Can indirect water heaters thermosiphon?

[DaveBP]

Anyone out there have a standard indirect water heater setup with a thermostat and circulator that will thermosiphon all by itself when the DHW loads are low.

I'm wondering if it could be piped to encourage self circulation from a pressurized heat storage tank by eliminating high and low spots in the pipes and keeping the DHW tank up higher than the bottom of the storage tank. The flow restriction through the circulator is my real unknown.

Any experience or opinions?

 

[steam man]

Some of the things that will affect natural circulation would be the difference in temperature between the tanks which dictates the density of the "heavier" colder water verses the "lighter" hot water. A good clean piping arrangement would work best as you stated. The flow should be so low that the flow resistance of the pump should be minor. An internal check valve in the pump may be a problem. I am wondering if installing a bypass around the pump with a low resistance check valve may alleviate that issue. My concern would be the type of heat exchanger in the indirect and how that would work. A sidearm would seem to work best for that application. Just my best guess.

Mike