What can a landlord do when the tenant increase the heating very high,
The tenant have the thermostat and put it on 90,is there a way for the landlord to
Control the boiler from the basement,that it shouldn't go more then 70 degrees?

There probably isn't much you can do. You can't make a material change to the premises or raise the rent. What type of premises is this? Sounds like a 2 family house.

You should be able to set up multiple heating zones, if the heat is affecting you as well.

You could always purchase a lockable thermostat box....keeps most tenants from messing with the thermostat. If you are sure you'll need better protection than a lock box you could always install a lockable thermostat, set temperatures and be done with it (see image)!

Otherwise, if you don't want to spend the money, and if you live on the first floor you could always relocate the thermostat wires and a new thermostat to the first floor....leave the thermostat on the second floor as it is, and then the tenants will still think they have control...at least for awhile...;)

Mark

This represents an interesting issue. On the one hand, the tenant rented the premises with the understanding they could control the heat. Putting a lock on the thermostat could be considered a change in the rental agreement.

On the other hand, setting the thermostat at 90 seems unreasonable and wasteful. So I would be inclined to tell the tenant that if he doesn't keep the thermostat at a reasonable level, you will place a lock on it. Then do it if he doesn't comply. If he takes you to court, I think the worse that will happen is you will be forced to take the lock off.