Calculating the EDR in an overhead

Paul_11

Hey people,I want to double check myself on something.

On Thursday I did a heating survey for a good customer where a new store totally destroyed his heating system. They just ripped out the 4" overhead and installed two 2" overheads. That is just for starters. I'm sorry I don't have pictures as the battery in my digital camera was dead.

Since I may have to question the design of an engineer and this will most likely end up in one or more lawsuits, I want to double check myself with you guys.

The chart on p.23 of the Golden rules" tells us that 2 + 2 does not equal four when it comes to EDR capacity of an overhead.

I did a connected load and have determined that the top three floors which is my main concern for now has 618 EDR.

If I was sizing a boiler I would look at p.75 in the "Lost Art". We know that we have to use 1.5 times the EDR to take into account the pick up factor (the pipign) when we size up a boiler. Wouldn't we do the same for an overhead. We still have to add the pickup factor in when sizing an overhead, right.

So 618 X 1.5 = 927 EDR for output of the boiler and the capacity required of the overhead.

Thus two inch overheads will not make it. A 3" would be sufficient though.

Am I right in my thinking here?

I will keep you posted of the developments with this wild one.
Thanks
Paul Shay

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[Deleted User]

an over head what?

are you talking about an overhead downfeed steam main?

Paul_11

AN OVERHEAD DOWN FEED STEAM MAIN IT IS

Yes, sorry I was not clear. They are the main overhead downfeed steam supply lines for a five story building. In thinking about it more I think 1.33 is probably a safe number as there are definitely no radiators that have been removed. I have serviced the building for over 20 years and know this to be true.
Paul Shay

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