The white color has been discontinued replaced with Dune. The lighter enamel interior is actually a sand color. The black enamel is better for high temp cooking so it's used on their frypans, grill pans and woks. It's better for that purpose. It's definitely not inferior, just better suited for the job. The only line that has the black enamel on all the pieces in the black matte or satin black. The advantage is the black will season with use, and doesn't show staining as the sand enamel will over time.

The answer to your question about "miracle chemicals" is "oh hell no!" How long ago were these installed? You need a good answer from your plumber/manufacturer and one that doesn't involve a dime out of your pocket. Look, you have a defective product/installation. If it's a year or less, they absolutely need to stand behind the entire cost of repair. More importantly, they need to assure you that the actual problem has been addressed - you don't want to be replacing all of these in 3 years.

I too would never have considered not using cast iron radiators because of the potential burn factor. We raised our three kids in this house and never gave it a second thought. I really don't think of hot water radiators as anything that would harm a child. Yes, this whole situation is a major pain, but we are trying to look at the up side of this and figure that we'll have a brand new heating system out of it. So, we are trying to make choices that will be the best for our particular house because, as we all know, every house has its own unique quirks and issues. The idea of zoning the sunroom separately is a good one that we'll consider. We live in super cold Minnesota so we need lots of heat, especially in a room that juts out, and has so many windows. We are now contemplating using in-floor heating under our hardwood floors for the entire first floor, with two radiators (the ones that already have built-in covers) as supplements for really bad weather. All of this work for in-floor could be done from our basement, so it wouldn't involve a ton of extra tear out and repair since our basement is minimally finished. We'd have to pay an upcharge over what insurance will cover, but, in the big picture, it isn't all that much money. Thanks again to all.

My house is 1260 square feet on two floors, with another 630 square feet in the basement. There are four radiators for each floor, and a gas-fired boiler in the basement. The basement has no radiators, but I have three manifold ports open for future expansion. I ran Everhot oxygen barrier PEX, but left the iron pipe sections running down to the basement and put PEX adapters on the end of each down-pipe. From there I ran the PEX to a manifold like one of these https://www.pexuniverse.com/radiant-heat-manifolds.  The manifold has individual flow meters and a balancing valve for each line. IIRC you can also buy an electrically operated balancing valve that could be turned on and off to zone the system. I put the two manifolds near the boiler, which was in one corner of the house. That meant some fairly long PEX runs to get to the other corner of the house. I also had to dip the PEX runs down low enough to get under the steel beam in the basement, so they are a bit curvy in that area. However, it went in with no problems. I can go to the PEX manifolds in the basement and see the input and return water temps for each manifold. I can also see the flow rate of the water running to each radiator. One surprise for the balancing valves is that they do not completely close off the flow, so you can't use them to completely shut off water to a radiator. That would have been convenient if I have to do work on one radiator. I had to install caps on the unused ports to completely cut off the flow. FYI - I installed the manifolds (referenced in my link above) upside down because all my radiators were above the manifold and that made the routing easier. It all works fine that way, except the labels and temp gauges are upside down. Bruce