Pressure draining Kitec hydronic tubing

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Mart

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I want to entirely decommission my Kitec in-floor hydronic heating system, which I intend to replace with a mini-split multi-zone air-to-air heat pump system. I am looking for advice on how to best clear any residual water from the loops/tubes and I am hoping to be able to do that with an air compressor set as low as possible.

After recently discovering one fixture was developing a leak on one zone, that brass Kitec T-connection was recently adapted to connect the Kitec PEX-AL-PEX tubing (orange) to new fittings via small segments of PEX tubing (red). But the return Kitec fitting at the manifold also started dripping, so I figure it’s only a matter of time before the rest of the Kitec fittings started leaking, and also possibly, the Kitec tubes rupturing from dezincification. To minimize any risk of a catastrophic water problem, I have gravity-drained the radiant heating system’s four zones by shutting off the boiler power and main water supply, opening each valve (fill tubes above each valve), and draining at the manifold return via the drain tube (bottom right). The boiler now shows no pressure.

Would it be possible to cut the Kitec tubing zone-by-zone on the supply-side (above the valves), adapt each of those Kitec tubes to PEX, re-connect those PEX tubes to an air compressor, and then blow out any remaining water at maybe 50-70 psi through the return drain manifold? The Kitec tubing is stamped with a max 125 psi rating @ 180F and the Slantfin boiler is rated at max 50psi, although I expect the latter wouldn’t be engaged at all if my proposed “solution” might suffice.

Also, knowing that oxygen is the ultimate boiler-killer, I am curious if anyone can tell me how long I can let it sit empty without doing too much more harm than I might have already done by draining it as far as possible with the power off. Will a few months empty make much difference, in the event I should decide to salvage it to only heat my basement with the non-Kitec tubing (PEX, I think) that currently runs under the concrete, as opposed to the Kitec tubing that was used for the main floor and upstairs?

Any feedback would be GREATLY appreciated, and apologies if this is not the best forum for this thread.

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John Gayewski

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You want to decommission a radiant system for a heat pump "hot air" heat? That's definitely a first.

Yes you can use air to clear the piping.

I think I would keep as much of the system intact as you can. I think you'll find the heat pump to be unsatisfying.
 

Mart

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Yes, that’s right. I’m going to go with a ductless mini-split heat pump system to replace the under-floor hydronic radiant heat system as our primary heating system, supplemented by existing gas fireplaces and electric baseboards. So I’m essentially wanting to completely drain the radiant heat tubing of water, leaving in place the installed Kitec tubing that I can’t otherwise remove without invasive extraction. It’s only the radiant heat tubing on two floors that’s Kitec; the basement tubing is not Kitec (though I’ll still hope to empty it) and the house plumbing is all PEX and/or copper.
 

John Gayewski

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Yes, that’s right. I’m going to go with a ductless mini-split heat pump system to replace the under-floor hydronic radiant heat system as our primary heating system, supplemented by existing gas fireplaces and electric baseboards. So I’m essentially wanting to completely drain the radiant heat tubing of water, leaving in place the installed Kitec tubing that I can’t otherwise remove without invasive extraction. It’s only the radiant heat tubing on two floors that’s Kitec; the basement tubing is not Kitec (though I’ll still hope to empty it) and the house plumbing is all PEX and/or copper.
Like I said leave it so you can reverse it later. Heat pumps contrary to their name aren't that good at making heat. They are better for making cold. Generally people who switch to heat pumps for heat aren't happy with them. Mainly because it doesn't feel warm.
 

Mart

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Thanks, John, but out here in Vancouver, the winters are mostly fairly temperate and most of our newer and retrofitted homes are employing heat pump systems. But I’ll leave that for another future thread. For now, I just want to minimize any potential water damage risks from our existing Kitec piping and fittings, without having to rip out walls and ceilings, etc., and also minimize any potential oxygen damage to the boiler while determining if the basement non-Kitec heating loops can/should be salvaged.
 

Mart

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Hey, John. Here’s a picture of what the inside of the failing Kitec pipe looks like at the short section that was replaced directly above its connection to the outflow valve. Looks like it started to melt, though the boiler was never set above 170F and the tubing was supposedly rated to 180F. Granted, that’s at the hottest spot in the most used zone of the system, but hence my concern. I gather that powdery black stuff is iron oxide, not dezincification, which I assume would be powdery-grey/white? Any thoughts?
 

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Weekend Handyman

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You want to decommission a radiant system for a heat pump "hot air" heat? That's definitely a first.

Yes you can use air to clear the piping.

I think I would keep as much of the system intact as you can. I think you'll find the heat pump to be unsatisfying.
Kaitec has been a disaster in Canada. I would be surprised it the OP could get it insured.
 
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