Steady fan vs on/Off on boiler

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I'm not sure of your exact setup but my boiler didnt stop sweating inside my heat exchanger until my temps hit almost 130 degrees.

Where exactly are you talking about putting this fan? If it's a fan to build the fire hotter then you will need an aquastat to control it on/off or you will be literally boiling your water.
 
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warno said:
I'm not sure of your exact setup but my boiler didnt stop sweating inside my heat exchanger until my temps hit almost 130 degrees.

Where exactly are you talking about putting this fan? If it's a fan to build the fire hotter then you will need an aquastat to control it on/off or you will be literally boiling your water.
Click to expand...

It's the fan in my forced air central system, heating the water in pellet stove and running
it thru a heat exchanger.
 
My system doesn't work very well when the water temp is below 145. I think you will need warmer water. As far as the fan running constant. It would depend on how fast you can recover water temps. I would think on/off would be better. That way your waste could recover temps.
 
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warno said:
My system doesn't work very well when the water temp is below 145. I think you will need warmer water. As far as the fan running constant. It would depend on how fast you can recover water temps. I would think on/off would be better. That way your waste could recover temps.
Click to expand...

Pretty new to this but with my furnace Fan OFF and a certain setting that I normally used
on my pellet stove I was able to reach 140F and it took 10 minutes to go down to 130F
and also 10 minutes to go back to 140F..
Regards..
 
I can't see you getting much heat off this 'boiler' setup with the water at only 110 (most water-air HXs need water in the 180 range), and I also can't see you getting much heat off it if it cycles off & on that much while only topping at 140.

I guess I can't see you getting much heat from it, period - but would like to see more details. Pictures maybe? How much water is in it?
 
maple1 said:
I can't see you getting much heat off this 'boiler' setup with the water at only 110 (most water-air HXs need water in the 180 range), and I also can't see you getting much heat off it if it cycles off & on that much while only topping at 140.

I guess I can't see you getting much heat from it, period - but would like to see more details. Pictures maybe? How much water is in it?
Click to expand...

Did look at your system,,,mine is a little smaller ;)
Look at post #5 in this thread for
picture..http://crosslinkconversions.com/forum/viewtopic.php?f=3&t=426&sid=1ee2c17d2e33598389725adee7929b21
 
maple1 said:
I can't see you getting much heat off this 'boiler' setup with the water at only 110 (most water-air HXs need water in the 180 range), and I also can't see you getting much heat off it if it cycles off & on that much while only topping at 140.

I guess I can't see you getting much heat from it, period - but would like to see more details. Pictures maybe? How much water is in it?
Click to expand...
This contains about 9 gallons in total.....
 
So with your numbers, 9 gallons going from 130 to 140 in 10 minutes is around 4300 btu/hr. I think.

Which I suppose might be enough to help a little bit, not sure it would be significant though - but it wouldn't take much fan action to disperse that much. If the water temp in the HX is 110 at constant running, I suspect the air coming out is less than that - which might get to feeling cool? So it would come down to comfort factor in which way to try - don't think it's making much difference in how much heat you're getting out of it. Although cooler water will theoretically pull more BTUs out of the fire.

Neat project none the less...
 
Last edited:
maple1 said:
So with your numbers, 9 gallons going from 130 to 140 in 10 minutes is around 4300 btu/hr. I think.

Which I suppose might be enough to help a little bit, not sure it would be significant though - but it wouldn't take much fan action to disperse that much. If the water temp in the HX is 110 at constant running, I suspect the air coming out is less than that - which might get to feeling cool? So it would come down to comfort factor in which way to try - don't think it's making much difference in how much heat you're getting out of it. Although cooler water will theoretically pull more BUTs out of the fire.

Neat project none the less...
Click to expand...

Thx for your response and explanation, makes a lot of sense to me.
I just received my aquastat, so i will try with it and see how it goes and feels.
Cheers..
 
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