on sizing: increasing EDR for third floor apartment in one pipe steam system

timmckenna

Hi,
I know that typically there is a 1.33 factor figured in for piping. What would be a good factor in the case where the new boiler is serving a third floor apartment? Compared to an apartment on the first floor, there are 7, 1 or 1-1/4 ~20', pipes (~ 140 more feet) running through the walls of other apartments to supply the 8 third floor radiators. EDR = 261, radiator load 62,500 BtuH

(thanks fred, sorry I was unclear)

Fred

For starters, There is no way one 1" pipe will supply 8 radiators totaling 261EDR, especially running 140 feet. We are talking steam right? Is this a 1 pipe or 2 pipe system? Either way, I can't see it happening.

timmckenna

No you are right. There are 7, ~20' 1" pipes running up from the basement through the walls of lower floor apartments. It is possible they are 1 -1/4 . I'll have to check

Jamie Hall

I hope it is two pipe... or at least 1 14... the 1inch risers are marginal for one pipe. Watch your pitch on any horizontal runouts or it will hammer.

However, to the question: The normal pickup factor will be fine.

Fred

timmckenna said:

No you are right. There are 7, ~20' 1" pipes running up from the basement through the walls of lower floor apartments. It is possible they are 1 -1/4 . I'll have to check

That makes me feel better. Is this a 1 pipe steam system (Only 1 pipe on each radiator, with a valve on it and a vent on the other side of the radiator)? I hope those pipes are 1-1/4" That would make me feel better too. In any case, as Jamie already said, you don't need to add anything to the boiler for additional Pick-up. It will be fine.

Fred

Also, be aware that you don't need to add any pick-up factor to the boiler when sizing it. The manufacturer has already built that into the boiler. Just use the Sq. Ft. Steam rating on the boiler plate and match that , as closely as possible to your total radiator EDR.

timmckenna

Yes, the tables are pretty clear for Utica, Peerless and Burnham. Problem is the supply house guy is telling my plumber that I need a 150,000 BTU/hr for boiler since it is on the third floor. I could see adding a little to the 1.33 but what they want to sell me seems crazy.

Fred

timmckenna said:

Yes, the tables are pretty clear for Utica, Peerless and Burnham. Problem is the supply house guy is telling my plumber that I need a 150,000 BTU/hr for boiler since it is on the third floor. I could see adding a little to the 1.33 but what they want to sell me seems crazy.

No, you don't size a boiler based on the number of floors. You size it based on Total EDR. That guy doesn't know what he is talking about.

KC_Jones

timmckenna said:

Yes, the tables are pretty clear for Utica, Peerless and Burnham. Problem is the supply house guy is telling my plumber that I need a 150,000 BTU/hr for boiler since it is on the third floor. I could see adding a little to the 1.33 but what they want to sell me seems crazy.

You would be massively oversized at 150k. You only need around a 100k input boiler for 261 sq ft. A 150k boiler would probably short cycle like mad. Don't do it for sure.

Jamie Hall

That plumber is bats. Suggest he stick to installing faucets. Steam doesn't care what floor it's on. It's all in the EDR. Match that, and your good to go.

EBEBRATT-Ed

OMG. Another one that thinks you have to "lift" the steam because it's the third floor.

I tell my students with hot water closed loop 5 story building that the pump only overcomes the resistance of the system, pipe, fittings etc That if I pushed the building on it's side and it was laying down and was now only two stories tall I could use the same pump. I get the deer in the headlights look.

nicholas bonham-carter

The game is over because the boiler cannot take the pressure; however if the boiler is removed, and the pump is just on a vertical loop, it can still circulate the water, (with some friction loss due to loop length).--NBC

EBEBRATT-Ed

I was only talking about using the same pump, same head, same gpm didn't mention the boiler. I know the static pressure will change. The resistance of the system (pipe, valves, fittings) stays the same weather the building is vertical or horizontal so the pump capacity (head & gpm) remain the same. That was my point in a closed loop you don't "lift" the water you only overcome the systems resistance.