You must check your first Etat de Lieu when you moved in the house.

Check also the lease and additional clauses in particular as well as tenancy rules in Geneva(or Vaud) canton which copy was handed on to you.

Most of the times it is mandatory to sign a maintenance contract for the boiler and the heater, but below are important points to consider:

1.Have you moved in a house with a brand new boiler just installed before you arrived? 2.Was the boiler decalked shortly before you moved in with all your furniture ?

3.Have you been notified with a receipt in that sense for point 1. or 2. ?

Besides, not knowing the size of the furnace, the type and the volume to be heated inside your "mansion" one cannot guess on the cost. Feel free to tell us more.

regarding having to pay, they reference the local Geneva rules in their letter so I guess they are right. It is for 'ongoing maintenance' which it appears is up to the tenant to pay.

I live in a normal size one bed flat. It has it's own boiler, I think this is quite a normal situation no? I will probably get a maintenance contract as it seems the norm (I wasn't made to get one when I moved in)

The cylinder was decalked 3 years ago (1 year before I moved in)

I'd just like to know how much I can expect to pay for the maintenance of the boiler and the water cylinder.

Ondrej:

The water boiler needs to be decalked on average every  3 years max when such unit is used frequently which is certainly the case in an apartment where there are individual charges with heating & hot water.

Now is the time for you to call the maintenance company. Estimating the size of the unit it might turn to treatment roughly ca. CHF 250.- done by a professional .

Better call several experts in the field to compare prices and estimates (unless you are renting a flat under strict LGZD building rules).