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[crankshaftdan II]

Newbie here-just trying to get some information about the type of Pex need for my lineset from house to OWB.  I have what I call clear(Whitesh color) tubes of 1/2" comming out of the floor-all are marked with the following letters stamped on side--1/2" SDR9 PEX A  100 psi  180 degree F.  180 PSI @ 200 degrees F. also  NSF-RFHASTMF876-F-877.  Am in process of making a decision on what TYPE & SIZE of Pex would be the BEST type for the lineset run of 100' to boiler & 60' from boiler to garage.  Would there be any advantages buying the more $$ Pex-AL or oxygen barrier due to cost for Iron circulators vs SS/Brass?  What type of adverse water problems if I run treatment in the system w/anode rod in boiler??  My boiler WJ is 409 SS.  Not trying to stump the pro's here-just looking for general information before I make the wrong purchases.  I am trying to keep things simple without a lot of bells & whistles.  Any and all comments appreciated-Goo-Bad-or-Indifferent.  Thanks....Cranky

[LittleJohn]

One of the major differences from open to close loop systems is the price of pumps; to go from cast iron (for closed loop, with barrier pipe) to SS or bronze (open loop, without barrier) is generally a big jump in $$$. Typically in Commercial setting that is why they run PEX pipes with out barrier, they spend a few extra dollars on pump and put in the relatively cheaper pipe (with out oxygen barrier) -> think stadiums where they have tubing on the order of 100k linear feet or more. 

I personally would choose a barrier pipe for this application, since more than likely the pipe in slab has a barrier on it already; I also prefer closed loop systems

In regards to pipe size, it would be hard to determine the size needed unless you know how much pipe you already have in the slab.  However, I would put in the largest tubing you can afford - you run less risk when running water slow thru a larger pipe, then when you have to jack up a pump to get more heat/GPM out of a smaller line.

HOPE THIS HELPS?

NOTE We always love pictures    Its nice to see other peoples projects once in a while.

[Sprinter]

Those are just standard pex approval numbers. PAP isn't necessary, just O2 barrier pipe will be fine. Even tho the system is open, your reducing the overall exposure of the system. Just limiting it to the actual open port. Running bronze or stainless isn't a must, but it eliminates the typical failures related to ferrous circ corrosion. And if Murphy's law has a say it will fail just when you need it most.
Only bronze and SS circs have a 3 yr warranty when used in open systems. Cast iron isn't warrantied in open sys.

[LittleJohn]

...and if Murphy's law has a say it will fail just when you need it most.
Only bronze and SS circs have a 3 yr warranty when used in open systems. Cast iron isn't warrantied in open sys.

Yeah, SS or bronze pumps cost more, but you more than likely do not have to replace as often.  You could TEMPORARILY use a Cast Iron pump, in an Emergency situation - but that is the only situation I would use one in.  Just remember Open system have oxygen, oxygen like to eat corrode ferrous metals, cast iron is a ferrous metal 

[Sloppy_Snood]

Just remember Open system have oxygen, oxygen like to eat corrode ferrous metals, cast iron is a ferrous metal 

This suceptibility would seem to be negated by using an appropriate chemical agent found in better boiler water treatment chemicals. 

Am I incorrect? 

[LittleJohn]

Water treatments only slow or reduce oxidation process (IN MY OPINION). 

The less ferrous metals you put in the system the less oxidation can happen.

[mlappin]

I must have got lucky again, cast iron pump on open system that's on it's 14th heating season. No leaks, pump still moves water well enough to heat the house when it was below zero.

[Sloppy_Snood]

Water treatments only slow or reduce oxidation process (IN MY OPINION). 

The less ferrous metals you put in the system the less oxidation can happen.

 

Actually, they can totally prevent corrosion if the boiler treatment additive is maintained (my guess is that most don't "want" to spend money on chemicals and change the boiler water out on a regular basis).

While I absolutely agree on minimizing the amount of ferrous metal contact surface areas on the open system, it is my chemical opinion that this is overemphasized predominantly for those not willing to perform the regular maintenance on an OWB (mainly, proper boiler treatment (additive) levels and manufacturer-recommended boiler water draining and refilling intervals).

That said, I did some Googling and did find a nice website with actual testing of treated boiler water on mild carbon steel.  Take a peek.

LINK:  Why Water Treatment? Article (Click Here; Contains Pictures of Treated and Un-treated Steel)

[mlappin]

Great article you linked to, I've saved it in my "gasifier" folder.

[Sprinter]

Good boiler treatments can provide excellent protection . But surprisingly it's the down time over the summer or long periods of stagnation that do the most damage. Some boilers or controllers have an excercise function that cycles the circs once a month or more frequent programmed interval to prevent circ failure. Often it's just a small bit of calcium , lime or rust around the impeller or shaft that locks'em up.

As far as the warranty goes, not many ever asked or payed attention but now they do ask if it was used in an open system. I seen quite a few bronze VDT's & Taco 2400 OWB series going out on orders when I was at the taco  warehouse last week picking mine up. I wanted to snatch the 0011 going to brown city hardware, but I have a temp in the greenhouse till another comes in.

[willieG]

here is a photo of my home made stove (if it works) of the inside after 10 years of use. the fire box failed at the bottom due to me using firebrick that was used and i found out later they were used to line an acid pit (dumb luck)  but if you look at the walls of the water jacket and anywhere else  on the fire box that the brick did not touch there is almost NO corrosion of any kind...10 years...idle all summer..well water and no treatment ever used

and upon inspection of the failed part of the fire box...all corrosion appears to be from the inside of the fire box out to the water side

http://i67.photobucket.com/albums/h308/billie_boy7/inside%20the%20bullet/017-2.jpg

and after ten years of running with this stove the originall taco 11 is still running the replacement stove

[Sprinter]

That's pretty cool, and unfortunate about the bricks. Do you think your water conditions apply to everyone's water?

[crankshaftdan II]

Thanks for all the informative stuff about the water quality and what others have given--my water quality is fairly good--biggest enemy if you chose to call it that would be high IRON content.  I do not choose to install a water softener as what some companies have suggested-as I'm on a septic system and don't want to pump a lot of salt into my tank/field--350' from the lake.  SS/Brass circulators probably will be best choice and most $$ well spent to alleviate future failures-down the road!  This will be a WIP for me-as the OWB has been purchased-waiting for better weather and have to do some site work before slab pouring and install time.  Will try to take some pictures and post them up as work progresses thru the summer.  Want to engineer this properly and not take any short cuts that will compromise maintenance and have failures down the road.  Please keep the suggestions/comments etc. comming!!   Cranky

[Sprinter]

An easy way to get the iron out is to just filter it. On some potable systems we inject air and let it sit in a precipitation tank( which is just a plain tank) this lets the iron turn from a liquid to a solid and the air allows it to rust, then it can be captured in a cheap filter. Your boiler acts like a precip tank and the open system circulating or during fill allows it to rust and turn into large solids which can be filtered. You could start with a 30 micron and go down from there , as long as it stays clear you can bypass the filter.

[Sloppy_Snood]

Thanks for all the informative stuff about the water quality and what others have given--my water quality is fairly good--biggest enemy if you chose to call it that would be high IRON content.  I do not choose to install a water softener as what some companies have suggested-as I'm on a septic system and don't want to pump a lot of salt into my tank/field--350' from the lake.

A dedicated water softener brine water drain that does not go to you septic field would seem to be an option.