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[Bull]

I have rear on here somewhere that if you lose 15* going through your water to air ex that you are not moving enough water. If this is the case would adding a second pump inline make a difference? Where would the best place be to add the second pump? First pump is at the owb.

[willieG]

adding a second pump  may  increase your gpm

i am no pump guru but maybe a second pump half way dow the system (say one pump on the stove and one in teh basement) would give you more gpm due to the fact you (i think) would be lessening the friction in the line on the pump

each pump would be pushing water for only half the distance, thus reducing the friction loss (added head pressure)

this is only a guess on my part.
 1 inch pex is not rated to go above about 12 gpm under normal conditions (above this may cause water hammer when pressure changes occur that may damage equipment and or the pipe itself)
pressure changes occur when a valve opens and closes

also at 12 gpm if your water is 180 degrees you are delivering to your home about 120,000 btu per hour

[BoilerHouse]

Bull
My guess is that a second inline pump would move more water, however the law of diminishing returns would kick in. If pump 1 produces 80% flow, adding pump 2 may only get you to 90%.  The manufactures normally recommend a 20 deg temp drop through the exchanger, however in a perfect world the exchanger, heat flow, and water flow are all sized for each other.  I think that more water flow would give more heat output with less water temp drop.  In industry we often see devices or products that do not operate within theoretical values, but before commiting the time and money to solve the issue the question becomes "But is it still doing the job it was intended to do"  If the exchanger in question is doing a satisfactory job of heating the space than it may be chasing a phantom problem. When I installed my system I used a lot of by-guess and by-gar engineering.  It all seems to work.  I don't think I should send a manned mission to Mars though.

[Bull]

BoilerHouse, yes it does the job just fine. I had read on here that 15* loss through the heat ex was to much. If the manufactures say 20* is ok then I am fine.