Non-O2 pex in finished space - solutions?

dynamitemonkey

Looking for some quick input on this.

We have a hydronic heating system which was zoned/redone when we refinished the entire house. But it appears the guy used Aquapex to run many of the lines, which doesn't have an O2 barrier. The rest of my lines are iron. So I imagine I can't just put a stainless boiler/etc because I'll still have iron in the system.

I have some techs doing work on the boiler here who just caught it and are suggesting adding glycol/inhibitor into the system to counter this. They say if I do this and have them test/adjust every year or two I shouldn't have any issues. Is this a reasonable long term solution or will I run into rust/corrosion issues with this anyway? My understanding is the glycol itself is corrosive and the inhibitor counters this. I'm worried it's counterproductive. My system is fully indoors.

I'm not thrilled with the idea of an annual expense in perpetuity but I don't think we can rip up the whole house either to replace the aquapex. It might even be easier to replace all the iron (still very destructive).

Any ideas?

hot_rod

just a hydronic conditioner with oxygen scavengers would be fine. No need to use glycol unless you need freeze protection
Rhomar, Fernox, Adey, Axiom, Sentinel are a few brands. Most have 12 ounce cans that you squirt into the system.

Go with a two part, cleaner first, the refill with conditioner

dynamitemonkey

Thank you for the response!

Do you think the conditioner is fine as a long term solution? He said he couldn't source any without glycol for some reason. We're in Canada. Would the conditioner be an annual thing? If so, is it something I could do as a homeowner?

If I plan to replace the boiler/pump/expansion tank either way (rust), do you think I would be wiser to just go fully non-ferrous? I actually think I could rip out the last two iron lines with minimal damage and cost (two horizontal drywall runs).

kcopp

I would definitely avoid the glycol. The other part is to try to keep your system water temperature as low as you can. What do you have for radiation? What boiler do you have?

dynamitemonkey

It's a very old Chromalox EDB-20-1. But retrofitted with an outdoor temp reset (Tekmar).

The rads are copper fin tubes mostly and one Myson panel. (Is the panel something that would also corrode?)

hot_rod

The test kits tell you when it is time for boost of the O2 scavenger component.

The lower the temperature you run, the less the O2 ingress. Radiant isn't nearly as bad a 180F baseboard for example.

The outdoor wood boiler manufacturers sell just oxygen scavenger.

The hydronic products have additional ingredients, film providers, Ph buffers, aluminum friendly, etc. And cost more as a result.

dynamitemonkey

hot_rod said:

The test kits tell you when it is time for boost of the O2 scavenger component.

The lower the temperature you run, the less the O2 ingress. Radiant isn't nearly as bad a 180F baseboard for example.

The outdoor wood boiler manufacturers sell just oxygen scavenger.

The hydronic products have additional ingredients, film providers, Ph buffers, aluminum friendly, etc. And cost more as a result.

I was running at about that temp though tbh.
Think inhibitor is a safe long term solution? Can I do it as a homeowner?

Smarter to remove the iron and go fully non-ferrous? I'm already replacing the major components and I can change out the last two iron lines.

Really discouraged as this system has been a massive money sink.

hot_rod

You could isolate the tubing with a plate heat exchanger. A stainless pump and a lined expansion tank would be needed on the tubing side.
All the boiler piping could stay ferrous.

The chemical fix would be ongoing. The HX fix is one time, but $$

Or play the odds and see how much it corrodes. Expansion tanks are usually the first to fail. Circulators can scale to the point of not spinning.

The early high temperature rubber tube systems would fail within a couple years, tanks, threaded pipe, all the ferrous metals take a hit.

HomerJSmith

Concerning hot-rod's last post, I have done that this way. On the load circuit I have installed a 30 psi pressure gauge and pumped the Ex tank air bladder to 5-8 psi and then pumped the fluid up to 15psi on the gauge. This would allow the fluid in the tank to fill the sys as the air is eliminated. It would also allow you to monitor the sys pressure. You can also refill the fluid when the pressure falls to 8 psi. I've done this on glyco sys.
I have also put a strainer on both side of a flat tube heat exchanger.

dynamitemonkey

I have iron and aquapex in the same loops/runs so I think I'm SOL on that one

Derheatmeister

One could go the Chemical or the Non Chemical route...
In system such as described we remove as much of the iron components we can gain access to and replace them with non ferrous components such as Stainless Steel expansion tanks,boilers,circulating pumps Brass valves,"Magnetic filters" such as the Fernox TF 1",Replace iron Rads with Rad walls..
We also perform a reverse flush,install a system cleaner, flush the cleaner followed by installing deironized water in conjunction with a sacrificial anode as per VDI 2035 or ANSI H 1001.1
Many opinions on this subject...It all depends on the what you are up against.