Unorthodox open loop pump.

Discussion in 'Open Loop' started by pfer10, Jan 24, 2015.

  1. pfer10

    pfer10 Member

    Last year I had a water leak right by the well casing where there is a hydrant hook up. A fitting ended up snapping after it sprung a pin hole leak. I had to dig down and fix the fitting and replace the well pump as it burnt up during the night pumping wide open. When I dug down the hole filled up with water that I had to pump to work on the fitting. Water was also slowly running out of the well supply line so the water table was really high. I have noticed sometimes my water level in the well is over the top of the pitless adapter.

    So I got to thinking about pumping power as I am using a 1/2 hp 4" submersible pump that uses about 900 watts running 30-50 psi. With my current bladder tank setup it runs ~30% of the time that the geo is on or avg of 300 watts plus start up surge. (73 secs on 164 secs off). So with the high water level and the water inlet being in the basement I thought the water level in the well might be close to the basement floor level.

    I ended up getting a circulator pump (Stiebel Eltron CP3S15-62FC) and using it directly off the well line. I seem to be getting about 4 gpm using 95 watts flowing to a bucket. I hooked it up to geo but flow dropped to 1.5 gpm. They used 1/2" line and there is probably 75 ft out to the dump leach field. When I am flowing to the bucket at 4 gpm that equates to ~14 ft of head. Problem is I am just dumping to a bucket so my head is coming from "drawing" the water from the well. I assume this is worse as pumps like to push.

    My question is if I upgrade to 3/4" line to pass thru the geo and out to the leach field do you think I will still flow close to 4gpm? Will always "drawing" water instead of pushing it wear out the pump faster? I believe my dump point should be lower than the water level in the well so It might also syphon a little if I am lucky.

    My other problem is I plan to check valve off the pressure tank but if someone uses water in the house while the geo is running and the submersible turns on then I will be flowing a bunch more out the 3/4" line than I do out the 1/2" line now. Any ideas how I can get around that? Here is the test setup. The black line from the top is the supply from the well. The blue line to the left goes to geo.

  2. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    You'll likely have to ensure both pumps run when your heat pump comes on.
  3. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    What you need to pull this off is a twin pipe pitless adapter. One pipe for domestic supply with your submersible, the other pipe for your pump to supply geo. Another option would be to install 2 pitless units on the well you have now. We install a lot of variable speed pumps to cover the fluctuating demand of domestic and geo. We have also installed 2 submersibles in 1 well to get it done. 1 pump for domestic, 1 pump for geo. You are only going to be limited by your imagination, and the money to satisfy that curiosity.
  4. pfer10

    pfer10 Member

    Thanks Eric. I didn't even know they made a twin pipe pitless adapters. I thought about doing 2 pitless adapters but I have this odd one that is full circle. It seals with two large o-rings. The only way to do it would place another below the full circle. Pull the full circle up and then move it to the side where I could get the disconnect pipe down to pull the other one up before the pump comes up from the first. Pretty sure the pump would never go by a pitless that was left in the pipe.

    How much restriction is there pulling through the submersible? I never knew you could do that until I tried it. It is good to know as I can get a hand pump and keep it in the basement in case I need water during a long power outage.

    One other thing I thought of is put a pressure reducer upstream of the circulator pump but I wasn't sure how much it would restrict the pump trying to pull through it under a vacuum. Then when the submersible turns on I can regulate what psi that gets through and I don't have 30-50 psi water blowing out a line that was designed for no head loss.
  5. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Everything you have described will work. The pressure reducing valve is a must have in any geo/domestic shared system IMHO. Have fun with it and be safe. If the modifications to your well get to involved, reach out to some local talent for a reality check on what you have planned.
  6. pfer10

    pfer10 Member

    In agreement there. After seeing my flow through my geo vary from 3 GPM to 4 GPM from the pressure tank running from 30 psi to 50 to psi the pressure reducer is a must. I was going to pick up a Watts LFN45BU-M1 but it is only adjustable from 25psi - 75psi. Right now my geo has ~20psi back pressure from the coil / valve and 1/2" dump line. I plan to minimize that first to get an idea where I am at then go from there. I have picked up 3/4" pex line and will replace the 1/2".
  7. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    What is the ID for that 3/4 pex? I would use pvc. The pipe is cheaper as well as the fittings. It is also less prone to water hammer. than some pex installs I have seen.
  8. pfer10

    pfer10 Member

    ID is 5/8" for the pex that I bought. Checked one of the brass swivel fittings and the ID is 9/16". I do hear water hammer every now and then but there is full well tank pressure over to the geo as the sprinkler valvle is downstream of the coil that the Geo controls. (Use to be before the coil when I moved here)

    The problem with PVC is there is ~40ft of 1/2" pex down this drain. They just coupled it together through the PVC fitting shown below. Exact duplicate on the other side of the PVC plug along with ~40ft of 1/2" pex. I guess that is just to ensure the water gets away from the basement.

    That goes out to what I think is a long leech field. I can see the depression where it was dug across the creek out back. They have an open "up" stand pipe right at the creek (~100ft out from the basement drain) I assume for an overflow if the leech field ever backed up. I have never seen it flow up out of that pipe although the rust color on the outside indicates it has. The well has some iron bacteria that I try to control.

    I borrowed a buddies laser level and his elevation rod and I plan to map that all out. I would like to shoot the elevation of the basement floor, top of the well casing and the top of the stand pipe at the creek. I believe the drain at the creek is lower than the water level in the well.

    If anyone has syphon experience I would like to hear it as I am just experimenting right now.
    Last edited: Jan 26, 2015
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Remind me. How many tons is the unit?
  10. pfer10

    pfer10 Member

    3.5 tons. I am working towards tightning the house and adding insulation as I would like to replace the unit (10 years old) with a 2 stage 3 ton before the 2016 credits expire. Right now with 3 to 3.8 GPM and EWT around 55F I am extracting around ~23k to 25k at 14.2 amps @238VAC.

    I believe 3 tons will do it with a little work. At around 10 degrees with no sun I run full time to keep 68F with some air leaks that need fixed and stock 1960 attic insulation. Located just a few miles north of Indianapolis. What design temp would you use here?
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I would need to do a bit of work to get a design temp for loops or conditioned space.

    I find that as I "mature", I am more comfortable at 73* than 70* maybe it is the conditions in the cave that I inhabit. The rest of our home is warm but I compute from a room with windows on two walls and outside exposure on the same two walls. The house was built in 1929 or so and I have 4 point Hudson's Bay blankets as drapery. I think it is the middle of the night at noon.

    Let us return to your unit. Spring will get to Cleveland some day.

    I will let Eric handle the incoming water, as he owes me a beer.

    Your piping leaving the HP is the red pex in the photo? It dumps into 3" PVC going out through the yard and ends up at the iron stained riser near the creek? There is a tail in the drain?

    What I see here is sort of a GIGO.

    I do not think you have enough flow through the machine to let it do what it can.

    I will take on the exit water only.

    In the Grundfos handbook on page 78 the maximum flow through 1/2" pipe is 3.2 gpm. Your calculations agree.

    Your unit is older as I recall, please correct me. It could be running R-22. R-22 systems want 3 gpm per ton to do the best they can. Guess what the 3 gpm is the same for R-410A units. They changed the sizing of the heat ex-changers to allow for the higher pressures.

    You need 3 gpm per ton, not total. 3 GPM X 3.5 tons = 10.5 gpm to the machine so it can be all that it can be.

    I am only doing the out it is up to you and Eric to do the in.

    Referring to Grundfos again, same page, 1" pex might get you 9.5 gpm. CPVC, which Eric recommends, could handle 10.9 gpm. CPVC is Cooper tube size, (CTS).

    How ever you pipe it you need more flow, if you want the best comfort for your utility bills.

    Find the pink cat or all of his buddies and raise the attic R to 30 or more. Caulk. Weather strip. Seal and so on.

  12. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Mark is correct as usual. On the incoming side I am also concerned with flow rates and friction loss. Having born witness to many clusters put to together with shark bites and pex pipe, I am not a fan. I prefer the IPS or CTS which has tables and charts for feet of pipe and fittings.
  13. pfer10

    pfer10 Member

    Yea it is R22. I'll look at getting more flow to see if performance comes up. Should be easy enough to get something setup to try it. Never liked the 1/2" line on there. What is even more troubling is the line from the well is only 3/4".
  14. pfer10

    pfer10 Member

    Eric what is IPS?
  15. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    IPS = iron pipe size.

    CTS+ copper tube size.

    Flow difference is not a deal breaker to most.

    PVC is IPS

    CPVC is CTS

    Pex IS CTS
  16. pfer10

    pfer10 Member

    Just noticed this in one of the suppliers manuals:

    Supply and return water piping should be limited to copper, HPDE, or other acceptable high temperature material. Note that PVC or CPVC material is not recommended as they are not compatible with the polyolester oil used in R-410A products.

    Wouldn't you have worse problems if the oil is in the water?
  17. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    I would think so.

    I think I will find some oil and dip PVC and CPVC into it and see what happens.
  18. urthbuoy

    urthbuoy Well-Known Member Industry Professional Forum Leader

    It's one thing to have a refrigerant leak in to your water supply. It is another thing to have a water leak in to your basement.
    Palace GeoThermal likes this.
  19. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Not to besmirch any manufacturer..... but the manuals are crap. That statement may apply generally to a closed loop, but not to a open loop. The manuals make little distinction between the two, just broad sweeping statements. Generalities if you will. The discussion we were having related to the friction loss and lack of capacity in your pex pipe to deliver or reject the required amount of water in the open loop side of things.
  20. pfer10

    pfer10 Member

    The section talking about the oils was in the open loop section. I would assume they are worried in a pressure situation the oil must weaken the strength of the pipe. In reality you really shouldn't have pressure with an open loop. Unfortunately my system has 20psi at the exit of the coil right now. I took a Dole flow restriction device out since I figured it wasn't doing anything. The 1/2" line at 60 - 70 ft total is my restriction.

    I am confused about something else though. Right now with my flow I get about a 15 degree delta 55 to 40. Why would increasing the flow pick up performance? Mark mentioned r22 needs 3GPM. So if I bring my flow up why will I see an increase in performance? Isn't BTU extracted BTU extracted? Why does it matter how I get there? It must be something in the refrigerant cycle that I don't understand.
    Last edited: Jan 28, 2015

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