Flat Panel replacements for Cast Iron

robstlaurent

Last year I bought a modest-sized condo in 100 year old building in Boston outfitted with standing cast iron radiators. I'm considering replacing them with low profile, flat panel, wall-mounted radiators. One contractor has told me that Runtal Charleston Pro is really the only option (and that the European-style radiators won't work). Another contractor didn't mention anything about this. Is Runtal really the the only replacement option? Is Myson? I'm not sure what to believe and what the real options are. 

EBEBRATT-Ed

Steam or water?

hot_rod

really the best way to choose a different radiator is to do a room by room heatless, then look for a radiator that can supply that output. If you are looking for the flat panel radiator there are quite a few options.
Runtal, Myson, Buderus, Dianorm, etc

www.slantfin.com has a free load calculator to do your heat load analysis.

robstlaurent

EBEBRATT-Ed, They are single-pipe steam radiators.

Jamie Hall

The Runtal Charleston Pro may be the only option which will work. At all. Make sure that the radiator is properly matched to the heating load, as @hot_rod said.

KC_Jones

Do you have individual control of the steam system for your condo, or does the boiler have a single control for the whole building?

If the second, I'd be a bit leery about making this change. Panel radiators will have different heating characteristics from cast iron. I would do some research before making this type of change. Others that have more experience with this may chime in on this subject.

jumper

I believe that one can pipe a panel as two pipe with a one pipe system?
Forget exactly how, especially where to vent.

bburd

The concern here is that cast-iron radiators hold heat much longer than the newer, lightweight panel style radiators. 

Unless the OP’s condo has its own heating zone and thermostat, if this change is made they are likely to end up with an underheated home.

hot_rod

But panel rads with all the forward facing metal surface area probably provide more radiant energy transfer compared to column cast rads. Panel rads come close to radiant panels for comfort. Especially when you are in front of them, or anywhere in their line of sight.

mattmia2

The steel with much less mass than the CI will likely want shorter,more frequent cycles to maintain even temp.

hot_rod

mattmia2 said:

The steel with much less mass than the CI will likely want shorter,more frequent cycles to maintain even temp.

I think the best way to run panels is constant circulation, or TRV with outdoor reset which if you take some time and dial it in you pretty much get constant circulation with room by room control via the TRV.

That why the US method of hydronic control was always at odds with boilers like Viessman and Buderus. The controls on the Euro boilers are really optimized for constant circ, modulate the SWT and firing rate with indoor reset via the TRVs, and outdoor reset via a sensor.

As turndown rates continue to go up, at some point the boiler and the circulators could maybe run non stop, modulate heat input to low end and high end load.

mattmia2

It is one pipe steam.

jumper

hot_rod said:

But panel rads with all the forward facing metal surface area probably provide more radiant energy transfer compared to column cast rads. Panel rads come close to radiant panels for comfort. Especially when you are in front of them, or anywhere in their line of sight.

Yes. At steam temperature there is a re-radiating benefit from less convection. Some comfort even after panel cools.

robstlaurent

So another contractor offered up another option (an alternative to Runtal Charleston Pro): replacing the standing cast iron radiators with cast iron baseboard--something like Burham Baseray, I guess. The baseboard option seems like it would solve the issue of reclaiming space taken up by the standing radiators. It might be cheaper than the Runtal wall-mounted option, too. Anyone have thoughts on whether the cast iron baseboards might be a better way to go?

mattmia2

CI baseboard is a great option if you have enough space to get the output you need. Set it up as 2 pipe since there can be issues with the condensate returning properly in baseboard set up as 1 pipe. Someone that understand steam can add this to a 1 pipe system.

leonz

Believe me understand the space issues,

but if the single pipe radiators are working and the pitch is correct and there is no banging causing issues with noise perhaps it would be wiser to having a meeting with all the condo owners and the building owner(s) and ask if they are using drop headers with a second larger drop header below the first one to make more dry steam more quickly and have TRVs installed on the radiators.

If it were me I would like to know if the steam boiler is not using a drop header or not using both tapping's in the steam chest to feed steam to the condos through a drop header employing a larger header below the first drop header to allow the dry steam to travel that much faster to the radiators above the boiler.

It would make more sense to ask the building owner about fixing the piping on the steam boiler and installing a drop header with a second larger drop header for even more dry steam that can be fed to the condominiums and perhaps the utility bill for heating fuel would be much less as less fuel would be required especially if TRV's are installed on the radiators.

The boiler will run less and maker more dry steam to be fed through the 2 pipe drop header with the second drop header or headers if paired and if space permits and will heat the condominiums faster and the radiators will cool down that much slower if I remember my reading correctly.

My being a novice that loved steam heat growing up and if I were you would want to know if:

1. is the steam boiler in use is plumbed using both tapping's in the steam chest?
2. is it using a drop header or drop headers to make dry steam for the condominiums?
3. if it has a drop header or a pair of drop headers does it have a second drop header or headers of larger size to allow the dry steam to expand that much faster to allow it to travel that much faster to the header pipe in the basement to purge the air in the header pipe vents and then to the risers to the condominiums??

By allowing the steam created by the boiler to dry and allowing that dry steam to expand that much faster with the same amount of fuel allows it to travel to the condominiums that much faster to heat the radiators and cool down that much slower especially if TRV's are used. I would be willing to say that you are using much more fuel than you all need to for sure.

One drop of water heated to made steam then dried and expanded to 1,700+ times its size will make a lot of dry steam heat that will heat the building that much faster using the same number of BTU's if my math is right and I did not fall off the steam locomotive tracks ha, ha.

Being a novice I have learned a lot about what not to do and how to do it right; thank you Dan and all.

Its time for this "stupid kid" to waddle off and do chores.

AS my father was fond of saying, "each man is my teacher and I learn from him".

He made it a point to have yearly thick high quality calendar wallet cards printed for his business with the 12 months of the current year which also had the entire "Optimist Creed" printed on the opposite side that he gave to his customers for thier benefit.

Jamie Hall

Cast iron baseboard units can be made to work on single pipe steam. It takes a lot of work and a lot of care on the part of the installing contractor to get them adequately pitched so they don't hammer and gurgle, but in shorter units that can be done. In longer units -- say over 4 feet -- it is possible to add a return pipe under them going back to the supply line. If that is adequately pitched it can help... some. It may be necessary to put a steam trap on the outlet, however.

On the whole it might well be better to for the OP to make his or her peace with what they have...

dopey27177

In my opinion, you can install cast iron recessed radiators. They supply heat in two ways.
1. heat by convection.
2. heat by air flow up through the tubes and out the openings at the top to provide circulation by air flow.

When you purchase the radiators add 5 sq feet to the new cast iron rads because the are mostly inside the wall. If you are going to do this install aluminum foil against the interior wall to help reflect the het to the inside of the room.

Using the CI rads will keep your comfort level very similar to what you have now. all CI rads in the building.

Jake