I have a 2900 sq ft house in Central NJ that is heated by a hybrid (mixed) steam / hydronic baseboard system (house came this way!).

I have a largish enclosed unheated front porch (38x 10) with four six ft wide x 4 ft high thermopane windows on the north facing side and an 8 ft x 4 ft thermopane window on the east facing side. It is over a crawl space.

I am contemplating installing 3 six ft lenghts of high output slantfin baseboard on the north wall. For a variety of reasons, its not possible to put a baseboard under one of the end front windows or on the east window.

I am planning to use the existing circulator pump and install two zone control valves with the porch as its own zone. I only need to get the temp in the porch up to about 50/55 degrees.

All this is probably too much info for the basic question...
Should I use 3/4 copper or 3/4 PEX for the lines? Its a longish run ( 37 feet as the crow flys) from the porch outer wall to the furnace....and its NOT a straight shot.

I'm handier than the average home owner and have installed/repaired hydronic systems myself several times successfully.

While I have all the tools I need for copper, I don't have any for PEX. I'm considering using short copper risers to the baseboard and transition to PEX in the crawl space if I use PEX.... othewise harddrawn copper and elbows all the way if copper.

The crawl space in spots has less than 2 ft head room and the house is over 80 yrs old with remnants of the old asbetos steam pipe insulation around. I don't want to spend the whole day in the crawl space.

I like copper but the correct style PEX would also work. I suggest you read up on PEX before you make a purchase since there are many different types/styles/and requirements.

So your ultimate question is whether you should use copper or PEX? Some people (usually plumbers) will swear by PEX, but I don't see too many differences in either to make one better than the other. They both have good and bad qualities that, in my opinion offset. I haven't ran PEX myself but I have worked on job sites where a plumber was installing it. Some love it for ease of install. In my opinion copper has 'soul' ;)

Thanks for your answers. I looked at the current price for the approx 120 ft of copper I'll need to buy and that pretty much made the decision for me.

The only issues now are:
1) crimp on (needs tool) vs one of the other connectors...e.g. "Watts"
2) Apparently for the same flow, I'll need 1" PEX to be equal to 3/4 copper?