Keeping The Heat In The Tank

[trehugr]

The EKO brings the tank up to temp. Around 170º Now, as the boiler is on the downhill run, cooling off that is, i've found that if I shut the main circ pump off as soon as the fire is almost out, I can prolong a higher tank temp. If I allow the EKO to shut itself down, FUEL signal, and circ pump shutdown at 140º, it seems to cool the tank down quickly. The Boiler is 90' from the tank.

Does that make sense to anyone ?

It seems that by circulating the water until the pump shuts off is a waste of electricity and stored heat becomes heat loss.

Is there a way to program the controller to shut the pump down after the fire is on the downhill run ?

I think if I can stop the pump at 180º I could have quite a few more hours of stored heat.

Kev

 

[Nofossil]

This gets back to the whole differential controller thread from a few days ago. You need logic that will not run the circ if the tank is not at least a few degrees colder than the boiler.

Besides a differential controller, a timer is one solution, and a switch based on flue temp is another.

 

[Tarmsolo60]

I installed a Tekmar 156 differential controller a few days a go and am happy with it so far.
Still playing around with the settings.

 

[EricV]

This gets back to the whole differential controller thread from a few days ago. You need logic that will not run the circ if the tank is not at least a few degrees colder than the boiler.

Besides a differential controller, a timer is one solution, and a switch based on flue temp is another.

Do you have a recommendation for a basic controller to handle this? I am real pleased with my system but this is a good tweak that would make it more effecient.

Thanks
Eric

 

[stee6043]

If you have the newer EKO controller you should be able to set your circ pump to shut off at 158. This would at least keep you from getting down to 140...not as good as a differential control but better than nothing.

The directions in that part of the controller manual are a little hard to follow but I believe you can set your circ pump launch to 160 and your launch "hysteresis" to 2 degrees. So if the inlet temp drops to 158 (160-2) the pump shuts off.

 

[WoodNotOil]

From the "Topping off the tank" thread https://www.hearth.com/talk/threads/24518/ we came up with the following fixes

For differential controls we found:
Azel 7772 (broken link removed to http://www.azeltec.com/catalog.0.html.0.html#DST-777)
Tekmar 156 http://www.tekmarcontrols.com/prod/156.shtml

You could also put in a stack probe so the circ shuts down when the fire goes out.

 

[88rxn/a]

after shutting off the circ, how long is that stored heat lasting?

 

[ManiacPD]

I'm going off half informed here, but wouldn't a close on temperature rise aquastat work? That way the circulator only runs if the temperature in the boiler goes up, and shuts off if it does down. Or perhaps I'm missing something???

 

[Tarmsolo60]

I'm going off half informed here, but wouldn't a close on temperature rise aquastat work? That way the circulator only runs if the temperature in the boiler goes up, and shuts off if it does down. Or perhaps I'm missing something???

The return water from a fully heated storage tank is enough to keep the aquastat closed. When that happens you start losing stored heat from continued circulaton after the fire goes out.

The Tekmar 156 has a sensor on both your storage and your boiler and will not pump unless user selected parameters are met.