Flushing 25yr old in-floor hePex before replacing everything (except the hePex) ?

Dave Carpentier

Replacing everything about our hydronics system except the in-floor pipes ( and the two circs, plus AH). Currently a cast iron boiler. Before I start cutting things open, I bet I should clean and maybe refill with city water (it has mostly well water in it now, I would think).

Plan is to valve off all zones but one (at a time) , then pump in/out of the unused manifold ports.

I could have a 200gal tote full of city water ready to go, but how do I know what size pump is good enough but not so powerful that it could damage my poor old HePex in the slab ?

Once "rinsed" , I could circulate a cleaner of some sort , using a bucket and pump. Any recommendations on type or brand of cleaner ?

Finally, another 200gal tote to rinse the cleaner and crud out and then leave the pipes full of that city water.

Once the old plumbing is out and all the new stuff is connected, I will have an Axiom fill tank to add stuff and a Caleffi dirtmag to catch any strays.

Let me know if Im missing something please.

GroundUp

Pretty sure HePex wasn't even produced 25 years ago. City water is likely of worse quality than well water, but a simple water test would tell the story. Why are we using totes instead of using site water for flushing? Is there no purge station? No standard pump is going to hurt HePex or any PEX for that matter; use whatever you see fit just keep the pressure below the danger zone (I try not to exceed system operating pressure, just in case). Chemical will depend on what's actually in there, but something like Fernox F3 is pretty effective in most cases without being too aggressive.

hot_rod

A pump like this from any box store will give you plenty of gpm flow without over -pressurizing the system.

Isolate the boiler if you plan on going over 30psi.

Or buy the complete kit from Fernox

As far as water, hardness and TDS are what you want to know.

As you can see there are various water quality numbers from 6 different boiler manufacturers.

Viessmann shows hardness in PPM and based on the boiler BTU output.

I'd say hardness below 7 GPG. Simple hardness test strips get you close enough.

It is rare to find ph way out of wack from well or city water. The hydronic conditioners have a ph balance added. Along with O2 scavangers and film providers to coat the cleaned surfaces.

If you need to adjust the fill water

Axiom has a kit with a cleaner, deionizer, and final inhibitor.

Back in the day TSP or even dishwasher detergent was the go to. These products are all basically strong detergents. The hydronic cleaners do have some additives friendly to hydronic components.

With aluminum boilers, be sure the cleaner and conditioner is AL rated.

Dave Carpentier

We built in 2001 and the lines are stamped Wirsbo hePEX.

No purge station per se. I remember we filled it at the boiler drain point.

I'll incorporate a pressure gauge and a valve to throttle the flow, and see if they have that Fernox at the supply house. Thanks !

The new boiler manuf has required water specs. I happen to have a detailed water analysis of my well water that the province did (part of a wide study).

My Ph, Chloride, Iron, and Copper are within specs.

Hardness, TDS, and Conductivity are all quite a bit higher than boiler specs.

Im not sure how city water compares, but I will try to find out.