Steam

Unknown

Looking at a job right now that is a 2 pipe counterflow steam system, I beleive it was a vapor system at one time. It has the variable inlet valve going into the top of the radiator and the condensate line going out the bottom. The piping leaving the radiator doesnt have have any special fittings, just a regular 90, no trap. The customer wants to convert to hot water. Question is?... can I replace the steam valves on the radiators with TRV,s and feed the water to the top of the radiators as they are piped now. And if I do that can I still use the integral head for the TRV or will that screw up the temperature sensing because it is located at the top of the radiator or should I just figure on using remote sensing TRV,S.

Jim Pompetti

First

Are the radiators capable to run as hot water

Unknown

Yes

they are nipple conected top and bottom, also they mains are large enough for the btu,s required. Im just not sure how well the system will work with the water entering the radiators in the top.

Steamhead (in transit)

You have a can of worms here

First, the pipes and radiators have been running on maybe a pound or two at most. You propose to increase the working pressure at least twelve times. This will do a fine job of uncovering any and all weak points in the piping and radiators which will result in leaks- sometimes major ones. And guess who will be liable?

Second, the return lines on the existing system may not be big enough to carry the volume of water needed. So you would end up repiping them. Too bad if you didn't figure this into the job........

Third, are the radiators themselves big enough to heat the building on hot-water? Remember, a steam radiator will emit 240 BTUs per square foot. A hot-water one will only emit 150 BTU per square foot, and that's with a water temp of 180. This also means a condensing boiler won't be condensing most of the time, so there goes the higher efficiency.

And do any of the risers pass thru outside walls? If so, they may freeze if you fill them with water.

For these and other reasons, our company does not recommend or perform a conversion from steam to hot-water, and will not work on a system someone else has converted. We don't need the liability.

With the piping pattern you describe, you're probably looking at an original Tudor system. This is by far the simplest system of any type out there. With so few moving parts, it is extremely rugged and reliable. Keep in mind that if you convert this system, you could turn it into a nightmare, for you as well as the customer.

You can use TRVs on a Tudor system. We've done it. Just make sure they are properly orificed so the steam does not enter the dry returns.

For more on the Tudor system, go here:

http://www.heatinghelp.com/pdfs/492.pdf

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ttekushan_3

In addition

to what steamhead just said, the type steam system you have is one of those that will run with great economy if everything is readjusted back to the original design concept, including a proper sized boiler.

I have witnessed and done the tuning of ultra low pressure steam systems where a 30 to 40 percent decrease in fuel consumption has occurred. Its amazing how easy it is to perform this "miracle" for the client when you take the time to understand the theory of the system you have in front of you.

And yes, TRV's work great on these steam systems.

-Terry

P.S. The top connection increases the chance of air locking the radiator.

Unknown

It appears to be

a tudor system Steamhead except the main is run in a counterflow, pitched back to the supply. The return also is pitched back to the boiler. This appears to be the cause of alot of banging on startup. Looking at the pdf you posted it appears the tudor supply main pitches away from the boiler, is trapped then heads back to the boiler.
I removed some of the feed valves and the rubber washers are disinigrated. Can you still buy new valves or replacement parts? Do you think it would be better to repipe the steam as in the patents?

Steamhead (in transit)

Counterflow mains

will work fine if insulated and pitched properly. The Tudors I've seen in the Baltimore area are all counterflow. They do have problems if they get off pitch, as from a broken pipe hanger, but that's easy to fix. No need to completely repipe it.

You should be able to get replacement washers from any industrial supplier who has parts for larger globe valves.

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Jamie Hall

I'll jump in here, too...

I don't think you'll get any argument from anyone on the Wall: converting steam to hot water is not something which is recommended. At all. You will not save anything on fuel, and you will cost somewhere between a mini and major fortune in the process. Just Don't Do It. If the customer insists, walk away.

Having said that.

The steam mains can pitch either way, provided that the condensate which forms in them has somewhere to go. If they pitch away, they might be less likely to bang, but... it really shouldn't bang, though. There are a number of reasons for banging on startup, but all of them are fixable. One to check -- and really easy to fix -- is to be certain there are no sags or low spots in the supply lines; those can collect a lot of condensate on startup and bang like crazy. Another probably obvious point is are the steam mains insulated? If not, it is likely that a lot of condensate is forming on startup in the mains; that can cause rather interesting banging on startup too. That's easy enough to fix. Less easy to fix is wet steam; I'd tackle the first two possibilities first, and see what happens.

As to finding new valves or replacement parts, you should be able to; several sources (all of which escape me at the moment; senior moments, you know) have been mentioned on the wall. Main thing with a Tudor is, as Steamhead notes, you have to sure that the valves when open only just far enough to fill the radiator with steam, and no farther.

Oh yes -- one last thing. Make sure your pressure is low enough. You don't mention that, but I'd not go above 12 ounces per square inch on that system.

ttekushan_3

Hi Frank,

Do I recall correctly that you worked on a tudor system with in-line plug valves for regulation? I suppose that or inlet orifices would do the trick in lieu of graduated hand valves...

-Terry

Unknown

OK guys

I am going to take your advice and keep it steam but I have one last question..after I rebuild the valves how do I set them that I know the steam is not going all the way to the return

Steamhead (in transit)

Simple

depending on the valve you have. Some have an adjustable shutter, some regulate the height of the washer above the seat, still others have a plug inside the valve body and containing the valve itself, that can be rotated to more or less align the holes. This last is the one that we found here. Pics will help.

Low pressure is key. Set the Vaporstat at 8 ounces or so, and the differential at 1 ounce, then start with all valves nearly closed. With the pressure maintaining at the level you have set, set each valve so the radiator fills with steam to no more than 85% of its volume. This will insure that the steam does not reach the dry returns.

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Steamhead (in transit)

Those valves

have a plug inside the valve body which contains the valve itself. You rotate the plug to align the holes more or less. This regulates the maximum throughput.

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Steamhead (in transit)

Some Tudor System Valves We've Seen

Looked like these...

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