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[ambonci]

I have a few questions about setting the temp on the OWB.  The first two years I've lived in my current home and used my OWB my temp was always set at 180 using the factory thermos disc.  last year after I reinsulated it and hooked up the ranco I ran at 170 with a differential of 7.  Burned great all year(80% oak and maple).  This year I added some insulation used on nuclear power plants thinking it will be even better. They claim 2000 degrees on one side and u can touch the insulation with your hand and not feel any heat.  Anyway, this year I set my aqua stat at 190 with a differential of 5(mix of cherry, beach, soft maple, not really seasoned 100%).  I don't really see much a difference running 190.  May I add I also swapped from a gundfos 15-58 running on medium to a 26-99 running on medium.  This year has been very mild and it seems like I'm during more wood.  I don't believe its the insulation because I still using the same insulation as last year just added to it.  So my question is, is it because I'm running 190 and the differential is only at 5 or am I circulating water to fast?  I am around 50 feet away so a total of 100 feet loop.  Sorry for the long winded stuff but you guys are great on here and thought id give as much info as I could.  Thanks.

[mlappin]

I always ran at 180 on my old boiler, tried running at 190 a few times and it seemed like it took a lot more wood to keep the water ten degrees warmer than “normal”. But, last time I tried that was before I replaced my old underground line with Logstor.

[RSI]

If you don't need the higher temp, you could turn it back down and see if you notice any difference. If you have the pump pulling water out of the top port, I wouldn't run it that hot.

Were you having excessive delta t with the 15-58 pump? It should have been big enough if you don't have a lot of fittings and restrictive heat exchangers. The speeds on the 15-58 and 26-99 are spaced fairly even so with the new pump, it is like gaining speed 4,5 and 6. Low speed on the 26-99 will pump more than the 15-58 on high.

It could be a circulation issue. With the lower flow, a good portion of the boiler may have been running at a lower temp which could have resulted in less heat loss in certain parts of the boiler. Normally it is the other way around but could vary depending on heat load and wood quality.

Do you notice if the stove is hotter around the door and bottom?

[slimjim]

The hotter the water, the higher the stack temp losses will be on a conventional unit.
As Marty said, underground heat losses with poor quality pipe  could also be an issue, look at it this way, the hotter the boiler water and colder the ground water, the more heat will transfer into the ground water because the differential is higher.

[ambonci]

The reason I went for a bigger pump and higher temps was I have a hard time getting my house above 72 when its near 0 or with a windchill below 0.  I was thinking the higher water temps would give me more available btus inside.  I have a fairly big plate exchanger(50 plate for heat and a 30 plate for DHW).  My thought was the 15-58 couldn't give the plate exchanger enough flow for it to work to its full potential.  We have yet to have those days this winter so I can see if it helped my problem.  From past experience I don't think its gonna help. 

RSI- I switched my pump to feed off the bottom for my house loop and my garage loop is feeding off the top.  I had cavitation issues earlier this year with both on top.  since switching pump has had no issues.  May I ask what excessive delta T is? 

I think my issue with house heat it the lack of baseboard heaters inside my house.  my house is only 1600 sq ft.  so that big plate exchanger should heat this place fairly well I believe.  Slim I wish you where closer to NY because Id love to have you redo my whole system because I don't think its hooked up that well.  I am going to turn temp down to 180 today(we have a cold front coming through) and see what happens.  What abut the temp differential?  leave at 5 or go more?  Thanks again.

[agriffinjd]

I do 190 set point with a 12 degree differential.  Second season with my boiler and it's running better than ever. 

[ambonci]

Correct me if I'm wrong but I think having my differential at 5, the blower kicks on a lot more often and then burns more wood.  am I way out to lunch with that thinking?  I think I am gonna play around with settings this week to find out.  Agriffin, is your boiler a conventional or a gasser?  Wonder if that makes a difference because they burn different.

[tinfoilhat2020]

Natural draft units should have a smaller differential as they take a while to get a fire rolling after the damper opens....forced draft units can have a bigger differential bc they recover much faster....I personally don't like differentials any bigger than 20°...too much expansion and contraction on the steel IMO

[shepherd boy]

The biggest difference I see in shorter burn differentials is in creosote build up. The fire never gets hot enough to burn it out. Higher burn temps  using more fuel is almost always linked to conversion of heat to water inside the furnace. Your fire needs to work harder to keep the higher temps. With enough heat extraction in the exhaust this is kept to a minimum.Stoves with a chimney straight out the firebox are less efficient with heavier heat draw. More heat goes out the stack. More heat conversion inside your house has got to help. More baseboard or splice in a cast iron radiator will give a big lift.

[ambonci]

The biggest difference I see in shorter burn differentials is in creosote build up. The fire never gets hot enough to burn it out. Higher burn temps  using more fuel is almost always linked to conversion of heat to water inside the furnace. Your fire needs to work harder to keep the higher temps. With enough heat extraction in the exhaust this is kept to a minimum.Stoves with a chimney straight out the firebox are less efficient with heavier heat draw. More heat goes out the stack. More heat conversion inside your house has got to help. More baseboard or splice in a cast iron radiator will give a big lift.

great post.  I read it 3 times but I understand what you posted.  thanks.  I was thinking about needing more baseboard but now I'm convinced.  sounds like a new summer project.

[ambonci]

so I turned temp down to 180 and differential to 8 gonna leave that way till Wednesday then try different differential and see where the sweet spot is till I can add more baseboard.

[agriffinjd]

Correct me if I'm wrong but I think having my differential at 5, the blower kicks on a lot more often and then burns more wood.  am I way out to lunch with that thinking?  I think I am gonna play around with settings this week to find out.  Agriffin, is your boiler a conventional or a gasser?  Wonder if that makes a difference because they burn different.

Mine is a conventional stove, but it does have some firebrick and one zig-zag the smoke goes through before going out the chimney.  When it's firing well, only hot air comes out the chimney meaning better efficiency.  I never had those good burns with a differential set at 5.  My stove is forced air with air coming up from the bottom and across from front to back from under the loading door.

[kybaseball]

I go with 180 with a 10 difference. My stove usually shots over 2 degrees so it gets to 182. I have tried several different settings and this works best with my stove and burn times.

[Sloppy_Snood]

What kind of burn times are you achieving with your 190 degrees F and 12 degrees F temperature differential a griffins? 

[ambonci]

Agriffin, mine is almost like that except I don't have fire brick and my chimney comes down into firebox.  Good ol shaver.  I want to cut that sucker off but don't know what the side effects would be.  I barely ever have just clear air coming out of chimney.  Before I posted this topic I thought it was stupid of me but ive learned quite a bit so far.