running circ pump to prevent hard water deposits

Jared Volpe

Hello Dan and all.

We are working with a boiler operator at a mid-sized public school in Vermont. Our job is to identify and eliminate electricity that is being wasted. During the summer he is running a pump to circulate hard water because he believes that it will result in fewer mineral deposits in his system.

Is there anyone out there who could offer an opinion on the topic?

Do you know anyone we could contact to verify that opinion (ie. boiler manufacturers)?

Thanks,

Jared Volpe
Kilawatt Partners
jvolpe@kilawatt.com
www.kilawatt.com

hr

Get rid

of the hard water! If the hard water is in the closed loop boiler system I would advise addressing that first. I doubt the pumps circulating are keeping the deposits from sticking to the pipes, and worse the heat exchange surfaces of the boiler itself and any other HX. There would have to be some pretty high velocities to scour the pipes clean. you'd hear it! Heat transfer experts claim evena few thousands of build up really drives exchange efficiencies down.

Doesn't take much mineral build up to really hamper the heat transfer from flame to water via the boiler tubes. Have a water treatment pro bring the water to spec in the system first. Hardness, ph, TDS are among some of the tests to be performed on that fluid.

If you do shut down pumps for extended periods consider a weekly pump exerciser control, helps keep them from sticking come heating season. The electricial energy savings may disapper if a plumber has to remove and un stick pumps.

If you refer to the DHW open side, think I would still exercise pumps instead of a complete 6 month shut down.

hot rod

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Aidan (UK)

Something similar

I was once involved in replacing a chiller plant. The old plant had roof-top cooling towers with the pumps and water-cooled chillers in a basement. If the pumps stopped, all the suspended lime-scale particles (which had been left by the water evaporated from the cooling towers) settled to the lowest part of the system and blocked up the pumps and the chiller heat exchangers. The plant was replaced with air-cooled chillers.

There may be something in what the man says, but if so it suggests a water treatment problem. If he wants to run a heating pump in summer, maybe he could get it circulating the water through a filter to get the stuff out of the system and do something useful. I think I'd consider the percentage of the electric consumption that the pump represents before deciding whether to spend time in resolving the problem.