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  1. #1

    Triangle Tube High Temp Set Point Question

    I have a Triangle Tube Prestiege 250 condensing boiler (TT)

    I also have an out-door wood boiler (OWB) that is supporting the TT via water-water heat exchanger.

    What i want:
    When the water temp of the OWB is high enough to heat the TT main boiler loop, i don't want the TT boiler to fire when heat is called for in the house.

    What is happening:
    TT high temp set point is 150 degrees.
    I have a temp sensor on the TT main boiler loop. When it reads 155 degrees,
    and heat is called for, the TT still fires. The water temp in the main loop is 155 due to the OWB, not the TT.

    What am i missing here?


  2. #2
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,826
    Boiler high limit and high temperature set-point are two different things entirely.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  3. #3
    The set point i am referring to is parameter 4 - the max temp for the room heating.

    I think i have figured out what is happening. It's got to do w/ circulation. When the pool calls for heat, even though the water in the loop is > than 150, the water inside the boiler is not because the circ pump that pushes water into boiler has not been running. So, the boiler sees <150 degree water and fires and runs for only 1 minute to get through its normal start cycle.

  4. #4
    Join Date
    Jul 2004
    Location
    Massachusetts
    Posts
    6,826
    I don't know where a 'pool' slipped into the conversation but it seems your problem is that you have two units that are allowed to run simultaneously because they're both getting the same call for heat. I'd recommend someone install an aquastat controlled switching relay that will only fire the boiler when the wood boiler temperature is low. Whenever the TT boiler is called on, both the primary and secondary pumps must run or you run the risk of quickly burning out the boiler vessel. It is designed to short cycle if the primary pump fails but if that control circuit is in any way overridden, it will lead to a catastrophic failure of the boiler. That said, if the mentioned aquastat is installed in the wood boiler, it should be set to eliminate the heat demand circuit to the TT boiler. When the wood boiler temperature is insufficient, the aquastat should allow the heat demand to be switched to the TT boiler, the boiler will then take over and operate normally. It's a simple matter of transferring the heat demand to the appropriate heater.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

  5. #5
    i think you and i are on different pages here. I don't want my TT boiler to fire unless the water temp in the main loop is not sufficient to heat. It does not matter what thermostat is calling for heat, floor or pool. If the pool and the floor call for heat at the same time and the OWB is doing it's job, the water in the TT loop will be 160+degrees. There is a mixing valve in place to lower the water that is sent to the radiant zone that is calling.

    What i was struggling with was that the tt was firing when the water in the main loop was plenty hot. It puzzled me as to why. Water in main loop was 160 degrees, max temp set point on TT was 150. Why would it fire?

    Because the water "IN" the acutal boiler was only 120 degrees because the circ pump that pushes the water into the boiler will not run unless the boiler is firing. So, when heat is calling, boiler fires and then shuts down as soon as the circ pump pushes the previously OWB heated water through it.

    Hard to picture unless you see the plumbing but now i understand what was happening.

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