steam pipe sizing

Ken_40

up at the extreme upper right of this page.

Or, you could have it all. Buy Dan's book, "The Lost Art of Steam Heat."

I would the the highlighted top left tab, "Online Store" would be the source?

John V

steam pipe sizing

Where can i find a sizing chart for steam supply? I am going to pipe up a 100,000 btu unit heater with a ten pound supply but will need to lift the condensate 10', so i'm figuring around 5lbs. useable steam. What is the proper size supply and for that matter F & T Trap also?
thanks

JV

Brad White

Any good engineering textbook

such as those published by Carrier if you can find them, are priceless.

For your application, the pipe size I would use would be 2 inch. 1-1/2" is just too close in my opinion. My tables for 12 PSIG steam (8-16 PSIG range) says 100 PPH for 1-1/2" IPS and up to 160 for 2" IPS. 2" is a no-brainer in my book. The return should be at least 1" as a default minimum size. That will handle up to 175 PPH at one ounce per 100 feet PD. If dry return application I would go up a size.

As for trap sizing, it depends on the manufacturer and your rating preference and your assumed pressure differential. SHEMA ratings do not require a safety factor. I usually use manufacturer's ratings with a safety factor of 2.0 (twice the rated capacity for F&T traps to allow cold starts without hang-ups).

But your 100 MBH load (about 105 PPH) will be easily handled by a 3/4" or a 1" F&T according to Tunstall data for their TA-FT3-15 and TA-FT4-15. Those will each handle up to 279 PPH SHEMA rated, at 1/4 PSIG differential. Plenty of margin.

As for lifting, I personally would tread lightly. (I do not like to lift more than a couple of feet and prefer to do so only on vacuum systems). Maybe in actual practice and experience of others it is done routinely, but the Dead Men who taught me scolded me for thinking of it unless a vacuum system was involved. They also insisted that 2" IPS was the minimum pipe size for any steam.

My concern is if your UH has valve control (as opposed to constant steam-available and fan cycle control). The issue that concerns me is if the valve opens against that stack of water, it could be a banging or surging situation. I have seen (heard!) this where the lift condition was higher than the steam main.

If I were to do any lifting over two feet, I would use a series of lift fittings in two foot increments or use a pressure powered pump with prime steam.

Also if you use a control valve, I presume a 2-position valve with high Cv rating to maintain most available pressure downstream.

Steamhead (in transit)

Dan covers this in \"Lost Art\"

in chapter 10. But I'd want to know if the steam would be coming from a high-pressure or low-pressure system? If the latter, there's no reason to use such high steam pressures. Drain the heater thru a trap to a condensate transfer pump which will pump back to the boiler room. This will be much more economical to run.

If, however, the steam pressure is that high for some other reason such as process work, lifting the condensate might be practical.

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John V

Thanks

Guys. I knew you would sink your teeth into the question Brad.
The instalation will not include a control valve i.e. constant preasure will be available.

John V

The Unit

...is to be located in a tunnel just below the boiler room. It will replace an existing electric resistance UH. The system maintains 10 psi as an operating pressure already. None of my doing. Thanks for the reply Steamhead. I will check for further posts.

John V

Now you

.....have me wondering if i should question the reason for the 10 psi operating pressure. The installation is a couple of years old and replaces steam from a now defunk central plant . I believe it is for heating purposes only. If that is the case it may indeed be more economical for the customer to turn it down and install a lift pump.

p.s. i do own a copy of Dan's book.

Steamhead (in transit)

If you can crank the pressure down

you will save a lot of fuel. A small condensate transfer pump in the tunnel would handle the lifting.

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eric_35

a low pressure steam boiler (3 lbs pressure)exits the boiler using 1 1/2" copper pipe, travels vertically through the ceiling then 90's to a horizontal position to a 200 foot run through the attic to a F&T trap which returns back with 1/2" copper pipe back to the boiler. Why are there half curves (looking like a half moon curve about 4 feet) placed in the 200' run every 40'? could this be for expansion & contraction, and is this necessary if I were to duplicate this in another location?.

Brad White

You may want to post this as a \"New Thread\" Eric

It may get lost here at the tail of someone else's thread.