Low limit circulator shutoff

Paul Riddle

Hi,

I have a Weil McLain 68 series boiler with a DHW coil. The coil is no longer in use, having been replaced several years back by a standalone water heater. However, the Honeywell triple aquastat is still wired to shut off the circulator when the water temperature drops below the low limit. My understanding is that this is done to give the DHW priority over the house heat. I've noticed that when the heat comes on after an extended period of off-time, when the water in the pipes has cooled down a lot, the circulator tends to cycle on-off frequently while the water comes up to temperature. Without DHW, is there any reason to keep the circulator wired this way, or can it be rewired to run continuously any time there is a call for heat? There is no outdoor reset or other controller that affects the water temperature, just the aquastat.

Hope that made sense. Thanks for any input.
Paul

Unknown

The low side

of the aquastat is also used to protect the boiler from thermal shock and condensation problems from too low a return water temperature . Since you don't need a coil , I would widen the difference between the high and low limit . What is it set at now ?

Do keep some temperature in the boiler - the 68 series does not like wide temp swings on it's old O rings .

Paul Riddle

Current settings

Hi,

I figured as much, and I currently have low set to 110 and high about 200, with a differential of 25. Over the summer I just left the boiler on and set the diff down to 10.

Paul