I called and got an estimate, which was reasonable, and we set a date for them to do the work. When they arrived, they discovered I had forgotten to count one of the smoke detectors, in our office. Fortunately, Dmitry and Vladimir had extras, so they were able to include this, for just the extra cost of the unit (whew!). One electrician worked on the smoke detectors, while the other worked on the fan. The fan is very quiet and works well, and we are very pleased to not have the detectors randomly go off in the middle of the night anymore.