I need to remake a plastic icemaker line connection to the valve under a kitchen sink.

Long story, but I hired a countertop fabricator to install a granite countertop last week, and they decided to cut the hole for the sink in place since it's a drop in sink with tight tolerances. Dust were everywhere but when they finished cutting, the piece of the cutout, 3cm thick granite dropped down to the sink cabinet below and broke the sink cabinet floor.

I need to cut this hose 1/2" short to free the nut so I can pull back the IM line under the floor to replace the cabinet floor.



I notice it has a brass nut with a plastic ferrule. I can buy a new set of nut/ferrule for this I think 1/4" right? But I notice the new ferrule comes with a metal insert which acts as a stiffener. Should an insert be used or no in this case?

Yes, use the insert.

The insert prevents the plastic line from distorting and enables a good seal with the compression ferrule. Should be 1/4" line. You can buy just the inserts in a baggie at the big box store where they have all the brass fittings etc. You may be able to reuse the one that's in there if it's not damamged.

The existing connection, when I disconnected it, had no insert. Just the plastic tubing with a plastic ferrule and a brass nut, which made me wonder if the inserts are needed or not. I will try with the insert to sleep better at nights.

The stiffener insert is definitely needed. There is a high risk of blowout without the stiffener.

OK, I need to remake the connections with the inserts.

I looked at both the icemaker on the cold side (1/4" and the dishwasher on the hot side (3/8" both plastic tubing with just a plastic sleeve and nut. I need a metal insert into both of these right?

Yes, stiffeners are needed for both the 1/4 and 3/8 lines.

I use copper tubing whenever I can for feeding dishwashers. Occasionally I have to work with 3/8 plastic tubing and this is my assortment of 3/8 stiffeners and ferrules

george, I am not getting any luck doing the copper inserts into the plastic tubing.

I have two plastic tubing a 1/4" for the icemaker line and a 3/8" for the dishwasher line. So I bought new inserts and ferrules for 1/4" and 3/8".



But these inserts do not insert into the inside of the tubing. They are very close but they seem just a hair oversized. I thought may be these ends may be deformed by the old nuts and ferrule so I cut about an inch of the tubing off and tried again, still I wasn't able to insert them no matter how hard I try.





Are they suppose to insert easily or they need persuasion? Perhaps a bit of heat?

They need to be pushed in, they will not just slide in. Your tubing walls are thicker than average. A bit of heat on the tubing will not hurt, go for it. A bit of grease on the insert will also help.

Sum,

30 seconds under hot water is usually sufficient to soften up the tubing enough to push in the insert. As others have said, the inserts are necessary. Let the tubing cool before tightening the nut, You can cool it under cold water.

Plastic tubing is fine, I've had it fail from abuse, but not age. Just tuck it out of the way.

I have had customers' wood floors get damaged from leaking plastic tubing behind fridges. The fan blows air to cool the hot refrigerant in the condensor and the air comes out pretty warm and the heat deteriorates the plastic tubing. The tubing becomes brittle and eventualy cracks. I always use copper tubing behind fridges.
The refrigerator manufacturers use plastic tubing at the back of the refrigerators and they last. That tubing must be of better quality and heat resistant.
Sum, if that 1/4 inch plastic tubing is going behind a fridge, you should consider using copper instead.