4plex owner pays heat - how to factor in pricing

[Peter Fokas]

Found 4plex that owner pays heat. Heat is two units using oil. So if using 50% rule how much more should you factor in the expenses to cover this additional cost? 60% Also if you want to convert this heating system to use nat gas and be four separate systems so tenants would pay this. What sort of guesstimate in cost? I am figuring probably aroudn 15k as a rough rough guesstimate? Would it make sense to get a contractor quote prior to making an offer and factoring that in the offer?