Cleaning the Greenwood w/pics.

[DKerley]

Hi Doug
Just wondering if the loss in efficiency was so gradual that you never imagined that the HX was so coated , or did you know something was up and just needed time ??
By the way great job!!
Anthony

Hi Anthony,

The only way that I new something was up was by monitoring the flue gas temperatures and seeing the accumulation of creosote on the visible portions of the heat exchanger assembly. Even with all of the build-up, the greenwood heated my house and shop very well. I am hoping for slightly reduced wood consumption next season.

 

[antknee2]

Hi Doug
Just wondering if the loss in efficiency was so gradual that you never imagined that the HX was so coated , or did you know something was up and just needed time ??
By the way great job!!
Anthony

Hi Anthony,

The only way that I new something was up was by monitoring the flue gas temperatures and seeing the accumulation of creosote on the visible portions of the heat exchanger assembly. Even with all of the build-up, the greenwood heated my house and shop very well. I am hoping for slightly reduced wood consumption next season.

Doug just glad you found and cleaned the boiler before a massive back of boiler melt down had taken place . If you could figure a way to burn the beast full out for three or four hours at a time with no high limit shutdowns and store the energy for in between burns , all your creosote problems will be a thing of the past , the boiler will self clean it self , even the back tubes .
Maybe with your heat load and outdoor temperates you already can run the boiler full out , then I don't know what to say .
Anthony

 

[DKerley]

Hi Anthony,

I will be looking at water storage if the boiler protection doesn't work out as well as advertised.

 

[trailhound68]

That my good man is a mess. If your wood is running the moisture content that you indicated, I'd strongly suspect that you need to elevate your return temps somehow. With pine, fir, spruce etc. you have to run a hot fire and I'd suggest keeping your return temp in the 140-150 range via a mix valve or injection mixing setup. What type of heating system are you driving with this boiler?

I would make sure that your plumber understands that the mixing device is for the protection of the boiler by keeping return temps elevated. If you are driving a radiant floor slab or other low temp emitter, you will then need to include something to knock that supply temp down.

Kind of a catch22 situation. The boiler needs to be hot but the floor needs a lower temp than the boiler will tolerate. Ain't it fun though?

 

[trailhound68]

[quote author="heaterman" date="1208286296"]That my good man is a mess. If your wood is running the moisture content that you indicated, I'd strongly suspect that you need to elevate your return temps somehow. With pine, fir, spruce etc. you have to run a hot fire and I'd suggest keeping your return temp in the 140-150 range via a mix valve or injection mixing setup. What type of heating system are you driving with this boiler?

I would make sure that your plumber understands that the mixing device is for the protection of the boiler by keeping return temps elevated. If you are driving a radiant floor slab or other low temp emitter, you will then need to include something to knock that supply temp down.

Heaterman, I think your onto something. I have two radiant floor scenarios. One in particular is a big draw. I was thinking that hot water gets cut on the way in, it should be re-energized on the return with a mixing valve. The cool returns on the radiant reduces the return water considerably.

Anyone else see the gain in the re-mix theory?

 

[heaterman]

It's not a theory. We've had to deal with this in traditional cast iron boilers ever since radiant panel heating was invented. Basically anytime you have a heating load large enough to drag return water down into the <140* range you will get condensation of the flue gas regardless of what fuel is being burned. It doesn't matter if you are burning oil, LP, natural gas, wood, pellets, corn or whatever. The flue gases will condense in that temp range and when you condense you get massive creosote/or sooting along with damage to your boiler and flue. That's why incorporating a mixing valve or circ cutoff to elevate return water temps is so critical. The boiler has to be kept above 140*.

 

[wbush]

Doug has done us a great service in posting this thread.
For those interested, here's a link to "Greenwood Service Bulletin GSB0807.D - Manifold Inspection and Cleaning":

http://www.thiswarmhouse.com/_files/ManifoldInspectionAndCleaningServiceBulletin.pdf

I'm not sure it adds much to what we've learned from Doug, but there's a "Cleanout Kit" that they offer (for sale at 'thiswarmhouse.com' for $195 plus shipping).