Circ. Pump Running

greg_30

thanks guys, I did not think there could be boiler damage, but wanted to throw it out there for your comments.

greg_30

Circ. Pump Running

A Peerless hot water boiler model g-705-fda-wvp provides hot water to an air handler hw coil and some fintube cabinets. The circulating pump runs 24/7. To save pump energy it is under consideration to turn the circ. pump, boiler and AHU off when there is NO call for heat. A comment was made that cycling the pump could shorten the life of the boiler due to natural chemicals in the water (the system has no water treatment). Any thoughts?

Joe Brix

I would rather

replace a pump every 20 years then cause erosion of all the piping. Constant circ only makes sense to me in large water mass systems like gravity conversions.

Brad White_9

Never heard of such a thing.

Pumps are cycled on and off all the time. One does not often run their boiler or pump in the summer as one obvious example. But even in the off-season you want to at least exercise the circulator for a few minutes each week to prevent seizing. But that is to protect the pump not the boiler.

Most systems do not have chemical treatment (they should, that is another discussion). But absent new fresh oxygenated water, a system that has been run to limit without new free O2 added should work fine. It may have suspended black iron oxide particles and those should be filtered out.


Instead of running the circulator based on a demand, what I do at least is run it based on outdoor temperature. All temperatures below 60 the pump runs and if the boiler calls it also runs (those few chilly AM's when the house is colder than the outside).

I assume you have control valves and pressure differential bypass on your distribution piping of course.

Joe Mattiello_2

Taco pump

Pretty sure that pump is a Taco circulator, which is designed to run 24/7. However, cycling the pump on, and off will not be a detriment to the pump.
Joe Mattiello
Technical Support Technician
Tel. 401-942-8000 X 484
Fax. 401-942-2360
1160 Cranston St
Cranston, RI 02920
joemat@taco-hvac.com

Rodney Summers

why would you constantly run the pump on a gravity conversion?