Difference/DT Controller?

Unknown

I'll check it out, thanks HR!

Unknown

Hey All,

Ok: imagine you have two tanks of water.

You want to draw from whichever one is hotter, switching only when one or the other exceeds the other in temperature by some arbitrary amount, say five degrees.

your operating temperature is 90 degrees.

tanks can be anywhere from stone cold to 200, no idea which one will be heated first at any time, one can be cold, one can be hot, both can be hot.. no idea.

Do you know of a controllER, or a control strategy that would pick the hotter tank on a heat demand, and flip if the other tank gets hotter by 5 degrees?

Thanks in advance! Seems like this should be simple but darned if I can puzzle it out right now...

Radman

How about this...

Hi Rob,
You could use 2 DT controllers, say 2 GoldLine GL 30s.
Tank 1 gets the "Tank Sensor" and Tank 2 gets the "collector sensor" from Tank 1's GL30. If Tank 2 is hotter than tank 1, its corresponding 120v zone valve on the tank outlet is energized. The inverse here would be use another GL30 and zone valve for tank2, if Tank 1 is higher temp than T2, its zone valve opens. Get me here. Either way, the colder tank is always closed to your system. I don't know of a DT controller that would be able to look at 2 heat sources at the same time other than a RESOL Delta Sol Pro, or Steibel Eltron Som7, which is virtually the same. These controls allow you to look at 2 heat sources and charge either 1 or 2 tanks. It is basically its East/West configuration. I think the dual GL30s is simpler though.

Unknown

the two dt controllers works for picking the hottest, but then I don't have any control over the flip back and forth... say both tanks are at nearly the same temp, I wouldn't want to be flipping between them very rapidly.

I'll look at those solar controls though, thanks a lot!

Radman

Flipping out...

Hey your on target there, I wouldn't want them to be short cycling the zone valves either. I suppose you could put each on a time delay relay, but that depends on where the heat is coming from. Those GL30 DT controllers are dead simple, so that is why I suggested them. Interesting problem though!
Best,
Bo

Unknown

the RESOl Delta Pro looks promising: can I trick to to make this decision without having a "panel sensor" at a higher temperature than my "storage" temperature?

hot_rod

consider

the i solar plus from Caleffi it has the dual delta t function with variable speed outputs. That helps take the bang/ bang out and saves some energy by running reduced pump speeds.

hr