Insulate over a pipe union, or not?

Rav

I'm in the process of insulating my hot water (not steam) heating pipes in my unfinished basement.  I'm using 1"-thick-wall fiberglass tubes.  I've now come to my first union, and I need to know whether I should insulate over it (using a relief cut so it fits), or leave a gap for it so it remains uninsulated.  The reason I ask is that while researching pipe insulation installation, I found a video produced by the NIAC Association, which says "Unions on hotlines are usually left bare so they can be found and pipe wrenches used to disconnect them."  You can see the video at <a href="http://www.youtube.com/watch?v=fdw-NjfVDDk">http://www.youtube.com/watch?v=fdw-NjfVDDk</a> ; the relevant portion begins at 5:11.  Note that it says <em>usually</em>.  What do people here think?  Insulate over it, or leave a gap for it?  Thanks.

STEVEusaPA

If your in an insulating frame of mind.....

Insulate it. If its not obvious it's under there, you can always hang a tag. Use a piece of the next pipe size up to cover it. And remember, don't compress the insulation, makes it just about worthless

Rav

Insulate over a pipe union, or not?

Thanks for your response, Steve.  Since I'm  using 1"-thick tubes, I have enough room to do a relief cut with the correct size tube.  If I hang a tag marked UNION, why also cover it with a piece of larger pipe size insulation?

AlHeating

I wouldn't !

In my opinion, it's better if you don't.  With the small pourcentage it represents on the entire system, I would let them bare naked so it's easy to find them.  I would even leave a 2" on both side to have room to work. 

My personnal opinion though!

JasonA

Full thickness insulation

A nice clean and thermally effective way to deal with unions, valves, etc., is cover them with pipe insulation that is sized for the outside diameter of the insulation you are using on the pipes feeding the specific fitting. Cut the larger insulation longer to overlap the smaller insulation at each side of the fitting. If you are insulating cold water piping in an unconditioned space you will want to seal the raw ends of the larger insulation with a vapor barrier tape or mastic.

Rav

Insulate over a pipe union, or not?

Thanks for your response, Jason.  I'd like to under stand why, since my pipe insulation is thick enough to allow for a relief cut in order to fit around the union, you are suggesting instead covering the union (and smaller pipe insulation) with larger insulation?  Is it because doing a relief cut reduces the amount of thermal insulation, and the larger insulation (not needing a relief cut) is full thickness?  Thanks.

Rav

Insulate over a pipe union, or not?

Hmmm, I just noticed the title of your comment:  "Full thickness insulation."  I think that answers my question in the affirmative.