BOILER SIZING...GAS , STEAM

ALNY

I did a  EDR on a building, but was not allowed access to all parts of the house to do an EDR....



Based on the first floor, i have an EDR of 186 on the first floor...and i simply multiplied it by four for each level of the house. to get a total of 744 EDR..and 178,560 btu/h..





Based on research,

as far as Burnham IN9, Crown BSI276, Williamson GSA-300, and Weil McLAin EG-75.....now my question is can i go one size smaller, lets say a boiler



with the specs of :

654 square feet of steam, and 157,00 NEt IBR rating? which is the next size down....

from a 750 square feet steam  boiler producing 180K net IBR which is what i think i need...Also i did not ssee all parts of the house to to many issues, but is it safe to ASSUME that all upper floors same as the first?



If i get the smaller boiler, what would be the drawbacks, beside the boiler runing a bit longer to produce steam?.....thanks.

icesailor

Top floors:

It has always been my understanding that the top floor has a higher heat loss because of the exposed unheated outside to the roof. Where the lower floors have conditioned spaces below them.

As far as using the smaller steam boiler, I won't comment on that. Someone else may.

It would seem though, that if they won't let you into all the rooms, you should put a disclaimer in your quote about accuracy in size because of "unknowns". That usually gets their attention.

icesailor

Top floors:

It has always been my understanding that the top floor has a higher heat loss because of the exposed unheated outside to the roof. Where the lower floors have conditioned spaces below them.

As far as using the smaller steam boiler, I won't comment on that. Someone else may.

It would seem though, that if they won't let you into all the rooms, you should put a disclaimer in your quote about accuracy in size because of "unknowns". That usually gets their attention.

RJ_4

boileric

whats the size of the old boiler, I ran into the same problem, I had to use size of old boiler and take in account that the old 1940 boiler had a side arm domestic water heater. I did put in a disclaimer in the bid

nicholas bonham-carter

boiler choices

could the riser sizes lead to a more accurate guestimate?--nbc

ALNY

EXISTING BOILER

The bboiler is an older Weil McLain boiler with no name plate or anything on sizing, except for the Mclain name on it.... this boiler had a Robert Shaw gas valve 700-400

http://www.grainger.com/Grainger/ROBERTSHAW-Combination-Gas-Valve-4E123?Pid=search

This gas valve is rated for 240,000 BTUH capacity as you can see on the specs.



Based on the first floor sizing i get 744 EDR, and it could be less.



The smaller boiler size has

INPUT 250K BTUH rating, 650 square feet of steam, and 180,000 IBR net rating.



Whereas if i go with the multiple of the 1st floor times 4, i get 744 EDR, and the boilers in this range, the numbers are as follows:

INPUT 280K, 174K IBR rating, 725 sq ft of steam.



Now the gas valve from the old boiler had a capacity of 240K BTUH, and everything was fine in the building, so this is why i am leaning to the smaller boiler with the 650K of steam and 250K BTUH input, as its closer in size specs to the already installed boiler...this issue would be easy if i was able to see all the radiators in the building.  I know its alwasy easy to go bigger, but i hate going bigger and short cycling, whereas a slightly smaller one will do the job, but will have to work a lil harder, and in this case might be the right one.



Another factor is that the upper floors do not have radiators in the hallways like the first floor does, and this might knock the EDR some. The hallway radiator is about 18 EDR so this mar might knock down the EDR 54 (18*3 (missing boilers on floor 2,3,4)) or 12,960 BTUH.



Any suggestions...

ALNY

Riser Sizes

Riser sizes i dont use as a guide because every boiler is different....

on two equal sized boilers, one supply is 3.5" on the newer Weil McLAins, and Burnhams have 2" for supplies, and i like burnhams as its easier to thread on he field whereas with the McLains i have to purchase nipples, unions, etc for what i need.

nicholas bonham-carter

takeoffs to rads

maybe i should have called them the takeoffs for each rad, instead of risers. follw the main, and count all the takeoffs and their sizes. there should be a table to convert pipe size to edr.--nbc