need info on heating/hot water system please

Discussion in 'HVAC' started by donaldcarter55, Jul 7, 2009.

  1. Jul 7, 2009 #1

    donaldcarter55

    donaldcarter55

    donaldcarter55

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    Hello eveyone, I havent posted in a while, some of you may remember me from previous posts. Well, we made it to Maine! Moved from Florida and BAM! got hit with snow the first week we were here! So much for the mild maine winters last few years! LOL!! I love it!

    Can someone help me understand how my heating system works? I have a forced hot water oil burning heating system. It also heats the hot water for the faucets. It uses a normal thermostat on the wall to control the home heating, but i dont understand how it keeps the water hot for the faucets when the heat is not on. We are running out of hot water pretty fast, so I have to turn the thermostat up so that the furnace kicks on, then along with the house geting warmer, I get some more hot water. It does have a hot water storage tank, not very large, but I dont see any sensors or switches that control the furnace for just the hot water. How will we get hot water in the summer months? I must be missing something.... any help would be appreciated!

    Thanks!!
     
  2. Jul 10, 2009 #2

    slownsteady

    slownsteady

    slownsteady

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    I can think of three ways you can be getting hot water;

    A coil within the boiler
    A free-standing hot water heater
    A water heater/tank zoned off your boiler

    You probably don't have a free-standing unit. It would have its own fuel line, thermostat, and a burner at the bottom.

    You say you have a hot water storage tank. So there must be some plumbing between the tank and the boiler. Does the storage tank have its own thermostat (aquastat)? If it does then you probably have the third option.
    But if you have to raise the room temperature to create hot water then you might have an internal coil in the boiler.

    The lack of hot water might be because the coil has scaled up, which reduces the amount of heat that can be transferred to the hot water supply, or the storage tank might not be insulated well enough to keep the water hot, or the tank is too small for your needs.

    If you determine it is the coil, you should find many local services that offer coil cleaning.
     
  3. Jul 12, 2009 #3

    Nestor_Kelebay

    Nestor_Kelebay

    Nestor_Kelebay

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    I have a similar system with my boilers and indirect fired water heater.

    I have a coil in my indirect fired water heater that uses the 180 to 190 degree boiler water to heat the water surrounding that coil in the water heater up to 135 degrees C.

    Basically, when the indirect fired water heater calls for heat, it sends a signal to the Tekmar 265 controller that controls both of my Weil McLaine Ultra 310 boilers. One of the boilers will fire up and heat water up to about 180 degrees in a jiff. ONLY the circulating pump that pumps water through the indirect fired water heater will turn on, NOT the main circulating pump that pumps water through the radiators of my apartment block apartments. This indirect fired heating process will continue until the water temperature in the hot water heater is at 135 deg. C, when the Amtrol 120 gallon tank then tells the Tekmar 265 controller that it no longer needs to be heated, and the Tekmar controller then shuts the boiler off, but keeps that pump mentioned earlier on for 5 minutes more so that the remaining 180 degree heat in the boiler can be transfered to the 135 degree heat in the hot water tank. Thereafter, both the boiler and the Amtrol indirect fired water heater just sit there losing heat to their surroundings until the temperature of the water in the Amtrol 120 gallon tank falls below 120 degrees C. Then the dance starts anew.

    That's how my system works, but my system uses two high efficiency boilers that only hold about 10 gallons of water each in a 15 pound aluminum heat exchanger to heat up 120 gallons of water in my hot water tank. I am not heating up a 400 pound cast iron boiler with 100 pounds of boiler water in it every time I want to heat up 40 gallons of potable water. There would be a tremendous difference in the thermal efficiency of our respective systems, I'd venture to guess.

    Still, your system has to be reasonably efficient (either thermally or economically) for it to have become as popular as it is.
     
    Last edited: Jul 12, 2009
  4. Jul 12, 2009 #4

    ccarlisle

    ccarlisle

    ccarlisle

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    Where are you in Switzerland? I grew up there...
     

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