Massachusetts Issue with Single speed pump and electrical usage

My first posting in this forum. We moved into a new house in Dec 2014 and have installed the following:
- Waterfurnace series 7, NVV060
- 5 ton split into 3 zones.
- Intellizone 2 with 3 zones
- House is 2 storey colonial about 3700SF
- I have an open loop well. The well is 600' deep. pump at 140', water table at 20'
incoming water temp is currently at 50 degrees and exiting around 45
- Pump is Goulds 18GS07 . 18 GPM and peaks at 26 GPM
- Controller is CentriPro Model CB07412, HP3/4, V 230, 7.2 AMP,
- Stoneham, MA
- New construction, HERS rated at 33. all LED bulbs and high efficiency appliances. R28 Walls, great insulation and air tight
- HRV

• geo valve is set at 90% opening making the flow at 26 GPM. if we reduce the valve opening, then the water sound is loud)

Here is my issue, after running the system for a month, its awesome and we love it until i got the electrical bill. From a Waterfrunace perspective, the thermostat does energy consumption and is recording that i used 838kW in Jan. Which is averaging about 28 kW per day. No issues there, I only had electrical aux heat kickin for 30 minutes the whole month, based thermostat display. The house consumption for the month was 2700kW. So where is the whole draw coming from? I called my electrician and he brought his probe:

• Geo is using about 5 to 11 amps
• Pump using around 7 amps (consistent)
• I forced the geo to go into electrical aux, and it was using 50 to 65 amps (which is expected)
• based on my simple calculations (7 amps * 230V = 1.6kW/hour. geo runs for 20 hours/day = 32 kW per day x 30 days = 966 kW), the pump is consuming as much power as the geo during the month. The Geo used 838 kW in Jan for geo, the pump is using more. which is really crazy!!!!
• Considering how Cold Jan was what the geo consumed sounded reasonable and within the estimates that was provided by the geo installer
• the electrician measured the power at the panel incoming wires, and it registered 17.5 AMP. (inside the house). the pump and geo were running.

My geo installer suggested to replace the pump with a variable speed pump and controller/drive, but did not recommend any and mentioned that he does not sell them either.

My pump dealer, (GOULDS), has no idea on how to make the pump work with the variable speed control and the geo. My questions:

• what is the appropriate pump size/type or brand or specs for such a system?
• Anyone with a variable speed pump can share pump consumption data.
• If using a variable speed pumps, what is the typical usage of those pumps? brands?
• I know that the thermostat meters power consumption used by the geo, however, the pump is not metered. Can it be metered? Which pump can be metered by the pump
• my pump dealer suggests adding a variable speed controller to the same pump, is this right?
• my geo guy says that the gep demand for flow can range from 6 GPM to 18 GPM. that is why he is recommending a variable speed.
• I'm not sure what to do?

Any help here would be greatly appreciated. !!!!

 

http://welserver.com/WEL0762/

3 x 7 series on a single central variable speed well pump.

You are clearly over pumping. The valve should modulate, allowing only as much water as needed. You should need a maximum of 9 gpm. If this is a new house, why didn't the installer put in a variable speed?

 

Unfortunately situations like this are all too common in open loop applications. Optimizing both the flow and the pressure are crucial to realizing promised efficiency. Most geo systems need just a few pounds of pressure to move water through the heat exchanger. Operating a system needing only 5 or so pounds of pressure with domestic water pumped up to 50 pounds can be the height of folly.

 

In an honest world one gets what one pays for.

 

Thank you for your replies. Anyone with variable speed pump would share pump electrical consumption? What brand of pump and controller?

 

I'm not sure why he did not install a variable speed pump. He mentioned that he never done it before.

 

What is your extracted temp (EWT-LWT) ? In an open loop well system the pumping power is a significant portion of the total power used and needs to be optimized. There is a good paper written by Gary Phetteplace, PhD, PE on the topic. You are paying a lot to reduce water noise!

http://www.efficiencyvermont.com/do...Efficency_Impact_of_GHP_System_Components.PDF

I am just a bit north of you in VT and also have an open loop well system. We have a 420ft well designed for a 5 Ton system using a porter shroud. (way more than we need) We are using a variable speed constant pressure pump capable of up to 20gpm. I have a flow meter in the 1" feed line and when I open up to 15gpm we are using right around 5A @ 230vac. At 11 gpm 3A and at 8 gpm less than 2A.

We also have had to work on the water noise as the valves are partially shut. I control the flow with a ball valve in coming to the heat pump but I also have a set of valves on the return which help me set up the ability to dump some if necessary. When I adjust these it seems to quiet down the flow control valve. Then I use sound insulation...

I can get you the pump model and specs if you would like or get you in touch with the Co who installed. They are close friends of mine and one of the owners has a water furnace installed in his home as well. The pump controller has a wireless output so with the receiver you can monitor the power and temperature of the pump.

Regards, Dan

 

Dan

That is exactly the details i'm looking for. What pump brand do you have? Yes, anything you can provide me would be really appreciated, if you can forward that info or provide them with my info. At this point i'm not getting the efficiencies that I was targetting from the installed system.

 

I will connect you to them. drop me an eMail so I have your eMail dsdillner@aol.com

 

Keep in mind that a 5 ton 7 series is OK with 8 gpm at the highest capacity, so don't oversize your variable sped well pump.

 

He should understand the impact of 6000 annual run hours of a well pump on your electrical consumption, if he installs a 7 series open loop geo system.

 

Update.

My GOULDS pump dealer/installer recommends just replacing CentriPro Model CB07412 with 1AS15 and should solve my issue. Since I did not trust him, I called Gould technical support and they recommended for most optimal performance:

• reduce the size of the pump to 13GS05 pump (1/2 HP, and 3 phase)
• M07432 motor, ¾ HP
• 3AS20 VFD (1 phase input 3 phase output)
• Pressure set to 40 psi to provide 10gpm
• OR just replace pump 13GS05 pump and use the 1AS15

Pump dealer/installer said that Goulds technical support don't know what they are talking about.

I'm not sure what to do?

 

Do you have three phase power?

 

its a single phase power. However the VFD will take 1 phase and convert to 3 phase

 

Will that use less power? Even phase converter usage?

 

Slightly less, it uses 3.9 amps but the calculations are different. so kw used are about 5-10% less.

 

Seems two threads. I'll pick this one.

WF puts out a PWN signal that you can likely use to directly control the VFD and the resulting flow.

 

Neat. I have to look into this.

 

PWM (Pulse Width Modulation)?

 

Yes. I haven't mucked with it (outside of the AID tool). But it is how they control the variable speed pump and secondarily the flow valve. Can't see why this couldn't be sorted out for a variable speed well pump.