Hot water too hot!


  #1  
Old 01-25-04, 07:35 PM
tylerg
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Hot water too hot!

Hi I am a new home owner and have an oil fired hot water boiler Thermo Dynamics (that heats my hot water and my home). My firing rate is 1.00 39 PSI if that helps.
My hot water teperature is 190 degrees and is way way too hot.
I have my low set on 160 and my high on 180. What do you recommend to adjust please?
 
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Old 01-25-04, 08:09 PM
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Well, in the winter when the heat is running, the boiler gets up to the high limit which in your case is 180. That is the temperature that the first shot of domestic water will be. A tempering valve can be helpful but it can be a source of problems too eventually. It installs in the pipes near the hot water coil and mixes a small amount of cold water with the hot to achieve a set temperature. It will prevent scalding.
 
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Old 01-26-04, 06:40 AM
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I may be overlooking something, but I remember reading a hot water heater should be set to not much higher than 120 degrees.
 
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Old 01-26-04, 09:46 AM
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You are correct. But you don't have a water heater. In a water heater the water at the top of the tank will be hotter than the water in the middle so it is better to set the thermostats a little lower than you want the outlet water temp to be. There is also an ample reserve of hot water in the tank. In your system, there is only a coil of copper inside the boiler. It is immersed in boiler water and picks up its heat through the walls of the copper. The boiler temperature varies and there is about a 10-15 degree difference between the boielr water temp and the temp of the domestic water due to heat transfer properties of the coil. The added boiler temp also helps to make up for the lack of time the domestic water spends inside the coil. It must be heated in about 5 seconds when you are filling the bathtub. All those combined things prevent you from setting the boiler temp where you want it and having a constant domestic water temp. Boilers with coils are becoming less popular and indirect water heaters are taking over the market. And rightfully so, they are great.
 
 

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