The BIG Tank has landed

[mole]

What do you have for return water protection? Should be able to provide boiler supply 160F+ no matter how cold the water from the tank might be.

Until now, I'd been relying on the Econoburn's 'standard' protection arrangement, which turns off the system circulator and turns on a boiler bypass circulator whenever the boiler top temperature goes below 150. With the boiler feeding only the house water-to-air HX until now (via the primary-secondary piping in between), that has worked OK, but, from what I'm seeing, the immense heat sink presented by the cold tank is going to require some additional measure, so that the boiler doesn't have to go through cycles of diving temperature followed by gradual recovery. I expect that the tank won't be such a daunting load to the boiler once the tank is not starting from about 55 degrees (my old house cellar ambient temp), but I still want some management of the heat flow from boiler to heat-depleted tank.

Ideally, I'd like to find a variable speed control that can (a) keep boiler return temp above about 160 while the tank is loading; and (b) also serve as a differential-control so that the flow is only delivered to the tank when the boiler is above the temperature of the bottom of the tank.

I've been reading specs on some of the solar delta-T controls, but so far have not run across anything that will seemingly do (a) and (b) above in one box-- please clue me in if any of you know of any products that I am overlooking.

Cozy Heat sells a 160F EBSE Thermic Valve. It's a 3 -way Danfoss type valve that mounts on the boiler oultet. It starts to open at 160F and is fully open by about 175. Below 160F, it returns to the boiler inlet . I got one so I could heat my house while I'm charging a cold tank. It works well.

 

[tom in maine]

Being as it is a holiday, and we are just testing liners and sitting around today,
I have been chewing on the control issue you have.

Could it be as simple as installing a return line aquastat on the return to your boiler from the plate hx to your tank.
When the return temp drops below 160F, it turns off the tank side pump until the return line temp comes back up since the
boiler side pump is still running. This would cycle heat into the tank until the return temp gets above the 160F set point and then it would run continuously.

Or am I misinterpreting the question?

 

[pybyr]

Being as it is a holiday, and we are just testing liners and sitting around today,
I have been chewing on the control issue you have.

Could it be as simple as installing a return line aquastat on the return to your boiler from the plate hx to your tank.
When the return temp drops below 160F, it turns off the tank side pump until the return line temp comes back up since the
boiler side pump is still running. This would cycle heat into the tank until the return temp gets above the 160F set point and then it would run continuously.

Or am I misinterpreting the question?

That might do it, but from what I've been reading up on regarding return temp protection, it appears that part of the goal is avoiding low temperatures that would allow sustained flue gas condensation, and the other part of the goal is avoiding sudden temperature changes that lead to quick expansion/ contraction of the boiler's inner structure.

Variable speed return protection would seem to handle the latter better.

Hoping that HR sees this thread and might have some suggestions.

Thanks