Boiler Sizing

subcooler

water will do that. You need to calculate the connected load of the system. Then calculate the buildings heat loss. Usually the connected load will exceed the heat loss. Then find a happy medium. But most of all install a water meter ahead of the fill device and monitor water make-up. I cannot count the number of units I have seen go this way.

Jim Chamberlain

Steam boiler sizing and correct thermostat


Unfortunately, my church's steam boiler cracked well before its time due to faulty installation and/or underground leak in the condensate pipe that resulted in lots of fresh water being poured in. The 13 year old WM LGB8 has >900k BTU's. One contractor did a calculation of the radiation and said it was closer to 450k and to go with the LGB6 rated 650k.

Another contractor said we could use the same boiler model with higher BTU rating but now it had a low and high flame control that would not cause the same problems that an oversized boiler can cause, which we always had (rapid cycling, hammering).

Are both correct?

Also, we have digital thermostats which I am now told are a no no for steam. I gather the standard circle thermostat by Honeywell is the best, but is there one that allows some settings between night and day, etc. that also work well with steam?

Jim

Guy_6

steam

I agree with calculating an actual heat loss and sizing the boiler accordingly.
I don't see the setback on steam causing the failure, but you will face the usual "setback" dilemna of how much swing in temp can you incur and have a significant savings?

The nagging questions on the failure are
a) Is this a pumped return system, and therefore was the system shocked with a "load" of cold water from a tank or feed system?
b) Is the flame impinging on the section, causing undue stress?
c) (This hurts to ask, as I sell a competetive boiler)-Can you replace the defective section, solve the issue, and move on?

Guy_6

steam

I agree with calculating an actual heat loss and sizing the boiler accordingly.
I don't see the setback on steam causing the failure, but you will face the usual "setback" dilemna of how much swing in temp can you incur and have a significant savings?

The nagging questions on the failure are
a) Is this a pumped return system, and therefore was the system shocked with a "load" of cold water from a tank or feed system?
b) Is the flame impinging on the section, causing undue stress?
c) (This hurts to ask, as I sell a competetive boiler)-Can you replace the defective section, solve the issue, and move on?