steam velocity

tariq

If one were to add another boiler to an existing system;thus making a multiple boiler system with a common header, does the velocity of the main off of the common header change? How would one calculate this. Please

Fred Harwood

velocity

Think of your radiators and mains as the load. The header adds little load. Another boiler adds to steam quantity, which still can only go to the load. Unless you increase the mains and radiation, velocity should approximate that created by the single boiler, unless it was unable to match the load in the first place.

JimGPE_3

Hah!

I got that one right! But I wasn't going to say that unless someone else said it first....

Also, this is all provided the steam pressure remains the same with one boiler or two.

tariq

velocity

From what you said,I understand it that the larger boiler of the two boilers sets or determines the velosity of the steam leaving the commn header. Is this correct? If the situation was such that a given main off of the commn header was over sized for its connected load. How could you fix the problem of the this connected load (Radiators) not receiving enough heat within a normal on cycle of boiler. How do you increase the velocity and not raise the pressure too much?

jesse the great

im confussed... with what your asking, do you
1) want to add a boiler?
2) or are you having an issue where your radiators aren't getting hot enough???

Fred Harwood

velocity

I think you mean that you want your radiators to get hot faster. Is that right? If so, you start by ensuring that the mains vents and the radiator vents work, if one-pipe, and the main vent and traps work, if two-pipe. We aren't sure just what problem you have. Try again.

Tom Blackwell

Steam velocity

To sum it up-the velocity in the header will depend on the amount of steam passing through this part of the system. If the original boiler is able to maintain pressure, then the velocity would not change - the velocity would track the load,not the connected boiler size. Why the additional boiler?

Rich Kontny_2

steam velosity

Well to explain the situation alittle more in detail, I will start by stating that I don'nt have two boilers.I do have radiators that is connected to this one main that feeds the farther side of system, that consist of four Radiators.Two on the first floor and two on second floor.The load connected to this main is 40.62pounds/hr steam.
The boiler is Utica PEG-262 rated for 663EDR that computes to 165.75 pounds/hr.
The total connected load to boiler is around 573.37 EDR
If I multiply 573.37 by 1.5 the product is 860.055 EDR
then multiply by 240 this = 206,413.2BTU. The BTU rating for the PEG-262 is 212,000 BTU. My thoughts are, boiler might be a little small.
You see, the house formerly had forced air space heater and small furnace to heat that side of house because it was a rental. But this has all been changed and entire house is steam connected.
So my thoughts concerning the radiators connected to the main in question was the velocity was too low because the pipe sizing of the main is too large. It starts out 2 1/2 pipe for 15ft then 2"pipe for 15ft. The supply to radiator is piped to top and return go wet return for each radiator.
Is the main too large? The entire system runs on very low pressure,has far as I can determine it, no more than .5 psi.
Or, Is Boiler to small. I tired writing now . What do you think?

Steamhead

Looks good to me

Those large mains have a very low pressure drop. This, along with proper main vents, helps steam reach the ends of the mains quickly.

A pickup factor of 1.33 is built into the boiler's rating. So if your mains are insulated well, the boiler size should be OK.

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J.C.A._3

As usual Frank,

You got it. VENT the main and if the piping is right, the rest will take care of itself.

If you find that there are hard to heat or overheating areas, I suggest TRV's or adjustable vents.

The "system" is only as good as the piping connected to it. If it is done properly, find the hot spots and control them thermostatically. If not, the reason lies in the piping and the only answer for that is experience.

Steam is a fickle creature. It does what the laws of physics say it will. Anything that seems to make sense to you will need to thought about in the "reverse universe" also. 20 years have taught me that I have to look at it in the whole picture sense. One particular problem is a part of the big picture...find it,figure out why, and all problems will be fixed. JMHO. Chris