Chauffe eau

[CeeJay]

Circumstances have changed and I now wish to turn down the chauffe eau to less heat. It is a De Dietrich 150litre about 5 years old. I have taken the cover off the bottom and could only find a longish black thing with a screwdriver slot in the end and a plus and minus sign either side. Is there other indication as to how it is possible to achieve a certain temperature other by trial and error. The long black thing clicks as it is turned so does that mean that it is gradiated in some way?

[Théière]

Yes that's the thermostat and the click is the switch operating. My note of caution is reducing the temperature could leave you open to bacterial growth.

[Quillan]

The 'black thing' is more likely to be the thermostat and it no doubt works the way you have said. I know at least two of mine have deg centigrade marked on them but then they were bought from one of the Brico sheds.

I would measure the temp as it now is first think in the morning. Turn it as far as you can in the minus direction and wait 24/48 hours and measure again. You should then be able to roughly work out the value of each increment and then set it accordingly. Best of luck.

[Quillan]

[quote user="Théière"]Yes that's the thermostat and the click is the switch operating. My note of caution is reducing the temperature could leave you open to bacterial growth.[/quote]

Thats actually a very good point.

[CeeJay]

Point taken, so how far down could I go with safety, however, thinking about it wouldn't the same thing apply if I only put it on every other day for example. What you are implying seems to be that the heater needs to be fairly high all the time! Please excuse my ignorance.

[AnOther]

I don't wish to pry but why would you want to do such a thing ?

If running costs are a concern then you might be interested to know that my chauffe eau which has power available to it for 3 hours a night (it takes what it needs in that period) is turned up to the max but still only costs €10/mth to run. I use flat rate electricity.

It's easy to imagine it being more but I put an energy monitor on it when I installed it about 4 years ago and monitored it for over a year so I know that the €10 figure is pretty well spot on.

We've never ever run out of hot water either not even when there were eight people in the house in the Summer or 2013 !

One visitor does like to take baths and that rips the ar5e out of it but she wasn't one of the eight !

[andyh4]

quote user="CeeJay"

Point taken, so how far down could I go with safety, however, thinking about it wouldn't the same thing apply if I only put it on every other day for example. What you are implying seems to be that the heater needs to be fairly high all the time! Please excuse my ignorance.

unquote

At or below 50 degrees you are likely to promote the growth of Legionella. At 55 degrees you kill it.

Once it is dead, it is dead and will not reappear until you get fresh bacteria brought in with a supply below 55 degrees. Once heated to 55 this then also dies.

A "safe " minimum should then be taken as 55 degrees. 60 would be safer.

[Théière]

From the talks I have attended and the information from the HSE at 55 deg most pathogenic bacteria are killed but Legionella strains can survive for 5-6 hours so 60 deg is recommended.  There has been a steady increase in Legionella cases throughout Europe and it is now a mandate from the HSE that all buildings are regularly checked and monitored, France being a warmer climate again would mean precautions should be taken.

[AnOther]

Again without wishing to pry without understanding what the actual end objective is its impossible to properly advise how to achieve it.

It can't just be cooler water though can it because that can be achieved at the tap !

ALL buildings regularly checked Théière, surely you don't mean that ?

[Théière]

[quote user="AnOther"]

ALL buildings regularly checked Théière, surely you don't mean that ?

[/quote]

Yes a little open ended with that, all commercial buildings and multi occupancy residential blocks with communal boilers/aircon/cooling towers etc must now test and log for legionella.  The build up of limescale is seen as a great hiding place for  legiononella.  There was a case not too far back when a person caught the infection from a shower head on a campsite and it's in the papers almost every week.

[CeeJay]

Thanks for all the replies, very interesting.

The end result? Well, from going to a household of four to now just two OAP's I thought we could reduce the bill somewhat and either lower the temp or elso have it on every other day.

However, the figure that AnOther quoted is totally manageable, and the scare of Legionaires disease now has me backtracking somewhat!

[Théière]

Probably for the best and AnOther has shown it can be done economically.  something to be said for the old copper cylinders as they could sit there and just kill bacteria.

[andyh4]

quote user="CeeJay"

Thanks for all the replies, very interesting.

The end result? Well, from going to a household of four to now just two OAP's I thought we could reduce the bill somewhat and either lower the temp or elso have it on every other day.

However, the figure that AnOther quoted is totally manageable, and the scare of Legionaires disease now has me backtracking somewhat! UNquote

Having a downsized family, you probably have some duvets or blankets that are not being used on regular basis.

These can be draped over the hot water cylinder. Even though they have a polyurethane coating to insulate them, you will find the coverings become warm against the cylinder, showing that they are helping reduce heat loss and keeping the bills down a little.

[AnOther]

If you don't feel any warmth on it's exterior when it's at full temp then it's not losing heat !

A 5 year old quality chauffe eau (De Dietrich) should be perfectly well insulated and will not benefit from external wrapping.

[Théière]

Unfortunately considerable heat can be felt on the outer casing of my Sautier heater.

[andyh4]

quote user="AnOther"

If you don't feel any warmth on it's exterior when it's at full temp then it's not losing heat !

Unquote

Strangely not true (I would have thought that as well). The effect was found by accident when a blanket was just placed on top of the cylinder for want of somewhere to put it.

The coating is not perceptibly warm to the touch when uncovered. When covered by the blanket, the inner surface of the blanket and the coating now feel warm to the touch.

I can only put this down to a very slow rate of heat loss when uncovered - not enough to make the insulation feel warm. This means it would never be worth buying a cover, but using excess blankets/duvets etc. provides a benefit at no cost.

I am sure you will be sceptical and can only suggest that you just try it with a spare blanket and see if it feels warm underneath after say 24 hours.

[AnOther]

It would be a minor miracle if the heat loss were absolutely and completely zero, that would defy the laws of physics, but even triple wrapped in Winter duvets I doubt you could even measure a difference [;-)]

[Théière]

[quote user="AnOther"]It would be a minor miracle if the heat loss were absolutely and completely zero, that would defy the laws of physics, but even triple wrapped in Winter duvets I doubt you could even measure a difference [;-)]

[/quote]

Now that's the point I want to improve on, my cylinder is a horizontal and from the shops I have visited these retail around €850 so not going to change it on a whim.  I am relocating it later and will reflective foil line the new home with insulation backing this up.  The old cabinet you could feel the warmth through the plywood lid and the water would be too cold after 30 hours.