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Posted by HeatPro on November 29, 2005 at 21:09:35:
In Reply to: To HeatPro and Joe Brix posted by Dave on November 29, 2005 at 20:44:40:
You are misunderstanding the difference between Jim's request and your situation. You already have a zero-balance system installed that has a loop where the boiler is piped to itself with a 0012 running water around the primary loop.
Jim does not have a primary loop, he had an ordinary multi-zone system without a primary loop, but he wanted to put the buffer tank in the manifold feeding multiple series zones. That would have made the buffer tank a useless addition.
The instruction (and drawings I provided Jim through and email at http://heatpro.bluedomino.com/design/bufferz.htm )
show that he would have better success with a system similar to yours where the buffer is placed in the loop pumping from the boiler back to the boiler, with the zones coming off one side of that primary loop (it happens that the buffer tank, boiler and circulator is in series with each other in the primary loop; but that is not the same a a series loop heating design.) You are in a similar situation to his with a partial load zone coming off the primary loop, and it is the added water in the buffer tank that provides the mass to give time for the boiler controls to react.
Condensation can (and does) occur in the boiler when the water temperature is low. In your situation, it could occur for the 4 minutes it takes for the water temperature to rise (that is called 'wet time.' However, when firing off 140,000 btuh on low stage, the water will heat up rapidly. A condensate problem occurs when a boiler condenses water for a longer time than the boiler would take to dry off after rising in temperature beyond that point or not shutting off at that point. You would do well to use an outdoor reset that keeps the boiler above a condensing temperature. In fact, the buffer tank could provide heat to the indirect or other small zone without even firing the burner at times.
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