Corrosion on Runtal radiators

vivi

We had Runtal baseboard radiators installed approximately 8 years ago. Two days ago, we found a small pool of water under one of them. We removed the trim found a great deal of rust and corrosion on 2 different units. I am attaching photos. Looking at the photos, can anybody tell what is causing this?
Can it be repaired or do we need to replace them? Has anyone else seen this kind of problem with Runtal radiators?
The first 6 photos are from the unit that is leaking. The last 2 show the corrosion on the other unit.
Thanks

Leon82

That looks worse than corrosion. Even if you had it sandblasted and recoated I would be worried about the threaded area.

More qualified members will want to know more about the system like what type of pex if used.

kcopp

Yikes...
I must say I have seen that on a number of Runtals over the years.
That is toast. No fixing that.
Runtals are not cheap either.
Water quality is going to be (if not already) an issue w/ Hydronic systems.
Tell us more about the system.
What do you have for system piping? Boiler? Water? City water? Softener?

vivi

Leon82 & Kcopp, thanks for your responses.
We have a Viessmann boiler. The piping is all copper. No pex. Water is city water which here is neutral. No softener. We also have some 60 year old fin/tube baseboard on the same loop.
The corrosion on the first unit is on the entry side and on the exit of the other one.
I sent an email to Runtal with the photos and am waiting for a response.
Kcopp, do you know what caused the corrosion on the other Runtals you've seen? I don't want to replace anything until I know why this happened. Are there any other reputable manufacturers out there with a similar product? Myson?

Mark Eatherton

I suspect a major leak somewhere in your system. That much corrosion is indicative of significant oxygen in the system fluid. The lesser of the two metals (steel) is suffering degradation. I'd turn off the make up and keep an eye on the pressure. If it drops quick, you need to locate the leak and fix it quick before (if it hasn't already) it affected the boiler.

ME

kcopp

I one case it was bad plastic tubing. One case was in bathroom but the plastic tubing was good quality. Both public water. Some public water supplies can be less than optimal. Is/was there anti freeze in the system?

vivi

Mark, our water bill has been constant which I think would indicate that we don't have a major leak and there is no sign of a leak anywhere. Could air in the system cause corrosion? The last time the HVAC people drained and refilled the system, they had trouble getting all the air out. Maybe there was some left.
Kcopp, no antifreeze in the system.

Zman

Mark Eatherton said:

I suspect a major leak somewhere in your system. That much corrosion is indicative of significant oxygen in the system fluid. The lesser of the two metals (steel) is suffering degradation. I'd turn off the make up and keep an eye on the pressure. If it drops quick, you need to locate the leak and fix it quick before (if it hasn't already) it affected the boiler.

ME

This is almost certainly what is going on.
It won't be a leak you notice on your water bill. I could be a slow drip through a relief valve or in a concealed space. It could even be inside the boiler.
It is oxygenated water not air that is causing the problem.

Mark Eatherton

Does your Viessmann boiler also do your domestic hot water? If yes, what does your city water pressure come into the house at?

Has anyone done a water analysis (raw and in the heating system)?

ME

vivi

Mark, we have a Viessmann indirect fired hot water storage tank.
Pressure gauge at the boiler reads 17 psi. We've never had a water analysis. Water dripping from the leak on the Runtal is fairly clear - maybe a bit yellowish but definitely not dark - if this means anything. Thanks so much to all of you for trying to help solve this most distressing problem.

SWEI

Turn off the auto-feeder and see how long the system holds pressure.

jonny88

How did they connect to the rads.Im with Hatt as it would take a lot of makeup water.Not s fan of the street elbow going into the female.Its been a while since I put in a runtal but what do the provide for you to adapt to is it a stainless nipple.We know the plumber burnt the hell out of whatever it was with the str fitting.

bob_46

that looks like a 3/4 sweat by 1/2 mpt copper male adaptor and I'll bet he screwed it in before he sweat the joint and burned the dope on the threads. i've learned the hard way that if you hate leaks you solder first let it cool and then screw. It's a bit of a pain but it always works.

jonny88

in my opinion this is where the problem is maybe a reaction between copper and stainless nipple.Expensive rad but certainly their cost does not meet their quality.

vivi

Thanks All! It's important for me to know why this happened before I replace the radiators. Don't want to ever have this issue again. As a homeowner, I really can't verify if the work is being done correctly.
This forum is so helpful. I also had a problem with the Viessmann installation which I posted on this website in 2011. Inappropriate transition from boiler to venting could have resulted in CO poisoning.
Here's the URL:
http://forum.heatinghelp.com/discussion/137076/Vertical-venting-thru-walls-floors

Leon82

It looks like there is rust under the paint so it could be less severe on the other rads, but still being eaten away. If you decide to keep them I would inspect all of them