-eau-chaude/chauffe-eau-electrique/).
So, if yours has a bad rating, yes it is worth adding some insulation.

There is a small part of the hot water tank that does not (yet) have insulation.

I used a hand held thermal leak detector and found out that there is just over 1C difference between the uninsulated & insulated surfaces.

Used one of these: