Perform a smoke test to either confirm or eliminate it being on your plumbing sewer drain or vent lines.

This is primarily based on population growth (demand for units) and new construction (supply of units).

She is most likely blowing smoke.

I suspect you will also have to get hard-wired and interconnected smoke detectors installed since you are in the process of re-wiring.

I always either go with them to purchase the supplies or tell them bring a receipt and I will write a check then I pay in two week intervals as jobs become close to completion.Also to keep them in line I may bring another contractor by for another project to keep them on their toes about prices for upcoming projects ( usually they get the work over the other guy but just so they stay straight.)

In addition, many units with older setups require modification to the power supply.

That is why I recommend using a 3.5% down, FHA loan.Your loan officer should supply you with a Good Faith Estimate, which is a break down of the costs associated with your home purchase.

Your insurer likely uses standard area multipliers supplied by some rating agency or developed in house.

I bought mine at a commercial carpet cleaning supply store for about $30.

That will let you know if you have a supply line leak somewhere.With HVAC, the general age shoudl give you a good indicator on how much life it has left.