Time to reach operating temps from a cold start?

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kuribo

Feeling the Heat
Dec 10, 2007
388
SW WI
I'm wondering how long it takes folks to go from a cold start, say boiler water at 60F, to either 140F return temps, or say 180F out temps? Specifically, for those with Econoburn 200 boilers so I can make an apples to apples comparison....Thanks....
 
Hardly ever let my boiler get that cold, but I would guess 30 minutes or less. If you want to speed things up figure out a way to send warm water from storage to boiler on start up.

That would be 165 launch temp of circulator.

The 180 is really going to depend on how many gpm you are flowing.
 
My boiler is usually in the 80-85 degree range when it is time to start a burn. I have been messing around with different ways to get the temp up fast. Right now I am finding the best way is to start a small fire (maybe 1/3 of a load) and leave the circulator off until I reach about 160, which takes about 30- 40 minutes. I will then start the circulator at low speed. I fill the firebox and do not move the speed of the circulator up until I am at about 170-175. I use pretty big splits in my boiler though. Smaller splits would probably go faster.
 
Thanks for the replies....

Assuming one was running the 200 full out, with a full firebox (I calculate about 100 lb of firewood), how long, ball park average, is a typical burn, say until the output drops below maybe, 160F?

I am trying to sketch up a BTU output vs time profile...

For those with the Econoburn 200, does the fan have different speeds such that you could run the fan on a lower speed to lengthen the burn time? I am assuming this would basically allow one to spread the heat output over a longer period of time...
 
I will guess about 3 hours for a full burn, assuming I had some good coals before I filled the box.
I don't think the fan speed can be controlled by the operator. It is a variable speed fan but it controls itself and only slows down when the boiler has reached upper temp set. If you are using storage, I don't think you want to slow down the burn as burning high and hard is most efficient.
 
I should add that like gg said earlier, the temp of the boiler has a lot to do with how much water you are moving and what the bottom temp of storage is.
 
Thanks for the replies....

Assuming one was running the 200 full out, with a full firebox (I calculate about 100 lb of firewood), how long, ball park average, is a typical burn, say until the output drops below maybe, 160F?

I am trying to sketch up a BTU output vs time profile...

For those with the Econoburn 200, does the fan have different speeds such that you could run the fan on a lower speed to lengthen the burn time? I am assuming this would basically allow one to spread the heat output over a longer period of time...

Hey gg. I know you weigh your wood. Does the 100 pounds sound right to you for a full fire box?
 
Here's my attempt at one rough output profile estimate for the Econoburn 200....Some assumptions are:

42 gallon capacity, 80F start up water temp, 160F circ start, 30 minutes to 160F
100LB charge, 6000 btu/lb, 75% efficiency, length of burn based on anecdotal reports, peak output of 225,000btu/hr from conversations with Econoburn.

Area under the curve is total heat output...

econoburn 200 heat output profile.jpg
 
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My boiler is usually in the 80-85 degree range when it is time to start a burn. I have been messing around with different ways to get the temp up fast. Right now I am finding the best way is to start a small fire (maybe 1/3 of a load) and leave the circulator off until I reach about 160, which takes about 30- 40 minutes. I will then start the circulator at low speed. I fill the firebox and do not move the speed of the circulator up until I am at about 170-175. I use pretty big splits in my boiler though. Smaller splits would probably go faster.

Wouldn't it be nice if a circulator could be programmed so that it would only send 185F water into your storage tank? It would speed up and slow down automatically depending on where the burn cycle was. Someday...maybe ...LOL
 
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You got it. That would save me a lot of trips to the garage. I did however learn how to turn a couple of old android phones into a security camera and a viewer. That makes life a little easier. I just point the camera at the boiler controls. At least then I know when to go out.
 
Wouldn't it be nice if a circulator could be programmed so that it would only send 185F water into your storage tank? It would speed up and slow down automatically depending on where the burn cycle was. Someday...maybe ...LOL

Actually, that is exactly what I am attempting to do....
 
Here's my attempt at one rough output profile estimate for the Econoburn 200.

Not sure if this means anything to you Kuribo but here is a little chart of one of my burns last summer when Maple and I were comparing notes. I did not have the load circuits turned off while burning but in June all that would have been on was a small load for hot water. It was not the best wood as I was burning some old stuff for the summer but it might give you an idea. I also don't weigh my wood so cannot tell you how many pounds it was. I think I have refined my burn process a little since then also. As you can see I created 323,000 btu, not 450 as in your chart. I think 450 would need to be in a pretty perfect world.
 

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  • Boiler Burn Data June 2 15.pdf
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Looks like I didnt' get that quote thing right but you get the point.
 
Actually, that is exactly what I am attempting to do....

Good luck, please let us know if you succeed. I actually tried once with one of the Taco variable setpoint circs, but it didn't work. I talked with a Taco tech guy before I bought it, and he said that it "should" work the way I wanted it to in "reverse acting mode" but it didn't. I ended up selling it.

Pat
 
Thanks, helpful indeed.

A few reasons why your figure may differ from my calculation:

your wood (smaller amount, not as dry)
you seemed to have shut the boiler down when there was still usable output
unknown heat loss in your system
 
Maple - for the old phone thing just go to app.webofcam.com and download the app. As long as your wifi signal can reach where your boiler is you are good. It turns one of the phones into an IP camera so you can view it on another phone or even on your computer. Just type the IP address it gives you into your computer. Works on apple and android but not blackberry.
Just use an old out of date or broken down phone for the camera.
 
Wouldn't it be nice if a circulator could be programmed so that it would only send 185F water into your storage tank? It would speed up and slow down automatically depending on where the burn cycle was. Someday...maybe ...LOL

Something like this? Circulator speed is in percent.
boilercircctl.png
 
Yeah, what type of circulator?
Grundfos 15-58, controlled with a Vesta. It's the wood boiler circ in the 'live' link in my sig. No fire tonight, though - we're skipping because we have enough in storage to last until tomorrow.
 
Here is my dilemma: I want to control the output temp of the boiler to say, 180-190F to fill storage in a "one and done" manner. Originally I planned to do this with two viridian temp set point pumps, one on the boiler loop controlling the boiler output temp, and one in the storage loop, with it set to maintain the boiler return temp at 150F. The problem I am seeing is at start-up and when the boiler heat output starts dropping to low levels at the end of the burn. The flow rates/heads at those points in the burn cycle are below the operating point of the viridian pumps. How does your controller control the pump? Is it a bang -bang type of control?
 
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