Does anyone have any information as to why a vertical pressure tank needs to be placed in a upright position or not. My neighbor asked if I would come over and help him finnish a pump installation. He doesn't like to spend money. I walked over and noticed his 42 gal bladder pressure tank was lying sideways on some 2" insulation under his crawl space. I told him he shouldn't do this. My neighbor asked why? His reply was that his friend has had one like this for 10+ years with no problems. There are companies that sell horizontal tanks, are they designed inside different, I can't see how, other than they are made to minimize space. Any one have an opinion ??? Does he have a valid point.