Tenant requrest for furnace/humidifier sytem

[Brian Zaug]

I own a duplex and one of the Tenants called and asked me if he could install a humidifier system onto the furnace.  He says he has sinus issues and needs this system so he can sleep at night.  Our lease states that any improvements to the apartment must be approved by the LL. 

Do any of you see a problem with him doing this?  He will have to pay for a professional to install this system.