"Will having a 3rd zone provide any measurable savings?"

Not necessarily, it may however provide greater comfort.

Perhaps rethinking 'Pump & Dump' may be the best route to long-term savings.

SR

Thanks. But why rethink pump and dump?

Pumping costs could be high depending on the depth of the well and maintenance costs could also be more than anticipated depending on water quality and long-term reliability of the water supply.

SR

It's very clean river water. Does that make a difference?

It may be prudent to know its mineral & biological content and concentrations. These are the things that can muck up your system.

SR

Thanks--we'll ask about that.

Found out this weekend that the in-coming water will come from an aquafer, and out-going water will be pumped into the river. What we're asking, though, is, because of having a third zone in the master wing at $4500 extra, will we get enough savings by turning back the temp on the rest of the house, upstairs and down (the two other zones). House will be approx. 3000 sf.

Your installer would be in the best position to inform you about the pay back of this third zone. I would imagine that it might be a long time for pay back. It sounds like it may be more a question of comfort, however 3-zones seems like a lot for a 3000sq ft home...

SR

Zoning is an incredibly small energy savings in the grand scheme of things. Obviously it depends how well the house is insulated.

Geo in NE NC is a bit of overkill IMO. My 5,000 sq ft house in NC cost $500 to heat this winter. A well insulated 3000 sq ft house with ASHP should be $400. Geo probably gets that to $300. Similar savings with A/C.

So your HVAC costs are probably $900 a year for conventional and $700 a year for GSHP. Zoning at best probably could save $100 a year (if you totally shut off a section of the house)

The $4500 really shocks me. I think I paid $2000 for an infinity zoning system. I am getting ready to add another zone for about $1500. This is the best zoning system for residential that money can buy. The stats are $400 for master $200 for slave, $350 for controller and $200 or so for each damper. I'm not sure where even with Infinity, you can get to $4500 for an extra zone. A really great install maybe but still that is a lot.

Payback is not usually the motivation for zoning. I love ours because we can sleep in the freezing cold and walk out to warmth.

david carey do you have geo and if so do you mind my asking what you paid for your system total? Actually it would be helpful to know air source hp cost (and year installed)if that's what you have. If you have geo I'm sure you reaped the benefits of the 30% fed credit. How about the NC credit that appears to be good until 2015? We just found out about that via internet. Doesn't seem like much, but a penny saved...

FWIW - 2009 new construction. $21k for 7 tons of Seer 15/16 ASHP with 90% NG backup. 4 ton unit on 1st floor (adding zone to basement which is getting finished). 3 ton upstairs with 2 zones.

These are 2 stage, variable speed systems. Dehumidify on demand, humidifier.

This is the almost the most expensive air source option. Lots of bells and whistles. We don't have land so geo was going to be fairly expensive and honestly not a lot of competition to keep the prices in check or the quality high.

Our energy audit had a baseline energy use of $3500. Then it would give estimated savings for each upgrade. Obviously it isn't perfect since the savings are not additive (they included insulation, ashp choices, duct locations etc.) Our actual energy use is more like $1800. Their estimated geothermal savings was $316 a year. Their savings from going from a seer 13 ASHP to seer 16 was $200 a year. So the difference between Seer 16 and GSHP is $100.

Mind you this is all estimating. It is based on code insulation. So upgrading the attic for instance to r-40 (which incidently cost me $200 I think), saves $70 a year. Well as you upgrade insulation, the incremental benefit from geo just decreases. So if heat costs $700 at baseline and you go to $630 after upgrading the attic, the benefit of geo just got cut from $100 a year to $90. And since our actual energy use was 1/2 the estimated, the benefit is probably closer to $50 a year (not entirely fair since some of that benefit is from the seer 16 ASHP)

Their are other benefits of geo like longevity of equipment and noise. But there are also pumps to fail.

There is no natural gas in our area, only electric and propane. We just found out about an NC state energy tax rebate supposedly good until 2015 and can be spread out over the years until then; we're checking with our builder to see if it's really valid since we saw it on the internet. Know anything about this? That would make geo even more attractive, altho we're still on the fence about that 3rd zone. Thanks much for your info and thoughts. It's very helpful.

Thats alot of money just for another zone. I think geo-thermal could be a good idea since the govt. is paying 30% of the cost. It certainly helps alot over airsource heatpump during the temperature extremes (very-hot and very-cold).

Zoning is more for comfort, not necessarily cost savings. I do understand how you are trying to achieve energy savings with your use of the zoning, but I don't think its worth $4,500.

We agree and are now re-thinking the third zone.