Home>Discussions>INSULATION & HVAC>adding 'radiator zone' to a hydronic radiant floor system
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adding 'radiator zone' to a hydronic radiant floor system

I have a radiant floor heating system using Radiantec supplied pex & pumps in 4 rooms (each is a zone with thermostat & pump) & the system also supplies our hot water. I had an old boiler steam system with radiators for the other rooms in the house. Boiler gave out so I would like to add some zones to the system but I don't want to rip up flooring (2nd floor rooms) & would like to use hot water radiators but they have to be 'potable' i.e. made of copper or stainless steel so the water is still drinkable after passing thru. Does anyone know where I can find a US manufacturer? When I google I find mfgs in Australia, the UK and China but nothing in the US.

Re: adding 'radiator zone' to a hydronic radiant floor system

I think your problem will be capacity. Even if you could reuse the radiators for hot water, you likely won't have enough BTU's to fully heat the house. Unless the existing system was oversized... which is common.

You need a HVAC contractor familiar with hydronic system to look at your installation and do some load calculations.

The likely outcome... when its really cold outside, you'll have to choose between heating the house to setpoint, or taking a hot shower.

It might be cheaper to just replace the existing boiler. You probably can downsize it substantially while your at it, since you have the other system in service.

Re: adding 'radiator zone' to a hydronic radiant floor system


After reading your post several times, still having problems understanding your present hydronic hot water setup.

How big a house are we talking about???----number of rooms # of floors total sq. footage in the radiant part & the old steam heat part---what general part of the country you are in.

What is the present size of the "boiler"/hw heater (measured in BTUs/as in "30,000 BTU") now being used for the radiant zone that doubles as your potable hw ???

You say originally you had a steam boiler and still have old steam rads for the "rest of the house"----how much square footage does this entail, and why wasn't this area included in the upgrade that was done when the radiant section was installed????

Many of these combo radiant heat/potable water setups are installed using a dedicated HW heater----is this the case in your situation???

Do you know the BTU output capacity of this HW heater/boiler????

I assume the installer of the radiant/potable water job checked with building codes in your town---many towns do not allow such an install where potable water is at issue.

Trying to find copper or stainless steel rads for an expanded radiant/potable water loop for the rest of the house could be costly----it would seem that it would be much easier to use standard copper tube fin baseboard as a way to heat the rest of the house.

motoguy128 made an important observation that you should be working with local HVAC hydronic installers on this problem---you will need knowledgeable installers to plan out & install any future installation that will be workable & do the job of effectively heating the house & providing domestic hot water (DWH).

Were you satisfied with the work the Tech who installed the present radiant system did & has that Tech been consulted???

Please post back with more info.

Re: adding 'radiator zone' to a hydronic radiant floor system

What I suggest is when you go the replace your boiler, get a hot water tank that heats off the boiler!! Never have to worry about not enough hot water-even in the summer!! So glad we did that when we had to replace our dinosaur boiler two weeks after moving in this 1905 built house!! Good luck!

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