Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

KeithNyst · March 2012

Hello, complete Newbie here,
My wife and I will be retiring to a rural, log home in northern Minnesota. The home has water-circulated heat (finned emitters) with dual boilers (propane and wood) in series. The well is 145’ deep with an AC submersible pump; excellent water and lots of it.

The submersible is 10+ years old, so I want to do some thoughtful planning for what I want as a replacement, and do the homework ahead of time. Might even go as far as buying everything ahead and stock-piling in my pole barn.

As a replacement strategy I am thinking contingency, contingency. I want to have the ability to provide water and heat during a long-term grid outage (weeks). By heat, I mean burn the wood boiler and circulate to emitters w/o relying on propane.
• If possible, a submersible that can run on both AC and DC
• If possible, replace the AC pump that circulates the water to the heat emitters in the house with a DC pump
• and have solar panels with battery bank sufficient to power them

This would provide added peace of mind/insurance for a long-term grid issue, whether driven by pandemic, solar flares, weather, … pick a scenario. Water and heat are right up there in priority.

Some design info: Well is 145’ deep. Will be pumping to a pressure tank that would shut off at 40 psi. Well head is 5’ lower than the pressure tank. I am assuming a static water level of 100’ + additional 90ft head for the 40psi pressure tank (40psi/0.433 psi/ft) for a total of 195’ foot of head. I’m thinking a design pump rate of 8-10 gpm (sound reasonable for 2 bathroom and will have kids coming with grandchildren periodically). If possible, I would want a submersible pump that can run AC and also DC. FYI … bulk surface storage is not an option … the state record was set at -60F ten miles away in 1996.

My questions are:
• Is this a technically feasible project?
• If it is, ballbark opinions on cost: <$5k, $5-10k, >$10k?

thanks in advance ... looking to learn a lot. Keith

westbranch · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

Welcome. Look at Grunfos circ pumps for your point #2 http://www.grundfos.com/products/find-product/alpha2.html
yes there are some expensive pumps that work on AC or DC Grundfos, Laing http://laingpumpdealer.com/
hth

pabloesguapo · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

I am building new in central AZ. I understand completely the desire to be ready for anything.

I've been looking around a LOT for pumps that run on both DC (PV panels) and AC (Generator backup). The only two I've found so far that do that are Grundfos and Lorentz.

A member here, tmarch, sells Lorentz. Our forum host, NAW&S, sells Grundfos.

NAWS sells grundfos pumps for just under $2000, the controllers for a little over $300.

I'll let Tmarch tell you what he sells the Lorentz stuff for. It's pretty comparable, though.

NAW&S sells other pumps suited for your other needs at pretty competitive prices too.

Welcome to the forum.

-P.

KeithNyst · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

Westbranch and paloesgapo,
thanks for the leads/infromation. I'll start reading up on the grundfos circulating pumps and the Gurndfos and Lorentz submersibles. I also need to research/understand the factors that go into determining the pump gpm sizing/house gpm demand/pressure tank sizing. With just a little reading, I now understand that the p-tank can deliver "X" gallons before the pump needs to run. I may not need a 8-10 gpm pump to satisfiy 8-10 gpm demand, as long as the demand does not last for extended time (example - I won't be watering lawn with this). Maybe a 6 gpm, possibly even a 3 gpm pump would actually suffice. I think the tradeoff will be ultimately be based on the risk I'm willing to take on not having sufficient flow rates, vs. the solar/battery infrastructure cost differnce to have enough power to run a 3 gpm vs a 6 gpm.

pabloesguapo · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

Someone suggested to me to double up (or more) on the # of pressure tanks you have to address the concern of running too quickly out of pressurized water.

Ralph Day · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

Keith,
I have a Danko booster pump on my cistern system (also have a grundfos submersible on the well). The booster pump pressurizes a big pressure tank. The pump is rated at 2.5gpm, but you don't notice any difference when going through a pressure tank system. The submersible pump delivers 10gpm and uses 1kw when in use. The booster 2.5gpm and 130watts when running.

If the pressure points are the same on both pressure systems (if they're separate, or used at different times of the year like mine) you won't notice any difference in flow or pressure during a shower or whatever. That being said, the booster pump is just boosting, not lifting.

I did some Kill a watt meter testing and found that using the submersible for whole house supply used slightly more kwhrs than the booster supplying the same house. Not much, and you don't hear the submersible pump run;)

Ralph

KeithNyst · March 2012

Re: Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

Thanks Ralph,
How big is your pressure tank and how many people/demand is it supporting? If your 2.5gpm booster meets your household demand via a large p-tank, I'm starting to think that a submersible that would provide 3-6gpm to a p-tank (40psi shutoff) will suffice. Home will be for wife and I, but we will have times with lots of company for holidays. It gets so cold in the winter, I've ruled out trying to use a bulk hold tank with a booster.

Newbie ... Alternaitves for AC well pump and AC heating water circulating pump

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