Radiant floor heating

G Twitchell

Is it necessary to use a bronze pump or can I use a cast iron pump for circ in a PEX (wirsbo) floor system???

Einsiedler_2

open vs closed

If you are using PEX pipe for infloor heating... I will assume that it is going on an "open system". as such, non-ferrous pumps must be used, so Bronze is the way to go.

If this is on a closed system. Wrong pipe to use. it will allow oxygen to permeate into the system, causing several issues including "rusting" all ferrous components.

I'd use PEX with OB (oxygen barrier). this allows you to go either way (open or closed) and allows for future installation of proper "Closed" system.

Only use Cast Pumps on closed systems.

EIN

Unknown

Hepex has an O2 barrier, so as long as you are not connected to an open system (water heater, no heat exchanger... which you shouldn't be!!!) you don't need a bronze pump.

Aquapex, another Wirsbo product, does not have an O2 barrier and would require a bronze pump.

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G Twitchell

I have a standard 50 gal water heater in the loop as a buffer/volume and I have HePex poured in the floor. I am using a TAKAGI tankless boiler/heater (190kbtu max) with no sidearm domestic hot water unit. I guess I can use the cast iron pump according to your reply.

Einsiedler_2

you have barrier pipe then

you are good to go.
Hepex is a great pipe c/w Oxygen Barrier.