United States Radiator Co.

majkaoil

So I am quoting a replacement oil fired steam boiler US Radiator 236H. Looking through my antiquities library I can not find an accurate rating. I am performing a heat loss but the small church may not be able to afford a replacement and the low speed burner is IMO grossly undersized for the boiler so I may offer a HS Burner replacement instead and need the rating of this boiler.
Now to the question. My reference material is "Hydronic Rating Handbook" by T.R. Byrley
In it it gives me the 8 Hour rating, but not how to covert that to a usable rating.
There is a paragraph in the front that states "The relationship between 8 hour ratings and any modern rating is apparently lost in the mist of antiquity."
Not helpful...lol...any ideas??

Steamhead

ISTR the 8-hour rating was how much radiation the boiler could operate if a single charge of coal in the firebox was used up in 8 hours.

But that's not how we size steam boilers. Go back and record the capacity of each radiator on the system. If radiators have been removed, include their capacities as well. Then size the new boiler to that amount of radiation.

If radiators have been removed and you can't determine what size they were, do this:

1- Record the existing radiators' capacities in square feet EDR;

2- Multiply the result by 240 which converts EDR to BTU per hour;

3- Add 50% to this;

4- Size the replacement boiler by the DOE or Gross capacity rating.

This removes the 33% pickup factor the boiler is rated for, and inserts a 50% factor. The increased pickup factor compensates for the extra metal you have to heat up, which is there to feed radiators that no longer exist.

For radiator ratings, get this book by @DanHolohan :

https://heatinghelp.com/store/detail/e-d-r-ratings-for-every-darn-radiator-and-convector-youll-probably-ever-see

EBEBRATT-Ed

@majkaoil

If the existing burner is undersized what are the combustion numbers? If underfired your stack temperature would be low.

You could probably install a new burner, fire it at the correct rating and baffle the boiler to increase the efficiency

ethicalpaul

Steamhead, why would the size of removed radiators affect the sizing of a boiler?

- the removed radiators certainly don't have to be heated
- Any steam supplies to them that still exist are presumably capped off and will not see steam anyway, or am I missing something?

Steamhead

@ethicalpaul , the main lines were sized larger so there's more metal to heat. See chapter 6 of Lost Art.

ethicalpaul

Thanks! But surely the minuscule increase in EDR of a larger main line (especially an insulated one) can't possibly compare to the additional (and I would say unnecessary) EDR of removed radiators and their capped supply lines?

Unless I read your reply wrong, you said they should count the EDR of the removed radiators?

Steamhead

Yes, if available.

If you size to existing radiation when radiators have been removed, you may end up with a boiler that's too small. That's because there is more piping than they assumed when they published the ratings.

This is all in Chapter 6 of Lost Art. @DanHolohan wrote about this so we wouldn't have to learn it the hard way.

ethicalpaul

Thanks! I'm thankful for the clarification although (as if it matters) I disagree with the practice heartily!

mattmia2

There is a whole argument here to be had about what happens if it is just a little undersized and can you mitigate that with proper venting and piping and such.

majkaoil

Thanks for all the replies. But its not the sizing of the new boiler that has me stumped, I have done the radiators (including total piping length, etc.)
Its finding out the rating on the existing boiler so that I can fire a new burner at the right GPH. The existing burner is the equivalent of a birthday candle trying to boil water in a saucepan.

EBEBRATT-Ed

Fire the burner to the radiation load plus the pickup factor (x 1.33) plus the boiler efficiency x (1.20) as long is the stack temp is above 320 or so your fine. Thats why I asked what the stack temperature is now with the existing burner. That will give you your clue.

If you haven't check it, you won't know. The old boiler rating is meaningless...you know it's oversized. If you fire at the boiler rating, it will be too much input as the boiler is too large.
The old coal ratings are meaningless.

ChrisJ

EBEBRATT-Ed said:

Fire the burner to the radiation load plus the pickup factor (x 1.33) plus the boiler efficiency x (1.20) as long is the stack temp is above 320 or so your fine. Thats why I asked what the stack temperature is now with the existing burner. That will give you your clue. If you haven't check it, you won't know. The old boiler rating is meaningless...you know it's oversized. If you fire at the boiler rating, it will be too much input as the boiler is too large. The old coal ratings are meaningless.

My old neighbors Redflash boiler that was converted to oil took absolutely forever to produce steam, especially if the water was cold.  I could see this being described as seeming like it's grossly underfired. 

But once it got boiling, it then produced too much steam for the system.  Way too much.

I'm assuming this is typical of older coal boilers with a lot of water.

Steamhead

@majkaoil , how much radiation does this system have? Has any been removed that you know of?

Also, I dug up my Byrley book and there are a couple different US Radiator #236 boilers listed. Can you post a pic of yours?

majkaoil

I will access the church this afternoon and check stack temp and also grad a better pic than I have. Thanks all...