Cast iron radiators?

[cbb]

Gentlemen;

Recently I picked up 7 Aero brand cast iron radiators. A house was being demoed and I got them for free. Probably late 1930's vintage.

They have been used every year with a oil boiler system in the old house.

I woul like to pressure test them and use them this fall.

What pressure should I apply? For how long, 24hrs.?

Should I clean internally? If so with what?

They need to be painted, anything special for paint? High temp stove paint?

 

[pbvermont]

You won't find much better heat delivery than those radiators, except radiant floor. Free is good. Household water pressure, as in garden hose would be sufficient. Up to 50-60 psi. is enough, considering ultimate system pressure will be around 12-15 psi. Test for a few hours or overnight. You could flush them well at the same time with plain old water, to get most loose particulate matter out. Put a dirt separater in the system when you build. Flat black Rustoleum is the most efficient heat-emitting paint. Other dark colors close to that are also good. Aesthetics come into play largely, with paint choice.

 

[ewdudley]

If they were frozen you'd probably already be well aware of some 'leaks', but other than that it's highly unlikely that they have developed any leaks since decommissioning.

For a pressure test, just test them. Maybe apply a single drop of ATF to each of the air vent's threading now, so they will all work when you do your leak test. Fill with cold water at 30 psig or more, wait a couple minutes for moisture to appear. Or use compressed air and a detergent spritz or brush swab to find any leaks.

You might be able to rinse out some crud by tilting them up and shooting in there with a garden host or pressure washer, can't hurt.

Sand blast if needed. Don't know about paint, although I wouldn't be concerned about temperature. I took mine to a body shop and left it to their professional discretion.

 

[ewdudley]

Flat black Rustoleum is the most efficient heat-emitting paint. Other dark colors close to that are also good.

Are we sure about this? I can appreciate that color affects heat absorption, but does if affect radiation negatively enough to matter, or negatively at all even? FWIW mine are all off-white and nobody's complaining about being cold. Virtually all the Euro rad panels are white.

 

[cbb]

Thanks guys.

They have never been frozen. Probably air test at 30lbs. for 10 hours and clean out with a hose , pressure wash outside and repaint.

 

[binfordw]

Lucky dog!

Our house has nice old radiators, and I could really use another 1 or 2. Its hard to find "good" ones without them being expensive.

 

[salecker]

Hi cbb
I just hooked up 2 zones of CIR in our loft of our house,have 4 more to go on the main floor.
I salvaged the rads from an old highway lodge.They had been out in the weather for years,willows had grown through them,there were 3 times as many as i thought.
The first thing i did was vacuum/blow out the loose debris,Then i flushed with water and did the first pressure test full of water to 80 psi.I left them for a while.Then i flushed them with an acid water mix,i hooked up an old circ pump and let it run for about 6 hrs with the acid,i used a barrel and recirculated.Then flushed with clean water,filled with water and retested to 80 psi.Then my wife wire brushed them to get rid of any loose paint,and painted them with Tremclad flat black.
We have TRV's on each zone,our weather is mild and the rads don't get overly warm yet,but the rooms always feel the same.The interesting thing is the first rad will be warm,and the second will be cool.So they do an excellent job getting the Btu's out of the water.
For yours i would still do the acid flush to make sure there isn't any scale buildup.
Could you post a pic of yours?I'm trying to find out who made ours and what vintage they are.
I just moved the next batch i have to process into our shop,hopefully start next week.
Thomas

 

[Bob Rohr]

Are they steam or HW rads? How many connections? I would stay below 30 psi test, if they were steam they were never pressurized.

Install with a good dirt separator as they may continue to flake rust and dirt. I used a pressure washer with a bend in the tip to push in the bottom connection and direct flow up all the sections to get crud out.

Powder coating sometimes destroys the types with rubber seals between the sections, painting seem to work fine

If they are single port steam use a TRV with a dip tube to try and get flow into all the sections.

 

[salecker]

I was told by the dealer i get all my hydronic supply's from to go to at least 80 psi.The way he explained the 80psi was, the last thing you want is a rad to start leaking after you have invested the time to clean,paint and install them into your new house with all the nice hardwood flooring,sanded log wall,or fresh drywall.Seeing that mine were out of service and out in the weather for 30 yrs or so it made sense to me.
When it was put that way it made sense.And when filled with water when you test there is little chance of getting hurt if you find a weak one.
And when you hook them up,hot water in the top fitting and cold out the bottom.
Thomas

 

[heaterman]

Test to the same pressure as the relief valve in your system which should be 30PSI. Don't go much above that. They were made to work on a system pressure of 10-20PSI (normal boiler pressure) and you may create a problem by going to much above 40.
If they are made to normal standard. The test pressure would be 1-1/2 X relief before failure so 45PSI would be where the factory tested them to originally. There is absolutely nothing to be gained by going higher than that and possibly everything to lose.

As mentioned above you should test hydraulically with water rather than air pressure.
Some of the most comfortable houses I have been in are full of CI rads operating with variable water temp based on outdoor reset of water temp.

 

[cbb]

Thanks guys, I will test with water! Also do a a good clean up on the inside.

Saleacker, I do not have a photo account and have never posted a pic. I can't help there. Mine says Aero on the top end in the cast. Probably from the 1930's. A google search I did turned up a number of pictures of similar kinds like mine.

I believe they were origanally a steam rad.

 

[BoilerMan]

I just lugged one to it's final destination in one of the kid's rooms last night.

I tested with air to 30psi, let them sit for a day or two. All were good, rinsed with hot water and a garden hose, blew out with compressed air, repeated several times. Sandblasted them in the back yard (wear a mask, lead paint) and painted them with automotive paint.

Couldn't be happier with the results, it's like having a wood-stove in every room. The only negative is that they are stinken' HEAVY! Mine are all on the second floor...........................

TS

 

[maple1]

They will likely stink with paint smell too for a bit, once you start heating them? I know my storage tank0k sure did - but might have been the cheap paint I used.

Still trying to convince my other half...