Is there any downside to cast iron radiators?

[SolarAndWood]

We were at my BILs house in VT for New Years. He picked up a late 70s tarm for less than a grand and 7 steam radiators for a couple hundred bucks. He did a simple single loop with a single pump from the barn through 4 of the radiators connected with PEX through their 3000 sq ft house. Seemed to work very well given its simplicity. Any downside to cast iron radiators?

 

[tom in maine]

They might be an issue in milder weather since the mass might hold heat and the room temps could overheat on warmer days.
That being said, if you can integrate an outdoor reset control with such a system(not easy without storage) or learn to operate it based on what the weather is doing, I think it is a great system.
The mass of the radiators does afford some heat storage.
100 year old radiant heaters!

 

[PJF1313]

The only thing I can see that MIGHT be a problem is the PEX. It is the weakest link.

If your BIL keeps the temps down on the PEX, as far as not to melt it, the radiators will last to New Years 2100!
That is, if they don't loose power too long and the rads freeze and crack ;-)

I wish that I had more C.I. than the cheezy aluminum that I have.

 

[harttj]

They might be an issue in milder weather since the mass might hold heat and the room temps could overheat on warmer days.
That being said, if you can integrate an outdoor reset control with such a system(not easy without storage) or learn to operate it based on what the weather is doing, I think it is a great system.
The mass of the radiators does afford some heat storage.
100 year old radiant heaters!

Outdoor reset shouldn't be hard to do at all depending on your type of boiler. I installed it with my setup and cast iron radiators. Worked very well this Fall keeping the house from overheating.

Tim

 

[benjamin]

downside?

When you drop them on your foot, or have to move them up or down stairs. Even if frozen they can be fixed, just not easily. I fixed several and then found some through craigslist that were the same style and a lot less work than fixing the rest. Probaly wouldn't recomend the job to anyone. Moved one that was seven feet long, must have been 600 pounds.

I haven't had any problems with overheating, the simple thermostat works just fine.

How well did four radiators heat 3,000 sf?

 

[SolarAndWood]

It was single digits and they had no problem heating the space even with the boiler set to idle at 150. It is a pretty open layout and fairly new construction with a lot of glass. The thing that impressed me was how even the heat was through the house.

 

[SolarAndWood]

The mass of the radiators does afford some heat storage.

Are you thinking it is a nice bonus or enough to actually offset some tank storage volume?

 

[djblech]

I put a cute little one 12x32x8 in my mud room (back porch) and it is great. The first one I put in the family room had cracked at the inlet so switched it with a different one. I think they are great, I would replace all my bb if my wife would let me.
Doug

 

[SolarAndWood]

Thanks Doug. My baseboards have electricity running through them, so the decision is a lot easier. The sale to the wife was complete when we got back from skating and all the gear went right on the 6 footer in the mud room. It also helps that in my area there seem to be a lot more people trying to get rid of them than people shopping for them.

 

[deerefanatic]

I put one in our milkhouse that I got.. It's a pretty large school-type radiator (short and fat) about 14 sections long.... It'll bake you out if you want it to.... I have it on a thermostat and totally eliminated the electric space heater for keeping the well thawed......

I also have a couple small ones on the porch in the house, just not hooked up yet... My goal is to get away from the forced air entirely and go Baseboard / CI rads.......

 

[webbie]

Some steam radiators need to be modified for hot water.
Obviously these did the job, though.

I can't think of any down side to cast iron radiation - the only reason they are not as popular these days are space and style issues.

 

[SolarAndWood]

Some steam radiators need to be modified for hot water.
Obviously these did the job, though.

It wasn't too bad, he only lost one of them in the conversion and that could be fixed if he was motivated to do so. He added bleeder valves, put new fittings on and then found some interesting paint...some early 70s Chevy Blue, copper, etc.

 

[SolarAndWood]

It's a pretty large school-type radiator (short and fat) about 14 sections long....

That is what I am shopping for...a couple of 20" tall 10 to 15 footers to put under the walls of windows. I figure the bigger I go, the lower temps I can run through them and still heat the space?

 

[Singed Eyebrows]

It's a pretty large school-type radiator (short and fat) about 14 sections long....

That is what I am shopping for...a couple of 20" tall 10 to 15 footers to put under the walls of windows. I figure the bigger I go, the lower temps I can run through them and still heat the space?

Unless you have a mansion these will roast you out. I have a 3' 7 tube & a 5' 6 tube CI rads that have been in 20 years. These are under the window rads. I can run very low temps & they still heat. I tried to save on gas heat last year & kept the house about 60 to 62, they were so cold they wouldn't thaw frozen corn, yet they still heated in cold weather in Wisconsin. I have my Atmos gasser piped into them now & with gravity feed, main ball valve closed halfway & each rad valve turned down I'm at 78 to 80 here. When I get a Taco EBV on the main line that will take care of it. Don't pass up some nice smaller rads because you are looking for 10 to 15 footers, Randy

 

[chuck172]

I think they work great on their own zone. Don't try to mix them in with fintube radiation.

 

[leeeallen]

What is the issue with using cast iron rads with fintube?

 

[SolarAndWood]

Don't pass up some nice smaller rads because you are looking for 10 to 15 footers, Randy

My current thinking is 2 long shorties in the 2 spaces that make up the majority of the house and then a few small ones for the rest of the house zoned separately.

Zone 1 is the main floor living space is 1300 sq ft, 10 ft ceilings and about 400 sq ft of glass. The glass is all on one 55' wall that faces S/SW. This space gets a long shorty roughly centered on the 55' wall.

Zone 2 is the lower 1100 sq ft walkout level below zone 1 with another 50' of glass. This space will house the boiler/storage. Another long shorty will be centered on this wall of glass.

Zone 3 will be 3 bedrooms and bath on the main floor. 4 small rads.

Zone 4 will be a bedroom and bath on the lower level. 2 small rads.

Zone 5 dhw. Superstor or similar.

Then leave expansion stubs for shop, garage, etc. Maybe 3 or 4 more zones.

It is a lot more complicated than my BILs system but offers a lot more control which should mean a lot less babysitting and temperature swings. Seem right?

 

[SolarAndWood]

I think they work great on their own zone. Don't try to mix them in with fintube radiation.

No worries there. I'm starting from scratch as my current baseboards have large diameter copper wire running through them instead of piping.

 

[chuck172]

Copper heats and cools nine times faster than cast iron.

 

[deerefanatic]

And THAT my friends is why CI rads heat so much more "evenly" is because of their thermal lag.....

 

[Eric Johnson]

What is the issue with using cast iron rads with fintube?

As Chuck suggests, they heat at different rates, making it difficult at times to regulate the output. In addition, baseboard requires much hotter water than ci rads, so if you're getting heat out of the baseboard, you're going to get a whole boatload of heat out of the radiator at the same time. That said, I've done it, and you won't go to jail for it, but it's an imperfect solution in most cases. For heating pros, it's a huge no-no (they're like that).

One of the nicest things about ci rads, IMO, is that it's like having little wood stoves in every room. Great place to warm your butt or dry out the mittens & ski gear. My wife puts bed sheets that have been hanging out on the line on a radiator in our sunroom, and the whole room smells like fresh linen.

I consider them functional works of art which, if properly maintained, will last several lifetimes--probably have already.

 

[Jeff S]

Eric its good to hear from you again,reading your many post on cast iron radiators was very influential in my own decision of installing them with my new EKO.

With my EKO 25,properly sized CI Rads,660 gallons of storage I have been able to keep my house a comfortable 70 -72F while only using 120 - 130F water.

 

[SolarAndWood]

Jeff, what did you use as your guide to sizing? My thought is to oversize them to always have the distribution capacity and have them be more effective at lower temps. Then, zone them to achieve control. Seems the only downside is a cold night that goes to a warm sunny day and having that big hunk of warm cast iron sitting there.

 

[Jeff S]

I used the chart from Colonial supply for both figuring the EDR of each radiator and how many BTU's the produce at different temps.

For rough figuring

120* = 50 BTU's per EDR
145* = 100 BTU's per EDR
170* = 150 BTU's per EDR

Of course you need to some type of heat loss calculation to get an idea how many EDR of radiation you need.

When dealing with used radiators its difficult to get exact sizes.In my case I bought a lot of 12 rads and used 8 in the house using
the oversize ones in rooms we use most and undersized ones in bedrooms,since we generally keep our interior doors open everything seems to even out.

 

[pybyr]

Any downside to cast iron radiators?

Aside from fashion preferences and the space that they take up, the only reason that I can think of is that they're material-intensive and hard/expensive to move; building material trends have been going to more uniform, lightweight, and sometimes short-lived products as compared to things that are designed to last indefinitely.