Time To Steam

Patrick_North

Another thread made me realized have no clear idea of how long it <em>should</em> take my boiler to create and distribute steam.

I'm running a Smith G-8 five section boiler with a Carlin EZ-Gas burner. From a cold start it takes 9 minutes to feel steam (not just warmth) at the boiler risers. After doing a little digging, I find it should take "about 5 minutes" to create steam. Here's where "common" sense fails me. On the one hand, that's only about 4 minutes. On the other hand, that's a nearly 100% increase.

It takes 4 additional minutes for steam to reach the "start" of one main. Yes, the header is well insulated, but it is 4", and that's a fair bit of ion to heat up.

Now here's the last part that makes me wonder if all's well. It takes an additional 5 minutes for steam to reach the end of this main. It is well insulated, 2" pipe- about 50' of it, with <em>three</em> Gorton #2s venting it. (Another shorter main vents a tad quicker.)

By my math, I only have about 1.15 cubic feet of air to vent. These vents (which all seem to be working) are capable of venting anywhere from 3.3-6.6 cfm, depending on opperating pressure. In other words, the air could be expelled in 10-20 seconds.

Now maybe this is perfectly fine- perhaps on the higher end of desirable performance, but fine. BUT when the boiler was installed the burner was not set up properly at first. No combustion test was done, and the air admittance bands on the burner hadn't been touched. The burner was actually blowing itself out because the air bands were wide open. I eventually deduced what had happened (I'm sure thanks to the help of Wallies) and got the installer to dial things in- at least so that the burner wouldn't go out.

BUT... When the boiler was first to be installed I noticed that a four section model had been delivered. I winced as I pointed this out to the poor guy who had to get the thing back up the stairs. Now I'm wondering- could my burner (which is a separate purchase, I understand) have been intended for the original, smaller boiler (read: smaller orifice)? Could underfiring this way cause the sluggish performance?  Any easy way to tell if this is the case?

Thanks to you brave souls still reading,

Patrick

nicholas bonham-carter

burner too small?

would you be able to identify the model number of burner now installed and compare it with the literature on the boiler mfg's website?

if the burner you have is for the smaller boiler, then at least you won't be short-cycling on pressure.--nbc

Patrick_North

Same model

I believe the EZ-Gas rating is varied by the orifice alone (it's a "nipple orifice"), so there doesn't seem to be any way to tell without taking it apart. Which would of course make it easier to make a mistake in this regard.

Thanks,

Patrick

Rod

Clock the Meter

Hi- Smith should have figures as to what the input (btus) is for that burner as properly set up for your model boiler. I would then just clock my gas meter (makes sure all other gas appliances are off) and if they match up reasonably well with Smith's figures, that would mean the burner settings are okay. They use to do it this way before they had good combustion instrumentation to test how well the "eyeball" setup was working.

  If it hasn't already been done I'd get a good pro to set the burner using the proper instrumentation and it's a good idea to get this checked annually. It isn't usually that hard to find a good burner man as long as steam knowledge isn't also required.

(Use this link for a chart that might be of help with the meter timing- http://www.hvacprotech.org/toc/clocking_gas_meter.htm   )

- Rod

Mark N

My Results

Patrick



A few years ago I ran some tests and these are my results.



Cold boiler (off 3 days) steam at boiler header: 9'40"



Boiler off 1 hour steam at header: 2'30"



Boiler off 2 hours steam at header: 4'05"



Boiler of 3 hours steam at header: 5'00"



My boiler is a Burnham IN-4, I've clocked the gas meter and it is right on the money.

Patrick_North

The results are in...

Well, I clocked the meter and things seem to be right on- thanks, Rod. And thanks for your input, too Mark- that's helping me feel a lot more "normal!" Not surprised to see your times are substantially quicker with warmer piping, etc.- a few hours post firing my header is still steam-hot to the touch.

I can't help but wish my distribution times were faster- 9 minutes to heat the header and mains still feels high- but lacking any evidence that anything is actually wrong it should be easier to stop fretting about it.

Thanks all,

Patrick