convert open system to closed system

tryagain

I installed a diy open radiant system in my new house 5 years ago, slab on grade with in floor heat.  I am not happy with the way it heats . In redoing my heat source and some of the piping i want to convert  the system to a closed system where my newly bought water heater, AO smith cyclone xi bth-150 95% efficient unit heats my floor water via a heat exchanger and still supplies my domestic hot water. After reading about diseases when you have an open system where potable and radiant water are mixed i figure this is safer  for my family.My problem is that when i was sold my pex tubing, it was designed for an open system and the tubing doesn't have a o2 barrier. What should i do to prevent oxidation in my pumps, valves, etc. i haven't bought the heat exchanger yet. should it be of a special material to resist oxidation. its hard to get help from anyone local when you did'nt buy the system or have it installed by them.

thank you for any help 

Paul Pollets

X-Block

A good solution would be to install the Taco X-Block,a module which has a built in flat plate HX, pumps and control. It will separate the non-barrier tubing from the heat source. You'll need to add an expansion tank, relief valve, tridicator gauge and feed source, per the manufacturers' instructions.  Using a water heater is not the best idea in hydronic heating. Try a mod-con boiler and an indirect tank for the upgrade...;

NRT_Rob

closed side non-ferrous?

I think the X-block has a cast iron pump on the system side? I might be wrong, but I think it's only non ferrous on the expected open side.



If I am right though, you can do what the xblock does with heat exchange, and non ferrous pumps on both sides.