Choosing Furnace & Heat Buffer Size for 114m2 House, Solar Panels & Underfloor Heating

spinkamidi wrote:

The question is what power should be heated with such a buffer.

We assumed that you have a peak demand of 5 [kW]. Let's assume that during this -20 frost you want to smoke once a day (24 [h]) for 4 [h]. You need a 5 * 24/4 = 30 [kW] boiler.

William Bonawentura
The stove has been purchased - it has 25KW (Kostrzewa Cermik). Thank you for your help in this regard.

miki_fx
Thanks for the diagram.
An interesting option is the water mixing system in the tank. How do you control the pump at the tank - does it run non-stop?

Is it a good solution to introduce a coil at the top of the DHW tank to the buffer, which will lead water to the bottom of the DHW tank. Thanks to this solution, while heating in the furnace, we can heat up the entire utility water tank.

lolson28 wrote:

Hello

I will write you briefly what it looks like with me. I smoke with wood. I pump from the boiler to the buffer with one pump, the second pump pumps from the DHW buffer, depending on the needs and the set temperature on the controller, the third pump works in the exchanger - 3D valve system, and the fourth largest pumps to radiators and floor heating. When I burn in the boiler, three pumps work, the fourth one from the DHW is rarely turned on.
The advantages of such a solution, a buffer as an additional protection of the boiler in the absence of voltage, I burn in the boiler all the time and all heat goes to the buffer and is stored, I do not throw dirty smoke into the atmosphere .
Minus: long heating up of the buffer with the daily firing up, or something wrong .
It seems to me that the system consumes a lot of electricity.

in case you had any questions, I'll be glad to help.

greetings

If you do not have a laddomat or even a mixing valve between the buffer and the stove, so that the return temperature is set to at least 65-72 degrees, it does not work properly. The furnace does not load the tank in layers from the top, but mixes the water in the tank (because there are large flows). Having a laddomat installed, after firing up in the furnace at the top of the tank, I have a temperature of 80 degrees and twenty centimeters lower the temperature drops drastically and is 30 degrees. Over time, the buffer is gradually loaded from the top, so the boundary between hot and cold water moves down.





Added after 29 [minutes]:
spinkamidi
If you have a lot of money, the pump is on non-stop, if little is a differential thermostat.

The coil idea sucks in my opinion. If it is a hot water tank in the buffer.

lolson28 wrote:

Hello

I will write you briefly what it looks like with me. I smoke with wood. I pump from the boiler to the buffer with one pump, the second pump pumps from the DHW buffer depending on the needs and the set temperature on the controller, the third pump works in the exchanger - 3D valve system, and the fourth largest pumps to the radiators and floor heating. When I burn in the boiler, three pumps work, the fourth one from the DHW is rarely turned on.
The advantages of such a solution, a buffer as an additional protection of the boiler in the absence of voltage, I burn in the boiler all the time and all heat goes to the buffer and is stored, I do not throw dirty smoke into the atmosphere .
Minus: long heating up of the buffer with the daily firing up, or something wrong .
It seems to me that the system consumes a lot of electricity.

in case you had any questions, I'll be glad to help

greetings

How do you heat the DHW from the stove? Do you have heat indicators in the buffer or in the DHW tank?
I would like to look at your connection diagram I wonder how you have the combined buffer and hot water and where is your entrance from the furnace to the buffer. Do you have one?

Added after 3 [minutes]:

[quote = "miki_fx"]

lolson28 wrote:

spinkamidi
If you have a lot of money, the pump is on non-stop, if little is a differential thermostat.

The coil idea sucks in my opinion. If it is, it is a water heater in the buffer.

I don't really have an idea how to heat DHW from a buffer.
I would like to achieve such an effect that with the stove turned off and hot water in the buffer, I would have non-stop hot water. If I use a DHW tank with 2 coils (solar panels + stove), only the upper part of the tank will be heated with the stove? The solution is another pump at the DHW tank to the mixing system, but this is to increase the number of all pumps.

miki_fx wrote:

If you do not have a laddomat or even a mixing valve between the buffer and the stove, so that the return temperature is set to at least 65-72 degrees, it does not work properly. The furnace does not load the tank in layers from the top, but mixes the water in the tank (because there are large flows). Having a laddomat installed, after firing up in the furnace at the top of the tank, I have a temperature of 80 degrees and twenty centimeters lower the temperature drops drastically and is 30 degrees. Over time, the buffer is gradually loaded from the top, so the boundary between hot and cold water moves down.

I have a mixing valve on the return to the boiler. The pump between the boiler and the buffer pumps to the buffer and additionally back to the boiler to protect against low temperature.
Overall, I have a very extensive installation and I don't fully understand how it works exactly

spinkamidi wrote:

I don't really have an idea how to heat DHW from a buffer.

Go back to the diagram that I have posted for you and look at it in more detail. Like an ox, there is a pump that pumps water from the buffer to the upper coil in the DHW tank.

spinkamidi wrote:

How do you heat the DHW from the stove? Do you have heat indicators in the buffer or in the DHW tank?
I would like to look at your connection diagram I wonder how you have the combined buffer and hot water and where is your entrance from the furnace to the buffer. Do you have one?

I heat the DHW through the buffer. So first I heat the buffer and the buffer heats the DHW and CO. The buffer has no coil. The buffer tank is 500 liters and now I think that it is definitely too small (a bigger one would not fit into the boiler room). It plays an accumulative role and protects the boiler against boiling. Holzgas boilers are high temperature boilers and the output must be around 80 degrees. However, when the boiler is heated to 80 degrees and fully loaded with wood and there is a puff and no energy, a large tank connected with a thick pipe to the boiler is useful, which will receive heat, and in extreme situations, a cooling valve that will let cold water into the boiler and hot water will flow into the sewage system. Currently, each boiler of this type should have such protection.

spinkamidi wrote:

I don't really have an idea how to heat DHW from a buffer.
I would like to achieve such an effect that with the stove turned off and hot water in the buffer, I would have non-stop hot water. If I use a DHW tank with 2 coils (solar panels + stove), only the upper part of the tank will be heated with the stove? The solution is another pump at the DHW tank to the mixing system, but this is to increase the number of all pumps.

For me, it looks like this that when I no longer heat the central heating and would like to heat only the hot utility water, I close the 3D valve and turn off the central heating pump controller. Then I heat the buffer to 70-80 degrees and set the DHW controller to 45 degrees. And depending on the needs, the DHW pump heats the water in the tank. I found this solution not economical enough and I heat the three warmest months of the year with electricity, then I close two valves in front of and behind the DHW tank.
I considered installing a solar system, but I know that a good installation with assembly costs money, and I do not know if someone will guarantee me 10-15 years of trouble-free use of such an installation.


greetings