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How low can you go ( storage temp )

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by stefan66, Jan 1, 2014.

  1. stefan66

    stefan66 Member

    Joined:
    Nov 26, 2010
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    Loc:
    ThunderBay Ontario
    Woke up this morning to minus 40 deg.F.
    Outdoor reset feeding 110 deg.F. to in-floor heat.
    House holding steady at 72 deg.F.
    Anybody getting by with less with the same conditions?
    Think I'm doing pretty good..
    Thoughts?
    hobbyheater likes this.

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  2. Bob Rohr

    Bob Rohr Minister of Fire

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    Nice! Is that the high end of your reset curve? What do you have on the low end, can you run down to 80F?
  3. George Webster

    George Webster New Member

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    Nov 3, 2012
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    I wish I had some radiant. Really not possible to go much below 130 and still get any usable heat. I only have 800 gals of storage, so I need to light a fire every day, except in shoulder season. It has helped a lot with keeping a constant temperature and I'm sure it's far better for the boiler as well. I was using backup oil to cut the cold first thing in the morning also, so with the storage I'm now 100% renewable. Haven't burned a drop of oil in a month.
  4. Tennman

    Tennman Minister of Fire

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    REALLY... 40 below?!?!... Wow.. I'd be happy if my house was +40 at those temps. You must have a really tight house. Congrats.
    hobbyheater likes this.
  5. 91LMS

    91LMS Member

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    first overnight with the new setup. we were -15 last night. 1000 gal. storage temp was 155-160 and woke up to radiant seemed to be kosher with the storage temps at 125 this morning however baseboard is not. i have water circulating constant right now to avoid freeze up, we have been -15 below since my first fire two days ago. need figure some of the bugs out.... at the same time not sure what to expect.
  6. stefan66

    stefan66 Member

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    Nov 26, 2010
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    Loc:
    ThunderBay Ontario

    My reset is set to max out at 110F
    80F is usable when outdoor temp is about 50F
    I use the system in the shoulder season as well.
    Rarely use the woodstove in the house anymore
    6year old house R20 walls R40 ceiling.
  7. stee6043

    stee6043 Minister of Fire

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    West Michigan
    With a forced air HX I prefer stay above 140 on my temps. With "average" winter weather this usually is not a problem. Currently we're having a bit of a cold spell here in MI. I was down in the upper 120's over the holiday break a couple times but was still able to heat. It takes a lot more fan on-time when the temps get that low, unfortunately.
  8. kopeck

    kopeck Minister of Fire

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    Maine
    I have baseboard and 135 is as far as I can push it and on a really cold morning (-10 or better) that's not really enough to do much of anything.

    Once I hit that point the oil boiler kicks on.

    K
  9. henfruit

    henfruit Minister of Fire

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    I have radiant, but with this weather I refill @ 150 so I don't have to play catch up.
    flyingcow likes this.
  10. 91LMS

    91LMS Member

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    how long does your 1000 gallons hold you guys.
  11. henfruit

    henfruit Minister of Fire

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    If the temps come to the 20 to 30s I can get by with two fills a day. Weather like this at 0 a fill and then a few more sticks to hold me over.
  12. JP11

    JP11 Minister of Fire

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    With -10.. I don't think I can get by on two loads. It would be close. A few weeks a year it's that cold. When I'm home, so many activities go thru to the basement. Putting wood in the boiler, and hanging around in my home office is just part of the daly routine.

    I use mine 195 down to about 140. But the fires are more timed like one morning, and one before bed. The size of the burn is the variable.
  13. 91LMS

    91LMS Member

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    i can see with this boiler i am going to have a hard time keeping wood at it to charge the tank. probably get 3 hours of good fire and only hold 30-40 lbs of wood. i have plenty of issues to address where i am only 3 days in with mine. pretty tough weather to start out with, wood stove can keep the pressure off to make sure i get this right. not sure if i am scared or anxious to see storage temp when i get home after 7 hours of no fire and -5 f high temp today.
  14. Nofossil

    Nofossil Moderator Emeritus

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    This weather really highlights the limitations of my storage scheme. I have unpressurized storage with a copper coil HX inside, and I heat with far too few feet of baseboard. Bottom line: at these temps (we're -10 right now and windy) I need water at 170 or so just to break even. It's tough to get the top of storage above 170, and storage at 170 gives me water at 165 at best in the baseboards. Not a recipe for ideal comfort.

    I'm now using the propane on-demand water heater to bring my supply temps up to 180. Storage is helping, but can't do the job by itself. I'll also need around 15 hours of fire per day to provide enough BTUs.
  15. maple1

    maple1 Minister of Fire

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    I had to make a fire on when I got up this morning, earliest fire yet. Storage was down to 140 at top, and I was going to be out for a while. House was still warm though. I have to get my schedule back on track, it got messed up over the holidays, firing too early. Last night my storage was up to 190/170 when I checked around 8pm, so I didn't put any more wood in the fire that was pretty well out at that time. I want to get back to where I make a fire in the afternoon, and do the last loading on the way to bed. I have to fire about 10-12 hours a day during the coldest times - which is pretty well right now. My firebox holds about 3 cu.ft., and I've got 660 gallons of pressurized.

    91LMS, if you can time your firings to your highest heat use, you will improve things. My zones all bump up a couple degrees at & just after the supper hour, and bump back down around 11pm. That's when I'm burning the hardest.
  16. kopeck

    kopeck Minister of Fire

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    This is how my house operates too. 80% of the winter I can get away with visiting my boiler twice a day. That other 20% I might have to go back down and throw and extra few logs on. Today is one of those days. My tank is already down to 150, I'll be starting a fire early and feeding it again before I go to bed.

    K
  17. Fred61

    Fred61 Minister of Fire

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    I think one thing happening today is that usually when it's sub zero the skies are usually clear and yours truly and perhaps several others capture the huge solar gain that goes with the typical weather scenario. Not so today. My zones have called for heat for most of the day. I'm stubborn enough to not want to break the regimen I have been on since I installed storage which is one fire at 4:00 every afternoon. Lit the Eko about 20 minutes ago. Although storage was still 120 the flow through the coil within the tank was only producing 115 degree water to the zones. At this afternoon's temperature, although I'm still maintaining 70 degrees in the house, 115 degree water is as low as I want to go. I've been able to stay comfortable with 100 degree storage temperatures in normal weather in the past.
  18. 91LMS

    91LMS Member

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    well all this info makes me feel much better (why i love this place). i was somewhat discouraged at first and can see that timed firings as apposed to continuous loading with significantly reduce wood consumption. not to mention sub-par wood to boot. house was still 64, so i am starting to fall behind, we'll see what storage temps are when i get home and how long it takes to recharge.... its all new, just need to pick at the bugs one at a time and get out of this wicked cold snap.

    my burn times and output are probably quite a bit lower than what you guys run for boilers. putting radiant in place of where i have baseboard is probably cheaper than a new boiler, lol. it needs such high supply temps its tough for storage to supply such with these outside temps.

    also noticing that my ultra-fin radiant likes hotter water with the higher heat demand during this cold snap
  19. skfire

    skfire Feeling the Heat

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    design temp of 10f, with overnight drops to 0, or so, doing 2 fires a day, morning about half a box(3.6 cubic ft), evening 3/4 box about 5.5 cb ft or so, total about 9 cb ft a day.
    In the morning before the fire up(when 0-10 outside), I usually have tanks down to 108t/100b and house is about 1 degree below average setpoin(7 zones ranging from 67 -70) of 68f, but floors are warm. Intermittent stand by losses and make for DHW are included.

    I heat with mixing vlvs, mixing down to100 and returning 80(at lowest loop temp), and best highest loop temp, mixing down to 125 returning 90. Nice to be able to dump 30f or more into the floors/house.

    SK

    Ps:..today LP truck came and went, no fill up, still at 75% capacity)...they are not happy.
    Last edited: Jan 2, 2014
  20. JP11

    JP11 Minister of Fire

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    I can get a bunch of solar gain.. lots of glass. I'm ok with needing a near constant fire with temps like this. It's rare after all.

    My wife seems to like to keep a fire going, instead of loading the boiler full. For the small increase in power costs to keep the circ and fans running.. I'll shut my mouth happy that we aren't using oil!

    JP
  21. flyingcow

    flyingcow Minister of Fire

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    This weather is a bit extreme. We hit a high of -11f during the day. My innova is maxing out. Keeping the house decent, but not helping the storage out that much. I have BB as the main source of delivery too. In this weather it's rough. But with my oil burner it would be the same.
  22. salecker

    salecker Feeling the Heat

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    Northern Canada
    Thats a fairly common temp up here in the winter.
    At -40 i have to burn about 11 hrs out of 24. Thats burning spruce.
  23. jebatty

    jebatty Minister of Fire

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    Today we have an above 0F respite from the bitter cold of the last several days and the end of the 2nd of two really cold snaps this season, with a 3rd to start tonight and another 5 days when the temp does not get above 0F, with lows in the high -20'sF and low -30'sF. At least we've not seen the -40's and 50'sF (real temp, not wind chill) of a few years ago.

    As to "how low can you go," I can discharge my storage down to about 110F but not going so low in this really cold weather. In my shop my supply to radiant floor is mixed down to 100F, typical 70F return, about 40,000 Btuh to the floor. Floor is now set to 63F constant, 1F differential, up from 61F, and interior air temp is in the high 50'sF. Shop design temp is -30F, and this endless really cold weather is the 1st time I'm not getting by on one long burn every other day. Now burning every day with shorter length burns. I'm pleased with the pine, although frequent re-loadings are necessary, because the pine burns hot, flue temps stay in the low to mid 400'sF, but that also means boiler output stays relatively close to spec output of 140,000 Btuh, probably about 120,000 to 140,000+.

    What do the trees say in -30F? ... crack - split, split - crack, crack - split.
  24. Fred61

    Fred61 Minister of Fire

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    :)

    And many other non human objects do a lot of talking at that temperature. But remember that tree prepared for winter the same as we did. It dumped most of it's internal moisture in order to keep quieter and incur less damage to it's body. Come dirt in March and April it will start to re-hydrate and a lot of the folks around here will steal some of the liquid and make maple syrup.
    sloeffle and flyingcow like this.
  25. stee6043

    stee6043 Minister of Fire

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    I saw -15 on my truck when I left for work this morning. I need about 12 hours of burning to keep up like this. I start my fire at 6pm with a 1/2 load, 2/3+ load at 7:30ish and then cram it full at 10:30pm. So far so good. This schedule would not work with low btu wood, however. I have to avoid grabbing the boxelder for the time being.

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