Combicore with Super Rusty Hot Water

Steve Garson_2

I happened to open a drain valve on the radiant hot water loop near the Bradford White Combicore water heater that heats it. I was amazed to find the water to be more rusty (almost like watery mud) than the blow off from my steam boiler. I blew off four buckets full and when I dumped it in the sink, it had lots of iron granules.

Does this mean that it is ready to spring a leak? Should I be planning a replacement now, before the dead of winter. Or is this normal? The heater is 7 years old this December. Is the coil inside the heater steel?

Steve

hot_rod

Is it connected to non barrier PEX tube

by chance? If so the O2 ingress could be rusting away any ferrous components.

The coil in that tank is a plastic/ aluminum composite tube. If it leaks it will show up at the top nipple at that leak detector string. If it fails completely you generally will see the tank side pressure in the radiant side.

That's a good lifecycle on an early Combi. I never got past 5 years on any of my installs.

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Dave_4

The tubing is Onix.

How is rust generated if the tubing is plastic, the pipes to the radiant loop are copper?

Sounds like I should plan a replacement now.

Steve

hot_rod

Plastic will actually

allow oxygen through the wall of the tubing. Enough to start rusting and corroding, believe it or not. Ask any polybutylene radiant installer about O2 ingress.

The plastic (PE), PEX tube manufactured for heating has an O2 barrier of some sort. Some are layered into the tube, others have an EVOH layer on the outside.

That Onix should be an O2 safe tube. It has both an aluminum layer and EVOH if I recall. Aluminum is a complete O2 barrier EVOH slows the O2 to some industry accepted level

Bradford White has been very good about warranties on those early versions. Although yours may not have failed yet?

It needs to leak, as in on the floor, develop the high pressure in the coil side, as in a failed coil.
Or leak out that leak path thread at the top which indicates the double walled tube protection has failed. Just rusty water may not pass for a failed tank, warranty claim.

Contact your local BW rep or distributor for some options.

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