Vacation home - vapor barrier in relation to attic insulation?

[etoo]

I have a vacation home where I usually maintain a heat of about 10 degrees during the winter. The house is currently heated by oil-filled electric radiators, but I am considering getting an air-to-air heat pump to reduce the overall heating costs, and also to have the option to increase the maintenance heat a bit higher and control the heating via an app. I believe this would also make me want to spend more time in the vacation home during the winter months, with normal room temperature for several days.

Now to my questions.
The house was built without a vapor barrier in dry areas. The insulation in the attic is between 10-20 cm of mineral wool, and it has been that way since the house was built in the 70s. There are no signs of condensation problems (like mold spots) either in the wood or in the insulation. The construction has obviously worked for over 40 years. I don't know exactly how previous owners used the house in winter, but I have only maintained the heat during my 10 years as an owner.

If I now get a heat pump and increase the heat during the winter, what can happen? Does the risk of condensation problems increase? I have read somewhere that no condensation occurs in insulation if it is thinner than 20 cm, so the heat goes through the entire insulation and then is ventilated away in the attic (if it is well-ventilated, which apparently is the case for me).
BUT, I would also like to add insulation to the attic to save more energy in the house and avoid running the pump and radiators too hard. Can I do this without causing condensation problems? Is what I have heard about condensation migration correct?

What would you do? Just add an air heat pump, or also add insulation to the attic?

 

[MagHam]

Condensation primarily occurs if someone is living in the house. Otherwise, the moisture load is negligible since nobody is washing, showering, cooking, or watering houseplants.
On the other hand, why make such an effort at all if you're only going to be there a few days at a time?
Mineral wool without a vapor barrier, where the condensation point is inside the insulation, is a risk construction.

 

[etoo]

Condensation usually occurs if someone lives in the house. Otherwise, the moisture load is negligible since no one is washing, showering, cooking, or watering pot plants.
On the other hand, why go to so much effort at all if you're only going to be there for a few days at a time?
Mineral wool without a vapor barrier, where the condensation point is inside the insulation, is a risk construction.

Yes, I'm trying to understand what is worth the effort. I'm thinking of starting with the air heat pump and testing that. Then I'll make new decisions.