Outdoor Wood Furnace Info

All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: new builder on January 24, 2014, 06:49:24 PM

Title: return temp ?
Post by: new builder on January 24, 2014, 06:49:24 PM
i usally see about ten degree differance at my heat exchanger between supply and return with out purance blower running and usally 20 to 25 differance with furance running just curious what the norm is ? this is a homemade boiler i built and it works perfect just wondering how it compares with everyone eles return temps.
Title: Re: return temp ?
Post by: hondaracer2oo4 on January 24, 2014, 07:51:39 PM
I lose 8 through the loop without the blower going but still feeding the sidearm. I get a delta t across the water to air hx of 25.
Title: Re: return temp ?
Post by: Scott7m on January 24, 2014, 08:24:52 PM
Delta t of 20 is what we hope for

It can be bigger as long as your running your stove hot enough
Title: Re: return temp ?
Post by: skorpyd on January 25, 2014, 12:33:39 PM
I'm getting about 5 degrees difference without the furnace blower running, and 20-25 with the blower going also.
Title: Re: return temp ?
Post by: new builder on January 25, 2014, 01:39:30 PM
Sounds like Im right in the ball park !
Title: Re: return temp ?
Post by: 46mech on January 28, 2014, 07:30:51 PM
Where are you guys measuring these temps? Is it at the boiler or at the exchanger? Also, I've tried an infared gun but the reading jumps around alot because of reflectivity, so I think I may try a contact temp. pen that I use for bearings. What do you guys use for taking your temps.?
Title: Re: return temp ?
Post by: hondaracer2oo4 on January 28, 2014, 07:36:50 PM
I need to revise my temps a little. I use a redi-check smoker wireless temp sensor with two sensors. I believe my return sensor is screwed up. It shows temps of 9 degrees lower then the incoming water temp to the hx. I switched probes and I actually have a 2 degree drop after it goes through my 24x24 water to air hx. My temp drop across the heat exchanger with this discrepency is 15 degree drop on speed 3 for the pump, 18 degree with speed 2 and 21 degree with speed 1. I have ran speed 3 for the past few years. I just started today running on speed 1 because I want to see if there is any noticeable differences anywhere. If there is not I will leave it at speed 1 since it costs half as much in electricity on this speed.
Title: Re: return temp ?
Post by: new builder on January 30, 2014, 07:42:47 PM
Im running my pump on high also I've thought about turning it down and wondered how it would work. Keep is posted on the results please.
Title: Re: return temp ?
Post by: 46mech on January 30, 2014, 08:23:44 PM
Same here - running on high speed and wondered about running slower. Here's my question. What are the advantages? The only thing I could see was saving a little current on the pump. I just like the lower delta T I get on high speed. Are there some other benefits that I am missing?
Title: Re: return temp ?
Post by: willieG on January 30, 2014, 08:37:38 PM
depending on the size of your piping, being able to run on a lower speed could prolong the life of your piping...less gpm = less friction= less wear