More backup generator discussion: Backing up well pump in a different structure

   / More backup generator discussion: Backing up well pump in a different structure #1  

rbstern

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May 23, 2011
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Location
GA
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LS MT225E, Yanmar 2210
I started a backup generator/propane tank sizing thread a while back, in anticipation of a new home build. The home site is now graded, and footers should get poured next week.

When done, our property will have two houses: The existing house is becoming our office/shop/guest home. New house will be where the wife and I reside. For water at the new house, I'm planning to branch a 1" line off the existing well system, after the pressure tank, which is in the basement of the existing house.

I plan to install a standby generator for the new house; probably 8 to 11kW, to handle just essential circuits. We have reasonably reliable local utility power. Worst case we've had was a two day outage during Hurricane Irma. Most outages last a few hours.

The existing house doesn't have a generator; I'd like to avoid putting a separate generator in, but the well pump is in the second house, so the standby for the new house will do nothing in terms of keeping water flowing. Trying to think of creative solutions, like maybe a cistern and a pressure boosting pump at the new house, or a dramatically oversized pressure tank. Or, I could use a portable genny for the existing home, in a real pinch/extended outage, although that would be inconvenient.

Here's a very simple diagram of the houses and systems. Suggestions appreciated.

power%20and%20water%20scenarios.jpg
 
   / More backup generator discussion: Backing up well pump in a different structure #2  
When you bury your water line run a 8/3 with a ground back to the old house pump panel. You could always power it from your new house or install a double pole double throw switch in the old house so it could be feed from either location. #8 wire may be a bit of overkill but you will not have the voltage drop that you might have with #10wire.
 
   / More backup generator discussion: Backing up well pump in a different structure #3  
Simply power it from your new house when u lay the pipe in the ground run the power wire.
 
   / More backup generator discussion: Backing up well pump in a different structure
  • Thread Starter
#4  
When you bury your water line run a 8/3 with a ground back to the old house pump panel. You could always power it from your new house or install a double pole double throw switch in the old house so it could be feed from either location. #8 wire may be a bit of overkill but you will not have the voltage drop that you might have with #10wire.

An interesting idea, might even be feasible with a second automatic transfer switch, to keep it automated. Only problem might be with the power company and/or state regs. I've read there are some prohibitions about powering multiple dwellings with a single generator, not sure if they apply to us. Power company engineer will be coming out to assess power run to the new house. I can ask if that's acceptable.
 
   / More backup generator discussion: Backing up well pump in a different structure #5  
Can you put a second over sized pressure tank in the new house? Then you could use a portable gen to power well. Would not have to fire it up as often so less inconvenient anyway.
 
   / More backup generator discussion: Backing up well pump in a different structure
  • Thread Starter
#6  
Can you put a second over sized pressure tank in the new house? Then you could use a portable gen to power well. Would not have to fire it up as often so less inconvenient anyway.

I'm not sure it's better than a cistern and a booster pump. The pressure tanks have big air bladders in them to provide the pressure, taking up a lot of the tank's capacity. Since the new house will already have a pressure tank in line between it and the well, the second pressure tank is not needed.
 
   / More backup generator discussion: Backing up well pump in a different structure #7  
When you bury your water line run a 8/3 with a ground back to the old house pump panel. You could always power it from your new house or install a double pole double throw switch in the old house so it could be feed from either location. #8 wire may be a bit of overkill but you will not have the voltage drop that you might have with #10wire.

Yep the “proper” thing to do is power it from the new house that has the backup generator. You will need to mark the old panel, new panel and the pump controller so someone in the future knows where the heck the power is coming from.
 
   / More backup generator discussion: Backing up well pump in a different structure #8  
You didn't say (or I didn't read) how the two houses are going to be electrically powered. Are they on separate meters, or is the whole property (both houses) all on one meter?
 
   / More backup generator discussion: Backing up well pump in a different structure #9  
You didn't say (or I didn't read) how the two houses are going to be electrically powered. Are they on separate meters, or is the whole property (both houses) all on one meter?

Mossroad, says it on the bottom right of the picture, separate meters.

This is so simple! Just power it from the new house! Bang done!
 
   / More backup generator discussion: Backing up well pump in a different structure #10  
I presume the well pump is powered from the panel in the existing house. I would consider removing it from that panel, and instead connecting it to the panel in the new home with the generator backup. To do this you need a "home run" direct electric line from the new house to the well pump, bypassing the existing house entirely.

If you do this, your standby emergency generator only needs to heat up the panel in the new house which includes a breaker for power to the well pump.

I would not try to have the generator heat up two separate panels in two separate residences-- seems like way too many things to go wrong.
 

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