Outdoor Wood Furnace Info

Outdoor Furnaces - Manufacturers WITH EPA-Certified Models => HeatMaster => Topic started by: Dillon1630 on November 13, 2018, 07:39:21 AM

Title: Adding a second exchanger...
Post by: Dillon1630 on November 13, 2018, 07:39:21 AM
My home is two stories with a basement.  I have two separate units heating my house, one in the basement, and one in the attic (2 stories away).  I currently have my heat exchanger in my basement unit which heats the majority of the house. I have the upstairs unit running with the fan only and it recirculates the air from downstairs to upstairs via the return air duct in the ceiling. This method is working ok, but doesn't provide for very even heat.  I was thinking of adding a second exchanger to the attic unit, but wasn't sure how far the pump would work without overstressing.  It would be about 25' vertical and 100' total loop added to my current loop which is about 80' total.  I know people run much longer loops, but not sure about the vertical run.  Any ideas?  Anyone else running this?  Thanks!
Title: Re: Adding a second exchanger...
Post by: tinfoilhat2020 on November 13, 2018, 02:42:08 PM
what size pump do you currently have?
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on November 13, 2018, 08:46:15 PM
I have a Badger GPD 25-10SFC. It is rated at 30’ on speed III, but that’s all I know.
Title: Re: Adding a second exchanger...
Post by: E Yoder on November 14, 2018, 02:18:51 AM
It should push it fine with that big pump.
You'll need to keep it the same size piping for the whole loop to keep flow rates up.
Also to purge the air out the first time you'll most likely need house water pressure teed in at the beginning of the loop near the water heater to help boost the pump. A ball valve on a line connecting domestic water and stove lines.
Once the air is out vertical makes no difference.
I would normally pump a main loop to the water heater, then a secondary with close tees to both the air handlers. Putting it all in one works too though.
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on November 14, 2018, 06:55:11 AM
Thanks....again!
Title: Re: Adding a second exchanger...
Post by: RSI on November 14, 2018, 07:39:36 PM
How does the elevation of the outdoor boiler compare to the heat exchanger in the attic?
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on November 15, 2018, 06:50:54 AM
It is at the same level as the basement, so 25' below the attic.
Title: Re: Adding a second exchanger...
Post by: RSI on November 15, 2018, 08:22:32 PM
With that much height you might need put a plate heat exchanger in and pressurize the lines to the attic.

Could try without first and see how well it works. I would probably set it up as a secondary Loop though so when it airlocks you don't lose flow to your entire system.
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on November 27, 2018, 03:45:53 PM
Thanks to Mr. Yoder, I got the second exchanger installed with no problem.  Tapping into the domestic water line was the key.  Makes a world of difference having both units blowing hot air now.  Too bad that I woke up to a stuck damper plate again this morning.  That is my one complaint about my G200....that damper plate being a constant maintenance item is a bad design.  I cleaned it like new to begin the season and it has already stuck.....it's hard to trust that thing unless you clean it once a week.
Title: Re: Adding a second exchanger...
Post by: RSI on November 27, 2018, 06:09:02 PM
What is the mfg date of your G200?
Title: Re: Adding a second exchanger...
Post by: E Yoder on November 29, 2018, 12:59:05 AM
That seems unusually often. I think we can get it to do better than that.
I'd notify your dealer first, and as RSI mentioned if we know the manufacture date we can troubleshoot more accurately.
Title: Re: Adding a second exchanger...
Post by: hoardac on November 29, 2018, 03:34:59 PM
Yeah I had the damper problem they sent the fix to me and it has not stuck since.
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on November 29, 2018, 07:12:34 PM
Build date was May, 2017.
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on December 13, 2018, 08:12:13 AM
Just spoke with my dealer again about the damper plate issue and he said that after speaking with his rep, they advised that I extend the length of my flue pipe and put a cap on it.  He said that should fix the problem and if it did not they would move forward with sending a new air box.  He said they think it's getting too much down draft. Thoughts??
Title: Re: Adding a second exchanger...
Post by: E Yoder on December 14, 2018, 03:36:10 AM
It makes sense that a taller chimney would put a slight vacuum on the unit at all times helping keep the smoke moving forward. It's worth a try and keep an eye on it.
Title: Re: Adding a second exchanger...
Post by: mlappin on January 01, 2019, 06:47:21 PM
Just spoke with my dealer again about the damper plate issue and he said that after speaking with his rep, they advised that I extend the length of my flue pipe and put a cap on it.  He said that should fix the problem and if it did not they would move forward with sending a new air box.  He said they think it's getting too much down draft. Thoughts??


It’s possible it can help. The way it was explained to me is its strictly an environmental issue. Due to the lay of the land someplace are more prone to temperature inversions which contributes to the damper sticking. I used to see it all the time with my old stove, smoke would go so far up out of the stack then drop and hug the ground down the hill, across the pasture and finally cross the road a 1/4 mile away. In my case installing I guess what would be called the second gen air box fixed it, running for over three moths and haven’t cleaned it yet, last year I just planned on weekly with the original box.
Title: Re: Adding a second exchanger...
Post by: E Yoder on January 05, 2019, 05:08:11 AM
It is at the same level as the basement, so 25' below the attic.
I'm finishing a job on an old 1860's farmhouse next week with 3 air handlers, the attic unit is at least 30' higher than the top of the outdoor furnace. Am tieing it into one of the basement secondary loops. I think it'll work fine, but it's about the highest I've done. Two stories plus the basement, 12' ceilings. Stove is downhill from the basement.
Homeowner said the original owners started the house in 1860, went off to war, came come home and finished it up. Interesting history.
Title: Re: Adding a second exchanger...
Post by: greasemonkoid on January 05, 2019, 11:21:25 PM
Doubt my math is right, but that looks to be approaching the point of needing a restriction on the return side to prevent boiling in the pipe on the way down, but aside from making noise what harm would boiling water on that side do anyway?
Title: Re: Adding a second exchanger...
Post by: wreckit87 on January 06, 2019, 01:38:19 AM
Doubt my math is right, but that looks to be approaching the point of needing a restriction on the return side to prevent boiling in the pipe on the way down, but aside from making noise what harm would boiling water on that side do anyway?

Genuine curiosity tells me to ask: why would it boil after the reduction in temp from the HX just due to the vertical drop?
Title: Re: Adding a second exchanger...
Post by: greasemonkoid on January 06, 2019, 08:42:00 AM
Mainly when the "if's" align, but in reality they probably never will unless you go significantly higher, but that's theory. It would be a neat experiment to try though. The absolute pressure at the crown of the loop is the concern, it doesn't have to be after the heat exchanger. That's several psi pulling down lowering the absolute pressure, certainly wouldn't want a pump up there. The variables are nothing out of the norm - velocity, areas of high turbulent flow, temperature, altitude, ect.
Title: Re: Adding a second exchanger...
Post by: wreckit87 on January 06, 2019, 05:34:13 PM
Mainly when the "if's" align, but in reality they probably never will unless you go significantly higher, but that's theory. It would be a neat experiment to try though. The absolute pressure at the crown of the loop is the concern, it doesn't have to be after the heat exchanger. That's several psi pulling down lowering the absolute pressure, certainly wouldn't want a pump up there. The variables are nothing out of the norm - velocity, areas of high turbulent flow, temperature, altitude, ect.

I'm no genius, but I don't think that's how this works. We have closed loops, therefore nothing can come down that doesn't go up and pressure throughout the loop remains fairly constant. Friction between the fluid and pipe wall will only allow (X) flow rate which happens to be roughly 3 feet per second on the high side in the majority of residential atmospheric systems. In order for it to flash at 180 degrees, we'd need to see a vacuum of almost 7 psi which would require a water column of 16 feet with a vacuum break on top, which is impossible with a closed loop. I don't see how this could even be accomplished on purpose, much less by accident. Very interesting topic of discussion, but unless there is something I've overlooked it seems to be debunked
Title: Re: Adding a second exchanger...
Post by: E Yoder on January 07, 2019, 01:36:12 AM
Here's a thought, stir it around guys. I propose-
 The point of no pressure change is the vent pipe on the outdoor furnace. So, anything above that point is in a slight vacuum. Anything below is under pressure. Both vacuum and pressure would be whatever the water column is, on the job I was describing the attic isabout 30' above the vent pipe, pump serving the attic is about level with the vent pipe.
Anybody be able to figure the temp it could boil? It's about 2000' elevation.
That's why (I feel) it is important to keep pumps as low as possible and at the beginning of any loop they are circulating. This would add the piping resistance in front of the pump to prevent the boiling and cavitation (rather than if the pump were pulling and adding to the vacuum).
I'm guessing that the reason I've never heard boiling in these really high loops is because it's always going through a coil and being cooled.
Thoughts?
Title: Re: Adding a second exchanger...
Post by: greasemonkoid on January 07, 2019, 04:39:45 AM
I don't know how to articulate the idea any better. Our closed loop systems are still exposed to atmosphere on both ends, so basically you've got a siphon tube, albeit a modified one, being the presence of a pump creating pressure and velocity of the fluid. We agree that if the pump were to stop, and velocity were to stop, and the loop being high enough, your max siphon height will see a limit.

Now, let's make our hypothetical loop 100' vertical initially filled with water, install an absolute pressure gauge (properly) at the peak of the loop, at the beginning of the upboud side (after the pump), and ending of the down bound side, slowly ramp up pump rpm. What do they read as impeller rpm transitions from 0 rpm to 2000 rpm? What is in the crest of the loop (water or water vapor) and at what rpm?

Sheer forces within the boundary layer (restriction) are on our side this time.
Title: Re: Adding a second exchanger...
Post by: E Yoder on January 15, 2019, 05:36:59 AM
This is the coil in the attic we did the other day. Took domestic water pressure to purge out, definitely gettting up there. . I'm guessing 30' above the outdoor furnace.
But it worked fine once the air was out.
Title: Re: Adding a second exchanger...
Post by: Dillon1630 on January 29, 2019, 10:45:44 AM
Update....My dealer sent the new air box and I installed it this weekend.  I was impressed with the changes and I hope that if fixes my sticking plate issue.  Was easy to install after I cut off a portion of the air tubes that stuck out too far.  Fingers crossed that it works.
Title: Re: Adding a second exchanger...
Post by: mlappin on January 29, 2019, 11:40:27 AM
Update....My dealer sent the new air box and I installed it this weekend.  I was impressed with the changes and I hope that if fixes my sticking plate issue.  Was easy to install after I cut off a portion of the air tubes that stuck out too far.  Fingers crossed that it works.

It should, I changed out my original for what I’d call the second generation airbox so I don’t even have the newest. I pulled it apart after three months just to check and was very little creosote, cleaned it anyways and lubed up with ATF, used to be a weekly thing.