hot water loop off steam boiler
good evening and hope all is well. does it matter if the check valves are above or below water level and does it make a difference which side of the purge valve they are on(loop is above water level)?
Check valves.
Keep everything under the water line. If the check valves are above the water line, nothing is going to keep water in the piping between them and the water line. And I don't think it makes a difference where you place them in relation to the purge drains, unless you were trying to fill/purge the loop water backwards through the return line.