Converting radiant slab to hydronic baseboard?

[John Shott]

At long last, I've developed a serious leak in half of my radiant slab heating system. Although it is a single zone system with a single thermostat, I actually have four supply lines and two return lines. As a result, I have been able to continue to heat the half of the house without the leak by adding ball valves to shut off the leaky side.

I am worried that trying to repair the leak my be a losing proposition on California clay soil that expands and contracts with moisture level. As a result, I'm considering adding a manifold to run PAP lines up to the attic and down the walls to add hydronic baseboard heat to the currently unheated side of the house. At a later date, I will likely replace the side of the house that is still slab heated with hydronic baseboards as well. I hope to use my existing AO Smith boiler (that currently runs at about 130-140 F) to heat the existing/remaining slab AND the new baseboard radiators.

If I run lines up to the attic and then down the walls, should I add air vents at the high point of each manifold loop? It appears as if Mr Pex and Shark Bite offer manifolds to accommodate PAP-based systems with adjusting valves and flow meters on each loop.

While I'm still in the process of getting the appropriate thermal analysis to select baseboard tube lengths, are there other things I should be anticipating or planning for?

Thank you for your consideration,

John

 

[Fitter30]

Most radiate floor heat only runs 10* over thermostat setting. Santa Fe get below freezing? Might want to consider 30% glycol for freeze protection with pipe running in the attic. If using automatic air vents in attic but put valves on them so they can be valved off after the air is out.

 

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[John Shott]

Most radiate floor heat only runs 10* over thermostat setting. Santa Fe get below freezing? Might want to consider 30% glycol for freeze protection with pipe running in the attic. If using automatic air vents in attic but put valves on them so they can be valved off after the air is out.

fitter30:

Thank you for those tips. I understand why valves on the air vents is important in an attic. Your mention of using glycol causes me to think of something else: my connection to the house cold water for makeup in the radiant heating system is a direct connection. My guess is that a newer requirement would be to add some sort of check valve or backflow preventer so that a glycol-filled radiant heating loop couldn't back it's way into the potable water system.

Thanks again,

John