A couple of things to think about...you must be certain that your lease stipulates what maintenance items are your responsibility and which ones are the LL's. Anything not specifically addressed as yours is the LLs. Secondly, make sure the law supports you if you decide to repair and deduct. I found the following info, does your situation fit these requirements?
"Rent Withholding: The Massachusetts Supreme Judicial Court ruled that when a landlord fails to maintain a dwelling in habitable condition, a tenant may properly withhold a portion of the rent from the date the landlord has notice of this breach of warranty of habitability. Rent withholding can be a useful tool to force repairs, but it is a serious step and should be dealt with carefully. You may want to get legal advice before withholding your rent since the landlord may try to evict you for non-payment of rent.
You may withhold a portion of your rent if:
You have appealed to your landlord in writing to make the necessary repairs;
Your local board of health has inspected your apartment and found health code violations and notified your landlord; and
You are current in your rent up until the time of the problem, you are not the cause of the problem, and the unsanitary conditions do not require the apartment to be vacated to make repairs.
Deciding how much to withhold is based on each situation. You need only pay the fair rent for your unit given its defective condition. (M.G.L. c. 239, §8A).
Repair and Deduct: You may make emergency repairs in an apartment or common living area and deduct up to four months future rent to pay for them, if three conditions are met:
The local board of health or other code enforcement agency has certified that the present conditions endanger your health or safety;
The landlord receives written notice of the existing violations from the inspecting agency; and
The landlord is given 5 days from the date of notice to begin repairs or to contract for outside services and 14 days to substantially complete all necessary repairs. (The inspecting agency or court may shorten this time frame.)
If you qualify under the requirements of "repair and deduct," you may treat the lease as void. You then have the right to move out if you choose not to make repairs. However, you must pay the fair rental value for the period you occupied the apartment, and you must vacate within a reasonable period of time. (M.G.L. c. 111, §127L)"
http://www.state.ma.us/consumer/Pubs/tenant.htm
I would make a written request for the maintenance. Since you anticipate problems, do the legwork, call around, get estimates, put all the info in the letter with phone numbers so your exBIL can't say he doesn't have time to check on these things. All he will have to do is make the call authorizing the work order and write the check. Same with the furnace cleaning. I'd suggest as a goodwill gesture if the cost isn't prohibitive that you might pay for the furnace cleaning yourself. He might see that you are being reasonable about these things and be helpful instead of fighting you every step of the way.
The septic and heat are definitely issues that affect habitability if they are not working properly. There is a difference between regular maintenance and repairs for something that isn't working. In that respect I'd be wary of repair and deduct simply because I don't know the extent of the repairs needed.
