Choosing the Right Gas Oven for 200m2 House: Single vs. Dual-Function & Economical Solutions

Dear forum users, I was left alone in an uninsulated house, about 200m2. The house has a furnace for eco-pea coal with a feeder, unfortunately I do not have the strength to pour coal, because 1 bag weighs 25 kg. I want to install gas heating to make my life easier. I would also like hot water from this furnace. I don't know anything about it and I don't know where to start. The gentleman who assembles such stoves said that I should have a single-function stove, but I read a bit and the dual-function one might heat water instead of keeping warm water in the tank. I do not hide that I want to have as much savings as possible, that is, I mean the most economical solution. If any of you have time and would like to discuss this with me, I would be grateful for any valuable advice or links to some interesting articles. I also have a gg number 64886516.

Zuzanna-ZG wrote:

200 m2 in a non-insulated house

Counting 100W / m2, this gives 20kW with frosts of -20, i.e. on an average winter day, it will be approx. 10kW, i.e. about 24m3 of gas per day, so it will not be cheap. More expensive than today, but clean and comfortable.

If you already have natural gas in your home, you can install a gas condensing boiler, because currently only fully condensing ones make sense. But all condensing boilers offer similar efficiency, so choosing a specific model or brand of boiler will not miraculously reduce gas bills in your home.
With such a large area and an uninsulated building, there will be a high demand for energy, so the importance of the minimum boiler power decreases, but it is still worth having a boiler that will offer a low minimum power, e.g. 2-function Junkers Cerapur Compact ZWB24-1 DE offers a minimum of 3.3kW, and its maximum is approx. 24kW.
If necessary, you can buy a 1-function equivalent of similar power or a slightly weaker model with a minimum of 2.2kW and a maximum of 15kW.

If you want to save, it is only through thermal modernization and replacement of windows with energy-saving ones with correct installation because an insulated building has lower losses, which means you will use less energy, which will be visible in smaller bills.
Additionally, you can lower the temperatures , i.e. in rooms where you do not usually stay, keep it, for example, at 16 degrees, so that they do not freeze.
You can heat up to 20-22 degrees Celsius only where you are on a daily basis, i.e. a room / kitchen / bathroom, which gives only 3 rooms instead of the whole house of 200 m2.

Replacing the boiler may mean the need to clean the old central heating system from sediments that have accumulated during operation, so that the exchanger in the new boiler does not become contaminated, because its efficiency will decrease despite the fact that it will be new.
A condensing boiler requires a special chimney insert, so it must be taken into account when calculating investment costs.

As for domestic hot water, a 2-function boiler heats the water in flow when you need it, but it makes sense if the boiler is close to water intake points. The length of the tubes from the boiler to the points counts. I have several meters to the bathroom, which means that after unscrewing the tap, you have to wait about 0.5 minutes before warm water from the shower comes out. If you have tubes without lagging, this time will be correspondingly longer.
Currently, the so-called DHW circulation, but it only makes sense with a water heater. Circulation raises costs, but offers the greatest comfort of domestic hot water, because you have hot water in the tap right after it is turned on, without waiting 0.5 minutes.

The flow heater has a limited capacity, as it is usually a dozen or so liters per minute.
Having a tray, the efficiency is much greater for the first several minutes, so it offers greater comfort. Hot water is available immediately, or you only wait for it to run through the pipes to the tap. If the tank is hot and you take some water to wash your hands, the boiler will not even start. However, in the case of instantaneous water heating, even the smallest flow causes heating interruption and switching the boiler to the domestic hot water mode.

You must take into account the specifics of your building, the location of the boiler room, pipe length, etc.. to find out if a tank or a 2-function boiler will be better. There are boilers on the market that have a built-in hot utility water tank with a capacity of approx. 50 liters, so it is a compromise between a 2-function boiler and a 1-function boiler + an additional tank.

200m, not insulated, can be expensive in gas. You will receive the approximate cost of selecting individual heating sources when you visit the heat proper.pl website
Enter all the required data there, but don't take the result for granted - it will give you a rough overview.
As for the boiler - 2f, if for one person and there is no bath or rain shower, it can be.
There can also be a boiler with a built-in coil or stratified cylinder.
You also need to take into account how the installation in the house is built - for example, how heaters are selected for rooms with a high supply parameter, not much for a gas boiler. If there is a mixed installation (radiators and floor heating), it is necessary to rebuild the installation (additional elements - clutch, pumps, 3-way valves, unless these elements are already in the installation)
So the cost is not limited to replacing the boiler itself

Added after 4 [minutes]:

O - colleague @BUCKS added a reply while I was writing my post but the head of the tabernacle does not hurt

hajtaler wrote:

As for the boiler - 2f, if for one person and there is no bath or rain shower, it can be.

As for the rain shower, it is agreed, because they usually require about 15 l / min, which would mean over 30kW for a flow heater.
I do not see a problem with the bathtub, even with the flow of 8 l / min, because if the water temperature is satisfactory, the downside is only a slightly longer filling time.
In the same way, a 2-function boiler will serve more than 1 person, you can wash the entire bus without worrying that there will be no water, and the tank will eventually run out and require charging ;)

At 2f, for me, the downside is switching the boiler to the domestic hot water mode, even with a low consumption of domestic hot water for temporary washing of hands or a cup, etc. With a reservoir such a small amount of water should not start the boiler, so you can easily initiate such a low water consumption.
The second disadvantage is that the water must first heat up in the boiler, and then it must reach the tap, so the waiting time for hot water is a little longer than at the tray where the water is waiting for use. With a gas boiler + tank and a suitable controller, you can program the time periods in which the boiler is to heat the domestic hot water, so as not to heat the container at night, when you do not need domestic hot water.

Of the gas boilers that I would recommend in your situation is the SaunierDuval Bear Condens KKS 25 boiler with a capacity of max. 25 kW - here technical data and description Link
These are standing single-function boilers intended for modernization of old installations with standing boilers (gas, coal and eco-pea coal). They do not have accessories such as a pump, diaphragm vessel, safety valve - they use these elements from the existing installation - of course in a closed system. If they are not there, you have to add the appropriate ones. But if you had an eco-pea boiler and a DHW tank, you already have pumps and you can use them. The great advantage of these boilers is the simplicity of construction, which simplifies servicing and is resistant to dirt from old installations. Of course, you should remember about sedimentation filters, but this boiler will last longer than a hanging boiler.

Of course, when filling the bathtub, you can set a low flow so that the water has time to heat up, but usually the tap turns to full speed to fill it as quickly as possible - with flow heating it will not work. But it's a matter of investor choice. It is important that he knows about it and makes decisions consciously and not regret it after the fact.
As for one person, I meant that there will be no simultaneous intake from several points, which, together with the option of a shower and a dishwasher, speaks for the 2f boiler. There is a minus that the aforementioned heating / DHW heating mode switching - if it is not a problem with the floor, then with radiators when leaving a longer shower you will feel discomfort, especially since the house is not insulated
Apart from the above, a coal-fired boiler works in the installation, so there is probably a container that should be used, so here again the argument for boiler 1f

It will be cheaper and I have a problem to pay someone a few zlotys twice a week for bringing and pouring coal and possible ash removal than to convert the installation to gas. Building insulation is always the best option.

Thanks to everyone for your valuable advice

70m2 apartments to be heated + CW what dual-function - Immergas Vitrix, Termet Silver 20kw, Vailant VCW 226 eco tecpure or Junkers cerapur compakt 3-24 kw ZwB help me choose ?? please answer

@ dg2018
i see you spam 2 threads it will decide where you write. In the latter, I wrote back about the selection of a gas boiler.
Choose the brand or model that suits you best. I personally like the Junkers Cerapur Compact ZWB24-1 DE but I do not analyze what can break down in it, because I treat that all boilers have a similar failure rate, similar efficiency, similar durability, and each purchase is a kind of lottery.

Oh, thank you for the answer because I thought about it too, akomin to give a pipe in a pipe or through a wall because I have a corner apartment? does it have any effect on the economy? And I'm sorry, but this is indeed my second query because I thought no one would come back here

dg2018 wrote:

the chimney should be a pipe in the pipe or through the wall because I have a corner flat?

The exhaust gases must go to the chimney to the roof, because there is no other option.
However, when it comes to sucking in fresh air for combustion, if you can, use a pipe in the pipe, and if you can't, you will think about other methods.
For this you need an on-site vision and assessment of the situation by a specialist to know your options.
Sometimes what seems obvious is not practical.

I can allow air to be sucked in through the wall, because I have already agreed in 1 apartment during the exchange, and I already have an acid-proof pipe in the chimney for this boiler, which is already getting out and I think I need it? I asked and a few people exchanged for ordinary combi boilers with a closed chamber, they do not see savings. But they saved on the chimney. And my dilemma continues because the atmosphere or the condensate? how does it look in use, thank you for the advice already given and I look forward to further ...

dg2018 wrote:

I can allow air intake through the wall, because the management has already agreed in 1 apartment during the exchange

If you don't mind the second pipe going to the outer wall, it can be too. For me, it would be a last resort, if there was no option for a double pipe variant, because such a pipe on the top of the apartment has a significant impact on the visual effect.
If the visual aspect is not important to you, you can make it the cheapest. There are several options for connecting a condensing boiler to a chimney, so talk to a specialist who will be the cheapest and applicable to you.

dg2018 wrote:

I asked and several people exchanged for ordinary combi boilers with a closed chamber, they do not see savings

What do you understand by the concept of an ordinary 2-function boiler with a closed combustion chamber?
Because I have the impression that you still do not know what a condensing boiler is.

dg2018 wrote:

And my dilemma continues because the atmosphere or the condensate?

I do not understand where your dilemma comes from.
In my opinion, there is no need to wonder, leave the atmosphere aside, when it's just condensation.
Anyway, you wrote above that you can give a second fresh air suction pipe for condensate, and now you write that you have doubts.

Condensate has a higher efficiency than an open chamber + a closed chamber means a low risk of carbon monoxide, so the safety and requirements for the inflow of fresh air for combustion increase, so lower heat losses + low minimum power, i.e. lower boiler timing and better energy dosing. For me, enough advantages to thank the atmosphere for many years of service and not to come back to it.

I have a boiler in the bathroom for BUCKS - aesthetics is important to me, but the costs also when passing the pipe through the wall are about 2m, and through the chimney it is about 7-8 m. Unless I do not know it more economically when using the chimney? for specifics. As for the boilers, it is said that the Junkers do not know or compact, but that they do in China, would then termet silver be better?

Added after 41 [minutes]:

I would like to add that for these 70 m2 another installer advised the vailant VCW226 eco Tec Pure boiler has a power from 6.8 Kw to 24 kW, is it not too much ??

With the chimney, unfortunately you have to let the exhaust pipe into the existing acid, and treat the existing pipe as a space for air suction. You cannot separate at the boiler and lead the flue gas to the existing chimney - unless it has been all folded up with gaskets. For condensate, it is an air-flue gas system, the so-called pressure and complete tightness is required. Otherwise, condensate may escape through the socket without gaskets and you will have blooms on the chimney over time.

that is, all the chimney is not through the wall anyway ??

UNICAL KONm C 24 or OSA someone heard about these boilers because there is nothing but their website and the parameters are good.I need help again in choosing a 70m2 combi boiler, because it's almost chosen, and here the installer tells me that for the first PLN 4,800 with installation can anyone help??

Two years ago, I replaced the stove. I live in a row house, the area is about 210 m2, not very well insulated, but since it is a row house, there are two walls to the neighbors, so warm.
The previous furnace - Junkers SUPRASTAR (I was satisfied, but parts production was discontinued), the new one - Condens 25 Bear.
Since the change was relatively recent, I can show you some sample costs.
All: stove + installation + water tank 130l + flue gas discharge: 12000
I was looking for a standing stove, because it suited me so well in the boiler room. The bear at that time was indisputably the cheapest offer - 5,500, twice less than other comparable ones.
The stove turned out to be a bit oversized, i.e. in the spring and autumn seasons the minimum power is a bit too high, a smaller model would probably suffice. However, hot water heats up quickly.
If you want to save money, hanging boilers can probably be cheaper. And the pellet stove is said to be even cheaper,
Service costs - a review of PLN 200 a year ago, and probably every year.
Annual heating costs - Poznań: 4700. On the one hand, recently winters were mild, on the other hand, however, the children (students) had classes so that almost every day someone was at home and we had to heat.