Yield Production Hot Water Electric

[PVresistif]

little theoretical reminder to those who would like to increase the thickness of the cover of their water heater:
- 1) by increasing the thickness you increase the outside diameter in contact with the cold atmosphere therefore you increase the exchange surface and therefore the losses.
-2) if you put a glass wool coat in an unheated and humid volume the wool will soak up moisture and the insulation will be destroyed
So putting on a coat is a bad idea. The good idea is to move the water heater as close as possible to the appliances and in the heated space
You reduce losses and in addition you keep the electrical parts and the cover subject to deterioration in the presence of moisture.

Another point: to put a water heater under the roof in the attic is to expose oneself to serious disappointments in case of water leakage (water damage) which is inevitable because the water heaters are more and more fragile (by planned obsolescence, it will most likely be corroded by the device)

[chatelot16]

no don't say anything!

adding insulation increases the total diameter ... but is it the inside or outside diameter that counts to calculate the loss?

neither one nor the other: each layer of insulation adds a thermal resistance which reduces the losses ... of course if we increase the number of layers to infinity we arrive at a point where the diameter of the layers becomes so much great that it does not bring much more ... but in practice we always stay away from this extreme absurd

condensation? Why ? an insulator must be ventilated on the cold side, and waterproof on the hot side ... so the tank of the water heater is waterproof and the glass wool on the cold side does not need any seal against condensation

so we can isolate a hot water tank anyway with any glass wool

the only problem is the thermostat of the current standard water heaters which absolutely needs to be cooled so as not to rise to the water temperature

[izentrop]

- 1) by increasing the thickness you increase the outside diameter in contact with the cold atmosphere therefore you increase the exchange surface and therefore the losses.

Obviously false, the measurements show it without question.

-2) if you put a glass wool coat in an unheated and humid volume the wool will soak up moisture and the insulation will be destroyed

The vapor barrier is not for dogs.

Another point: putting a water heater under the roof in the attic is exposing oneself to serious disappointments in the event of water leakage (water damage)

Only true statement.
An unforgettable memory of a baptism with a brother-in-law where the ceiling fell on the table. Fortunately, a warning sign made us move away in time

[Forhorse]

The vapor barrier is not for dogs. [/ Quote]

It's not even a story of vapor barrier ... it's just a story of vapor itself. From a water heater in good condition, no reason that there is the slightest vapor or any humidity that escapes. So no risk of condensation.

[izentrop]

Yes, you are right but in this case, it is the outer part of the glass wool that must be protected. Either the kraft paper of the coated insulation, or more solid: a waterproof membrane. http://www.apper-solaire.org/Pages/Expe ... %20ballon/

[PVresistif]

I see that here the thermal is really not well known; it is a beginner's exercise to calculate the thickness of insulation from which the insulation increases losses; on the other hand I remind you that for a cylinder (water heater) the thermal resistance does not depend on the thickness but on the logarithm of the ratio of the diameters inside and outside (see your math lessons of 1st for reminder on the logs.)
Humidity: no water heater is insulated with glass wool but with polyurethane which is a closed structure (therefore less sensitive to humidity,)
I challenge anyone who could measure the performance of the insulation of a water heater - all the manufacturer's loss data are calculation values ​​and therefore theoretical; one can think that they are underestimated.
React as a Buddhist: don't try to change everything but rather adapt yourself to reality; I assure you that a water heater in the bathroom is the ideal and the most profitable .... all performance is achieved:
Minimum investment, minimum losses, electrical equipment in a heated environment ideal for the duration of the equipment ...
Ciaoooooooo

[Ahmed]

Everyone agrees with your last point, even those who are not Buddhists!
For the rest, it's really anything: you probably confuse with the profitable thickness of insulation which is a compromise (valid only at the time of calculation) between a value of increase in insulation and the additional cost when the thermal gain becomes marginal ...
Is it isolating logarithms?

[dede2002]

There is one detail that should not be overlooked, and that is that a water heater is supplied "almost" permanently by very cold water at the bottom.

I have had a few "concerns" before seeing a puddle of water under the water heater in the morning, but these are not just condensation leaks.

So the insulation at the bottom is almost useless, as long as one draws hot water the bottom of the tank is cold.
As long as we don't heat the stratification, only the top stays hot, but as soon as we heat the water is stirred by convection and the bottom, which is more difficult to isolate, warm and radiates.

If you install the thermostat high enough (and have enough power), you rarely have lukewarm water at the bottom, but if you heat constantly with a small power you have no stratification and the water heater radiates from below.

[Forhorse]

If the water heaters are insulated with polyurethane it is primarily for mechanical reasons. For transport and storage, it can be put in any way without the risk of the insulation being packed when arriving at the end customer.
In industrial insulation (hot water, steam, ovens, or hot fluids in general), mostly rock wool is used without any particular problem.
Polyurethane is used for the insulation of cold fluids (installation of chilled water for example) because there is indeed a big problem of condensation.

[Forhorse]

If you install the thermostat high enough (and have enough power), you rarely have lukewarm water at the bottom, but if you heat constantly with a small power you have no stratification and the water heater radiates from below.

Stratification has nothing to do with heating power, it is simply a matter of density. Hot water is less dense, so it rises.
When the entire volume to be heated is at the same temperature and we continue to heat it, it starts again: the water a little warmer than the rest rises until the entire volume is again at the same temperature.
In short, convection cough ...