Energy Guy

Pepper · August 2010

I'm working on an energy analysis for a large New England campus built primarily in 1912. They have a vacuum return steam system, fail-closed steam traps, fail-open Thermostatic Radiator Valves, and have gotten their supply pressure down to about 1.5 psig. There is very little venting.

I have a few thoughts about the next steps. 1) Install fail-closed TRVs. I found these in google. 2) Convert the whole thing to hot water. I've seen reports that say that that can save 25% of the energy consumption. 3) Install wireless temperature sensors and wireless control valves so that each of the 2000 or so valves can be well controlled and monitored. I saw on the Empire State Buidling web site that that is what they are doing there. Does anyone know a vendor on these? I've left a message with Johnson Controls, but there may be a direct supplier of such a system.

Thank you.

Charlie from wmass · August 2010

Steam run properly is better on the wallet

than converting to hot water if the existing system is mostly salvageable. If you are not familiar with steam then sub it out to someone who is.

Rod · August 2010

Tuning Old Steam Systems

Hi- In reading your post the first thing that comes to mind is that it sounds like a perfect application for orifices. I’ve attached a good article by Henry Gifford about using orifices on a two pipe steam system. These can be used with TRVs http://www.tunstall-inc.com/inletorifice.html

Varying the orifice size also allows you to tune the steam volume going into the radiator to adjust for present heat loss. Many older steam systems of the era when your system was originally installed, used oversized radiators as they were sized to operate with the windows open as having “lots of fresh air” was a popular concept back then. If you operate with the windows shut and/or there has been an upgrade in the room insulation since the radiator originally were installed you are probably experiencing overheating now. Using the proper sized orifice will cure this and save steam, thereby saving fuel.

As for switching to hot water- I would study the length of payback very carefully as the operational savings may not justify the cost of a new system. There is also risk/liability of leaking when using the original pipes and radiators as you are now going from a gas (steam) system operating at a very lower pressure to a liquid system operating at ten times the pressure. With this in mind you maybe looking at the cost of completely removing the steam system and installing a new hot water system. While talking about payback you have to consider any equipment you change/add to the system with this in mind and decide if you are really getting an economic benefit from it.

I must state that I’m not a steam pro however there are professionals who frequent this site who would rate in the top ten nationally if steam pros were rated that way. If you go farther with this study it would be well worth your while to consult with one of them. Since most of these old systems haven’t been properly maintained over the years a good steam pro can find ways to quickly improve them`which can immediately affect the operational coast and comfort and they can also tell you what is practical in your application and what isn't.

- Rod

Steamhead · August 2010

The Empire State Building

is heated with steam. And, when the upgrades are done, it will still be heated with steam. They don't like to waste money, and they aren't going to convert to hot-water, so you don't need to either.

Those fuel-savings figures you've read don't tell the whole story. In order for them to actually mean anything, we'd have to know what condition the steam system was in. I have never seen a comparison of a properly-operating steam system with a hot-water system-in every one I've seen, the steam system was on the verge of complete failure. This is not an accurate comparison and never will be.

For a discussion of some of the other gotchas you might encounter, go here:

http://www.heatinghelp.com/article/11/Hot-Tech-Tips/152/Converting-from-steam-to-hot-water-heat

It is far more cost-effective to repair and maintain a steam system than to convert it.

Energy Guy

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