Taco 007e "Green" mode

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djdavenport

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We have radiant floor heating with a condensing combi boiler with three zones. Zone valves. The circulator is a Taco 007e I put in about a year ago. I've got the ODR curve dialed in pretty close such that, during the coldest days, the boiler loafs along, often all day. It's been working great.

I apparently have one of the first generation 007e's (with the old firmware) and it is programmed to go into "econo" mode after 12 hours of continuous operation (signified by the green LED). What I notice is that when it does, my delta tends to really shrink. Typically, on a day like today (14 degrees this AM), supply is about 118 and return is about 102--that's in non-econo mode (orange LED) and everything is totally groovy. Today, with the same outdoor temperature but in "econo" mode, we've got about 115 supply and 107 return. We still seem to be keeping up okay, but worry that if being in "green" mode throttles down the flow somehow, we might get behind. Then, again, wouldn't decreased flow result in a greater delta?

I know there's a chart that illustrates the head and flow for the various modes, but I'm not too good at interpreting what that really means. I also think that Taco has introduced new firmware for the 2nd generation of 007e's that only go into "econo" mode after 7 days of continuous operation rather than 12 hours, after a lot of pushback from people whose systems tend to run continuously.

I'd really like to understand better if this short trigger "green" mode is going to be a problem long term. Or if maybe the deltas I seeing today are just an outlier.

Thanks.
 

Dana

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The output of the radiation is less at 115F out than at 118F out, which is part of the lower delta-T. The delta-T across the radiation should INCREASE at lower speeds, not shrink, but if the boiler is plumbed primary/secondary (which it probably is, if it's an Navien?) the ratio of radiation pump gpm to primary pump gpm is lower, creating a lower delta-T.

I'm assuming the 007e is on the radiation side (?) not the primary, which would be the only way the symptoms would make sense.

Most systems are really over pumped. If it doesn't keep up, tweak the curve up a bit. But I suspect it probably WILL just keep up. At low temperature heating the delta-Ts on the radiation is pretty low at any pumping rate, and the heat emitted won't change much with pumping rate either.
 

djdavenport

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Yep. It is piped primary/secondary and the circulation pump is on the secondary supply side. It was about as cold as it generally gets around here, and the temperature in the house hasn't budged a degree, despite the 007e operating in the "eco" mode, so I think I'll just not worry about it. I was only concerned because of the hew and cry on places like heating help.com about the 12 hour threshold on the old firmware for the pump, and Taco changing shipping new firmware that kicks it out to 7 days. But, then, again, if it ain't broke don't fix it...and right now, at least in my application, it ain't broke.
 

Dana

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That's right!

"If it ain't fixed, don't break it!"

(At least that's how I was told. :) )

I think you'll be fine.
 
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