Calculate Water Heating Time: 2000W Heater, 140L Tank, 50 Degrees - Optimal Boiler Settings

Question

I hope the topic went to the right section. Maybe to the point. I am looking for the optimal boiler settings in order to obtain the best savings ratio by using a programmable socket. So the question is, is it possible to somehow calculate the time of heating the water to a certain temperature -...

Darom · Accepted Answer

Hello You need: Specific heat of water 4.19 kJ / kgK Water density 1 kg / dm3 Power (rate of supplied energy) 2kW = 2kJ / s Initial temperature: e.g. 15 degrees C. Final temperature 50 ° C Volume of heated water: 140l = 140dm3. It's so as not to bother Uncle Google anymore Just put it in the formula and you have time to heat up. Right - everything, assuming that the thermal insulation is perfect, and this is not true. kisses - GIFT-

CYRUS2 · Answer

Not easy only for those who played truant in physics lessons. Sometimes you don't program it. You need a temperature sensor.

Anonymous · Answer

~ 4.1 hours.

Loker · Answer

Wikipedia -> proper heat. It certainly was in physics. Another thing is that the result will be approximate - without taking into account the heat losses through the boiler insulation, without taking into account the influence of water consumption (i.e. fresh, cold inflow) during heating. Better not an ordinary thermostat? Most boilers have ... When the temperature is reached, it will turn off the heating.

arecoag · Answer

Not true, because 5 hours 11 minutes 34 seconds

arecoag · Answer

Why did you write the initial temperature, e.g. 15 degrees C, maybe 0.4 degrees C.

WędkarzStoLica · Answer

And I agree with that. There will not always be identical conditions - Ie. initial temperature of cold water in the tank.

arecoag · Answer

To calculate anything, you first need to give some initial conditions and specify what you want to calculate.

Darom · Answer

I wrote eg that means for example. It is different in summer and different in winter. You have to put on something. You wrote 5 hours ... without specifying the starting temperature, which may be misleading.

arecoag · Answer

It's best to measure.

Darom · Answer

I know what my water inlet temperature is at the moment, because I have a thermometer in the basement. In the case of spider_net this temperature may be slightly different. In addition, they have completely different values in winter and summer. kisses - GIFT-

spider_net · Answer

Dear gentlemen, you got to know each other ... and it's great As for my attraction to physics, yes - I didn't really like this subject. But maybe to the point - as for the input temperature, let's actually average these 15 degrees. I would be glad if some of you provided information about the formula of the formula mentioned above, because in this wiki article I get lost a bit: / You will reveal how to count it after railways? Or maybe a colleague arecoag or somers?

Darom · Answer

You multiply with yourself in the units I gave: Specific heat * amount of water * temperature difference (e.g. 35 ° C). You divide the result by the power. You get time in seconds. You divide it by 3600 and you get the result in hours. kisses - GIFT-

vodiczka · Answer

A difference of just a few degrees Celsius.

Darom · Answer

In my street, the water supply goes very deep and in fact there are no great differences. But I have a friend where it is more than 10 degrees. I don't know what it is conditioned on. kisses - GIFT-

vodiczka · Answer

Your thermostat is out? You optimally set the lowest possible temperature of the water in the boiler so that (whether mixed with cold or independently) you ensure a constant supply of hot water. I set up a 50-liter boiler at 35 degrees on the plot and that's enough for me. A programmable socket makes sense when you leave the house in the morning, come back in the evening and you do not want to heat the water unnecessarily during the day, but it will give you significant savings at 90 ° C settings. Up to 40 ° C, heat losses will be small and economy too

WędkarzStoLica · Answer

In summer, cold water reaches even 17 degrees. In winter it drops below 5 degrees. This is the case with me, for example

vodiczka · Answer

Water source: Deep well / shallow well / municipal water supply and the length and degree of heat losses per meter. connections. Added after 2 [minutes]: I have 16-12 from the municipal water supply. I skip the heating of the pipe section at home, because here, after a warm night, the water in the pipe is over 20 degrees.

Darom · Answer

I wanted to support my colleague here. These losses may be minor. Anyway, they can be easily estimated (having a thermometer). It is enough to check how many degrees the temperature has dropped when the boiler was not used, leaving it in the off state. These will be exactly the heat losses that we can potentially recover using the timer. kisses - GIFT-

shulc · Answer

They have already given them all, the specific heat of water, and here you have to calculate how much energy you need to heat the water by xxx degrees. Your heater takes energy and produces different energy, match the units and good luck, then correction, power (heat) loss etc.

Darom · Answer

One of my colleagues drew my attention to the sentence from the previous post: that it is not entirely true. Well, yes, and he is actually right. But I just didn't want to complicate matters. So yeah. First of all, this is true if the temperature drop is quite small, e.g. 5 degrees C. Then we can assume that it is approximately linear - in fact it will be the exponential function / exp (-t / tau) / and that would have to be taken into account. But then, when these temperature drops were significantly greater. Secondly. I assume that the user makes maximum use of the heated 140 liters. Well, because if it uses a small amount of water (for example, it consumes only 2 liters every day), the economy takes its toll here. And this regardless of whether it is with a timer or not, because why heat the remaining 138 liters (such an extreme case). kisses - GIFT-

zen_gac · Answer

What is the author of the topic of the boiler? 140 liters? Because in such a 140 L boiler for water heating, it can be used for further calculations only in the case of having circulation. Is it really so?

vodiczka · Answer

What is your colleague about? I can have a 300l tank without circulation and I will also count the time needed to heat this amount of water.

CYRUS2 · Answer

This is one correct answer. When taking the measurement, you take into account all losses. Because, for example, during heating, water is also cooled - heat dissipation. Why does your colleague need this time - for automation?

zen_gac · Answer

Let me give you an example. I have an 80L boiler without circulation. The heater is centrally located in the center. For example, set at 65 degrees C. Not all 80L will reach 65 degrees when the thermostat is activated. There will be cooler water in the lower part of the boiler. Therefore, I dare to say that having a boiler without circulation for the desired time unit, I will not have the entire content of the boiler at the expected temperature. Please correct me if I am thinking incorrectly. Greetings- zenek g.

Anonymous · Answer

You are right, if the heater is not at the bottom of the tank, there is no chance of heating the entire volume without circulation.

Frog_Qmak · Answer

Some kind of circulation will be created naturally (water after contact with the heater heats up and goes up), but the truth is that this circulation will not be extremely fast, so temperature gradients will arise in the tank, which may slightly extend the process (hot water is more difficult to heats, it will still be cold at the bottom)

vodiczka · Answer

Agreed, but the problem is the location of the heater, not the capacity of the tank or the existence or non-existence of circulation. When the heater is placed in the lower zone of the tank (say 5-10 cm above the bottom), natural circulation is created due to the difference in density of hot and cold water.

Frog_Qmak · Answer

one is related to the other

Calculate Water Heating Time: 2000W Heater, 140L Tank, 50 Degrees - Optimal Boiler Settings

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