If you use a low point drain,the sealed risers will drain,just takes an extra 45 minutes.

Usually the winterizing process involves an air compressor to force the water coming out of the heads. Then turning on the lower point drain to let the rest of water coming out (it is in my basement). Would that be sufficient to just use the lower point drain?

Usually the winterizing process involves an air compressor to force the water coming out of the heads. Then turning on the lower point drain to let the rest of water coming out (it is in my basement). Would that be sufficient to just use the lower point drain?

Use the prescribed method to winterize same as you always have. The caped risers will not make one whit difference other than needing a little extra time to drain.