Those nipples can be a real bugger to break loose......
Do you have enough room on Hot output line to install a shutoff valve?
If so just remove the internals of that nipple and install the valve.
1 valve system with the added shutoff valve on Hot line
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31