How to calculate the water expansion volume in atmospheric-pressure hot water boilers, and how to design make-up water tanks
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For an atmospheric pressure hot water boiler operating at full capacity, the following question arises: (1) When the water is heated from 20 degrees to 100 or 95 degrees while the boiler is running at full capacity, what is the amount of expansion that occurs? How to calculate it? Can it be converted into a level gauge height? Are there any articles or books I can refer to? (2) How large a make-up water tank needs to be designed to meet the requirements of thermal expansion? How is this calculated? (3) Are there any instructions or explanations regarding the automatic water replenishment system for boilers operating at atmospheric pressure? These are tasks I’ve encountered for the first time; I really don’t know where to start. I hope all the experienced users here can offer some guidance! Thank you!
When the water volume in the boiler and pipes is 0.2 cubic meters or less, the capacity of the expansion tank should be 0.02 cubic meters or more. For every 0.1 cubic meter increase in the water volume inside the boiler and pipes, the capacity of the expansion tank increases by 0.01 cubic meter.
May I ask where this information comes from, or is it based on your engineering design experience?
You have engineering experience; meanwhile, you can look up the manual for hot water boilers, which contains a section on expansion tanks that you can use as a reference.
The forum contains a Practical Manual for Boiler Installation; the corresponding piping diagram can be found on page 344, and the water inlet level can be controlled using a float valve.