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I have an indoor, unpressurized wood-fired gasification boiler with 700 gal storage. Transfer to

jacobsoj
jacobsoj Member Posts: 8
storage is via 16' of 1" copper loop(open) with a Taco 00R circ pump and a thermistatic mixing valve @ 162 deg F. Two problems: 1) heat is produced faster than it can be transfered from the boiler resulting in boiler shutdown and 2) due to apparent restiction because of thermo valve(?) liquid builds up in the boiler which can result in overflow of the boiler. Solution to 1) pump which can transfer more gpm ? 2) ??

Comments

  • Zman
    Zman Member Posts: 6,990
    edited February 2015
    Mixing valves intended for domestic systems can have too much resistance for hydronic applications. What type of mixer is it?
    Is this a new problem or has the system never worked correctly?
    Do you have pictures or a piping sketch?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • DZoro
    DZoro Member Posts: 1,048
    Gotta see this! Do you have some pics?
    icesailor
  • Zman
    Zman Member Posts: 6,990
    Dennis said:

    Gotta see this! Do you have some pics?

    If I were the OP, I would be reluctant to post pictures after seeing this.
    He may have designed it and installed it himself.
    The system maybe installed perfectly with just a bad mixer.
    Be nice. Be constructive.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    RobGBobbyBoy
  • DZoro
    DZoro Member Posts: 1,048
    Sorry got taken that way. Gasification with large storage to me is a great start. Should make it a very clean constant long burn. 162 deg. is a good thing too. Yes so far it sounds like low flow, for the storage amount.
  • Zman
    Zman Member Posts: 6,990
    Dennis, I agree the system has a great start.
    Hopefully there is just a little glitch to be worked out...
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • hot_rod
    hot_rod Member Posts: 15,033
    edited February 2015
    You may be a few hundred feet short of enough HX, if the boiler is trying to transfer into the tank via that coil.

    A typical HX for that application is 3 sixty foot loops of 1/2" copper, or more header into a 1-1/4 manifold.

    Tom up in Maine builds tanks and HX, like this.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • jacobsoj
    jacobsoj Member Posts: 8
    Zman said:

    Dennis, I agree the system has a great start.
    Hopefully there is just a little glitch to be worked out...

    jacobsoj said:

    storage is via 16' of 1" copper loop(open) with a Taco 00R circ pump and a thermistatic mixing valve @ 162 deg F. Two problems: 1) heat is produced faster than it can be transfered from the boiler resulting in boiler shutdown and 2) due to apparent restiction because of thermo valve(?) liquid builds up in the boiler which can result in overflow of the boiler. Solution to 1) pump which can transfer more gpm ? 2) ??

  • jacobsoj
    jacobsoj Member Posts: 8
    hot rod- no copper HX; the 16' of copper is an open loop with the copper pipe inlet 1' below the top of the h20 in storage and the outlet 1' above the bottom of the h2o in storage. Tank liner is from Tom in Maine.
  • jacobsoj
    jacobsoj Member Posts: 8
    Dennis said:

    Sorry got taken that way. Gasification with large storage to me is a great start. Should make it a very clean constant long burn. 162 deg. is a good thing too. Yes so far it sounds like low flow, for the storage amount.

    Taco 00R flow is about 12 gpm(high speed); looking for a variable
    speed pump which will ramp up as temp increases to maintain a max temp of about 180 deg F; don't want boiler to "idle" due to overheating. Type of pump/control to do this??
  • hot_rod
    hot_rod Member Posts: 15,033
    The challenge with wood heating is matching the load to the burn.
    Once the tank is at or near temperature the heat transfer slows the delta t closes. At that point you need to dump excess, or put out the fire :)

    If the tank and storage are both open it will be tricky to keep then levels consistent.

    Perhaps a drawing would help. Is the boiler and tank at the same water level?

    There are delta t pumps that ramp up and down based on temperature, but at high speed it would still over flow the tank or boiler, possibly?

    You could still maintain an open boiler with a HX coil in the tank.

    How do you remove heat from the tank?
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • DZoro
    DZoro Member Posts: 1,048
    again sorry I miss read original post last line as saying you have gpm 2. my bad. Again pic would be nice. what are the dimensions of storage tank and correlation of supply and return? What is your piping schematic? What are your tank temps, top, middle, bottom. Is tank tall, horizontal....What size firebox?
  • Zman
    Zman Member Posts: 6,990
    This thing should work.
    Pictures would really help.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • jacobsoj
    jacobsoj Member Posts: 8
    set-up: return to the boiler located at lowest pt from boiler,1" Cu piping thruout,pipe elbows down towards floor goes into a Taco 00R circ pump(pumps towards the boiler), pipe continues down to floor then is elbowed back up where it is elbowed to run horizontally and goes into a 1 1/2" LK Armatur thermostatic mixing valve(opens at 162 deg F); two other inlets to the mixing valve are1) from the bottom of the storage tank and 2) the outlet of the boiler(at the top of the boiler); the pipe from the boiler outlet to the mixing valve has a T installed which transfers hot water to the top of the storage tank; between this T and the mixing valve is a 1" ball valve. The storage tank is unpressurized 4'x4'x5' ht. Boiler is unpress. w/a 16"Wx24"Hx24"D firebox. Piping in and out of the storage tank are not connected in the tank. The boiler has about 40 gal of water. The static water level is the same in the boiler and the storage tank. It rises in the boiler when the pump runs during fire. Heat is removed from storage via a FPHE; which is the link between the unpress boiler side and the press house delivery side. THE PROBLEM: heat is not transfered quickly enough from the boiler to the storage tank once the boiler temps approach 170 deg F, regardless of the storage tank temp. At this point the boiler shuts down and goes into an idle mode,which I would like to avoid. Suggestions?? I know, pics would be nice.
  • Zman
    Zman Member Posts: 6,990
    edited February 2015
    The boiler has a anti condensing loop using the mixing valve. Is the circulator within this loop or outside it?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • jacobsoj
    jacobsoj Member Posts: 8

  • jacobsoj
    jacobsoj Member Posts: 8
    What is an anti condensing loop? Pic, if visisble, should be turned 90 degrees.
  • Zman
    Zman Member Posts: 6,990
    What model is the mixing valve?
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • Zman
    Zman Member Posts: 6,990
    It sure looks like you have this right.http://woodboilers.com/media/wysiwyg/Downloads/Product_Manuals/LK820MountingInstructions.pdf
    The ball valve should be open.
    Any chance some air is trapped?
    Could be a chunk of solder stuck in the valve.
    Check for air then take apart the valve.
    Has it ever worked?
    Carl
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • DZoro
    DZoro Member Posts: 1,048
    Does the return temp always stay at 162?
    170 outlet temp is only a 8 degree delta. Not much room there.
    How long does it take to go from 162 to 180?
    Does it start to boil at that time? or temp rise extremely fast?
    How long a burn does it take for all this to happen?
    Can you see water flow at tank?
  • SWEI
    SWEI Member Posts: 7,356
    It does look like an LK820, which requires a bypass. If you want to get rid of the bypass, you could replace it with an 823 (which we stock.) Which cartridge is in it?
  • Weezbo
    Weezbo Member Posts: 6,232
    edited March 2015
    Hello jacobsoj, ahoj , siza ... i would like to know if you have a way to move the T on the hot so it goes out the back of the boiler on a horizontal then down to the mixer . the reason i suggest that is if you have entrained air from the burn it has a chance to continue to roll straight out to the tank,...
    i see the check on the line and i think you have the right idea about water migrating back from the tank into the boiler , i have been looking at the boiler and i wonder if it has some fan that adds air to increase the burn or if you have some chain connected to a door that rises and falls to control burn.

    this interests me so if you read this would you have any record of how long the burn cycles are and maybe what amount of load you are using for your "Best burn" to date?
    like do you burn 10 4 " pieces 19 " long or seasoned lumber birch ?pine? a guy i know chops up crates throws them in the boiler shovels out the nails... another uses split stacked to dry two year seasoned birch... another throws lumber in and some kitchen grease from what i have seen each has some idea of the right amount of fuel for a burn that works for them.
    The other thing is is the mixer a limiter upward or downward level mix if it is down ward would you be better to use a mix that allowed flow at 140F rather than 160?

    sorry to ask so many things i just trying to get an idea how to help.
    Weezbo.

    Swei , does it require a by-pass from the boiler discharge to the return near or at the tank to mix the return temp up faster when it does start circulating from the boiler to the tank?
    As usual i am wondering about how we could have a paint program even in : blue, red, purple and black right here ... that we could draw things for people . right now i am wondering if the burn is regulated by water temp and if the 162 F is shutting down the burn to slow down the train while the pedal is on the gas and breaks at the same time.
  • SWEI
    SWEI Member Posts: 7,356
    edited March 2015
    Weezbo said:

    does it require a by-pass from the boiler discharge to the return near or at the tank to mix the return temp up faster when it does start circulating from the boiler to the tank?

    The LK820 regulates on one port only, which necessitates the bypass. The LK823 is a newer design that regulates on two ports, thus obviating the need for a bypass (and the inherent risk of some clueless owner or repair person opening or closing said valve completely at some point in the future.) Interestingly, the 823 actually costs less than an equivalently-sized 820.