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[George Scofield]

Can anybody tell me why the dealers recommend a bigger circulator that is more expensive when the normal 3 speed taco 007 that will pump the same gpm? My lines from the wood boiler to the house is 90' dead level. No rise on feed or return. It will be going through a 50 plate HX. Any help is appreciated.

[juddspaintballs]

Because they make more money selling the bigger, more expensive one.  Some people prefer one brand over another, such as Grundfos instead of Taco, so that could be why they're recommending it too.  It's like Ford vs. Chevy, though. 

[George Scofield]

In your opinion is a 007 taco sufficient for my above described application?

[hondaracer2oo4]

You will need to take the total number of feet of piping, the fittings and how much ft they add to the total feet of piping and the amount that the hx adds and figure out the head loss, then look at the pump curve http://taco-hvac.com/uploads/FileLibrary/102-339.pdf and see how many gpm you will be moving through the system. Water moving to slow will cause to much of a drop in temp back to the boiler (delta T). Anything over a 20 degree drop is considered to much. In order to get below the 20 degree drop you would need to move the water faster.

[willieG]

  if lines  are 1 inch pex al pex 07 should do (if the length of pipe quoted has taken into account all fittings and valves)

if the lines are only 1 inch pex...the pump would likely fail completely or deliver way less than the desired amount to run a delta of an acceptable level

[RSI]

What pump did they try selling you? How did you decide that it will deliver the same GPM? An 007 with what you described will deliver 5gpm if you are lucky. (unless as mentioned by Willie you have something larger than 1" pex)
A Taco 0015 (or 00R) or a Grundfos 15-58 is what I would use. You should get closer to 7.5 GPM with them on high speed.

[George Scofield]

You guys are right. I wasn't taking into consideration the overall length and HX addition to the equation. I will be installing the 0015 or replacement equivalent. Thanks for the education

[Wi woodburner]

Good info, but every time I search this site, it gives me new ideas and doubts my current setup.  As far has pump size, after reading this, I feel I have to small of a pump.  i have a taco 011 on my wood master 5500.  I am heating 5,000 sq feet of new well insulated home.   I tried calculating head loss and seem to have a very very high number.

BTU calculations: around 250,000
1.00" pex
Stove is 125 feet from house
25 feet from house to water heater
50 feet from water heater to forced air furnace.

I have the maverick temp on my supply and return lines at the water to air exchange in the furnace.These are installed on the copper fittings and insulated)  I get about a 9 degree drop from reading at boiler to inside house at furnace.  When the furnace is running, I see about a 15 degree drop from supply to return temps. When there is a call for hot water and air, return temps get to around 110-120.

I believe I should have another pump or at least another pump.  Stove is about 8 feet below exchangers in the house.

Any thoughts?