Tenant Utilities with shared metering and billing

[Steve K.]

We recently closed on a property, where some things slipped thru cracks, during our due diligence. We inherited (Old lease 8 months left) a tenant who doesn't pay for electric because gas furnace is hooked up to meter they were suppose to have on their name. Other common thing on their meter is 1 light bulb. Neither previous owner nor tenant would tell what arrangement they had, nothing is in writing and it doesn't matter.

I'm thinking to type up amendment to lease document where tenant will be responsible for entire electric bill minus cost to operate that furnace and a light bulb. Our Electrician said it cost $10-15/month to run the furnace and the bulb would be $2/month. We're thinking to keep electric meter on our name and plan to credit $25/month to tenant and bill the rest. Can we do that? Does that sound reasonable? 

I appreciate your comments and suggestions.