Adding a VFD to open loop geothermal system
Last Post 24 Feb 2020 02:17 PM by tkb4. 107 Replies.
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ValvemanUser is Offline
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15 Jul 2019 02:30 PM
tkb4 already has a CSV. He has had it for years, and is trying to tell you how good it works. Again you have not posted a pump curve to show "pumping the water to a high pressure" uses any more energy than "targeting flow rate only". You are just spouting off about things you think are true, but can't post a pump curve to prove it, because it is not true. I am not trying to sell a valve. I am trying to keep you from selling a load of Bull. Even a regular pressure tank system will beat the energy costs of a VFD. That maybe "How you did it". But it is "Sad.....lots and lots of money lost that you don't even realize.


cyclestopvalves.com
tkb4User is Offline
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16 Jul 2019 02:55 PM
I have the grundfus 10sq07 240 this is a 3/4 hp pump grundfus makes their model name gpm model type hp hp is 05=1/2hp 07=3/4hp 10=1hp etc the last number has to do with head rating but more difficult to describe. So mine is 10 gpm sq model 3/4 hp and the pump is at 160 feet 1 1/4 inch downpipe and static about 130 feet. I replaced previous owners 3hp Franklin pump. Don't know for sure the flow rate of well but judging from filling pool etc in past with the 3 hp its over 30 rpm. I considered VFD but several things affected my decision such as ability to save money and effort with DIY, cost of pump about $300 more the cu-301 controller about $500 the possibility of cu-301 lasting just a few years. I had to replace large bladder tank that leaked so either one would suffice. for about $800 more and only spending about $45 a month or less (rate .10 per kwhr) and the CSV costing $63 even if VFD saved 1/2 of pump energy costs over CSV savings it would take 3 years to break even .I doubt the VFD would save near that much since when geo on the pump is using significant portion of its max flow especially on stage 2 mostly in winter. If I had buy a large tank another several hundred dollars and much longer payback. The biggest consideration to me is the VFD would still be pumping at a large percentage of capacity much of the time . My well max supply is a about 11.5 rpm as measured by me at hydrant a few feet from well. The 3/4 hp pump was essentially a perfect match for what I required.


tkb4User is Offline
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16 Jul 2019 03:29 PM
I forgot to mention that my well is across wide asphalt driveway from the house thus added cost to make changes at well and changes on house side of driveway must be done in about 2 1/2 foot crawlspace or create a mechanical room ( I didn't build the house).


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14 Feb 2020 01:28 PM
I'm considering switching from a 2 pump system to a VFD like the PID10 - similar to your system Nathan. Are you still happy with the setup? Where do you source a PID10 at a reasonable price?


ValvemanUser is Offline
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16 Feb 2020 01:27 PM
You should check into how the PID works. It only runs for 1 minute at a time no matter how much water you are using. The PID runs the pump at any set speed for 1 minute, shuts the pump off, lets the pressure tank drain, and runs the pump for another minute. All the PID and two wire VFD's work that way. They are just glorified pressure switch on/of systems, not true variable speed.

I think the Intelitek series is the only one that really has variable speed. It just has a lot of settings to make it work properly, which is why they make the plug and play pieces of junk like the PID.


cyclestopvalves.com
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16 Feb 2020 04:25 PM
In our rebuild (post-fire), once I decided to go VFD, our plumber put in the Pentek Intellidrive system, driving a Waterfurnace Series 5 (and the rest of the house), and it's been flawless. He also put in a normal pressure gauge so I can see the "real" pressure, and it sits at a constant 58psi no matter what's happening inside, with maybe a 1/2psi fluctuation under load (ie, furnace and a tap or two).
Originally I wasn't going to, but decided the old well pump (Grundfos), while working fine pre-fire, was approaching 10 years old, and I didn't want the risk or failure. So we got a new pump plus the Intellidrive. And it turns out during the install that the pitless adapter at the well was cracked (10ft underground!), which we'd never have found if I hadn't gone for a replacement. So the builder had to dig it out and replace it (amazingly, at no extra cost to me).
I think the whole kit'n'kaboodle was around $4k (installed), but I consider it money well spent.


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16 Feb 2020 05:26 PM
Yeah "Intellidrive", not the PID. Big difference. Now we just need to know how long it and the pump last? Plus, it was probably about 2K more than a standard pump.


cyclestopvalves.com
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24 Feb 2020 02:17 PM
Update: I have had no further problems with anything associated with my well or climate master T064 or CSV valve to date going on 3 years now. My pump is the Grudfus 10SQ07 and it uses about 5.8 amps at highest draw but it is still pumping well water at about 50 psi. I have not found the time to run a dedicated line to the geothermal unit yet but would expect it may decrease amp draw to about 4.5 or less amps at that time. Whenever I get that done I will update here.My absolute highest electric bill since installation of that system is $299 and that also includes all electric appliances and running another 3 ton HVAC 21 seer and occasionally a 2 ton 13 seer unit in a separate portion of a 6500 square foot house.


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