Summary for hot water heating chrome tanks Discussion
Heating chrome tanks with hot water instead of steam was discussed as a possible way to replace a boiler loop that runs continuously. Thomas A. Spangler asked whether a tankless water heater could be used to heat 25 plating tanks to the temperature needed for good plating. In response, the answerer explained that hot water systems can be cheaper, simpler, and less bulky than steam, but they transfer less heat per unit of coil area because they lack steam’s phase change and larger temperature difference. That means hot-water coils usually need to be larger. The answerer said hot water can make sense for steel or stainless heating coils when operating temperatures are not near 200°F, but warned that chrome plating tanks often use expensive heat-transfer materials like Teflon, so the larger coil size and added cost may be problematic. The reply suggested reviewing related thread 0194 for more input.
Q. We have 25 tanks that have to be heated to a temp to plate well.
At this time we use a boiler that keeps a loop hot but runs 24-7. Was thinking about a tankless water heater instead of a boiler.
Has anyone tried this?
Thomas a Spangler
– Willowbrook [Illinois]
September 16, 2024
A. Hi Thomas. The reason that both hot water and steam heating are available is, of course, because one is better in some circumstances and the other is better in other circumstances.
I used hot water in a few plating plant designs and it is somewhat cheaper, simpler, and less bulky in terms of the pipelines. However, the disadvantage is that the heat transfer per unit of coil area from hot water is much lower than from steam (because of the lack of phase change and the smaller temperature differential).
If a process line uses primarily steel or even stainless steel heating coils, and the required operating temperatures are not close to 200°F, hot water is often justifiable even through the heating coils must be bigger.
In the case of chrome plating, however, where you are probably using expensive heat transfer coil materials like teflon, I think you may find that the increased coil size and cost will be problematic.
Please see thread 0194 or search the site for more input on this question.
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
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