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Definitely an improper installation. I would absolutely use it in my own home

Propress is tried and true. Have been using propress for years with little to no problems.
The few horror stories you may have read are probably incorrect installation problems.

I'd disagree on the comment that Propress is "Tried and True."

It's only been around for I believe 21 years.

Copper tubing with soldered fittings is tried and true. I'm not sure how long it has been in use. A little internet research said that it became dominant in home construction use in the 1940s'.

I have 65 year old soldered copper in my house, and during the installation of a water softer and creating an new soft cold water header I had to cut into some of it - it was in fantastic condition.

How long are those O-rings going to last? Who knows. I've spent much of my life in industrial plants and Power Plants and while the correct materials for O-ring applications do last a long time. I'm not sure that I have seen many that lasted over 40 years, and problems clearly develop once past 30 years. Of course, if the O-ring material is wrong... failure will be much quicker.

I'd hate to have to open up walls due to leaking fittings in the future (not to mention how the water damage until they are discovered and fixed).

My personal opinion: Anything inside of walls should be soldered. In open areas of the basement and utility rooms where future service would be easy I can see the use of Propress.

I personally think there should be a noticably long stub in the open area before the Propress fitting is installed - allowing for its future replacement (perhaps more than once). Thus, you might see a soldered 90 degree elbow clear of the wall or floor (which would be a good visual that what's inside the walls is soldered).

I see no issue with using it to construct the near boiler piping on a radiant heating system, as the boilers are likely to need replacing before the O-rings degrade.

Perry

The best information I can find is that Conex Banninger started to develop press fittings in Europe in the 1980's and by their own admission that things did not really get going until the 1990's; and they only claimed in 2019 to have only been producing press fittings for over 30 years (not 35, not 40, etc).

Here's their own summary statements on this in their 2019 history video

https://www.youtube.com/watch?v=FtOihpFHli4

So, they realistically Europe perhaps has about a 10+ year head-start.

My experience in Industrial and Power plants says the o-rings start failing in the 30-40 year range... which is not to say that in certain situations that they may last longer.

I'll again repeat that I personally don't believe they are suitable for use inside walls for standard construction.

But, again so much these days is about lowest initial cost and who currently cares about the long term. "not my problem" if it fails down the road and is very expensive to fix or replace.

I wish you all well with this.

Perry