Attached EDR vs Boiler SF of steam

Fizz

My attached radiation is 337.5 SF, and new Peerless gas steam boiler rated at 233SF. Is this sufficient? Single pipe with separate return.

JohnNY

If you're numbers are accurate, then no it is certainly not.

ethicalpaul

Well 233 * 1.333 = 310 so it's not TOO far off given the industry standard "pickup factor"

If the mains are insulated and/or the house has the typical oversized radiators, and/or the house insulation/windows have been updated, and given the higher design day temps since the house was probably built I would run it. You might not quite keep up with your setpoint if you had a cold snap, but you wouldn't freeze. Space heater would help. We're only talking about the coldest days where it might struggle I think.

As we all know, on a typical call for heat the radiators don't completely fill with steam anyway. It is the radiator vents that regulate which radiators get steam at what rate. The boiler doesn't know if you have 800 sq ft of radiation or 300 on a typical call for heat.

Isn't it true that a perfectly sized system should run 24 hours a day on the coldest design day? My boiler is only a little oversized and I have never even come close to a 50% duty cycle I think. Has anyone ever actually installed a system of any heating technology that actually runs 24 hours straight on the coldest day?

You'd hardly ever or never cycle on pressure, that's for sure, that's a plus. You could increase the gas regulator from the factory 3.5 inches of water column to like 4" to get more steam production.

You could buy a new burner tray from Peerless spare parts to upgrade it from 63-03L to 63-03 which would get you 308 sq ft of steam which is really 410 sq ft. Although my current understanding is that Peerless doesn't support doing that.

Finally, given that Peerless 63 series is now discontinued you might be able to find a buyer for it and get yourself a larger Weil-McLain or Utica.

How did you end up with Peerless's smallest steam boiler for this house?

Steamhead

https://forum.heatinghelp.com/discussion/comment/1874950#Comment_1874950

This.

Fizz

My apologies! My EDR is 237.5!!! I chose the one closest to EDR

109A_5

If the EDR is 237.5 and the boiler Sq.Ft. is 233 the system should work good.

Fizz

Thanks! What a relief. Posted wrong EDR in orig post. Old age doesn't come alone

dabrakeman

Sure you just didn't want to stir the pot?😁

ethicalpaul

OK in this case there is no "should" about it, this boiler will perform as good as any boiler you could pick.

Congratulations for getting one of the last 63 models ever produced

To quote one of my favorite movies, "it would be a shame to blow it up"

And congratulations for resisting going to the next larger one "just to be safe". You have somehow, some way, actually purchased the correct sized boiler, making you very rare around here!

Fizz

I sometimes think I'm in the pot!

Thanks guys.

109A_5

https://forum.heatinghelp.com/discussion/comment/1875069#Comment_1875069

Paul we don't know how if it is piped or skimmed correctly, so it 'should' work good. Since it is the correct size.

bdl

I have a question on matching EDR to a boiler. Should the boiler sq. ft be equal to the total radiator EDR? If not, how is the pickup factor applied? Can someone write out an equation? For some reason this isn't sticking in my head.

ChrisJ

https://forum.heatinghelp.com/discussion/comment/1875331#Comment_1875331

The EDR rating on a boiler includes the 33% pickup factor.

I'd never exceed that rating my self. IE. if the boiler's rating is a hair under, do not go to the next size bigger, it's a mistake.

EBEBRATT-Ed

@bdl as @ChrisJ mentioned total up the rad EDR and compare that # to the boiler nameplate. Don't add anything

bdl

Thanks for clearing that up. Umm, the boiler states sq ft of steam, not EDR. They have the same units, correct? Hmm, my current boiler is 450 sq ft, and my EDR is 404. I think the next boiler down was 350 sq ft.

pecmsg

I’d go with the 350.
you can always tighten up the envelope if needed

109A_5

Or go with a different brand boiler. For example the chart posted above the Peerless 63-04L is 383 Sq. Ft. if that makes you more comfortable.

My old 300 Sq. Ft. boiler and 347 of EDR works fine, even when it is below zero Fahrenheit outside.

ethicalpaul

https://forum.heatinghelp.com/discussion/comment/1875354#Comment_1875354

They are the same units. Always round down. Always

Fizz

In second day of Peerless 63, last nite 9degrees, today 25, tonite 6. I can't believe how well it's working…so quiet, radiators all doing what their supposed to. I've been a member for yrs. My prior house had a Richardson Vapor system, I actually got it working in vacuum. Actually had one of main steam guys here who came to house in Pittston, Pa. He was from Jersey and he was only one who'd work on pipe that needed to be addressed. It was wrapped with asbestos and no heat guys locally would touch it. After it was piped correctly, I was able to put a vacuum vent on which worked wonderfully. I chose the Peerless because it was closest to EDR. The company I dealt with installed only WM, PB and Nivien.

bdl

https://forum.heatinghelp.com/discussion/comment/1875474#Comment_1875474

How far should one round down? Say the next one down is 350 sq ft, your EDR is 400, next one up is 450? Which one?

Steamhead

450.

ethicalpaul

Well those aren't actual numbers. So if my EDR is 400 I pick Peerless 63-04L

Here's peerless:

Here's WM:

Here's Utica: (I think the first number is NG and the second number is LP)

dabrakeman

Lots of good options for a true 400sqft. I think a few % undersized could be a sweet spot for many homes. Your hypothetical example is 11% undersized if go the smaller route. There are many here that would probably say go for it. I'd say depends on how much you know about the performance history of that specific system and you perhaps as the homeowner are willing to manage the system such as insulating mains well, putting in adequate main venting and likely going through some trial and error balancing. So, depends. I think many professionals installing on someone else's house or business may not want to incur the risk.