Coal heat

soot_seeker_2

on if the system was continue to steam when on "low" fire, that is, when the thermostat isn't calling for heat. If steam is remaining in the system, then the speed of venting wouldn't matter much.

But it sounds like the steam cycles on and off with the thermostat. Every time the boiler produces steam, the pipes and radiators must vent the air. If the system vents slowly, that time spent venting is wasted fuel.

Vent fast and save fuel. But if you're obly venting once a season, as you would if the boiler was always steaming, your sevings would be moot.

Long Beach Ed

Frank_34

balancing coal fired boiler

In Dan's book, We got Steam Heat and on this site I often read that residential steam systems were designed for coal. Is it safe to read this as "hand fires" as opposed to a stoker? The rest of the question is althogh my EFM DF520 has constant heat like a hand fire it is thermostatically controlled and cycles like an oil fired boiler. Should I vent/balance my 1 pipe system like an oil fired boiler or a hand fire or a hybrid of the 2?

Long Beach Ed

Really doesn't cycle...

Frank,

If I'm correct about this boiler, it has a Will-burt stoker timer that operates the stoker two minutes every hour when the thermostat is calling for heat. I think it's somewhat adjustable and it may also be operated by an aquastat if you're using the thing to make hot water too.

Most of the references in Dan's book regading coal vs. oil fires relate to the immediate cooling of the oil fire when the burner shuts down. When the heat is removed, steam quickly condenses and forms a high vacuum. In the old days, with coal, air vents had check valves that permitted this vacuum to form. As the coal firs slowly burned lower and lower the vacuum would increase and the boiling temperature of the water would decrease. In theory, while holding a vacuum in early morning with a hlf cold fire, you could still be producting 160-degree steam.

With an oil fire, vacuum would form very quickly. Any air in the system would expand and whole portions of the system would become airbound.

I'd think that your system could be a candidate for vacuum vents, as even with the thermostat and stoker, heat is gradually reduced. There is one problem...

Nobody makes vacuum vents anymore. If you ever find some, I'd give it a try. It would save you perhaps 20% if the system was tight and it worked.

Long Beach Ed

Joe Grosso

Close.....

The stoker outfire control operates the unit every hour(adjustable) when the t-stat ISN"T calling.Then again, like you said, it does maintain, too. Yes, there is really no difference between hand fed and stoker as far as the fire, it's just that the stoker is more automatic.
So, basically the fire burns low until the stoker comes on due to a thermostat call or aqustat call or timer/outfire call.Due to the large EFM boiler water content it does not get to low limit too much, hence the need for the Will-burt or Honeywell timer.

Frank_34

coal vs. oil in balance steam radiators

so is it safe to say that very fast venting of the mains & radiators isn't as critical with a stoker as it would be with an oil fired boiler?

The hissing and air flow from my radiator vents that occured with my W-M Gold SGO4 boiler is no longer detectable with the DF520. This is not to say that the radiators do not heat because they do. I'm just trying balance them so that all the rooms are around the same temp.