Power reducer ???

[chris34]

Hello !

I would like to have information on a certain "Power reducer" It would be an accessory allowing to trigger an accumulation of EC with a power lower than that required from factory for the resistance ??? Is this system reliable? what are the constraints ???

Thanks in advance; O)

[raymon]

I already made this kind of modification replace a resistance of 2000 w by a resistance of 1200w that allows to have a little more power available for other uses only small drawback you sometimes risk running out of hot water longer before the hot water stock is replenished.

[chatelot16]

as long as the thermostat cuts the heating at the same temperature, and this temperature is reached reducing the power of the resistance will not reduce the total energy consumed ... simply it will heat longer

reducing the power is useful especially when you have too low an EDF subscription and it trips when you use another device at the same time

a simple trick to divide the power by 2: put a diode in series with the resistance, it only heats on a single alternation ... and as the circuit breakers are thermal, they see a current divided by 2

[chris34]

Thank you Raymon and Chatelot,

what I want to do and actually heat my 1200 W cumulus ... lentemeeeeent! I am on an autonomous site, I have a lot of sun all day: so: I would like to heat my cumulus, with 300 W in 4 times longer ...
I do not want to modify the cumulus but I thought I saw that there are power reducers ... have you ever seen / tested this ???

[chatelot16]

in this case it is possible to send all the power available in the water heater, it will make a voltage completely variable according to the power made by the sun, provided that the power is lower than the maximum tolerated by the resistance

it is also possible to make a kind of load shedder which favors more noble use than heating water, and sends to the resistance only the rab when there is nothing better to do

[raymon]

A bit of a shame to use photovoltaics to heat water. A simple system is a plastic coil behind a glass that works much better even in winter! I have a friend that has it at home without storage and he does the dishes after lunch and no problem.
Of course we can do better but it's more complicated by looking a little on the forum.

[chatelot16]

shame of simply heating water with photovoltaics ... but when we install photovoltaics for self-consumption, when we do not consume everything, and that EDF still does not want to buy electricity without complication send the rab to heat water is less stupid than losing everything

the problem is the regulatory system: I don't see anything good in trade ... you have to be even

[izentrop]

Hello,
You can also supply the resistor with PWM regulation.
http://www.apper-solaire.org/Pages/Expe ... rsion%202/
Chatelot, do you have a ref to do it yourself?

[raymon]

shame of simply heating water with photovoltaics ... but when we install photovoltaics for self-consumption, when we do not consume everything, and that EDF still does not want to buy electricity without complication send the rab to heat water is less stupid than losing everything

Of course I agree there is also a beautiful scandal there.

[Gaston]

what I want to do and actually heat my 1200 W cumulus ... lentemeeeeent! I am on an autonomous site, I have a lot of sun all day: so: I would like to heat my cumulus, with 300 W in 4 times longer ...
I do not want to modify the cumulus but I thought I saw that there are power reducers ... have you ever seen / tested this ???

A simple timed relay can do the trick: 1 minute on / 3 minutes off = average power of 300W over 4 minutes (this is only a very slow PWM).

Otherwise, a transformer: by supplying the resistor with a voltage twice lower, we divide the power by 4, and that's good because transformers 220V / 110V, it's very common