Electric Boiler Usage: Monthly Costs, Tariffs, and Water Temperature Maintenance

Hello, honorable forum members. I wanted to know if any of you use domestic hot water heating through a boiler with an installed heater. The most important question is what is the cost of using such a boiler for currently two people. But it is known that this may change. Which tariff is better to use. And how quickly does the water temperature drop in such a boiler? The rest of the questions, etc., will certainly arise during the discussion. I will be very grateful. Greetings.

Radoslaw88 wrote:

The most important question is what is the cost of using such a boiler for currently two people.

It's only a fairy who knows.

Radoslaw88 wrote:

And how quickly does the water temperature drop in such a boiler?

What boiler? as above

Radoslaw88 wrote:

The rest of the questions, etc., will arise during the discussion.

Well, the discussion started.

Too little data. Enter for which boiler size, or heating only in a cheaper tariff, approximate daily demand for hot water and what temperature of this water would be considered hot by you.
Estimated, with the currently specified conditions, an amount from 150 to 300 PLN higher in the electricity bill should be taken into account.

A boiler, say, 80L. Once a day washing up Once a day, a bath of 30-40L, let's say. And in the morning I wash my face with my teeth, you know.

What boiler? Let's say this: ARISTON VELIS 80L (I shoot). You can recommend one. The tariff depends on how quickly the boiler cools down. Because if it is relatively slow. It can be thought of a nightstand. Warm up right in the morning, then in the afternoon well and, if necessary, heat up in the evening.

When it comes to a satisfactory temperature, I think 45 degrees?

So indicatively, you can calculate the costs yourself. Boiler capacity times the number of hours per day of heating (so on average) times the cost of a kilowatt hour in your tariff. it will come out how much you will have to pay per day.

Ok, so to be sure that my reasoning is good: On the example of this arista what I wrote there 80L.
Data:
Max working temperature 80 degrees.
dT = 45C is 3h.
1.5kW power.
Heat losses at 60C are 1.2kWh per day.

So assuming that we use 80L per day. This is 3 * 1.5 = 4.5kWh
In addition, 1.2kWh for heat losses, although I do not know how it changes with the temperature set to, say, 45-50 degrees. so we already have 5.7kW per day. I assume a gross price of PLN 60. Although I do not know what it is like in those regions. so from this daily it comes out: 5.7 * 0.6 = 3.42 PLN / day. Only I count it like this: I pour 80L, it warms to a certain temperature. I will wash it during the day. Then companies. And in the morning a morning toilet. I do not take into account that when bathing or washing dishes, fresh cold water will be poured into the boiler and it will heat it up. So I bet my calculations are quite wrong because it comes out of PLN 102 per month

And when I try to do it another way:
average statistical use per os. it is 1500L which gives 19 * boiler capacity
heating the boiler at 45C, i.e. 4.5kWh. So 19 * 4.5 = 85.5kWh * 2 people * 0.6 PLN = 102 PLN. What do you think about these calculations?

Also, if someone (like me) does not know anything about it, you can get confused because both methods produce the same results, but in the first method I use half as much water.

Two years ago, I also heated water at home with an electric boiler (in the summer season, i.e. somewhere from the beginning of April to the end of September). Ariston 50l boiler, 3 people lived in the house at that time, two of them often used to travel outside the house, so statistically it can be assumed that on average there were 2 people. Standard use as at home, but everyone was aware that it was water heated by electricity, so no one was sitting in the shower for an hour as long as it was necessary.
Bills on average higher by about PLN 100 - 110 than in winter, these are my calculations based on consumption written down every month and converted according to the current rates (I was also afraid of high consumption, so I counted everything).
The 50l boiler and I must admit that for two people it would be optimal, if there were three at home and it was time for a shower, the first had hot water, the second was still quite comfortable and the third had to wait at least half an hour. With time, all of them somehow "spaced out in time" and the problem was no longer there.

How was it used? Actually, without much control, the knob was set to 3 (on a scale of 4) and turned on when it wanted to. As they were all home then he was working at full capacity. I have no idea what temperatures it corresponds to, but I think it was about 45-50 degrees on the 3rd degree.

I think that the 80l boiler will have slightly greater heat losses due to its dimensions, and there are also slightly higher electricity rates than two years ago. Nevertheless, I believe that two people should not exceed PLN 150 per month. Of course, with prudent use, because it is known that 20.30l can be poured into a conventional bathtub and 150l can be poured into it, so this is where you can lose / gain the most.

Hello.

Radoslaw88 wrote:

... you can get stupid because both methods work the same, but in the first method I use half as much water.

You count reasonably well, think about the temperature of the water in the first and second methods.

Maybe a bit off the topic, but I can tell you what it looks like with water heating with natural gas, and I think the costs will be comparable or maybe even smaller because the consumption of a few to a dozen m3 include costs related to distribution, such as: costs for readiness, costs fixed costs, variable costs and others. Which colleague already pays in electricity. So for two people a month is about PLN 70, with a daily bath for 2 people, washing dishes and a daily morning toilet.

that is, according to a colleague oregon25, with 2-3 people, such heating will come out about PLN 100 per month. The boiler 80 is also characterized by the fact that, compared to 50, there is a smaller temperature difference between the set and the current temperature after mixing, so it heats up shorter.

As for my friend Berg's question, I assumed that in both cases I set the temperature at 45 degrees.

While talking to one friend who has a 150L boiler, he did a test and heated it only with an electric heater in the summer. The heater has some 2-2.5 kW, it does not know itself. And after connecting the meter, the energy came out for 3 people during the week about PLN 20. What according to for me is probably too low a result. But then the rates were also lower. And the colleague has a fixed rate.

And I am still wondering if in the case of the G11 tariff it is not a better solution to use a flow heater of appropriate power, e.g. multi-point? Because in this case, the boiler does lose this energy. The boiler would be a good solution for the G12 tariff and some clock.

And if we are talking about the G11, it is a flow type with, say, 18kW, if a 3 ~ power supply is available. It according to me, such a heater takes 18kW from the network in the case of the set maximum temperature and the maximum load of its outputs. And if, for example, the bath water is heated in one moment, he will take, say, 10kW. to warm it to 45 degrees. And if, for example, the max flow of such a heater is 9L and I jerk 4, in 10 minutes it will swallow 10kW / 6. Which gives 1.5kWh, or about 1.1 PLN. for a bath.

And going back to the assumption that statistically a person consumes 1500L of water per month, 2 people consume 3000L. so at a maximum flow of 9L / min. this gives an operating time of 334 minutes at its maximum power of 18kW. Moving on, 334min / 60 = 5.6 hours of heater operation, consuming 18kW. i.e. some 108kWh (rounded up). from this it comes out at a price of PLN 0.7 per kwh PLN 75 / month. What do you think?

@ Radoslaw88 These calculations of yours are a corner ...
First, the consumption of 1.5 m3 / month / person is according to me unreal. We have a family of 4 and we consume about 12 m3 / month. We don't have a bathtub, only a shower. Maybe we are wasteful and raccoon dogs, but conversations with other families show that we are "middle class".
With two people, the consumption should be greater per person, because the so-called almost constant costs like washing pots. Generally, the fewer people in the common household, the more per capita.
Let's leave the amount of water aside. You take as much as you get out of the meter.
Now the problem of estimating the amount of hot water, i.e. the one that needs to be heated, in relation to cold water. You can initially assume 50%.
Now thermophilic. is water at 38 oC warm for you as it is assumed by, for example, manufacturers of thermostatic batteries, or maybe 45 oC. Take as much as you can.
With the amount of water to be heated and its final temperature, you can count:
Energy needed to heat the water = mass of water to be heated * its specific heat * difference in water temperature before and after heating * unit conversion factor (kJ per kWh)
Assuming 2 people, 3 m3 / month each, we have 6 m3 of cold water, of which 3 m3 are heated.
Now there is a "little thing". Mains water has a different temperature in summer and winter. From about 18-20 to about 6-8 oC. Taking for winter, you can calculate for yourself for summer, and the hot water temperature is 40oC we have:
3000kg / mc * 4.19 kJ / kg / K * (40-8) K * 0.000278 kWh / kJ = 112kWh mc
The calculation does not take into account downtime losses!
The cost depends on the tariff.
This is an average calculation. This is what a flow heater would take under these conditions.
And now the stairs and trouble in estimates begin.
The smaller the capacity of the heater, the higher the temperature you need to heat the water so that there is no shortage of it. Standstill losses are increasing. They also increase when the capacity of the heater is reduced, because its surface changes more slowly than its volume. Pure geometry.
The second tariff makes sense (in the sense of water heating!) Only for large heaters, so that the water heated at night will last for the whole day, but the downtime losses increase again - a long waiting time for the evening increased water consumption.

Pi * doors will be about 150 kWh per month.
PS. I consider the proposals to install a flow heater to be senseless because:
1. Usually installation is 1F and / or in terrible condition. Such a heater is min. 18kW to avoid taking a shower in cold water. The power allocation for 1F is max 5kW! Even for the typical 3F power allocation - 11kW is not enough!
Not only that, with a greater allocation of power, the costs constantly "donated" to electricity (power plants) grow
2. The investment costs are higher and the device more complicated and given to failures.
The optimal solution for heating DHW with electricity in terms of operating costs is a heat pump, but it only sleeps in single-family houses - a place - and with higher water consumption. The investment costs are considerable and the complication even greater.

jack63 wrote:

The optimal solution for heating DHW with electricity in terms of operating costs is a heat pump, but it only sleeps in single-family houses - a place - and with higher water consumption. The investment costs are considerable and the complication even greater.

Could you elaborate on the cost and complication of installing a DHW heat pump?

yarecki16 wrote:

Complications when installing a heat pump for DHW

I wrote about the complication of the device as such.
Assembly is usually not complicated. With compact pumps, it is probably even simpler than that of a gas boiler. As always, the matter is very individual. It all depends on the "local conditions" and the type of heat pump. There are many more variants than gas boilers.
There is no need to hide the investment costs, especially when it comes to CO. In the case of DHW, they are much lower, but they will not break, for example, a capacitive electric heater.
As I wrote. Everyone has a slightly different starting position, leading to completely different end costs.

I am thinking of reducing the cost of DHW heating and changing the central heating heating. But I don't know how yet because the situation is complex.

Currently, I have a solid fuel boiler with no gravity control and CO. Electric boiler, no connection to the stove. I also do not have a gas connection at home. There are basically two options:

1. Making a gas connection - 1F boiler with a tank, heating DHW with gas all year round
2. Replacing the boiler with a modern boiler with a feeder, DHW in winter from the boiler, in summer just so as not to heat it with electricity, it is a compact heat pump. I mean a pump, e.g. by Defro:
http://www.defro.pl/kotly_pompa_ciepla.html
Or Galmet
http://www.galmet.com.pl/pl/news/12-pompa_ciepla_galmet_energia_pelna_oszczednosci
I do not mean these devices in particular, but this kind and type.
Such a pump is quite universal because it has a coil like a boiler. I could buy it today and use the cheaper DHW heating with a pump compared to an electric heater, and then after buying a boiler with a feeder or a gas boiler, I would connect it to this boiler.

Everything is fine, but what does it have to do with the topic ??
Create your topic, we'll discuss.

Well, it actually deviated from the topic a bit, so I'll put my own.

Hmmm, since the topic deviates from the track and we explained everything, I think that we can close the topic. In the event that someone would have any new sensible suggestions, write to the pw. I'll open the topic again.

It is true that the cost of DHW depends on many factors that are difficult to estimate (shower / bath, adults / small children, etc.), it can be a little bit averaged. In my opinion, you can take 1 thousand kWh per person and more or less this is what comes out in my house (shower, only adults). And this is a good starting point for calculating the cost of DHW - PLN 600 / person per day (approx. PLN 0.60 / kWh), and PLN 300 / person per year at night (approx. PLN 0.30 / kWh). At the same time, there are regional differences and different G12 tariffs. The regular G12 overnight is the cheapest, but for those working Monday through Friday, the slightly more expensive G12w weekend may be better. It is simply enough to do household chores such as washing, ironing, mowing lawns with an electric mower. etc. to perform on Saturdays. To this, let's add the electricity consumed by TV, computers, refrigerators, etc. on Saturdays, Sundays and holidays (and nights) and the average cost of kWh goes to the head. On the G12w, it is cheaper for approx. (Approx. Because there are holidays) 100 hours a week (168 hours a week!). When I did not have a collector, I paid about PLN 50 a month for electricity to the boiler (2 people).

When choosing a boiler, it is worth paying attention to two things: capacity and thermal insulation. Personally, I prefer this setting when the hot water from the boiler is optimal for washing and bathing without turning on the cold water. This requires a boiler with a larger capacity, but at the same time there is less heat loss. These depend on the external surface of the boiler as well as the quality and thickness of the thermal insulation and, most importantly, the temperature difference between the water in the boiler and the surroundings. When I improved my boiler in such a way that I put aluminum foil under the leatherette cover, and an additional layer of foam insulation under the upper lid, heat losses are basically negligible. Currently, I heat the water with a collector and the temperature in the evening is 1 degree higher than in the morning, five times the door, 300Wh of losses in a 200 l boiler per day.

gaz4 wrote:

1 thousand kWh per person can be assumed

Add how many hours, days, months are there in this thousand? Because you stress people.

gaz4 wrote:

I paid about PLN 50 a month for electricity to the boiler (2 people).

So close to my estimates. No?

Obviously, 1,000 kWh per person per year And it's a maximum of a thousand, by saving hot water, you can go down to 700 kWh, and if you limit the losses on the boiler + super-efficient showers, you can get even 500-600 kWh per year per person. As they say, the devil is in the details, and there are a lot of them, and a little bit more.

This cannot be compared. Some shower 2-3 times a week and others take a full bath every day. Some people brush their teeth, shave or wash them under running water, and how does this compare with those who save? Well, it is not possible for everyone, it is an individual matter.

yarecki16 wrote:

This cannot be compared.

Can be. A water meter is enough - less accurate. How two separate it is more precisely. How two and a heat meter are great. This is "without grace" for those who have DHW after the MPEC exchanger.

Well, actually, people in the city who have DHW from the heating plant have a hot water meter, but I meant people who prepare DHW on their own. I could set up a DHW counter, but firstly, it is a cost, secondly, flow limitation, and thirdly, not needed.

yarecki16 wrote:

I could set up a DHW meter, but first of all it is a cost,

The cost of the water meter itself (not the energy meter) is small.
The flow restriction is bearable too. You want to play accounting, that's the free way.
It makes little sense to me, because I will not reduce the costs thanks to the measurement. Well, unless I start walking dirty ...
However, in the case of renting a premises for gastronomic purposes, the installation of a heat meter pays off. The simple ones based on a mechanical water meter cost several hundred zlotys.
Regenerated and without legalization for less than 300.
You want to buy and assemble. If you do not want flow resistance, for about 2k PLN you have a heat meter with ultrasonic flow measurement.
I prefer to pay PLN 100 a month and ... not to be nervous.

I have a stove with a DEFRO feeder and in the previous years, in the summer season, I heated the boiler with 200l eco-pea coal. On average, a day for a family of 4 goes to 5 kg / day of eco-pea coal, i.e. the cost of about PLN 4. This year I changed the tariff from G11 to the weekend G12W and the boiler heater is switched on during the hours of cheap electricity (PLN 0.25 per KW / h) using the control clock. The boiler uses an average of 7 to 8 KW / h per day, i.e. the cost of electric heating is half cheaper than coal, and the additional profit is that you do not need to select ash, you do not need to clean the furnace, you do not need to add eco-pea coal and the most important thing is additional electricity savings due to the fact that the furnace is disconnected, i.e. the feeder, fan, circulation pump do not consume electricity , stove controller.
Electricity in the tariff with a price of 0.25 groszy per 1KW / h, hot water for a family of 4, Galmet insulated boiler, 2KW heater costs around PLN 60 per month, and coal around PLN 120

I have g12w. In addition, a timer that switches on the boiler only at a cheap rate. 100-liter boiler. At home, two women, a small child and I use the bathtub often because of my profession. Corner bathtub 150x150 cm, so quite large. It's about 150 zeta a month. It never happened that there was no shortage of hot water.

Bałdyzer wrote:

I have a stove with a DEFRO feeder and in the previous years, in the summer season, I heated the boiler with 200l eco-pea coal. On average, a day for a family of 4 goes to 5 kg / day of eco-pea coal, i.e. the cost of about PLN 4. This year I changed the tariff from G11 to the weekend G12W and the boiler heater is switched on during the hours of cheap electricity (PLN 0.25 per KW / h) using the control clock. The boiler uses an average of 7 to 8 KW / h per day, i.e. the cost of electric heating is half cheaper than coal, and the additional profit is that you do not need to select ash, you do not need to clean the furnace, you do not need to add eco-pea coal and the most important thing is additional electricity savings due to the fact that the furnace is disconnected, i.e. the feeder, fan, circulation pump do not consume electricity , stove controller.
Electricity in the tariff with a price of 0.25 groszy per 1KW / h, hot water for a family of 4, Galmet insulated boiler, 2KW heater costs around PLN 60 per month, and coal around PLN 120

This is 60 PLN, it is a bit reduced because the electricity is more expensive in the remaining hours - I know, during rush hours, my wife never connects a washing machine, a refrigerator, a TV, laptops, etc.
But besides, I would choose the heater in your place anyway, despite the fact that 5 kg of coal is a bit of exaggeration or you should play with the settings on the controller, and maybe clean the exchanger.
Everyone forgets about one more important matter - the coal boiler, after all, it warms up the walls a bit, which is not cool in the summer.

It is just the opposite for me. The amount of PLN 60 is the nominal cost of heating hot water, counting the amount of KW / h used by the boiler and multiplying it by 0.25 groszy. However, compared to previous years, the electricity bill will remain at the same or a minimum level of about PLN 10 / month lower because the electricity costs 68 groszy per KW / h in more expensive hours, which is only 13 groszy more than it was in previous years, i.e. a uniform rate of 55 pennies. On the other hand, electricity in cheap hours is as much as PLN 0.30 cheaper, taking into account that in one weekly cycle there are 98 hours of electricity cheaper, and only 70 hours of electricity more expensive. My structure of KW / h consumption during the week is 120 KW / h of cheap electricity and 36 KW / h of more expensive electricity.
To sum up, the boiler consumes about PLN 60 per month, but the overall savings due to the low electricity price at the time when I use it the most (the proportion of almost 1 KW / h more expensive to 4 KW / h cheaper) is about PLN 70, so the bill will not increase compared to previous years, and it may even decrease slightly due to the fact that the boiler is turned off all summer season, and it consumes about 1 KW / h a day (pump, blower, controller, feeder). The saving is about 1 ton of unburned eco-pea coal in the summer season. Finally, I would like to add that at home we pay attention to the hours of cheaper electricity only when using three power-hungry devices: washing machine, boiler, dishwasher.

In my example, a boiler 220L heater 1800W, the test is exactly 31 days
2 people shower daily normal use, dishes to be washed 2x daily morning toilet.
Within a month (31 days) the heater consumed 428kWh, which is according to my current tariff 428x0.6 PLN 256.8
I skipped heating the water with electricity after this test and I continue to heat it with pellets even in summer because it is a bit cheaper.