How does pump speed effect heat transfer?

[sstan]

Just wondering ... the pump on my OWB has three speeds.. how does the flow rate effect the heat exchange? I believe the pumps on my house zones also are adjustable .. should I play with them?

steve

 

[ericjeeper]

Pump speeds

If you move the water to fast it will not leave enough heat behind when trying to dump the heat into a HX. Nor will it pick up enough heat when trying to pick it up out of the boiler.
Slow speed will often allow the blower in a fan coil to actually cool the water to much. Making what is called a high delta T.
Great site to browse. heatinghelp.com , the wall.

 

[AOD]

BTU's = GPM x Delta T x 500

 

[sstan]

ok .. in plain lanquage ... I believe your saying I should try and slow the pump down and see if the oil burner loop picks up more heat. I am assuming the blower cooling the water is in refernce to hot air heating systems .. mine is hot water base board. I am not technical enough to do all the calculations .. so I think I will try it and see.

 

[KsWoodsMan]

BTU's = GPM x Delta T x 500

:agree2:

The heat control on the dash of your PU is probably a valve, as most are. Sliding the control lever over to cool limits the volume of water getting to your heater core. Lower volume equals slower water speed which means less heat output. Faster water speed through the core means more volume and gets more of the waste BTUs from the engine into the cab.

The PU engine can produce more heat than the heater core can dissipate. Hopefully the heat requirement for your home doesnt exceeed the heat output from your OWB. Turning up the pump speed will raise the temperature of the air going through the air handler and at the registers

 

[Blazin]

Definitely slower speed for a coil type exchanger for hot air, But with a baseboard system if you have a flat plate exchanger I found that faster moving water is the way to go. I originally had a taco #9 on the plate exchanger loop and wound up going to a #11 on the OWB(130ft run),and a grunfos 3speed on med on the inside circut to heat the inside boiler. I noticed an immediate difference how the temp on the inside system was not pulled down as fast when there is a call for heat.

 

[mtfallsmikey]

Did my piping primary-secondary; 009's on the primary loops, 007's on the secondary...get "Pumping away" by Dan H. from heatinghelp.com. That explains pump/pipe/load sizing.

 

[AOD]

Since when did Taco stihl model #'s from Stihl?