In my experience I recommend that oil fired furnaces and boilers should be cleaned and serviced annually to prolong the life and increase the efficiency of the unit.
Forced air heating systems (oil, gas, electric) ductwork should be cleaned every 2 years to keep the air quality in your home healthy. If you have allergies or respiratory problems I recommend cleaning the ductwork annually.
Air filters should be vacuumed every 2 months and replaced once a year, normally when the furnace is cleaned.
Dryer vents should be cleaned every 1 to 5 years depending on the length of the dryer vent run and usage. Dryers that are situated on an outside wall that have a very short run (6 inches) can be checked by the homeowner and don’t usually need cleaning.
Bathroom exhaust fans should be cleaned 1 to 5 years depending on usage.
Bathroom venting should be checked 1 to 10 years depending on usage and length.
Oil fired furnaces and boilers should be cleaned annually. However, if your furnace or boiler malfunctions due to combustion problems (usually your service technician will require your unit to be cleaned before any service work is done) your unit should be cleaned.
Vents and ductwork should be cleaned every 2 years except for allergy/respiratory sufferers (should be cleaned annually). However, if you have had renovations or your home is very dusty or your filters are plugging up quickly I would recommend checking your vents to see if they need cleaning.
To check your vents remove one of the cold air return vents and look down the vent with a flashlight and mirror. If you see a lot of dust then your vents should be cleaned.
Dryer vents should be cleaned every 1 to 5 years. If your clothes are taking a long time to dry or your dryer feels extremely hot or the discharge vent has poor air flow you should have your dryer vent cleaned.
Bathroom exhaust fans and venting should be cleaned every 1 to 5 years. If your bathroom is condensating heavily or you see mold forming you should remove the plastic cover over the fan and look to see how dirty the fan is. If the fan is dirty then the fan should be cleaned. If there is poor air flow through the venting then the venting should be cleaned.
We use truck mounted Pringles power vacuums with Quincy air compressors.