Pump run time ?

Vince

I have a hot water system with a pump. Would it be more efficent to keep the pump running after the boiler shuts off?. If so how do i do it. I have a new Weil Mclain boiler. no zones ( old house) My high limit is set at 140*. Thanks for any advice.

Terry

pros & cons

Upside:
-running the pump after boiler shutdown would purge any remining heat from the boiler into the heating system as opposed to losing the heat thru the chimney & jacket.
-additional electrical cost nominal (fractional HP)

Downside:
-pump may overshoot your t'stat setting (sending additional heat into house after boiler shuts down)

Mike T., Swampeast MO

If you want to try it

Likely the easiest (not to mention safest) way to experiment would be to get an adjustable time-delay, delay ON BREAK, relay. "Coil" voltage same as t-stat voltage, contacts rated to handle your circulator. Not all electric supply houses carry these but you should be able to find one (at least to order). They're a tad expensive (but under $100) and extremely reliable. I've used quite a few for many years and quite heavily and never experienced failure.

You'd connect the "trigger" to the t-stat and line voltage and circulator through the relay contacts. Different makes are triggered in different ways so make sure to read the instructions! "Play" with the delay setting to see if you get the desired result.

While there's not much in the way of hazard, please don't try it unless you're comfortable working with house current and have a decent understanding of switching/relays.