Outdoor Wood Furnace Info

All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: free heat on November 23, 2014, 08:16:52 PM

Title: pump speeds
Post by: free heat on November 23, 2014, 08:16:52 PM

I currently have a 3 speed pump with a 95 ft run. The whole past season I left in on medium setting with a decent 5 wrap from badger. My typical heat loss is around 4 degrees on that run which I'm OK with. My question is would it be beneficial to speed that pump up to the highest setting or even try dropping it down to the lowest setting. It probably doesn't matter much either way which speed but I just wanted to see what  you guys thought. I'm just trying to fine tune my setup. Thank you in advance

Title: Re: pump speeds
Post by: RSI on November 23, 2014, 09:00:42 PM

It depends on the pump model. High speed on one pump could be less flow than low on another.

Title: Re: pump speeds
Post by: free heat on November 23, 2014, 09:46:09 PM

Its a badger pump gpd15-6sfc. The specs say on high 100 watts 926 gph on medium 70 watts and 688 gph and on low 55 watts 423 gph. Thank you much appreciated

Title: Re: pump speeds
Post by: RSI on November 23, 2014, 11:19:14 PM

You should probably be running that pump on high but if the return temp isn't that low under load then you can probably use medium. The GPH listed is with no head. You will be getting a lot less than those numbers.

Title: Re: pump speeds
Post by: JDfarmer on December 06, 2014, 02:01:31 PM

So, are you guys saying that it's better to run the pump on higher settings, so that the water temp will drop less across the water/air exchanger?
I have a Grundfos pump 3 speed; 0-20 gpm.

Title: Re: pump speeds
Post by: RSI on December 06, 2014, 06:36:45 PM

Yes, you don't want cold water returning to the boiler. It will also reduce the heat output if the water is pumping too slow.

Title: Re: pump speeds
Post by: JDfarmer on December 06, 2014, 06:46:28 PM

thank you.

Quote from: RSI on December 06, 2014, 06:36:45 PM

Yes, you don't want cold water returning to the boiler. It will also reduce the heat output if the water is pumping too slow.

Title: Re: pump speeds
Post by: JDfarmer on December 07, 2014, 05:07:09 PM

I did a test; with pump speed variations.
At low speed there is 30f drop
At mid speed 15-16
at high same 15-16 same as mid speed.
Drop across the air water exchanger with central blower.

So mid speed it is for me.

Title: Re: pump speeds
Post by: caper on December 08, 2014, 09:18:03 AM

don't really know a whole lot about gpm on the pumps, so im replacing my grun 1558 on my loop going out to the boiler to a 2699, does anyone know the numbers for slow.med high on each pump, I run the 1558 on med,question is when I get the 2699,which speed do I run that on,  thanks guys