2 pump system

Discussion in 'Open Loop' started by geopete01, Nov 12, 2015.

  1. geopete01

    geopete01 New Member

    I currently have an open loop 3 ton running off of a shared domestic well. Static water level is about 25 ft or so down and I have a submerged pump (unsure of power). I am planning on lowering the submerged pump pressure to 20/40 or lower and upgrading the tank to an 85gallon then running a separate 1/2 hp jet pump off of that to a 12 gallon tank for domestic use.

    I'm thinking that this should allow the submerged pump longer/less frequent runtimes and also save pumping energy by lowering the pressure of the water put through the geo.

    Anyone familiar with this type of setup? I'm not finding too much info on it but it seems like it would be a sensible way to go. Only downside, I think, is more complicated than one pump/tank?
  2. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Your thinking is on the right track, your execution may be problematic. Data collection should come first.
    1. what size pump is in service now?
    2. how many gpm are you running through your unit?
    3. what is your domestic demand?

    An open loop can be scaled back in gpm to as low as 1 gallon per minute. The pressure required to feed the geo unit can be as low as around 5 psi. A better solution to your puzzle may be to scale down your gpm, reduce your pressure, and possibly downsize your current pump. The knee jerk reaction to un evolved { thanx Doc} is pumping equipment that is oversized in gpm and pressure.
  3. geopete01

    geopete01 New Member

    WP - I don't have records of the pump HP all I have is that is is a sta-rite 10sp40025. Googling that part number gets me no where. I guess I could pull the pump. 1/2 - 3/4 would be my guess.

    You have a great point about the gpm. Right now it is running 3/ton. This is the climatmaster te series so I would need to get ahold of the service tool to adjust the water temp differential for the internal valves (as I understand it). Is there a lower bounds temp to stay above to avoid freezing? It looks like I can go as low as 1gpt as you said. Currently ewt is 49, lwt is 43 so cant go too much lower I would guess.

    Don't forget, since it is a shared system, I can't lower psi without putting in the 2nd pump to boost the domestic pressure. Right now it is one system running 40/60 psi and the geo is feed off of that with a pressure reducer.
  4. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    If the geo is already fed via a pressure reducer, you have done all you can to maximize the operation of your pump in regard to your geo. To prevent short cycling of the existing pump you can add more storage/ tanks/ to extend that interval. The other trick is to fiddle with your pump controls and get your pump to come on and stay on when the geo is running. Pumps love to run, the starting and stopping kills them. Then we get into the efficiency of electric consumption of the pump vs. efficiency of the geo. Everything is a trade off to something... By collecting the data and exploring cost benefits prior to execution you will be wiser for the exercise. If you stumble accrossed the variable speed pump application, I would be careful. The upfront cost is steep and it may not last any longer than your current set up, which may be the right choice in the end. Confused yet?

  5. geopete01

    geopete01 New Member

    The pressure reducer does nothing to mitigate the cost of the energy required to pump the water used by the geo to the 40/60 that my current switch is set at. Every gallon sent through the system is first pumped to 40/60 then reduced to 15. All of that pumping power is wasted. Maybe it's peanuts, but 40psi = 92 feet of head equivalent. That turns my 25 foot static water level into a 117ft of pumping head.
  6. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Gallons of extraction from the well effect pumping levels in wells, not the pressure that they provide those gallons. If it is energy consumption that is driving your wheel, pony up and by a variable speed drive pump. I would be interested what your projected ROI is for that exercise.
  7. geopete01

    geopete01 New Member

    I had to reread your reply a few times - I think you're missing what I'm getting at. I realize that higher psi will not literally lower the static water level in the well. But there is a cost to pumping to higher pressure. In my previous post, I used a formula (1psi = 2.3 ft of head) to try to put the difference in perspective. It's almost 5x the amount of pumping head.

    Valveman explains it better here - https://www.geoexchange.org/forum/threads/open-loop-2-pumps-vrs-1-pump-supply.991/

    I am well aware of variable speed pumps but a 2 pump system (in theory) should be more efficient. A variable speed pump will still spend that extra energy to pressurize the water to the domestic pressure before sending it to the heat pump.
  8. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    Beetle Juice!

    Beetle Juice!

    ChrisJ likes this.
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

  10. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Tell me how the pumps are piped.
  11. pfer10

    pfer10 Member

    I have went to this type of setup a month ago. Pretty much the exact same setup that you suggest. I did this to kill two birds with one stone. One I wanted to run the geo at a much lower pressure than "house" pressure. No sense in wasting energy pumping it to a high pressure then dropping it to go through the geo with a regulator. Two I have iron and iron bacteria and over the summer I collected a chlorine injection system from someone that sold it off as they went to city water. Dividing the two different uses made it easy to run two different optimum pressures that each use needs and I am now I am able to run the chlorine injection only when the house calls for water.

    Last year I had 1/2 hp submerged and 2 parallel bladder tanks running at 30/50 serving house and geo. The 3.5 ton geo was restricted with 1/2" PEX that limited my flow. The flow would change pretty good over the pressure range (no regulator). My well pump run time ratio when the geo was running was about 31% for the pump. That is something Valveman won't tell you as his device makes your pump run the whole time the geo is calling for water even if it is at reduced power it is still running. I bet the reduced power isn't lower than 80% of full pumping power. My power draw for the pump is a little over 925 watts. So while the geo is running my average pumping power is ~277 watts.

    I had one of the parallel bladder tanks become water logged over the summer so I picked up a 86 gallon tank in preparation for the changes to go as big as I could on the geo side. Finished everything up a month ago and so far it is working good. I have lowered my pump run time ratio down to ~19% of the time the geo runs. Should be down close to 176 watts of pumping power average while the geo is running. My pump now runs 105 secs on and is off for 453 seconds. It use to be about 73 seconds on and 164 secs off.

    I did lower the flow to the geo some as I added a Watts pressure regulator at the lowest it will go so it gives a pretty good 20 psi to the geo now. I did replace the feed line from bladder tank to geo with a 3/4" line that is much bigger than the 1/2" pex. (never knew the ID on the sizes was different until the guys here explained it to me). Now I don't get much flow fluctuation at the geo as it has a much more consistent pressure going to it but I still need to replace the 1/2" PEX drain line that is close to 30 - 40 ft after the geo.

    Once I do this I will start to tweak the system more as I should be able to lower the geo and the 1st bladder tank pressure. Doing this helps in several different ways. The bladder tank holds more water operating at a lower pressure and the pump also flows more water pumping at a lower pressure.

    So my system as it stand now is 1/2 hp submerged pumping into an 86 gallon (part number only) bladder tank operating on a pressure switch set at 20-40 psi. On the same line I plumbed in a harbor freight booster pump (remove their junk plastic pressure switch and use a standard bladder tank switch). Right out of the harbor freight pump I put a check valve to separate the system pressures. I then inject the chlorine with a dosing pump as the water enters a 60 gallon mixing / holding tank. Out of the holding tank it goes into a 30 gallon bladder tank (again part number only). That bladder tank had it's own switch that I raised from 30/50 to 40/60 psi. The dosing pump and harbor freight booster pump are both controlled from this switch so the dosage is always consistent. Out of the bladder tank I run it through a 20" filter, then a back washing charcoal filter made from the old water softener that was overcome by iron bacteria and then finally into a new water softener that I built from mail order parts.

    So far the system seems to be working good and I did reduce the average pumping power which is what I was after. Not sure what closed loops systems are at but I got to be getting close. Also no more staining of the sinks, toilets and shower and no iron bacteria growing in the toilet tanks. Really couldn't be happier just from the improvement in water quality and the dual pumps enabled it pretty easily. Now since I got it functioning when I get time I will start to optimize as I think I can squeak out some more performance.
  12. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    What was the cost of the parts you installed? What is the cost to run your booster pump? The combined pumping cost is the true cost of operating your system.
  13. pfer10

    pfer10 Member

    Eric are you asking about all the equipment or just the additional pumping stuff? Just to go to the dual pump setup rough numbers but bladder tank was $310 (I needed to replace the 30 gallon anyway), pump was $135 (screwed up and didn't have a valid 20% off coupon), pressure switch $20, Tank T $35, pressure gauge $10, pressure regulator $40,, 1" check valve $15 and misc fittings etc another $50 or so. Total would be around $650 or so. I needed to replace my water logged tank which a 30 would have run $145 but I wanted to extend pump off time so I went with as big as I could get for another $165.

    The harbor freight pump is 110 volt as my dosing pump I picked up for the chlorine is 110 volts. I need to run them at the same time. HF claims it is 1 1/2 HP pump but it is more like 3/4 hp. It draws 1100 watts. Right now it runs about 32 seconds each run and the 30 gallon tanks holds about 5.5 gallons of usable water at 40-60 psi.

    I don't consider the combined pumping costs as the amount of time the house pump runs is minimal compared to the submerged. When the big tank is fully pumped up it holds ~18 gallons. (I haven't got actual measured numbers yet on the big tank but from what flows through the geo and off time I know it is close to 18 gallons give or take some. So my 1100 watt pump might run 2 times before the well pump was to run again on just house use. So yes there is more pumping cost for the house but they don't always run at the same time every time. I can take a shower and only have the booster pump come on twice.

    Yesterday my geo run time was 9 hours 3 mins. Last year my run time ratio of the pump was 31% of the geo time. So .31 * 9 * 0.925 kw = 2.6 kWhr that my pump contributed while the geo called for heat for the day. Now I am at 18% so .18 * 9 * 0.925 kw = 1.5 kwHr of pump energy. Multiply by 30 days and that is 77.4 kWh compared to 45 kWh or a savings of $3.56 at $.11 / kWh. Payoff would be 15 years if I used 9 hours everyday of geo. Like I said the geo pump runs far more time as I don't use much water in the house. Laundry every 3 weeks, 1 shower per day. 4 - 1o toilet flushes per day.

    These numbers are just what I can remember. I would have to go look at last years data as I know how much runtime per degree day I averaged last year based off 65 degrees to get real good numbers on what I actually use over a heating season. If I take the difference of the big tank off it is more like 10 years as I needed another pressure tank anyway as I had parallel tanks before to get my pump on/off time up. I figured I would spend the money on the biggest tank now to get the number even higher.

    I don't have anyway of recording how much the house pump runs right now but I will see if I can get the ratio of it's runtime compared to how often it makes the submerged pump run. I have tried the house pressure pump without any pressure boost from the big tank and it is able to suck water from the well and pressure the house. I haven't checked flow using it that way but I figure that pump doesn't have much strain on it since it is only taking 20-40 psi and raising it to 60 psi. If I wanted I could put another check valve upstream of the house pump and before the large bladder and only run 1 pump independently as the 20-40 psi wouldn't push back to the house pump. Then the house pump would always have to draw from the well. I didn't do this because some for some months in the spring and fall the geo doesn't run for weeks at a time so I figure it is best to get some water moving when I use the houses capacity it mainly comes from the big bladder right now.

    How much does a variable speed run these days?
    urthbuoy likes this.
  14. waterpirate

    waterpirate Well-Known Member Industry Professional Forum Leader

    I was not being aggressive, just curious as to what the exercise cost to install and operate. A variable speed pump still costs bunches and I do not advocate them unless needed. In your case and the OP case I felt it was a re-invention of a mouse trap that worked fine, unless you are off the grid. If off the grid then every watt must be accounted for. If on the grid, it is a solution to a problem that was not that critical.
  15. pfer10

    pfer10 Member

    Eric understood. I have looked at the costs and know the payback isn't that great. I just figured I am in it for the long haul and if I can make the submersible last as long as it can it isn't going to hurt anything. If the submersible goes out at least I can still have house pressure but no geo without a little re-plumbing. Hopefully that won't be for a while as I lost it a couple years ago when a fitting broke outside and burned up the pump overnight. I'll get to tweaking after my trip next week and see if I can get the geo operating pressure down once I remove the restrictive 1/2" PEX drain line.
  16. geopete01

    geopete01 New Member


    Thank you for sharing..

    It sounds like you have it setup the way I was thinking except I would not be doing the chlorine injection system. Curious if you are able to get the pressure down after replacing the line. Seems like 10/20 would be better (or lower?).
    How many gpm would you estimate you are putting through your geo?

    It sounds like for cost savings I really need to know what my well pump uses. I guess I should invest in one of those clamp amp meters.

    I did measure my well cycle time when the heat pump was running and it is cycling every 2.5 minutes - 24 times/hour. Running all day, that would be 576 times per day. I already have the 85 gallon tank to replace the 12 gallon one which should reduce the cycles greatly.

    I did consider variable. Was quoted $3600 to have one installed. My understanding is that they are not much (if any) more reliable than a standard well pump. Can't imagine the payback on those to be much better - or is it?
  17. geopete01

    geopete01 New Member

    waterpirate - I didn't mean to lead you down the wrong path with the valveman link. I'm not suggesting a CSV and I wasn't aware of his pushing them when I linked his post. When I searched, I didn't find many posts on running 2 different pressures. Could be because open loops are loosing popularity or because the payoff would be too far out...

    Here is a crude drawing. http://i.imgur.com/pYEGHVA.jpg
  18. geopete01

    geopete01 New Member

    Installed the 85 gallon tank today and now the runtime is 14:40 for each cycle. 67% of the cycle the pump is running. Heat pump is using 5.5 gallons per minute. I plumbed in a valve to add the booster pump in the future.
  19. pfer10

    pfer10 Member

    Geopete the tanks are built to run at a 20 psi differential. You are leaving some capacity of the tank on the table by only cycling it from 10 to 20. You might adjust up to 10/30 to see how much you can get to see if it is worth it. The pump will work against an additional 23 ft of head which will decrease the flow some. Increasing your cycle time is a big improvement and it should help your pump last. Do you know how many HP your pump is? At $3600 I can replace a lot of pumps and tanks. ;-) A variable speed will be less reliable as it has more stuff to go wrong unless you are just treating your pump wrong. The SQE setup can be had for $1400 or so. The pump has the inverter built in it so they could use the single phase wiring of the old pumps they replace. With the inverter built into the pump the pump runs about $900. The other way is to have 3 phase wiring to the pump and have the inverter inside. Probably a better setup but not feasible unless you plan the wiring from the start of the well build.

    I was gone for a week and just haven't had the time to replace my restriction yet so I can't give any feedback there.

    I don't have a feel for how much the power is reduced when the pump is dead headed like it is with the CSV but I doubt it is 33% like you are getting now as with the CSV your pump would run 100% of the time the geo was on. You do still have some startup power each cycle by they are short lived. It does seem that a particular pumps power will be reduced when the CSV is doing it's thing but mine sure didn't decrease any that I could see. I am getting a much better savings by reducing my % on time.

    Have you looked at your in and out temps at the geo? You are doing good with 14.67 minute cycle times as mine is at 9.3 minutes (unless we are saying different things but comparing the number). Our numbers seem to be far off though if you are flowing 5.5 gpm. Have you actually measured your flow? One thing that might be good is at 10/20 the tank bladder might last longer as it shouldn't have to stretch as far but that is a guess on my part. I suspect most tank failures happen when people don't check the pressure in the bladder and it loses some over the years then gets stretched more than normal since the water pressure is working against less air pressure buy could be totally wrong on that.

    I would be interested in seeing why our numbers are so far different as my unit is 3.5 tons but from my calcs last year I am only putting out about 3 tons of heat. My entering water temp is usually around 55F or so if I remember right. I didn't run my data acquisition all summer and when I tried it this winter it didn't work right so I need to tinker with it. Just haven't had time as when I made the changes I have the unit is working good so not really a priority.

    Also I don't think waterpirate meant anything wrong with his odd response when you mentioned valveman. Valveman just had bad internet social skills and seemed to get banned on many forums he would visit. I am not sure if he is banned here or not.
  20. geopete01

    geopete01 New Member

    pfer10 - I haven't installed the buster pump yet so I am running the entire system at domestic pressure until I get the booster installed. I actually have it set at 35/60 currently - that might be the difference in run times we are getting. The gpm of the well pump will affect it as well. Your pump seems to be filling your pressure tank with much less runtime. I wonder if I might have some mineral buildup on the well line to house or something causing a restriction... Unfortunately I don't know the HP of the pump.

    I measured water flow using an analog gauge that I have in line with the discharge line. How many gpm are you using?

    EWT is 49 LWT is 43. I might be able to lower flow a bit but I'm going to wait until it has really gotten cold outside to see if the EWT gets any lower. Climatmaster doesn't recommend going much lower than 40 for LWT from what I gather. 5.5 gpm is running in 1st stage, 2nd stage is 9 gpm.

Share This Page