Heat Loss of Steam Pipes / Pick-up Factor - yes, or no on the boiler?

MilanD

I was not sure if anyone was aware of this site - so here's a share of it.

http://www.engineeringtoolbox.com/heat-loss-steam-pipes-d_268.html

With that, I was wondering what is the current thought on pick-up factor? Is it still EDR x 1.33 to include the pick-up factor when sizing the replacement steam boiler? And finally when calculating the EDR to BTU and picking the boiler, do steam boilers include the pick-up factor when showing the rating (meaning, if it's rated for, say, 100,000 BTU on the sticker, does this actually mean it's a 133,000 BTU with pick-up being included)?

Thanks!

Jamie Hall

My understanding of it is that the pickup factor is included in the EDR rating, if one is given (it usually is).

EBEBRATT-Ed

Download the brochure for the boiler with the ratings. Read the "fine print" it will explain the ratings and the pic-up factor.

As @Jamie Hall mentioned it is included

MilanD

Ok, got it! I see there is gross and net btu. Net corresponds to edr x 240, without pickup. This no. x 1.33 = gross btu. Cool. They also call edr "steam sq. ft."

EBEBRATT-Ed

You got it!!

MilanD

So, when you guys are looking at replacement boilers, do you all still factor in pick up at 1.33? What's the latest on that?

@EBEBRATT-Ed @KC_Jones @Hatterasguy @SWEI @Abracadabra @Jamie Hall @ChrisJ @Solid_Fuel_Man @Gordy @GW

kcopp

I don't... Unless the piping to the system is really wonk and huge. It also presumes that the piping is reasonably insulated.

EBEBRATT-Ed

@MilanD , I think there is no right or wrong answer to the percentage of pick up it varies fro job-job in my opinion.

Some jobs need little to none. Insulation, length of run, basement temperature, multi family with additional boiler(s) other heating equipment, hot water heaters affecting the basement temperature, open windows or undampered combustion air ducts etc, etc

No two jobs are the same.

Just my opinion

MilanD

@EBEBRATT-Ed @kcopp

Thank you. I just keep wondering what the "oversized" system would actually mean if there is a 33% wiggle factor in this art. We all know many systems are hugely oversized, and aside from 2-staging or Tekmar 279/EcoSteam/Delay on make timers, I wonder how do you make sure you are both efficient most of the time while also effective on the coldest design day when replacing. 33% wiggle is a lot of wiggle.

I see now you have to figure and also factor in how tight the building is, esp. on rehabs with exisisting steam, and perhaps also, the ability to remove rads/lower the needed edr because of this improvement in bldng envelope, in addition to insulating all piping, and as you both mentioned, various other factors.

I suppose at some point it becomes "good enough" somewhere between .0 and .33 pickup, with .33 being on old and historic buildings, and less than that on more tight and sealed buildings with dampers.

Thanks again for sharing your experience and expertise.

kcopp

Youre over thinking it. Measure the rads and see what you have for EDR. If you are reasonable close to that # w/ the boiler go for it. The house will be fine. Remember you are basing it off radiation not heatloss.

MilanD

I get that @kcopp. As there is both gross and net btu, and edr can get to be somewhere between the gross and net, I just wonder how you all decide nowadays what the appropriate pick up factor is, that's all.

Thanks again!

GW

yes to all of those answers, if it's well insulated then it can be lower than 33%

Jason_13

I have seen some manufacturers state 1.33% and if the piping is run through crawl spaces use 1.5%. They also assume all exposed steam mains are insulated. You should never operate a steam system without the mains insulated as it really affects the cost of operation and the amount of water that ends up in the steam main. If there is no insulation the piping must be added as a radiator and this would of course increase the installation and operation cost for the homeowner.

MilanD

Thank you everyone!