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Thread: Baseboard heat or other radiant heat with no fan using espar for heat source.

  1. #11
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    A calorifier is the same as a hot water heater correct? Seems like once the calorifier was fully heat soaked it would no longer prevent short cycling.

  2. #12
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    Default Water volume

    Adding a calorfier adds volume to the hydronic system.

    Larger volumes will result in longer cycle times. Energy is initially stored in the water and released over time to the cabin. More water holds more energy and takes more time to release enough energy to decrease its temp below the cut in temperature set point of the heater. For faster reaction time, mixing valves could be used to prioritize components allowing to calorific or any other heat storage to only accept energy after to cabin loops have been sufficiently warmed all day.

    Do the espar heaters have adjustable cut in and cut out temperature set points? Setting these points as wide as possible would also allow for longer cycle times.

  3. #13
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    No the espar heats to a certain temp, then cycles to low and then shuts off if the temp keeps rising. I am beginning to realize why people have such complex systems now. You have to have enough volume and radiators or towel racks or in floor heat to shed the heat made by the espar or it will short cycle. I guess I just have to build my system and see how it does with my camper. I feel like it will be too hot unless it's very cold out. So I will have to find a way to shed the excess heat from the system if I have a short cycling problem.

  4. #14
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    How about two loops? One to insert heat into the calorifier, and another to extract it.

  5. #15
    I feel like it will be too hot unless it's very cold out.
    Not a problem - they come with thermostats - not sure why you see an issue?

    My adding a 5 gal tank to my system was just to increase the volume of the hot water to allow a long (quiet) time between the webasto coming on. The tank & manifold & most of the plumbing are in/under cabinets that are connected in such a way that air flows in one end & out through the radiator/fan. So there is no wasted heat - it's all contained within the camper envelope (except the webasto & inlet/outlet hose). The bed is above the tank...The point is there can be a number of ways to enhance the passive, unpowered or low powered extraction of heat from the system - which was the central question of your first post. Moe
    Last edited by fluffyprinceton; 12-12-2016 at 05:59 PM.

  6. #16
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    Quote Originally Posted by dwh View Post
    How about two loops? One to insert heat into the calorifier, and another to extract it.
    Well from what I see, a calorifier is just a hot water heater. So it's stores hot fresh water, not hot coolant. The loop inside doesn't have much volume. So unless people are running fresh water in a loop through their heating circuit I am missing something.

  7. #17
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    Quote Originally Posted by fluffyprinceton View Post
    Not a problem - they come with thermostats - not sure why you see an issue?

    My adding a 5 gal tank to my system was just to increase the volume of the hot water to allow a long (quiet) time between the webasto coming on. The tank & manifold & most of the plumbing are in/under cabinets that are connected in such a way that air flows in one end & out through the radiator/fan. So there is no wasted heat - it's all contained within the camper envelope (except the webasto & inlet/outlet hose). The bed is above the tank...The point is there can be a number of ways to enhance the passive, unpowered or low powered extraction of heat from the system - which was the central question of your first post. Moe


    Maybe I am over thinking it. I know you can control one thermostatically but that could mean short cycling in a small camper like mine.

    So with your 5 gallon tank, you run a separate pump that circulates the hot coolant to your radiator and floor heat circuit correct? I think that is the part I was missing. The internal pump on the espar normally does that job while the espar is running. I suppose I could switch on just the pump inside the espar to avoid having two pumps. Do the webasto units have an internal pump?

  8. #18
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    Quote Originally Posted by javajoe79 View Post
    Well from what I see, a calorifier is just a hot water heater. So it's stores hot fresh water, not hot coolant. The loop inside doesn't have much volume. So unless people are running fresh water in a loop through their heating circuit I am missing something.
    Circulate hot coolant in a loop through the hot water tank. Water absorbs heat. Hydronic shuts off.

    Circulate coolant through a second loop in the hot water tank to extract heat. Eventually, water temp drops and hydronic comes on to bring water temp back up.

    Two things prevent short cycling - the mass of the water takes time to heat, and the water can be heated to a very high temp, which also takes time.

  9. #19
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    In other words, you can accumulate heat in a big jug of coolant, or a big jug of water. Same effect either way.

  10. #20
    DWH is correct. By adding the calorifier in the loop, it acts as a energy (thermal) storage device that can absorb and store the heat produced by the hydronic heater. A side effect is prolonged run times which prevents the hydronic heater from starting up and only running for a very short period before shutting down. The same thing will happen in an improperly bled system when the circulation pump catches a pocket of air and the flow of coolant is interrupted.

    Here is a simple example of a single series circuit that might work. By using the calorifier with the addition of a circulation pump connected to a thermostat, it can allow you to slowly take energy (thermal) from the calorifier and dissipate it by way of the active or passive radiator(s) in your system. When turned on, the hydronic heater is constantly checking to make sure the coolant is maintained above the set point (~85 degrees C) and restarts the combustion chanber when needed - dumping additional energy into both the calorifier and the radiator(s). Some hydronic heaters might be able to be programmed to run the on board circulation pump (if so equipped) to do the above (YMMV).

    A more complex series/parallel or parallel circuit could add more user control to the system if desired.
    1986 U1300L Unimog Expedition Camper

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