At what temp do you run your OWB?

Dave Shepard · November 25, 2014, 06:31:01 PM

My Central 6048 was set at 185, which is the factory setting for my boiler. It has a range of I think 150 to 195. It has no problem maintaining that temp, but sometimes I can hear what sounds like violent boiling going on, almost to the point that it sounds like there is someone in there with a mallet banging on the inside of the boiler with a mallet. :D It never boils over, and hasn't required any make-up water. I was wondering if running at a lower temp would eliminate the boiling? What are the pros and cons of various water temps? Thanks.

DR Buck · November 25, 2014, 07:05:52 PM

Do you have a temperature gauge on your line? If yes, what is the actual water temp? If not, maybe you should add one. The temp display on the OWB should be pretty accurate though. I've never boiled mine that I am aware of. I'm heating ~3800 sq ft through a water to air heat exchanger in the heat pump plenum.

My 6048 temp is set for 192º. That's when the damper closes. It reopens at 182º. If my fire burns down at 152º my propane backup kick on and runs it back up to 192º I don't remember, but I think you can program the range between open and close points to be something different. I set mine up 5 years ago and haven't messed with it. I can check the owners manual if you like to know.

Dave Shepard · November 25, 2014, 07:10:09 PM

I only have the temp on the boiler, nothing in the house. The temp gauge on my oil boiler isn't working very well, but only says 130 at the highest. I have a little infrared thermometer, and the highest I see in at the heat exchanger is about 150. Open and close on the 6048 are always 10 degrees apart.

Gearbox · November 25, 2014, 08:28:01 PM

I have a Crown Royal and if I set the temp at 190 it will start making what I call a chunking noise . That is the water in the cross tubes starting to boil . This only happens in the last few degrees befor the high temp is reached . Hope this helps you . Gearbox

DR Buck · November 25, 2014, 08:31:53 PM

Quote from: Gearbox on November 25, 2014, 08:28:01 PM
I have a Crown Royal and if I set the temp at 190 it will start making what I call a chunking noise . That is the water in the cross tubes starting to boil . This only happens in the last few degrees befor the high temp is reached . Hope this helps you . Gearbox

The Central Boiler units don't have any tubes in the heating chamber. Just a large reservoir with angled bottoms to provide more surface area to heat the water.

bandmiller2 · November 25, 2014, 08:35:32 PM

My water temp seldom goes over 140 , OWB runs constantly no cycling on and off, hydronic baseboard in the house. The boiler is a water tube of my own build, and has worked well for 12 years or so. Boilers that run intermittently should run at a higher temp. Frank C.

thecfarm · November 25, 2014, 08:38:28 PM

About 175-185.

whitepine2 · November 25, 2014, 08:38:54 PM

I"v got a P&M run it at 180 but kick it up to 190 in the dead of winter

whitepine2 · November 25, 2014, 08:40:52 PM

I"v got a P&M run it at 180 but kick it up to 190 in the dead of winter

ohiowoodchuck · November 25, 2014, 09:33:19 PM

Ridgewood 7500 here. Damper open at 170 and close at 180. I'm thinking of turning it down to 160 open and 170 close.

ohiowoodchuck · November 25, 2014, 09:33:43 PM

Ridgewood 7500 here. Damper open at 170 and close at 180. I'm thinking of turning it down to 160 open and 170 close.

Ivan49 · November 25, 2014, 09:53:16 PM

I have a wood master the water temp is set at 150 on and 160 off. When the temps drop down to -10 or below I turn it up to 170 or 175

hoardac · November 25, 2014, 11:41:59 PM

180 you really do not want your return water temps below 150 due to moisture in the firebox leading to corrosion. That is how I understand it anyways.

beenthere · November 26, 2014, 12:19:44 AM

hoardac
I don't understand that, and have normal 100° to 170° range in temperature of water in my boiler unit.

It is not an OWB, but rather has been inside and operating every year since 1980. So this is the 35th year and no corrosion (although it is a closed system).

Maybe someone else does understand why 150° return water leads to corrosion. My damper closes at 170° and opens when water temps get slightly below that. No draft blower, just damper open. The rest depends on water circulation temps and amount of wood in the firebox.
Maybe due to being an open system?

stratton · November 26, 2014, 03:36:13 AM

Beenthere, I to have an indoor closed system. Just curious as to the make size btu specs your running. 35 yrs is close to century is it not ???? ha ha Please share your insight and experience. Luke

DeerMeadowFarm · November 26, 2014, 08:14:50 AM

My CB is factory set at 185. I have seen the water temp as low as 170-ish+ before it fired back up and as high as 190. This is from the temp probe in the house 100' away from the OWB

beenthere · November 26, 2014, 10:12:45 AM

Luke
My boiler isn't made any more, and it is a simple "barrel within a barrel" design with a 9 gal. water jacket.

Pictured and described some in this older thread. Off and on, other threads include more or less about the system if interested in a bit of searching and reading.
indoor wood boiler

Dave Shepard · November 26, 2014, 10:41:19 AM

My water jacket holds 393 gallons. :D

beenthere · November 26, 2014, 11:21:48 AM

:D :D :D

WmFritz · November 26, 2014, 12:14:42 PM

Quote from: beenthere on November 26, 2014, 12:19:44 AM

It is not an OWB, but rather has been inside and operating every year since 1980. So this is the 35th year and no corrosion (although it is a closed system).

Maybe someone else does understand why 150° return water leads to corrosion.

beenthere,
A boiler that is still 'alive' after 35 years is amazing. I think a lot of folks are tickled to have one last 15-20 years. I would blame the longevity of your unit on; a good installation (i.e. no fitting leaks means no make-up water being added regularly), a quality boiler and even though you may not have low temperature protection, I'm guessing you probabably stay above 140° on the return side by having a low delta T.

Everything I learned is 140° the return temperature boiler manufacturers recommend staying above. Below 140°, the firebox is prone to sweat or condensation on the inside, causing corrosion issues.

Maybe if your boiler wasn't built so tough, they may have in stayed in business.

No repeat customers. :D

doctorb · November 26, 2014, 12:19:12 PM

My CB e-2300 is set between 185-195 degrees. I need the higher OWB water temp to maintain at least 180 degrees in the indoor furnace. This is due to the 300' run from my OWB to my basement. My heat loss is about 5 degrees in both directions. My installer/plumber suggests 180 degrees for my hot water baseboard system.

beenthere · November 26, 2014, 01:05:28 PM

bill

QuoteI'm guessing you probabably stay above 140° on the return side by having a low delta T.

I'd just say it stays above 100°, with an average 130-140.

I find we have much more even heat when the high water temps are not available.
That knowledge/experience comes from the times I am not burning wood but have the propane boiler running which keeps water temps around 180°. Pumps kick on when a thermostat on one of three loops calls for heat, hot water is pumped through the baseboard radiators, and the room heats up quick. By the time the thermostat says "warm enough" as set temp is reached, the swing in room temp is noticeably greater than when 100 - 140 deg water is distributed as no noticeable swing in temp is noted.

So, I'm not a fan of high temp hot water being distributed through my heat runs. These heat runs were installed when I built the home in 1968, about 46+ years now. I did have a very slow leak in one of the runs for the downstairs rec room area, I believe caused by movement in the 40' straight run along an exposed wall where the supply and return lines dropped down under the slab. But when adding a room on in 2001 we changed an entry door and dug up that corner of the concrete slab, exposing that leak so could fix it. System hasn't leaked a drop since, that I recall.

My day may be coming when the system rusts through, and I truly do not look forward to it happening.

gspren · November 26, 2014, 01:37:55 PM

I remember reading that 140 is the temp that you need to go over to cook the oxygen out of the water which then inhibits corrosion.

beenthere · November 26, 2014, 01:44:13 PM

Right, but this is in a closed system, and any fresh water that is added (I do it manually, not auto) is "cooked" right away at 170° so oxygen is not a problem at any temp below that 170°.

The last time that I added water was when the system was shut down to repair the copper pipe under the concrete slab. That was Oct. 2001.

Firewoodjoe · November 26, 2014, 07:21:01 PM

I turn mine down from 180 to 170 last year. 160-170 kick on kick off. Interesting on the 140 to cook oxygen out. Never heard that. My stove is a $500 home made one I never intended to use. The builder said it was junk. I bought it for the eccessories. But figured I'd hook it up just to see. Been running four years and I abuse it. Don't clean it, burn everything that's not running away and the 2" fill spout is wide open to the air. Though I have had to weld the door hinges. But I feel that's becasue he built the door on to the water jacket. 3'x3' water filled door is way to heavy to hang on your jacket. Should have been hung on the firebox. With all that being said I think the only reason stoves rust is operator mistakes and sitting stagnant all summer. Rust from the firebox in. And round the chimney when they exit the top. When my new one is done it will run year round.