Best Heater Options for 120L Boiler: Power Requirements & Top Brands for 2-Person Household

Hello. I would like to install a summer heater in my boiler. I do not know what power of the heater needs and which companies are the best. My boiler has 120 liters and there are two of us at home. We bathe in the shower and use the dishwasher.
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2kw should be approx

And if I buy 2500w or 3000w, will I save on electricity bills or will I pay more? And will the water heat up faster?

jejeje00 wrote:

And if I buy 2500w or 3000w, will I save on electricity bills or will I pay more? And will the water heat up faster?

The water will heat up faster when you use a greater power heater. As for electricity bills, theoretically there should be no difference. Electricity bills will depend on the amount of hot water consumed and the effectiveness of the thermal insulation of the boiler as well as the insulation of the pipes between the boiler and the taps. Electricity bills will not depend on the power of the heater used.
When choosing the power of the heater, check the power to which the electrical installation powering this boiler is intended.

DiZMar wrote:

When choosing the power of the heater, check the power to which the electrical installation powering this boiler is intended.

Assuming that for a conductor with a cross-section of:
- 1.5mm ^ 2, 10A overcurrent protection is used, which gives us a maximum of 2300W for such a circuit.
- 2.5mm ^ 2, 16A overcurrent protection is used, which gives us a maximum of 3680W for such a circuit.

@ jejeje00
In such a system, it would be appropriate for the boiler to have its own separate electric circuit, because if you share it with other electrical devices, it may be a problem, the higher the energy consumption of the other devices is.

16A fuses are often used for 1.5 mm2 cables, because the 10-amp ones cause that they often "go out". Automatic washing machine + fridge can sometimes blow up a 10. In many buildings, electrical installations are not adapted to today's loads (and gas installations - usually oversized, because in the past there was city gas with a much lower calorific value than natural gas).

BUCKS wrote:

...

@ jejeje00
In such a system, it would be appropriate for the boiler to have its own separate electric circuit ...

Not would be appropriate just obligatory . According to the regulations, a power receiver of 2000W or higher is to have its own power supply circuit from the switchgear, regardless of the wire cross-section and protections used.

jejeje00 wrote:

2500w or 3000w will I save on electricity bills or will I pay more?

You will pay the least by lighting the stove, I know you don't want to do it in summer, but it is the most economical and it will heat up faster because the coil has a power of more than 4 kW.

FishuPro wrote:

...
You will pay the least by lighting the stove ...

Additionally, use flammable rubbish as fuel

DiZMar wrote:

Additionally, use flammable rubbish as fuel

No, wood is enough.

FishuPro wrote:

DiZMar wrote:

Additionally, use flammable rubbish as fuel

No, wood is enough.

However, wood costs something and the rubbish still needs to be segregated and thrown into a suitable container. In the furnace, it will burn without segregation.
Of course it's ironic. It is not allowed to burn garbage in any ovens . Please do not take my advice literally.

DiZMar wrote:

Of course it's ironic.

You don't think that someone in their right mind would take garbage advice seriously

FishuPro wrote:

DiZMar wrote:

Of course it's ironic.

You don't think that someone in their right mind would take garbage advice seriously

You never know. Someone else could report to the relevant services.

jejeje00 wrote:

Hello. I would like to install a summer heater in my boiler. I do not know what power of the heater needs and which companies are the best. My boiler has 120 liters and there are two of us at home. We bathe in the shower and use the dishwasher.

My colleagues described possible problems with fuses and cables - the larger the heater, the more serious they can be. I know from experience that it is not worth overdoing the heater's power because you never know when it will turn on. 2-3 kW added to 2 kW in a dishwasher or washing machine + 2 kW electric kettle and we are already exhausting the 1-phase power allocation.

A 120-liter boiler to heat the water by 1 degree requires almost 150 Wh, including the heat loss in the boiler, this value can be assumed. This means that the 1.5 kW heater will increase the temperature by about 10 degrees within an hour. To reduce the cost of heating water, it is worth ordering the G12as tariff. But only if last year the water was not heated by electricity because there are limits. They rely on the fact that the electricity from 22 to 6 times costs about 20 cents on condition that more than the year before the tariff change to G12as has been used . As long as we do not use more electricity than last year, the normal rate for electricity at night is about PLN 0.60. In this tariff, the rates for electricity during the day are normal, only the monthly ones are slightly higher. 1.5 kW heater in 8 hours can almost boil 120l so it can be considered too big. A good solution is to buy a double heater, e.g. 2x1 kW, which, working with a power of 1 kW, will heat the boiler by approx. 50 degrees in 8 hours, i.e. in summer it will be around 70 degrees. And if the need arises, we turn on 2 kW and the heating rate increases twice. In the old days I had a boiler with switchable power (60l 2x0.8kW) and it was a perfect solution - I did not have unnecessary power on the cables.

DiZMar wrote:

BUCKS wrote:

...

@ jejeje00
In such a system, it would be appropriate for the boiler to have its own separate electric circuit ...

Not would be appropriate just obligatory . According to the regulations, a power receiver of 2000W or higher is to have its own power supply circuit from the switchgear, regardless of the wire cross-section and protections used.

This is often a fiction, not only in pre-war construction, but also in the People's Republic of Poland, where for one apartment (not a suitcase or a room with a kitchen, but e.g. a 3-room) one lighting circuit was used (usually a 10A fuse, although for 6A light would be enough) and one circuit for all sockets (rooms, kitchen, bathroom) - also secured with 10A. In such installations it is very easy to overload because they are not adapted to the current needs. The washing machine itself is loaded with a current of 10A or sometimes even 10A "with a hook", and for example, the refrigerator is not removed from the socket for the duration of washing (supposedly below 1A, but everything adds up). The electric kettle (unfortunately, people use them with gas cookers) is 10A. These earlier electrical installations were rather designed for radios, TV sets (the radio consumes minimal power). Currently, even irons have about 2000W of power (I think 1000W is just right for an iron).

In order for there to be no problems, the power should be as provided by the manufacturer. (And not as advised, 1- 4 kW.)
The power should be read from:
an old heater or a phone call to the service, manufacturer of a similarly manufactured device.
As the rest of the boiler's installation, including its electrical part, is adjusted to the specified power assumed by the manufacturer, these parameters cannot be exceeded!
Jt. electric-pressure device.
When you exceed the recommended parameters against the instructions and regulations, you have to take into account the consequences of your own liability.

@ROWE
This is not a classic electric storage water heater. It is a tank with a coil (heat exchanger) fed from a CO furnace for solid, liquid or gaseous fuel. The heater is to be used in the summer when we do not use the stove. And it is a heater with a built-in thermostat. In the case of a 120l tank, the absolute minimum to ensure the comfort of use is 2kW. If the electrical installation and power allocation allow it, I would rather aim at 3-3.5kW.

teskot wrote:

If the electrical installation and power allocation allow it, I would rather aim at 3-3.5kW.

For what purpose?

jejeje00 wrote:

there are two of us at home. We bathe in the shower and use the dishwasher.

2 kW is enough. of course, it depends on the type of heating, whether normally on the thermostat or occasional heating. In the latter case, either you have to turn on ahead of time or more power to be faster.

It doesn't matter, and so does it. Jt. an energy device regardless of the method of energy delivered to it. The regulations concerning safety and exceeding the factory parameters are as above. the same for all these devices.

ROWE wrote:

It doesn't matter, and so does it. Jt. an energy device regardless of the method of energy delivered to it. The regulations concerning safety and exceeding the factory parameters are as above. the same for all these devices.

Please provide the recipes for the power of the heater for the 120l boiler. There are no such, the manufacturer can only recommend something and that's it. What is the point of using a 2 kW heater in such a small boiler, since in 8 hours (the duration of the cheaper tariff) it can heat the water by over 100 degrees? Apart from the pointless network congestion, I don't see any. The thermostat will turn off the heating not after 8 hours, as in the case of 1 kW, but only after 4 hours, and at 23 o'clock someone wants to drink, after turning on the kettle, they will have 4 kW on the cables, not 3 kW. When the boiler is used sporadically, even 3 kW will be too little power because heating the water from 20 to 40 degrees will take an hour. 2 kW will do it in one and a half times, i.e. the temporary gain from greater cable load is small ...

A double heater is a good compromise. If we care about speed, we turn on full power and make sure not to turn on larger loads during this time. And normally at half power because, as our first post-PRP prime minister said, "haste is good when catching fleas".

gaz4: How is it gone!
Descriptively, stage 1 is valid for the manufacturer and the manufacturer produces based on them and then gives guidelines for the user, service technician, maintenance technician, etc.
And the law verifies this in practice.
You can find what you are interested in on the Internet. This is not the place for any electro-energetic qualification course.
If you ignore it all, I have nothing to add to your reasoning and theories.

I have 2 kW in a 120-liter boiler and I can easily do it, but it all depends on specific users, it's an individual matter. From what I have seen, the manufacturer provides 1.5 and 2 kW heaters for 240V.

ROWE wrote:

If you ignore it all, I have nothing to add to your reasoning and theories.

I just think that the laws of physics take precedence over the statutes. If someone writes in the act that min. the heater for the 120l boiler should be 2 kW, it will senselessly increase the heat loss in boilers heated only with the night tariff. Not to mention that it will unnecessarily burden the national energy system. I doubt that there are any guidelines as to the heater's power, Google is not giving me anything ...

As I wrote earlier, I had a 60l boiler (Elektorolux) with a 2x0.8 kW switchable heater. Calculated for 120l, it gives 2x1.6 kW (in practice, 2x1.5 kW as they are in the market). When used cheaper, the G12as will still generate greater losses than 2x1kW. In both cases, in the morning the boiler will be 70 degrees Celsius, a higher temperature does not make sense.

DiZMar wrote:

BUCKS wrote:

...

@ jejeje00
In such a system, it would be appropriate for the boiler to have its own separate electric circuit ...

Not would be appropriate just obligatory . According to the regulations, a power receiver of 2000W or higher is to have its own power supply circuit from the switchgear, regardless of the wire cross-section and protections used.

Do you also give the electric kettle a separate circuit?

gregorypalasz wrote:

Do you also give the electric kettle a separate circuit?

not, because the regulations have probably required it for over a dozen years.
But from what I know, these are fixed devices such as a boiler, washing machine, etc., and not portable, such as a kettle.

ROWE wrote:

gaz4: How is it gone!
Descriptively, stage 1 is valid for the manufacturer and the manufacturer produces based on them and then gives guidelines for the user, service technician, maintenance technician, etc.
And the law verifies this in practice

Nonsense. You don't know what you are writing about. Boiler with a coil. It does not have its own electrical installation and the boiler manufacturer has nothing to do with it, nor will he give any recommendations. Provide a heater with a built-in thermostat 3-3.5kW and, if necessary, a timer to turn on the heating at the appropriate times.

Added after 13 [minutes]:

jejeje00 wrote:

And if I buy 2500w or 3000w, will I save on electricity bills or will I pay more? And will the water heat up faster?

If there is a greater power heater, the water heats up faster. You will not pay more, and maybe a little less because, for example, with a low-power heater, e.g. 1kW, water heating takes a long time, and heat losses through boiler insulation are always there. By heating the water for e.g. 8 hours, these losses are greater than heating the water for 2 hours and bathing without waiting for the water to cool down. After the bath, the water will not be so warm anymore and the losses will also be lower. By using a timer and a powerful heater, you can set it on, for example, 2.5-3 hours before the bath, and thus reduce the heat loss from the boiler that must be covered by the heater. Also, do not heat the water to a high temperature, because the higher the temperature, the greater the losses. I will write it for example: you give a 400W heater to such a boiler and heat it. The temperature reaches, say, 45-50 ° C and does not increase further because at this temperature the heat losses through the boiler insulation are so large that the heater only covers these losses. Then you pay a lot for heating. With a strong heater, the temperature rises quickly and the heater turns off, and it does not heat all the time, and if you give a time clock, it will not heat up and supplement heat losses when it is unnecessary.

How long does the water in such a 120l boiler cool down? It depends on isolation, of course, but on average.
Let's say it is 60 ° C. how long does it take to reach 40 ° C.

About 5-6 hours. I am writing it on my own example. 140l boiler with a coil, insulated with black polystyrene. I heat up to 80 ° C from 18 to 21 (in summer) (4 people) and from 4 to 5 am (you also have to wash in warm water before going to work). At noon it is still warm (not hot). I have Afrisco reg temp for the bathroom, direct to the kitchen (sometimes you have to steam something). I have had a 3.5kW heater for 2 years. The previous one was 2kW and I had to heat longer. The power consumption is now lower, although not much. In any case, it has not increased.

No separate circuit is needed for the powered boiler.

Strumien swiadomosc... wrote:

No separate circuit is needed for the powered boiler.

I know that a separate circuit is required for a washing machine, and the washing machine also has a plug, so I assumed that this applies to any "fixed" appliance with a power of 2kW upwards.
I didn't look into the rules themselves, so I don't know any exceptions and details.