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boiler plumbing question

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by drewmo, Jan 6, 2008.

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  1. drewmo

    drewmo Feeling the Heat

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    Excuse my inexperience with boilers, but I'm asking this question for my neighbor, Jean-Pierre. He's recently doubled the size of his house to 150m2, not including the basement (a good 60m2). Too young to fight in WWI and too old for WWII, this is his first go with any non-oil based-heat. He has just installed an HS Tarm MB-Solo, which uses wood pellets (or is that evident by the mark?). He's been running the boiler now for about 2 weeks and is absolutely thrilled with the results. His old heating system was a stand alone oil burner placed in his dining room. The burner did a good job of keeping the immediate vicinity warm, but that was about it. The boiler, with floor and radiator heating, keeps the house at 20C and the basement 12C, to his dismay. Here are a couple photos, the first with some numbers, of his system.

    [​IMG]

    [​IMG]

    [​IMG]

    Jean-Pierre apologizes if any of the photos look "untidy." I think the French codes might be a bit more lax than those in States.

    Can anyone offer an explanation or provide a solution to the following:

    The 800-liter storage tank holds 150 for hot water use, and 650 for heating. The tank is broken into four levels, as you can see by the thermometers. The bottom fourth of the tank will be dedicated to solar hot water, which he has yet to set up. His first question is why is the water in the top-fourth of the tank cooler than 2nd quarter? Could be the thermometer itself, but seems unlikely. From what we could deduce, the water from the boiler enters the tank at the top. Heat rises, right?

    His second question has to do with the bit of pipe I outlined in red. The left half of the copper piping in the tank photo feeds the in-floor heating. The water exiting the tank through those pipes leaves at less than 30C. All the piping on the left side remain below 30C as well - except for the small bit in the middle that gets mixed with the cold in the thermostat. On the right side of the piping, which feeds the radiators, water exits in the 80C range. The portion of pipe outlined in red is also 80C, while the rest of the piping is nearer 20C. We think that the hot portion of that pipe should be in the 20C range, also. Why is it hot? Should it be hot?

    Hopefully I have explained the situation in enough detail for anyone willing to offer an explanation. If not, please let me know what questions need to be answered first, so JP and I can get you the info.

    Finally, if anyone has any tips on how to gain maximum efficiency out of such boilers, please advise. Thanks!

    -drewmo

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  2. Eric Johnson

    Eric Johnson Mod Emeritus

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    That's a tidy looking setup, but, tres complex! I don't have a clue, but I suspect the guy who piped it, does. Or maybe one of our resident piping wizards. The key to maximum efficiency is probably contained somewhere within that fancy tank.

    I just love the whole concept of a pellet-burning boiler, and this looks like a very sweet setup.

    Too old for WWII? How old is this guy, anyway?
  3. Nofossil

    Nofossil Moderator Emeritus

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    I need a plumbing diagram. What are the gray rectangular units with the three plumbing connections? I'm assuming that the round red units are circulator pumps. Is the tank physically divided into four unconnected sections?

    I've scratched my head on this one, but I don't have enough hair left to scratch any more.
  4. skeetska

    skeetska New Member

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    The gray boxes look like mixing valves that mix cooler water with the supply lines. the radiant floor tubing runs at a lower temp than the radiators. nice idea
  5. Eric Johnson

    Eric Johnson Mod Emeritus

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    Welcome to the Boiler Room, heatman.

    Sounds to me like a mixing valve problem of some sort, but I wouldn't know where to start.
  6. Bartman

    Bartman Member

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    I would sure like to see the schematic on that, it is one beautiful installation. I would certainly guess that a mixing valve would possibly need adjustment or replacement.
  7. skeetska

    skeetska New Member

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    I think i may know how this system works, this only a quess. The supply for the tank has a mixing valve to the tank, the top section of the tank is for domestic water and the second for heat, the bottom two are returns to the boiler. The two gray boxes are temp controls for the two zones of heat (water temp). When the solar gets tied in that will also get tied into the return for the boiler. New equipment is well insulated against heat loss so not surpising not much radiant is coming off the boiler to heat the basement
  8. jebatty

    jebatty Minister of Fire

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    It seems to me that anything that looks this good has got to work as good as it looks. Good luck.
  9. drewmo

    drewmo Feeling the Heat

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    I'll see if I can get a schematic off my neighbor. Maybe that will give a better clue as to why that portion of pipe remains hot to the touch. The two gray boxes are thermostats for the floor and radiator heating. The box to the right is set to a higher temp than the one to the left. Not sure if that top quarter of tank is for domestic hot water, but it makes sense and gives reason why the tank temp is different above and below. Although the tank and a majority of piping are insulated, the neighbor is actually upset that his basement is so hot. There's very little insulation in the basement itself and given it's size, he thinks he's losing as much heat in the basement as he uses to keep the rest of the house at 20C. Thanks for the responses.
  10. Sting

    Sting Feeling the Heat

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    Nothing finer than a Tarm pellet boiler

    Comparing my old Traeger is a hot dog compared steak

    More pictures please!
  11. Gooserider

    Gooserider Mod Emeritus

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    One thing that is certainly a factor, or so it looks from the photos, is it appears to me that all of his plumbing is not insulated. The tank itself might be, but the pipes look like they aren't - I'd suspect that it's a good part of his heat loss to the basement. I would certainly suggest insulation on all the pipes that are warmer than the basement, and possibly on the valves, pumps, etc. if that won't hurt them (don't know how much air cooling they should have).

    Gooserider
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