EDR boiler size round up or round down

GW

I hate to ask a question for the bazillionth time, I have a job where i'm right between a 3 and a 4, I think some of you all go to 20% when the pipes are insulated?

Thanks for the comments

Danny Scully

The pickup factor can be excessive sometimes @GW. When piping is insulated I feel comfortable rounding down. If it isn’t insulated, you can always measure the pipe length/diameter etc.

pecmsg

From a cooling standpoint we round down: (Within reason)

90+ % of the time the equipment is oversized anyway.
On the few times your at or near design conditions (in your case) a sweater or blanket can be used.
The envelope can and always is tightened.

Steamhead

Is this for a steam or hot-water system?

Danny Scully

Well it’s in strictly steam @Steamhead, but i guess we shouldn’t assume.

GW

Lol steamer, pick up is .33 in the manufacture sizing charts. But if we’re talking 15 or 20 then that means smaller. Thanks

The Steam Whisperer

In addition to the above, if it is low mass convectors, then definitely round down. With convectors, it seems if the boiler is sized using conventional methods it tends to bounce off the pressure control during standard heat calls, creating a lot of short cycling. The newer low mass radiators can tend to do that more too, but not nearly like convectors.

GW

Thanks it’s good old USA cast iron rads.

EBEBRATT-Ed

If you round down and still have some pickup I would say you are ok.

Steamhead

Danny Scully said:

Well it’s in strictly steam @Steamhead, but i guess we shouldn’t assume.

You know what they say "assume" means..............

What model series of boiler do you plan to use? It may be possible to use a 4 section and down-fire it, which might result in better efficiency.

GW

Merry Christmas to all heat people

I’m at 450 sq ft

One local vendor doesn’t carry lots of oil steam. I normally go with peerless . One other vendor does have the Smith, so I’ll probably go with the 4 section and be a bit oversized

Ironman

If its oil, you can't beat the MegaSteam.

EBEBRATT-Ed

Both the Peerless and Smith small steamers seem pretty good

SuperJ

If the rads are painted a metallic color or enclosed with some sort of limiting cover, would be safe to downsize accordingly?

Dave0176

Peerless EC-03 puts you right there at 446 sq ft.

GW

SuperJ said:

If the rads are painted a metallic color or enclosed with some sort of limiting cover, would be safe to downsize accordingly?

good call yet all the rads are out in the open

GW

Dave0176 said:

Peerless EC-03 puts you right there at 446 sq ft.

hummm I missed that lemme see if the vendor can grab one from one of their branch stores, thanks

mikeg2015

> @GW said:
> If the rads are painted a metallic color or enclosed with some sort of limiting cover, would be safe to downsize accordingly?
>
> good call yet all the rads are out in the open

TRVs can work. But pricey.

Some baffles between sections or attached to the bottom of the radiator would reduce capacity.

Some black silicone coated canvas cut to shape might work. Can glue with RTV.

GW

Thanks I got an SGO-4 on the way