I can't give you an accurate answer on the accumulator as Richard will have made the decision to eliminate it. We do have the parts here to add it to the system if you wish to do so.

The system has a similar failsafe setup as to the HFS-6, with the reset time fixed and no direct circuit for the MAC valve( but the normal contacts con drive a MAC valve fine). So a full flow based failsafe is provided in the 3.

The manual will be published when completed, we have a good deal of product info on our site here:

http://howertonengineering.com/Aquamist_hfs3.html

Even though there are some differences to the HFS-6, installation and basic operation are similar to the 6.