Decision aid for new gas heating for single-family house

Hello!

A new gas heating system is to be installed in my parents-in-law's house in Italy. I still have a few questions and would like to have your opinion on them. We have two offers. The first is for a Ferroli Bluehelix K50, the second for a Viessmann Vitodens 222W. I am not very familiar with heating systems. Does anyone here know Ferroli and can say something about it? I am also wondering about the sizing. According to the offers, both have a capacity of 32kW. The house area is around 400m2 and I wonder if that is not a bit too little.

Thank you very much in advance for your answers.

Philipp

Hi,
that depends on the insulation of the house. Modern houses around 200 sqm often have a heating load of less than 10 kW. Usually, something around 20 kW is installed to be able to produce the hot water quickly enough.

So if it’s a modern house, I would almost call 32 kW a lot.

Without a heating load calculation, it’s all just guessing. What kind of heating system is currently installed? How much power does it have?

I don’t know Ferroli. What’s important is that the installer on site has experience with the heating system he is supposed to install.

Best regards,

Andreas

@ Andreas: Thank you.

I will take a look at how much capacity the old heating system has. The house was built about 20 years ago. With incredibly thick walls but without particularly sophisticated insulation. After a bit of internet research, I am leaning towards Viessmann. One reads about many failures and poor spare parts supply for Ferroli. I know that this is hardly representative, but I can't go too wrong with a Viessmann.

Further thoughts from you are very welcome.

Still waiting for the data of the old heating system. Do you know how well it works with the hot water and the storage tank? The situation is that the house is partially unoccupied for 3 months and then 15 people come who want to shower with warm water. Is the storage tank suitable for that?

For the dimensioning of a heating system, the building heating load must be determined in a heating load calculation. For this, the component structures of the heat-transferring exterior components including the windows with their U-values (thermal transmittance coefficient) must be known or determined. Without this calculative proof and only with a heating dimensioning according to the old installer rule "Pi x thumb + 20% safety margin," it is not possible to design a roughly fitting and efficient heating system.

Since I have no idea whether there is a state regulation for building insulation in Italy – comparable to the Energy Saving Ordinance in Germany – you should best contact a local architect or an engineering office for building technology and get advice on this. It is correct that the heating engineer must of course be familiar with the respective product and also be able to maintain it. Viessmann is a good and reliable brand. The 32 kW can be just sufficient for 400 m2 (corresponding to about 170 kWh/m2 x a), which would be rather very little for a completely uninsulated new building.

A functioning and contemporary heating system naturally also includes a well-insulated heat distribution system and the decision for underfloor heating or radiators, etc., as well as for hot water storage. Solar thermal energy may also be considered as heating support or for hot water consumption. So the whole matter is a bit more complicated if it is to be well solved.