ᐅ Decision Guide for Installing a New Gas Heating System in a Single-Family Home

Hello!

A new gas heating system is planned for my in-laws’ house in Italy. I have a few questions and would appreciate your opinions.
We have two quotes. The first is for a Ferroli Bluehelix K50, and the second for a Viessmann Vitodens 222W.
I’m not very familiar with heating systems. Does anyone here know Ferroli and can share some insights?
Also, I’m wondering about the sizing. Both units are rated at 32 kW. The house area is about 400 m² (4,300 sq ft), and I’m concerned that might be a bit low.

Thanks in advance for your responses.

Philipp

Hello,
that depends on the insulation of the house. Modern houses around 200 sqm (2,150 sq ft) often have a heating load of less than 10 kW. Usually, a system with about 20 kW is installed to ensure hot water can be produced quickly enough.

If it’s a modern house, I would actually consider 32 kW to be quite a lot.

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

I’m not familiar with Ferroli. It’s important that the installer on site has experience with the type of heating system they are supposed to install.

Best regards,

Andreas

@ Andreas: Thank you.

I will check how much output the old heating system has. The house was built about 20 years ago, with very thick walls but without particularly advanced insulation.
After some online research, I’m leaning towards Viessmann. I’ve read about many failures and poor spare parts availability with Ferroli. I know that might not be very representative, but with a Viessmann, I don’t think I can go very wrong.

Any additional thoughts from your side are very welcome.

Still waiting for the data on the old heating system.
Do you know how well the hot water and the thermal storage tank work? The situation is that the house is unoccupied for up to 3 months and then 15 people arrive who want to shower with hot water. Is the thermal storage tank suitable for this?

To size a heating system properly, the building heating load must be determined through a heat load calculation. For this, the construction details of the heat-transferring external components, including the windows with their U-values (thermal transmittance), need to be known or established. Without this calculated evidence and relying only on an old installer’s rule of thumb such as “Pi times finger width plus 20% safety margin,” it is not possible to design an accurately fitting and efficient heating system.

Since I have no knowledge of whether there is a national regulation for building insulation in Italy—comparable to the Energy Saving Ordinance in Germany—you should ideally consult a local architect or an engineering office specialized in building technology for advice. It is correct that the heating installer should be familiar with the chosen product and be capable of servicing it. Viessmann is a good and reliable brand. A 32 kW system can be barely sufficient for 400 m² (approx. 170 kWh/m² per year), but this would be rather low for a completely uninsulated new building.

A functional and modern heating system also requires a well-insulated heat distribution system and a decision between underfloor heating or radiators, as well as provisions for domestic hot water storage. Solar thermal systems could also be considered as heating support or for hot water consumption. So, the whole matter is somewhat more complex if it is to be done properly.