How long should my HVAC system last? February 24, 2011 â Art Avent, hvac advice. Among manufacturers, you are unlikeley to find anything definitive in writing on this question, but my personal opinion is that an electric heat pump & air conditioner SHOULD last 12-15 years & a gas furnace SHOULD last 15-20 years or more. Truth is, they last anywhere between 1 â 20 years.
Otherwise you may be asked to change your clothes and wear a hospital gown. It is best to leave all valuables at home. You may be asked to remove any jewelry, dentures, glasses, or any metal objects that may interfere with the CT scan.
Back to TopHow to Prepare for the Test. You may be asked not to eat or drink anything for 4 to 6 hours before the scan. Tell your doctor if you are afraid of close spaces (have claustrophobia). You may be given a medicine to help you feel sleepy and less anxious, or your doctor may suggest an open. MRI, in which the machine is not as close to the body.