Copper pipe compensating under insulation

[mycoran]

Copper pipe is sweating under closed cell pipe insulation (5.1R-value). Basement humidity is 40%, all the hot water pipes are insulated and seams sealed with foil tape. The condensation will drip out of the pipe insulation at the water heater connection. When I removed the insulation, the pipe was visible wet. I removed the insulation from the hot water side, up to the "T" ( approx. 3') and the condensation stops. I am at a loss, it defies logic (at least to me). This is an 80gal Heat Pump water heater. Any thoughts?
Thanks

 

[Slomoola]

Is your pipe wrap fully tight around the pipes? Doesn't make sense unless you have a pipe leaking. Insulation needs to be as air tight as possible to stop the condensation issue.

What is the basement temp?

 

[Sponsor]

 

[Fitter30]

Think there's a pipe leak. There's no white staining at the pipefitting joints. Take tp wrap it around the joints if there's a drop of water it will show up on the paper. Here's a wet bulb calculator.
www.omnicalculator.com/physics/wet-bulb
Punched in some numbers
55° space 40% = 43.6° to sweat has to be below the 43.6°
65° 40%= 51.7°

 

[Slomoola]

What is the basement temp?

 

[Master Plumber Mark]

Just leave the insulation off the pipe for a week or two and look for a leak....
or just leave that section of insulation off the line and let it breathe like it seems to
need to do and forget about it.....

you dont have to save every last little bit of btu
if its gonna be a pain in your ass to do it.
and its gonna sweat like a pig on you...

 

[Slomoola]

Can I have those extra BTU's please? LOL