Optimum Steam Heating

ImYoungxD

Say you have the most optimum setting. Boiler is not oversized, insulated main line, main venting fast, rads have good vents, etc...
How long should all CI radiator take to reach 200F+, cold start when outside temp is 50s?

KC_Jones

Depends on the system type (1 pipe 2 pipe), the amount of venting, the size of the radiator, output of the boiler. I don't think there is any way to answer this question.

You could take the time to calculate system volume, venting capacity, boiler output, condensing rate in pipes feeding the rad and maybe come up with a theoretical number...maybe.

Gsmith

First, at 50 deg outside temperature it is unlikely that your steam radiators will get hot all the way across, most likely just the first one or 2 sections.

You could take a few measurements of your own and post the times you get for the following here to get some feedback:
From a call for heat by the thermostat (you can turn up a few degrees to start it):
1. How long does it take until the boiler steam outlet pipes get too hot to touch (how long for the boiler to boil the water in it to make steam at the boiler outlet).
2. How long after #1 above until the ends of the steam mains get too hot to touch (steam gets to the main vents).
3. How long after #2 abvoe until the radiators first sections get steam hot.
4. How long after #3 above until the tstat is satisfied and the boiler turns off or cycles on the pressuretrol. And what are the pressuretrol settings.
You may have to wait until much colder weather to see if #4 is reasonable. Note: the above are assuming you have a typical one-pipe steam system, if you have 2-pipe, let us know and perhaps some other measurements can be taken.

pecmsg

Optimum

At design conditions:
The boiler never shuts down
The Radiators never get cold
The house maintains perfect temperature

lcw5

pecmsg said:

Optimum

At design conditions:
The boiler never shuts down
The Radiators never get cold
The house maintains perfect temperature

That is obviously ideal. My (limited) understanding though, is that for most steam systems and current house conditions there is more EDR than necessary to keep the house at perfect temperature. So, most steam boilers are necessarily oversized relative to the heat needs of the home. What should the homeowner expect then?

Jamie Hall

My first reaction is... if you are trying to come up with an answer that will satisfy the homeowner, you have about the same odds as the folks playing the lottery.

Having gotten past that reaction, however... My own observations suggest that after steam has actually been raised -- which is variable depending on the boiler and the burner -- expecting steam to travel in a cold, insulated main much faster than 10 to 15 feet per minute is asking a bit much. A riser may be a bit slower -- since they usually aren't insulated, and that makes a difference. So you can figure that for the time to first heat in any given radiator. Plus or minus a huge fudge factor.

Now -- how long for all the radiators to get hot across? Ho ho hee hee hee… depends on the size of the radiator, how cool the room is... in one pipe, how big the vent is. Way too many variables.

However, except for coming out of a setback or on a very cold day, it is likely that the biggest radiators, at least, will never get hot all the way across.

Now. How long will the boiler run to do this? Again, too many variables and depends on the system. The whole system.

jumper

Warm up time is mostly influenced by ratio of burner output to amount of water in boiler. At least I think so.

For steam heating there are reasons to prefer larger water volume so I doubt that quick warm up is considered.

mikeg2015

Depending on your location, at 50F, our like if more than 1/4 of the radiators heats up. Temperature usually overshoots after the system shuts down. Runs more smoothly at 30F for temp swings. Around 10F or lower it hits the sweet spot and radiators are hot all the time, boiler runs about 50-75% of the time.

Most old homes are overradiated because coal heat required you to play catch up sometimes, and when the fire died you needed enough EDR to continue to take all the steam as it went into vacuum and kept boiling at a lower temp all night.

nicholas bonham-carter

With good main venting, all the radiators should get heat at the same time, and melt pats of butter on plates placed on the intake end of the radiators all together. Two ounces pressure should be sufficient, provided the main venting is adequate.
A good loaf of sourdough bread will provide toast to reward yourself for the effort with all the butter left over!—NBC