anyone try running cast iron radiators @ 130f?

[daddylama]

i can get the things dirt cheap... i can repair 'em if need be... so not concerned with cost or use...

the average temperature available will be 130f. i know this would be well suited for subfloor hydronic heating, or perimeter baseboard... but not sure about cast iron radiators.

i've run radiators on steam, with great results... but don't and won't have a steam source here. the source is solar, with a large mass storage tank, and a backup tankless heater if needed (when needed, i should say). closed system, btw.


if it doesn't work, we can do subfloor... but i'd like to avoid it if possible. it'll be on the 2nd floor, can't pour any type of slab. headroom is at a premium, so don't want to build up. Warmboard is out of the budget. that leaves stapling to the underside of the subfloor, with aluminum heat spreaders... but the tricky part to that is it'll have to go onto the subfloor BEFORE it's installed... there's a ceiling below.
i don't think the temperature is high enough for just laying the PEX in, without it being attached... nor do i like the low efficiency of that. "efficiency" is the key word since it'll be mostly solar powered.

we do have backup heat sources... but oil fueled forced air gets 'spensive

 

[Blue]

Huh. Interesting idea.


I got a lot of info on steam radiators and such on this site: http://www.heatinghelp.com/

 

[RAYJAY]

try this for info

www.fwwebb.com/pdf/htgcat03/2003htgcat_p221-222.pdf

Jeff

 

[Franz©]

I think your biggest problem will be cleaning inside of the radiators before connecting the system up.
Used radiators that come from a steam system will probably have a lot of scale from boiler compounding. Radiators from a hot water system will have scale too, and scale impedes heat transferr.

Given the radiational quality of iron as opposed to copper, 130° fluid will probably work very well. The only downside I see is temperature recovery in the room may be a little slower with 130° as opposed to 180° fluid. Of course it will also give yo a 50° lower maximum room temperature, but not many people want to hang out in a space hotter than 130° anyhow.

Many large building HW systems use lower fluid temperatures for tighter control of room temp.

 

[daddylama]

thanks for the replies... some good information in the links provided... and i actually hadn't thought of the scale removal...

when we used to repair radiators, they'd be sent out and hot dipped to remove all the paint before we'd touch 'em. come to think of it, that'd likely remove the scale too.
any ideas on home-shop removal of scale? boiling vinegar seems like it might do the job (or might just scald and smell bad)


our coldest outside temperatures are in the high 20s, at night... but that's not too common. high 30s is more average. daytime is rarely below mid 40s... so in all the climate is pretty mild, as far as winters go. tons of insulation going into the home, biodiesel furnace forced air for backup heat... and eventually a modern/efficient wood burning stove going into the main floor living room.

we get the radiators for $25/each, for a 6 fin hot water type... the occasional 12 fin lowboy can be found, too... we even got one of those that showed up for free a couple months back

 

[Franz©]

I'd try a 20% solution of Muriatic Acid & water and see how clean it leaves the radiator. If you get good results from a test patch using that set up a small pump and let it circulate for a while. Definitely want to employ a colser reservoir for the solution though to minimize the vapors, and do it outside.
Muriatic is cheap at most pool supliers.

Worst case you may have to replace some of the seals between sections, but they are far better found and replaced before they piss all over the floor.

Hot caustic tanks are pretty much a thing of the past due to EPA regulations. Oddly caustic is a hazard when in a small hottank, but thousands of gallons used in the brewing industry for cleaning are no problem. I wonder if the EPA guy gets free beer?

 

[daddylama]

Franz: your answers are awesome! thanks!

just ran out to the shop, where a gallon of muriatic acid just happens to be sitting (i use it for etching concrete)...

i put a crusty cast elbow and the air valve from the radiator in a ~20% solution... i'll let it sit for a while, and look at it later. (i'm not reusing the air valve, so not concerned about it... fine test piece)


brewing industry, eh? we've got more local breweries than anywhere in the country, here in Portland... free beer is a damned good thing... wonder if the EPA is hiring?

 

[Franz©]

I did a job in Genesee brewing the winter of 66/67, and enjoyed the warm considering it averaged around 0 that winter outside. Of course the walk out to my truck at the ned of 8 hours was brutal, but the money was good, and all the free beer you could drink. Odd thing was I had exactly 1 beer the entire winter with a couple limburger sandwiches one day for lunch. After seeing that stuff made, and learning the Genesecret, I wasn't all that interested. I even swapped the free case I got for Christmas with somebody for a second case of ornages.

Spent the next 2 winters in a much warmer climate on the opposite side of the planet, complements of LBJ's moneymakin effort, and wasn't interested in beer then either.

 

[daddylama]

yeah, i did a job for Anheuser Busch..
the odor of the hops and fermentation process would overpower anything from the welding... all day every day for 2 months.

couldn't stand beer for a few years, after that. the smell would make me a bit queasy.

i got over it, though



btw- the muriatic acid looks like it might well do the trick. the crusty cast elbow came out of it's bath looking pretty decent. interesting (helpful) side effect: it stripped the 3 layers of paint off, to boot!

i'll set up something to pump the mix through a radiator and see how that does.
thanks again for the tip!

 

[David Conwill]

What became of this? I’ve got an antique radiator that could stand to be cleaned up. It rusted through from the inside, I’ve been thinking about finding a cast-iron welder to fix it, since it’s on the backside of the radiator. I hate to just throw it away, it’s original to the house.

-Dave