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Two indirect water heaters

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by mikefrommaine, Jul 1, 2012.

  1. My 5 year old indirect started leaking (a lot) Enough so that the aquastat got rusty and stopped working. I had a spare boilermate that I had picked up a few years ago for $75 but I got tired of looking at it so I sold it last year on CL for $450! Apparently a lot of people have leaking indirects and these things sell quickly. I spent six months looking for a good deal on a replacement and eventually found two Triangle Tube TR120's for $200. So this whole project didn't cost too much.

    I hooked them up today as there was way too much leaking out of my existing water heater. I have one set up as a pre heater -- might eventually add solar. The other one replaced the existing heater.

    Between the two DHW inner tanks I have a recirculating pump. This way when I do solar if the pre heat tank gets above say 150 I can have the pump come on and heat the primary tank. Until then I will manually turn that pump on whenever the woodboiler is running and I have extra btu's available.

    Attached Files:

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  2. Bob Rohr

    Bob Rohr Minister of Fire

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    How is the primary tank heated? in other words what is your source of DHW now, is it just supplied by wood fired? If the primary tank is always maintained at 120- 140F you will not be able to shuttle much heat from the solar assisted tank.

    When you do add the solar, consider a 3 way motorized valve between the tanks. Pull the DHW from the solar tank first, which may supply 100% of your DHW in the summer months, then only fire the primary tank as needed. This will assure the solar runs at it's highest efficiency, and possibly drop the primary tank, and the shuttle pump off line completely.

    hr
  3. The primary tank is heated by either the oil or wood boiler. If the wood boiler is up to temp the oil boiler is automatically shut off, though all winter I had the burner turned off so I wouldn't burn any oil. Which was ok but I often found that we ran out of hot water before the house cooled off enough to really need the wood boiler running.

    50 gallons of hot water lasted us about 24-36 hours. I'm not sure what the standby losses will be but I'm hoping I can use the wood boiler to get all 240 gallons of DHW up to 180 degrees and go 4 days between fires and not have to burn any oil during the summer.

    My next project will be to add 1000 gallons of boiler storage so solar might be a ways off if ever. I just missed out and free collectors on CL...
  4. Bob Rohr

    Bob Rohr Minister of Fire

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    I'm running with a instant DHW system now. With 80 gfallons of solar storage a 30 plate HX gives me 2- 2.5 gpm of hot water. Now I don't need to store solar/ wood , and DHW in a separate tank.

    When you end up with that much storage the external DHW production could be a real work horse. With 1000 gallons of wood storage you might run a month between fires!
  5. BoilerMan

    BoilerMan Minister of Fire

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    Glad to see you figured out what to do with those TR120s Mike. $200!!!!!!!????? Wow good thing I didn't see them on CL before you :p

    Funny thing, I was in a basement today removing a "Top Performer" identical to yours in an apartment building, the place even has a Pierless boiler (which it looks like you have too) Replaced it with a 40gal electric though :confused: Landlords like electric, make the tennant PAY!

    Taylor
  6. For 200 I couldn't pass them up, a little overkill for my needs though. They used to supply all the DHW for a local YMCA. They were taken out of service during an expansion. I was a little worried when water started bubbling up through the spray foam insulation. Turned out the aquastat well fitting needed to be tightened up a little.

    I bought this house as a fixer after a DIY type tried to build a house. The "top performer" was paired with Weil-Mclain propane boiler that seemed to run all the time and never really keep up. I replaced the whole heating system when I put on a 30x50 addition but re-used the indirect. The water here is aggressive or the original plumber used the cheapest money could buy --- I just had to replace the well's expansion tank too.
  7. infinitymike

    infinitymike Minister of Fire

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    So the pre heat tank isn't supplied with any hot water right now? Just the primary is fed by wood or oil?

    I have 2 indirect tanks that need to be hooked up as well. I was thinking I would heat the first one with wood or oil and that would then flow into the second one which is where I would pull off of. Would that work?
  8. maple1

    maple1 Minister of Fire

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    If you mean the heat source only going to the first tank, I don't think that's a good idea. If you don't use any DHW for a while (like away for a weekend), the second tank would cool off, and you'd have to run the water a while before you got hot out of the tap again.

    I think.
  9. BoilerMan

    BoilerMan Minister of Fire

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    Yes you are right m1. If you wanted a lot of hot water you could pipe the two heat coils in series supply to the second tank (the one you draw off) then to the frist tank then back to the boiler(s). 240gal of well insulated DHW should last quite awhile, and be a good load to heat up to 175 or so with your BMW. I'd do it.

    Taylor
  10. infinitymike

    infinitymike Minister of Fire

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    So I should have each tank supplied from my primary loop as an individual zone, then take the two lines that would supply the house and join them together, so the house demand would be pulling from each tank simultaneously. The cold street water supply should be split and enter each tank.
  11. That would be a 'paralell' setup. If you did it in series like Taylor suggested you wouldn't have the expense of second pump and controls.

    Mine is setup so well water enters the first tank which currently has no heat source. It then goes into the second tank which is heated by the boiler. Eventually I will add solar panels to heat the first tank. Which is why I plumbed in a pump between the two Dhw tanks. It will allow me to even out the temp between the two tanks. When there is adequate sunshine I'll be able to get both tanks hot. If it is marginally sunny then I will be pre heating the water that goes into the tank which is heated by the boilers.
    ewdudley likes this.

  12. As a test I just went 72 hours with the boiler off. Wanted to see how long we could go with 1 tank of hot water. Started with the primary tank at 155. This morning it was down to 110 which was hot enough for showers. So if I heat up both tanks to 175 I should be able to go 5 days between firings.

    Only problem I see is the wod boiler may idle to much as I only used 3/4" pipe to plumb the zone. Once I add boiler storage it shouldn't be a problem. I've only used the oil burner to heat the tank so far.
  13. maple1

    maple1 Minister of Fire

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    That's what I'd try first. One boiler loop - through tank 2 then tank 1 then back to boiler. One DHW loop - through tank 1 then tank 2 then to the taps.

    I started out looking for indirect tanks but couldn't find any, around here at least, that had electric elements in them for backup for when the wood goes out for a while. So now I've gotten a sidearm & am waiting for an electric tank sale to get my last major system component.
  14. BoilerMan

    BoilerMan Minister of Fire

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    You might be ok with the 3/4" if you do the series piping, but I havn't done the numbers. You'd get a HUGE deltaT heating all that water from cold. The first tank (well water into) will be around 55 by the time the second (draw off) tank is around 110. You should be getting water out of the first coil after it's been through the second around 100, so a 70-80 degree delta is reasonable, not needing that much flow for 3/4". Try it and see if you can heat them up from cold (110 second tank) in one fireing w/o idle. You already have the 3/4" so it shouldn't cost too much. Are you primary/secondary? A 007 should push quite a bit of water through the shell of each tank. I assume there is little flow restriction with the tank in tank design. Boiler piping shouild be in series as well as the domestic piping just reverse flow of each other. BTW nice piping job with brass reducing couplings!

    Taylor

    PS I have only one 115 gal indirect (see sig) and my wife and I can go for three days, it's great during the shoulder seasons when there is little call for heat. The large storage of DHW makes the gap between fireings.
  15. velvetfoot

    velvetfoot Minister of Fire

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    Why are the indirect tanks leaking so young?
    My tank is about 8 years old and so far so good, knock on wood.
  16. Certain brands were made to just outlast there warranty. Around here everyone and there brother had boilermates installed. They seem to be going bad after about ten years. I know a plumber who installed hundreds. He's now replacing them with htp superstors. Triangle tubes are supposed to be good too.
  17. My wife is heading up to the county tommorow, so I'll get a chance this weekend to see how it goes with the wood boiler.
    I was concerned that if I hooked up up the boiler in series through both indirects that he large delta t would cause prolonged low return temps when using the oil boiler from a cold start.
    I do have return protection on the wood side, not the oil boiler.
  18. velvetfoot

    velvetfoot Minister of Fire

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    Thanks. Mine's a BoilerMate, knocking on some more wood.
  19. BoilerMan

    BoilerMan Minister of Fire

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    The VAST majority of indirects I see are Amtrol (boiler mate) as well, or the afromentioned "TOP PERFORMER" from F.W. Webb which have the same makup as Amtrol. Finned copper heat exchangers, and steel tanks are just not good for the long haul. Mike, I'm from "The County" and I'm headed downstate this weekend, I'll wave to your wife on the interstate........LOL My wife is from Waldoboro and we're going to a family reunion.

    Taylor
  20. Never thought I'd start fire in my house when it 85 and muggy outside!

    But I now have 240 gallons of dhw at 155 ready to go. I'll see how long it will last. Boiler room got a little toasty but it didnt seem to warm the house noticeably.
  21. infinitymike

    infinitymike Minister of Fire

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    Congratulations.

    Why do you have 240 gallons heated. I thought the first tank was going to be heated by solar.
    Did you hook solar up?
  22. I turned on the 'shuttle' pump. Its a stainless pump that goes between the two 120 dhw tanks. It allows me flexibility in charging the tanks. I can charge one or both tanks with either the boilers or future solar collectors.

    For now I just attached a cord to the shuttle pump that I plug into the wall when charging both tanks from the wood boiler. I think I will use the aquastat on the future solar tank and a RIB relay to turn on the shuttle pump when the tank hits 140-150.


    I've attached a pdf of how I currently have it setup.

    Attached Files:

  23. infinitymike

    infinitymike Minister of Fire

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    let us know how long before you need to recharge the tanks.

  24. Water felt a little cool this morning so I checked the temps. Water temp was down to 105 after 3.5 days. Was a little disappointed, but I did notice that both tanks were at exactly same temp. So it looks like there is some thermosiphonong happening between the two tanks. I will have to add a heat trap after the shuttle pump and try again.
  25. BoilerMan

    BoilerMan Minister of Fire

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    A brass swing check should do the trick.

    TS

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