Help with unusual gravity steam system

ralphslate · January 2022

I have a 120 year old house that has a single pipe steam system which heats most of the first floor via gravity air ducts. There are 4 large radiators which sit above the boiler on steel i-beams. The boiler space is an enclosure that heats up, and the heat travels through large ducts to the rooms above.

There are several leaks in these radiators, and I think they may need to be replaced. Problem is, I have never seen anything like them before, and I don't think I can get replacements.

There are 4 interconnected radiators, each is made up of 10 sections which are 6.5" tall, 40" long, and 2" wide. The radiators have lots of little protrusions on them to increase surface area, however they appear to be solid (no tubes). Here is a photo:

The space isn't large enough to stand a radiator up the way in the traditional way. My question is, can I replace these radiators with new cast iron radiators which are turned on their side (provided that we can figure out how to calculate/compare the BTU sizing)?

Or does anyone have any suggestions as to how to replicate the function of these radiators without turning to hot water? Other than the leaks, the system works perfectly otherwise, with all other steam radiators on the 3 floors of the house balanced nicely.

ethicalpaul · January 2022

This is pretty cool. So there are large grates in the floors where you can look down into this space?

Those "radiators" look like boiler sections to me...did the guy who made this work in a boiler manufacturing plant and bring them home in his lunchbox I wonder?

If it were me I would consider a new radiant floor to replace the grating that may be there?

Or maybe (instead or in addition) buying some renovation-victim traditional radiators for the space (water or steam)

I'm not sure I would be so hesitant to look at hot water...without the piping and radiators it would be like building a brand new steam system...which would be OK if you love love love steam but hot water is nice too.

(Edit, oh there are normal steam radiators on the other floors? Then yeah I would look for used steam radiators to put on the first floor. In the current setup the basement must be HOT)

pecmsg · January 2022

Can we get a pic from further away?

KC_Jones · January 2022

Those appear to be indirect radiators, if that's the case it's likely they originally had duct work on them connected to the outside to bring in fresh air, which I'm guessing has long since been removed.

If the above is true, then most likely those are widely oversized and could potentially be replaced with standard free standing radiators, or perhaps convector elements in the same location, but it would take a lot of them. You may need to have a heat loss done to the space to verify sizing on the new radiation.

I'm curious though, can you elaborate more on the leaking? are you positive they have holes in them? Perhaps the leaks are at pipe joints or some other repairable location?

If they do need replaced, I think it will be a tough situation that will need to be handled by someone who really knows steam.

Where are you located? We may know someone who knows steam that services your area.

Jamie Hall · January 2022

In answer to one of your questions, there's no reason at all that you can't put a standard radiator on its side. You do have to hold it up... but it will work. What I would do, however, is pipe it as a two pipe radiator, not a one pipe. That is, I would tip it slightly so that one side (what would have been the top in a regular installation!) is slightly higher -- and inch or two -- than the other side (which would have been the bottom!), and the end with the inlet on the whole slightly higher -- again an inch or two -- than the outlet. Then I would run the outlet first into a regular radiator trap, then into the leg of a T. The top of the T would have an steam vent -- regular radiator vent -- on it, and the bottom would drop into a wet return, if you have one handy, or could drop into a water seal and back up to the steam main. Harder to describe than to do.

I agree with @KC_Jones -- the existing convectors are probably bigger than they need to be in terms of EDR. I would simply pick a conventional radiator which would fit the space nicely.

This will be simplest and least expensive way to handle these things...

ralphslate · January 2022

Here is a photo from the front. The room where the boiler sits isn't big enough to get a photo of the entire setup at once.

Jamie Hall · January 2022

Oh good. You really do have the boiler right there. Drop the bottom of the T I mentioned for them right into the boiler's wet return.

You're going to need help getting the new radiators in place, though, and the old ones out! Those puppies are heavy, and you really don't want to drop one on the boiler.

delcrossv · January 2022

Seems steam coils would be a modern replacement.

E.G.: https://emergentcoils.com/pages/steam-coil-application?keyword=%2B%5Bsteam%20to%20air%5D%20%2Bheat%20%2Bexchanger&gclid=Cj0KCQiAosmPBhCPARIsAHOen-MuYA1w6FKDb9TS1lsLTOZtNsXPirgeGMr79raQPLXfc5fnJQX4T-oaAot4EALw_wcB

There's a German company (Kablitz) that makes CI steam to air exchangers, looks pricy though.

JUGHNE · January 2022

Perhaps something like this. This is connected as a 2 pipe system in a school house basement.
There are more like this there. I believe available for the price of scrap...if you take them down.

But in central Nebr.

delcrossv · January 2022

Or maybe some convectors:
governaleindustries.com/products/convectors/

I agree, that with the external air inlet gone, those exchangers are probably grossly oversized.

mattmia2 · January 2022

I'm not sure I like the boiler trying to take combustion air from the plenum space for these indirect radiators. They do look like boiler sections and they may be for some boiler, but they were definitely sold as indirect radiators in that configuration, there have been other posts on the wall with similar indirect radiators.

A possible retrofit could be to run hot water coils for this section off of a hot water loop off of the steam boiler, fit duct work to the grates and us an air handler or a couple air handlers to heat the space. I think you lose the radiant heat benefits of a hydronic system when you have indirect radiators like that. If you want to lose the space, you could use salvaged or new radiators set up as steam or as hot water in a similar manner as others have suggested. I really think you should isolate the return air space from the boiler somehow.

JUGHNE · January 2022

Can we see where the hot air comes out upstairs?
Any other grills in the rooms...floor or wall?

pecmsg · January 2022

Is my guesstimate correct......50°f crawlspace air being heated to 80°f and flowing up into the residence? Sounds like a costly heating system.

ralphslate · January 2022

Jamie, I'm in Western MA. I most certainly want to hire a professional, but I have no idea as to who might even begin to understand how to do this properly.

You're right, there used to be a duct in the chamber to bring in fresh air, this was originally a coal boiler and the chamber was totally sealed with the coal furnace built in. We closed up that duct when we bought the house, so it now heats the basement air. It's not the most efficient setup, but it 100% works, all rooms get warm at the same time, and we burn about 1,200 gallons of oil for a 3000+ square foot house each winter, which isn't horrible.

Each of the 4 radiators in the chamber has an air vent on it, so I govern the system by venting them a bit more slowly with a vent-rite #1.

The leaks do seem to be at the joints, but the worst case scenario is that we disassemble those radiators and can't get them back together, or make the problem worse. It may be worth trying (though I have no idea what kind of professional would even do such a job) before buying something new.

And yes, I think you're right about this currently being a 2-pipe setup!

EBEBRATT-Ed · January 2022

@ralphslate

As @KC_Jones said those are indirect radiation

Best bet would be to first do a heat loss of the space the indirects heat. Then do a heat loss of the other spaces. If you find on the upper floors that the radiation is oversized (say by 10%) then you need to keep any replacement system for the indirects sized 10% over in order to balance the system.

The indirect system probably takes outside air in and heats it which is very costly

Then you have to decide weather to install:

Standing traditional CI radiators in the space upstairs (which will involve a lot of piping) but will be the best alternative.

Remove the indirect radiators and install an air handler with a steam coil in it.

It will be labor intensive to replace the indirect radiation with something that will work as indirect radiation

And @mattmia2 concern for the boiler in the same space as the indirects and both of them competing for combustion air is valid and is a concern

I would suggest a good steam contractor check "find a contractor" or post your location. Someone may have a recommendation.

mattmia2 · January 2022

ralphslate said:
Jamie, I'm in Western MA. I most certainly want to hire a professional, but I have no idea as to who might even begin to understand how to do this properly.

@Charlie from wmass sounds like a good place to start.

EBEBRATT-Ed · January 2022

@ralphslate @Charlie from wmass is your guy for sure. Be patient he is busy

WMno57 · January 2022

@Jamie Hall
I'm not so sure about using an upright two pipe steam radiator turned on it's side. Look at the photo @JUGHNE posted. The steam inlet on the left side of the photo is oriented the same as a standup radiator. So far so good. Now, look at the outlet for condensate on the right side of the photo. The outlet is on the bottom. I assume this is to drain all the condensate. An upright radiator turned on it's side will not have this type of outlet. No matter how it is pitched some condensate will stay in the radiator.

Jamie Hall · January 2022

WMno57 said:
@Jamie Hall
I'm not so sure about using an upright two pipe steam radiator turned on it's side. Look at the photo @JUGHNE posted. The steam inlet on the left side of the photo is oriented the same as a standup radiator. So far so good. Now, look at the outlet for condensate on the right side of the photo. The outlet is on the bottom. I assume this is to drain all the condensate. An upright radiator turned on it's side will not have this type of outlet. No matter how it is pitched some condensate will stay in the radiator.

The big radiators in the basement in Cedric's home have both the inlet and outlet in the usual locations for a standup radiator, but are on their sides. They work fine.

delcrossv · January 2022

Jamie Hall said:

WMno57 said:
@Jamie Hall
I'm not so sure about using an upright two pipe steam radiator turned on it's side. Look at the photo @JUGHNE posted. The steam inlet on the left side of the photo is oriented the same as a standup radiator. So far so good. Now, look at the outlet for condensate on the right side of the photo. The outlet is on the bottom. I assume this is to drain all the condensate. An upright radiator turned on it's side will not have this type of outlet. No matter how it is pitched some condensate will stay in the radiator.
The big radiators in the basement in Cedric's home have both the inlet and outlet in the usual locations for a standup radiator, but are on their sides. They work fine.

I'd think they'd fill with condensate up to the port and the "top" half would fill normally. Less EDR as they're half filled with water, but they'd get hot.

Personally, I'd go with cast convectors- more suited to the proposed use.

mattmia2 · January 2022

steam meeting large amounts of condensate doesn't go well

delcrossv · January 2022

tommay said:
Since they lay flat in the ceiling, they normally have a steam inlet and a drain/return on the bottom somewhere. They can be piped for hot water also. As long as the steam feed is pitched back to the boiler you should be able to eliminate the return on a new radiator. It's right above the boiler so it shouldn't be a biggie...

Not if it's a standard radiator laying on its side. Convectors? yes.

Help with unusual gravity steam system

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