# Is there any downside to cast iron radiators?



## SolarAndWood (Jan 6, 2010)

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?


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## tom in maine (Jan 6, 2010)

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!


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## PJF1313 (Jan 6, 2010)

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.


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## harttj (Jan 6, 2010)

Tom in Maine said:
			
		

> 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


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## benjamin (Jan 6, 2010)

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?


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## SolarAndWood (Jan 6, 2010)

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.


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## SolarAndWood (Jan 6, 2010)

Tom in Maine said:
			
		

> 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?


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## djblech (Jan 6, 2010)

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


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## SolarAndWood (Jan 6, 2010)

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.


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## deerefanatic (Jan 12, 2010)

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.......


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## webbie (Jan 12, 2010)

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.


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## SolarAndWood (Jan 12, 2010)

Webmaster said:
			
		

> 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.


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## SolarAndWood (Jan 12, 2010)

deerefanatic said:
			
		

> 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?


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## Singed Eyebrows (Jan 12, 2010)

SolarAndWood said:
			
		

> deerefanatic said:
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 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


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## chuck172 (Jan 12, 2010)

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


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## leeeallen (Jan 12, 2010)

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


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## SolarAndWood (Jan 12, 2010)

Singed Eyebrows said:
			
		

> 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?


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## SolarAndWood (Jan 12, 2010)

chuck172 said:
			
		

> 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.


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## chuck172 (Jan 12, 2010)

Copper heats and cools nine times faster than cast iron.


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## deerefanatic (Jan 12, 2010)

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


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## Eric Johnson (Jan 12, 2010)

MEHEAT said:
			
		

> 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.


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## Jeff S (Jan 12, 2010)

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.


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## SolarAndWood (Jan 12, 2010)

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.


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## Jeff S (Jan 12, 2010)

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.


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## pybyr (Jan 12, 2010)

SolarAndWood said:
			
		

> 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.


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## Singed Eyebrows (Jan 12, 2010)

SolarAndWood said:
			
		

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 I don't really have the expertise to answer that. My experience is that CI rads seem to heat a lot more than their BTU ratings. Also rads that are too cold aren't going to be much of a "radiator", Randy


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## karri0n (Jan 12, 2010)

SolarAndWood said:
			
		

> Singed Eyebrows said:
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Seems really complex, possibly unnecessarily so. CI rads hold heat for a while, but they aren't going to still be heating you out of the room hours after the circ stops cycling. It's a matter of lowering the thermo by 2-5 degrees if you are anticipating that they are going to continue heating far past the temp you set them to.


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## Singed Eyebrows (Jan 12, 2010)

They shouldn't overshoot much with a Flo Chek on the line. At least mine didn't with the gas boiler. I didn't put one in with my Atmos & I'm being cooked out. A Taco EBV should also take care of overshoot & thats what I'm going to install next as I need the unrestricted flow for gravity feed, Randy


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## Singed Eyebrows (Jan 12, 2010)

I was assuming storage & this might not be correct. Obviously you can't just shut off flow to the heat sink with a solid fuel boiler, Randy


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## SolarAndWood (Jan 13, 2010)

Definitely doing storage and also very much into non-uniform, heavy things that are designed to last indefinitely.  We'll see how the cast iron and propane tank scrounging goes.


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## Singed Eyebrows (Jan 13, 2010)

S&W; Run a 2 pipe system, all the inlets  on one & outlets on the other. Pitch everything upward & you won't trap air. A heating contractor came over many years ago & gave this advice & this has worked well ever since, Randy


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## SolarAndWood (Jan 13, 2010)

Singed Eyebrows said:
			
		

> Run a 2 pipe system, all the inlets  on one & outlets on the other.



Parallel as opposed to series?  I have very few rooms in the house with very different solar gain.  That is kind of why I am thinking that I need 4 zones + dhw to maintain control.  The 2 big shorties, maybe a half dozen smaller units and I think I am done.  I am toying of the idea of not even using a radiator at all on the lower walkout level and just coming up with a way of exposing some of the propane storage tank(s) to heat the space.


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## Singed Eyebrows (Jan 13, 2010)

Thats what works for me. I was going to suggest a bunch of zones & you have that handled already. I'd be surprised if series(inlet to outlet,outlet to inlet) would work well. With parallel you can adjust heat with a valve(on rad) or use a thermostatic valve(no electricity) etc. I have found nice rads at the scrap yard. I once got a 400 pounder for $19.00. I don't think I ever heard anybody say they made a mistake putting in CI rads. I can't say the same about a number of people that took out CI rads for baseboard, Randy


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## DBoon (Jan 13, 2010)

Cast iron radiators are the most nearly perfect form of heating.  I'd love to combine mine with a wood boiler someday.  If you buy them new or used, just make sure to size them all correctly for a room and/or get some adjustment valves on each one.  I wouldn't plumb them in series - I have a parallel arrangement and I can't imagine how long it would take for the last cast iron radiator in a series arrangement to get warm - maybe never.  

You'll find that you don't need to set the thermostat as high as with baseboard radiators since they are radiating heat for a long time to the room.  This radiant heat will make you feel warmer than you otherwise would. 

Only drawback is size (they do limit furniture placement) and some people find them ugly.  I don't feel this way at all about them.  I've looked at buying more than one house over the years where the owner was so proud to have replaced all the "ugly old" cast iron radiators with (ugly, new) baseboard radiators.  People who visit (when I am running the oil heat and not the woodstove) naturally gravitate to them and sit on them like furniture.


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## Eric Johnson (Jan 13, 2010)

Like you, I think they're beautiful. I have one in my greenhouse with a lion image cast into it. Here's a couple of pics. You can see that in this instance, I violated the "don't mix 'em" rule. The baseboard is pretty worthless. What I need in there are more ci rads!


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