Adding radiant to cast iron hot water system

dmcs

Hi, Question for a family member who has a small 2 bedroom house with single zone hot water system with cast iron radiators. She is finishing off the top floor to be a master bed and bath suite, where she wants radiant heat.  They are using Quick-Trak.  When I added radiant zone to my single pipe steam system, I used a flat plate heat exchanger so as not to introduce water from the steam system into the radiant loop.  Is that a concern at all with adding radiant to existing cast iron hot water system? 

Paul Pollets

RFH for HW

The radiant floor heating zone would use either a 3 way or 4 way mixing valve and pump for the new radiant zone. If there's a mod-con boiler, a 3 way valve is used. If a cast iron boiler, a 4 way motorized valve is used with a control (usually Tekmar) to prevent thermal shock of the cast iron boiler.

dmcs

heat exchanger not required?

Thank you for the response.  So there is no problem with running the same water that goes throuh cast iron hot water radiators through the pex for radiant system (with appropriate mixing valves of course to get the right temperature)?  For cast iron steam boilers I understood rust and debris in the pipes would cause problems in the pex and just wanted to make sure that issue is not present with hot water cast iron radiators. 

Paul Pollets

Correct

as long as you use barrier PEX piping, and the correct mixing valve/control, there will be no problems.

dmcs

Thanks!

Ok, thank you.