arresting oil hot air HX rust?

[pybyr]

for those of you who haven't happened across my other mutterings of what I am building--

here's the background for my question

I have an existing warm air heating system, with a 125,000 btu/hr ThermoPride oil furnace

I am installing an Econoburn 150 gasifier boiler + 1350 gallon superinsulated storage

I am going to foist a huge water/air HX over the bonnet of the ThermoPride, and then the blower in the oil furnace will do double-duty to move air through the ducts regardless of heat source (oil or wood). The actual "oil burner" within the ThermoPride will then operate only in fall-back mode, such as if I am away from home for a truly extended time and need to be sure pipes don't freeze.

As I took the old plenum off my ThermoPride to make room for installing the big water-air HX coil, the good news is that most of the heat exchanger in the 11 year old oil unit looks to be in great and almost entirely un-corroded shape, even though it's been in an old farmhouse cellar.

the bad news is that there is _one_ patch of rust-- see attached photo--

before I hoist the 70+/- pound water to air coil over and onto the ThermoPride's bonnet, I want to do what I can to halt this pocket of rust- as I know that corrosion is the eventual doom of all heating appliances, especially warm air ones, where corrosion eventually equals Carbon Monoxide blowing straight through ductwork.

I have a can of "cold galvanize" spray paint, but am not sure if it is a good idea at the temps that the ThermoPride's HX will see

I am also familiar with some of the phosphate-based "rust converters" that do indeed work well for automotive purposes, but I again don't know if they'd be a good thing for a really hot surface.

Ideas or suggestions, please?

Thanks

 

[Redox]

That's wierd. Was there a humidifier dripping on it or something? I wouldn't expect there to be rust in just one spot. It probably is just a pinhole or thin spot in the weld.

Before you do anything, check to see if there is an extended warranty on the HX. Most mfrs put at least a 20 year warranty on them. It's probably prorated, but worth a look. It also probably isn't covered unless the rust goes through the steel. Try scrubbing it with a wire brush and see if there are any holes in it. Any hole is a problem and should be fixed or replaced. If it's small, you can just goop on some furnace cement or try rewelding over it. Patching is okay as long as you realize you have a problem and recheck it occasionally. Hopefully you won't be burning much oil after the Econoburn is up and running!

Chris

 

[steam man]

Clean it and test it. I don't know why you couldn't use a high temperature barbecue grill type paint on it. I have seen some that go to really high temperatures for exhaust systems.

Mike

 

[Dredknot]

Thermopride is one of the best oil furnaces you can buy in my opinion. They have a limited lifetime warrentee on the heat exchangers. Here is a link to their web page I have personaly only ever had to replace one HX in the last 5 yrs and they are very easy company to deal with.

(broken link removed to http://www.thermopride.com/thermo_pride_oil_furnaces.cfm)

 

[pybyr]

Thermopride is one of the best oil furnaces you can buy in my opinion.

thanks and I agree. that's why I bought it. when I was in high school, I used to haunt the scrapyard behind the local cola/oil/feed/fertilizer dealer where I grew up. and I dug into every carcass of every cast-off furnace or air conditioner that showed up over about 3 years, digging out various odds and ends to use for other projects. It helped that their main sales guy often sold fertilizer and pesticides to my dad (a post-mortem salute here to Dave Tymedyski, said big-hearted sales guy!) , so I was a "known quantity" and considered safe, even if they thought it was a bit odd.

Of all the makes and things I cannibalized parts from, the ThermoPrides made all the others look like crap.

So when I bought an old house with no functional heating system, which I knew I;d be in for a long time, at least if I can help it, there was only one make to seriously look at- and that's how I own a ThermoPride

I'll call TP tomorrow and ask what they think

 

[mtfallsmikey]

Eiether use POR-15, or some of the cold galvanizing spray in rattle-cans.