Greenwood 100

[djblech]

How is everyone else running there greenwood type furnaces, open system or closed. Greenwood sent me a large tank to mount on top of my furnace that I am not using because I am running a closed system. I was told, and it made sense to me, that a closed system was better.

djblech
greenwood 100

 

[lancegillette]

I've got an open system. I bought the tank. Did Greenwood include your's with the boiler? My system is closed and I have a heat exchanger. So the Greenwood has its own supply of glycol and the house loop has a separate supply of glycol.

 

[djblech]

I have about 75 ft of pex from my garage to my utility room in my basement. This loop is to a water to water heat ex and is filled with glycol. (even though I don't think it would freeze, its 5' in the ground.) I just teed my gas boiler and ran about a 10 ft loop through the htex. Greenwood sold me an installation kit that included the open system tank, brackets and piping, which I am not using. I bought the furnace on july 3 and did not get my installation kits untill the middle of Dec. I wasn't very happy about the wait. I think I got the last furnace from last year, I had to change all the piping on the back and top. Its working pretty good now, but still can't keep up when its really cold unless I stoke every 4-6 hrs.

djblech
greenwood 100

 

[lancegillette]

We recently had an extended period of -25 to -41 temps at our house (more than two weeks). I found that I had to adjust the aquastat from the recommended 165-180, to 180-190. Otherwise house temperature would not go above 66-67. When it was -30 to -35 I was getting about 6 hours of burn time with the house thermostats set to 72. When I lowered the thermostats to 70 I got 8 hours burn time.

 

[JMann]

Closed system, running into 30 plate HX. From there it connects to the loop that my existing oil furnace uses. I can either run both, using the oil as backup heat if the temp drops too low, or flip a switch and use only the Seton to heat the house and DHW. Seton is approx 100' from house in what was formally my garage. Very pleased with the results.

 

[91220da]

I am running an open system, I wanted the fluid management kit (tank for on Top) but they (Greenwood) would not sell it to me back in Sept. Oct. If your tank is galvanized it can react with glycol causing the tank to deteriorate and leak or block heat exchangers. . I ended up making my own version of the tank and it works fine. I am currently in communication with Greenwood about my warranty being affected by not using there tank. I am hopeful they will honor the warranty since they did not have a tank for me to use at the time. It is like they sold me a brand new car without a transmission. I am also about 75 feet from the house running through a 30 plate exchanger. Glycol in the greenwood loop and water in the house boiler side. So far very pleased with the performance and operation. Have used alot more wood the last 3 weeks but then again it has been -6 to 15 degrees lately.

 

[lancegillette]

I'm pretty sure my tank is ungalvanized.

So you are using a 30 plate exchanger. I guess that enables you to have 120,000 BTU output instead of just 100,000. This is the information I got through the grapevine from Greenwood about running your 100 model at 120,00 BTU.

"Operating the model 100 at 120,000 is not impossible but it is also not
recommended. In order to do this the furnace will need to be loaded
freqently with very high quality wood at the ideal moisture content
(19-25%). A typical MAXIMUM burn cycle will start at 85,000 BTU/hr and
will peak a 134,000 BTU/hr and trail off to 55,000-60,000 BTU/hr during
the charcoal-burn phase. The damper will NEVER close. In order to stay
at 120,000 BTU/hr, fuel must be loaded at least every hour to maintain a
constant output."

 

[91220da]

I was advised, and decided to go with the 30 plate as a little overkill for the open system, glycol, and exchanger reduction you normally experience. Like a lot of greenwood posts I too have turned up my aquastat. Damper opens around 170 and closes about 185 with the heat retention kit shutting it down at 200. The damper cycles open and closed in what seems to be a normal fashion. The house is a comfortable 69-71 when the unit is up and running strong. My oil furnace contoller kicks in when my supply drops to 138. Oil boiler usually runs 1 cycle in the am at the end of a 7 hour burn (10 pm to 5 am). I just installed a hood and exhaust fan over the door last weekend. Really helps with the smoke issue while loading. I did not want to do it, but I figure the long term effect (hopefully 20 years) of inhaling smoke while loading could not be good. I can post some pictures if anyone shows and interest. This whole alternative heating thing can be frustrating to figure out, but what the heck else are you going to do when it is 5 degrees outside. Oh yeah, I quess you could always sit by the window waiting for the oil truck to arrive.

 

[djblech]

I would like to see how you did the hood and exhaust fan. My furnace is in my 24x72 garage/shop. It really gets smoky in there if I don't wait for the damper to open to stoke wood. I have my gas furnace set down to 140*. It rarely kicks in. When it does, it back heats the the glycol in the greenwood through the hx. I don't think this is a problem just a waste of heat. I think I have a 20 plate hx. It was rated for 100,000 btu. I started cutting trees for next year yesterday. Dropped about 12 large birch cut up about 3.

djblech
greenwood 100
Vermont Castings Dutchwest
Stihl 360 and 170

 

[91220da]

I have the same issue with the oil furnace back heating the glycol. I have not quite brainstormed a method to prevent this. It does bother me that I am using some extra oil during that fireing but then again it helps to keep the return temp above 135 as Greenwood recomends. I will take some pictures of my exhaust hood, and try to post them this weekend.

 

[lancegillette]

I also have the same problem of my oil boiler pumping hot water to my Greenwood when the Greenwood is out of fuel. My transfer pump that circulates from the Greenwood to the oil boiler is controlled by a differential thermostat. It only runs when there is a temperature differential between the Greenwood and the Oil Boiler of 8 degrees or greater. So if the Oil Boiler is 8 degrees or more colder, then the transfer pump turns on. It is turns off when the return temperature is lower than about 150 degrees (controlled by a separate aquastat).

But at my Oil boiler there is a taco 007 zone pump that manages to circulate to all my zones as well as back to the Greenwood. My transfer pump at the Greenwood is a Taco 007 with IFC (integral flow check) and the cracking pressure of the built in check valve is .5 psi. It slows down the circulation a bit but does not stop it. So next summer I'm going to put in a zone valve as well so that when the transfer pump is off the zone valve is closed. That will stop undesired circulation to the Greenwood when it is out of fuel and the oil boiler is supplying heat to the house zones.

 

[91220da]

I read your post several times and think I have a good picture in my mind of what you are doing. It sounds as if you are planning a bypass loop that will be controled by the additional zone valve. Do you have, or could you post any plumbing schematics of your system. No problem if you can't, It is just neat to be able to discuss each others set up and think collectively about the same issues.