CL5036 temperature setting.

[MTJAG]

Just received my CL5036 this past week.  My dealer suggested I set the heat at 185 degrees which I did.  It is still below freezing here at night, but I was thinking that 185 is pretty high.  My house is well insulated and about 2000 sq ft.
I have infloor heat with a 50 plate exchanger and I have a Rinnii (tankless) for my DHW with a 50 plate heat exchanger in from of it.  My Rinnii is set to 115 degrees and I have a mixer value in front of it set at 120 degrees.  The line coming in from the 5036 in the house is reading 178. 
Question:  Looks like I am heating too much and am thinking of dropping the temp on my 5036 down from 185 to 170 degrees.  If I do that, will it kick back on when the temperature drops to 154?  Also, I have been burning only limbs less than 4" in diameter this week and I have a pile of ashes and charcoal about 11" high.  I haven't added anything in the past 24 hours and it is still maintaining the 185.   Should I clean out the ashes or just pull them to the front and add some wood behind them for the time being?
thanks for anything you have to suggest.

[doctorb]

As I have an E-2300, I can't help you reprogram your stove, but I can tell you the discussions on the optimal water set point when heating radiant floor heat have been brought up before.  I have raised this same question, as the cooling dilution factor from obtaining the appropriate temp for radiant heat seems to be counter productive to the high heat levels delivered from the stove.

I think you would be wise to lower the high temp set point.  As the heat your stove is generating is "wasted" as it must then be cooled back down to about 120 degrees for the radiant heat loop.  The real downside is that the temp returning to the stove from your radiant loop is pretty low, and must be raised a bunch.

I think that FF member Holmes has posted his opinions on this, and his reasoning was pretty sound, if my memory serves me correctly.  I might suggest sending him a Personal Message to garner his input.

[Gary_C]

The water temp on your wood stove has been carefully selected to allow it to run at maximum efficiency, minimize fire side condensation of both tars and moisture on cold surfaces, and to avoid boiling water out of the unpressurized water jacket.

If you did anything to make the stove run better it would be to raise the temperature, not lower it. The only disadvantage to high temperatures is your fire can go out with low demand and long times between calls for heat. And you could minimize the fire going out problem by reducing the differential on the controller, but that could cause the stove to short cycle.

So it best left at the setpoint the dealer recommended unless you have some problem.

[doctorb]

Gary_C

But isn't there inefficiency built into the need to lower the temps for radiant heat. I don't think anybody recommends using 180 degree heat in the floor piping.  That temp is brought down by adding cool water into the loop.  This is done by the recirculation feature of the cooler water which is leaving the loop back into the hot water from the basement boiler to reach a temp of about 120 degrees, right?

The water that is not recirculated to the loop goes back to the boiler.  This needs to be reheated to whatever temp the indoor boiler is set.  My question is, wouldn't it be best to operate the OWB at max efficiency, as you have said, but lower the temp requirements on the indoor boilers that the temp gradient from the radiant heat loop and the indoor boiler are not so high?   I am no expert here, so please educate me.

[Gary_C]

There is really no efficiency or BTU"s lost in a heat exchanger in going from a higher temp to a lower one. And any heat "lost" to the environment in an uninsulated heat exchanger is put to good use in the building and the remainder is returned.

But there are many problems created in running a cooler water jacket in an OWB. Idealy you should run the wood stove with the interior surfaces of the fire box at or above the boiling point of water so no condensation can occur on interior surfaces, but those higher temperatures will obviously boil the water on the other side. So the best temp to run the boiler water temp at is the highest possible temp that does not boil the water out of the water side.

So if you lower the water temperature, you will increase corrosion on the fire side and increase the build up of creosote on interior surfaces. And that will reduce efficiency of the woodstove as more heat is lost up the stack.

[MTJAG]

There is really no efficiency or BTU"s lost in a heat exchanger in going from a higher temp to a lower one. And any heat "lost" to the environment in an uninsulated heat exchanger is put to good use in the building and the remainder is returned.

But there are many problems created in running a cooler water jacket in an OWB. Idealy you should run the wood stove with the interior surfaces of the fire box at or above the boiling point of water so no condensation can occur on interior surfaces, but those higher temperatures will obviously boil the water on the other side. So the best temp to run the boiler water temp at is the highest possible temp that does not boil the water out of the water side.

So if you lower the water temperature, you will increase corrosion on the fire side and increase the build up of creosote on interior surfaces. And that will reduce efficiency of the woodstove as more heat is lost up the stack.

I really appreciate the explanation.  Sounds like I need to leave it alone at the dealer set temperature of 185 degrees.  Thanks to all for their input.  These forums are a great source of information.

[pulse]

The water temp on your wood stove has been carefully selected to allow it to run at maximum efficiency, minimize fire side condensation of both tars and moisture on cold surfaces, and to avoid boiling water out of the unpressurized water jacket.

If you did anything to make the stove run better it would be to raise the temperature, not lower it. The only disadvantage to high temperatures is your fire can go out with low demand and long times between calls for heat. And you could minimize the fire going out problem by reducing the differential on the controller, but that could cause the stove to short cycle.




I am sorry but I have to respectfully disagree....

Before I start here I will give my disclaimer. My owb is a hawken. Before I changed anything I contacted hawken directly and was told they have no problem with owners adjusting the water temp set points.

Make sure you check with YOUR manufacture and be sure they don't have a problem with altering the setpoints before you change anything.

Anyway, I have been running a "standard" owb for 4 seasons now. When I say "standard" I mean non gassification. The original set points on my boiler were 150 on and 180 off. The first month or so I left it at that, but I seem to always have to adjust things I own. I wanted to see how lower water temp would heat the house.

To me it is more comfortable to have warm air coming out of the registers for a longer time vs hot air coming out for a short time and cycling more often. What I found was that setpoints of 135 on and 165 off work best for me all the way down to -15. At those set points I have no problem bringing the house up to temp and keeping it there. Note: my house is insulated quite well and the hx in my plenum is oversized by at least 50%.

As far as condensation, I have NEVER seen water form on the inside wall of the fire box (I don't even see how that is posssible during the heating season). As far as excessive creasolt or tar I don't see any more than I did with the higher set points. What I did notice was a decrease in wood consumption. At least 10%-15%, maybe more. I also found my house to be more comfortable. It seems to be a much more steady heat, almost like a radiant heat.

I think the 2 keys to efficency are: 1.Use as low of water temps as possible to heat your house. 2.Keep the set point spread as wide as possible to allow for a longer/hotter fire.       

[martyinmi]

Pulse-
  What do you suppose the "tar" that you are seeing in your firebox might be? In my old boiler, I noticed a bunch more condensation in the form of "tar" when I lowered my set points. More importantly, the creosote in the exhaust started building up so badly that I had to either clean it out weekly(6 inch triple wall) or every so often set my OFF point back up to 185 and hold the flapper open and burn it out. There was a lot more creosote in the burn chamber, which in my mind acts as an insulator to prevent proper heat transfer. My friend's homemade unit is the only one I know of that actually used less wood at a lower temperature, and the only reason for that was that he originally insulated it with only 3.5" Owens Corning wall insulation with duct tape at the seams. After he built a proper surround for it and insulated it properly, he too burnt(burns) less wood by maintaining a higher temperature. We figured that a boiler that is improperly insulated will leak heat disproportionately(more heat/higher percentage of heat loss). Most of the tar or creosote that might form during the idle cycle seem to burn off when it calls for heat when boiler has higher set points. I have seen quite a few CB's and they are insulated pretty well, so I believe heat loss will be much more proportionate as the temperatures are set up, as well as a lot less tar and creosote to act as a thermal insulator in the combustion chamber, which should translate less wood usage in the long haul. 
   I guess on a brand new unit, I would be reluctant to lower the set points unless the dealer was willing to sign something saying that the warranty would still be valid if the set points were not at the proper settings.
   So in a nutshell, I respectfully disagree with you on this subject, but I think you and everyone else who wants to be independent of electricity and fossil fuels are a bunch of ROCK STARS!
   Marty

[pulse]

I only used the word "tar" in responce to the "tar" Gary C talks about. Probably a poor word to use as a description to what I see. I don't have anything that resembles real tar. What I have is a thin black coating over all the metal. That coating was on everything after the first 12 hours of use and has not changed with the lower water temps. In fact I have never seen any owb that didn't have this coating regardless of brand or water temp. If I have a chance I will snap a few pics of my firebox later. I just shut it down and cleaned out the ashes a couple of days ago. 

[MTJAG]

First, thank you all for the comments.  I still have my unit set at 185 F with the drop point down to 174 F.  What have noticed is that I can set my thermostat in my house for 68 F and it will not stay there, but rise to 72 F.  Water from the boiler is coming into the house at 175-178F, so it looks like I will need to mix more cooler water as I have some "phatom heat" going into my radiant floor lines.  Also, the inside of my unit was black after the first burn and is the same now.  It appears to be a thin black film inside.  Though I do have some creosote that has leaked out the bottom of my door on two occasions. 

[Gary_C]

What have noticed is that I can set my thermostat in my house for 68 F and it will not stay there, but rise to 72 F.  

That could be from other causes. One thing could be an inaccurate temperature sensor or controller. You should double check those temperatures with an calibrated temperature sensor.

[upsnake]

As far as the creosote leaking out of the bottom of the door, do you clean the metal around the door seal? I am not sure exactly on the 5036, but on the e classic, the dealer gave me a wonder bar to scrape any build up off the edge of the metal on the firebox opening.

This should help prevent the creosote from not all allowing the door seal to close tight.  8)

[MTJAG]

haven't done it yet, but I will scrape it.  It has only been burning for 6 days now and it leaked the first day and yesterday.  I am buring pinion pine branches which has a lot of pitch in it.

[Gary_C]

After thinking about the temperature overshoot, it's caused by the controller (thermostat) not being able to anticipate the temperature overshoot. I don't know if your thermostat has an adjustable anticipation setting, but that is what you need to look at for the temp overrun. Some of them have different settings for electric, baseboard, or forced air heat. Perhaps one of those other connections would have a greater anticipation setting.

You will not be able to solve that overrun by lowering the temperature of the wood stove.

[JSNH]

Keep the wood near the door.You need enough heat there when it is running to cook off any tar/creasote build up.When it is not cycling enough that gunk can build up and hold the damper open enough to allow air in and the stove to go over temp. My neighbor had that happen. I looked at his stove same as mine but he had a build up onthe inside of the door. He now loads closer to the door and has no issues. They run better with the wood toward the front and not centered.

With a new stove you will check it, poke it and feed it at least 4 times more often than you need to.
3 winter with mine I like it.

[Local4Fitter]

Hi MT, not sure what type of floor your radiant is under. Mine is under 4 inches of concrete and tile. It is not rare when you heat a large mass like that to get an overrun of heat. Temp set at 68, t stat reaches temp and is satisfied, circulator shuts down, but the 4" mass of concrete floor keeps heating. Just my .02

[MTJAG]

My garage is concrete and heats and holds.  But the area I am having difficulty with is upstairs with plywood underlayment over laminated engineered wood flooring.   It is starting to warm up here during the day, so I am going to watch it carefully to see if it is just solar gain from the windows early in the day  as opposed to heat creep in the lines.  I have my thermostat set at 68 and am leaving it there for the near term.  Right now, my wife is leaving the windows up at night to cool down and the temps have been in the high 30's to low 40's.