To disguish the "low" from the "high": the low side has a larger diameter tube than the high, also the low is "cold" wheras the high is Hot! (usually!) 10-4? <img src="/forums/images/graemlins/patriot.gif" alt="" /> <img src="/forums/images/graemlins/shame.gif" alt="" /> <img src="/forums/images/graemlins/kewl.gif" alt="" /> <img src="/forums/images/graemlins/cheers.gif" alt="" />