Monitors are not bad (propane or ng) but keep in mind ... with any "single source" heating idea, there will be challenges (one room cold, the other too hot, etc.) -- You mentioned propane.

BUT it is expensive compared to forced air NG.

Hello @Patrick Ng,I don't know a whole heck of a lot but have done a little research on Quit Claim and only feel able to give a little insight on question 3.

My wife's son lives there an he pays the mortgage every month.  

  :)   Also West Medford is beautiful but more $ Also, I hate to be a NH hater cause its a beautiful state to be in nature but its "cities" aren't any better or bigger than Lowell. 

So assuming your panel can handle the 2 double poled 40amp breakers it would be a lot less expensive than running a gas line & the venting of a NG unit.

@Tu Anh Nguyen sorry to hear about your situation.If everything you’re saying is accurate, and your lease is a standard residential lease agreement, I believe your tenant is violating your agreement.

Albert Ng As mentioned earlier it would depend on your goals and strategy.

@Rich Ng

So depending on the wording of the lease, I would still consult a NH landlord attorney.