Category Archives: Interior

Mar 02 9 comments
Electrical, Interior, Solar Energy

Solar power backup for the basement sump pumps

I am working on the design for the sump pump solar powered backup. There are several design criteria that need to be considered. These are:

  1. The size of the electrical load.
  2. The amount of usage.
  3. Length of potential independent operation e.g. power outage
  4. Cost effectiveness of the design

First consideration is the actual electrical load that will need to be satisfied. The pumps are rated at 0.3 HP each. The name plate rating gives the voltage as 115 volts AC, 9.7 Amps. Ohms law states that:

P=IxE

Where P is the power in Watts, I is the current in Amps and E is the Voltage. So we have Pwatts= 115 Volts X 9.7 Amps = 1115.5 Watts. That seems like a lot for a 1/3 HP motor.

I find this curious. A unit of horsepower is equivalent to 745.6 watts of electrical power. A mathematically inclined person might take 745.6 watts and multiply it by 0.3 and get 223.68 watts. However, motors are not 100% efficient, so some efficiency factor needs to be figured into the equation. A conservative guess would be a motor is 60 percent efficient. If you take 100 percent and subtract 60 percent you have 40 percent, which is energy that is lost, usually due to heat. Therefore if you take 223.68 watts and multiply by 1.4 the result is 313.15 watts. Using Ohm’s law, P=I x E, The result for 313 watts/115 volts = 2.72 Amps.

Sump pump AC current

I decided that I needed to confirm the power being used by the sump pumps. I did not bring my Kill A Watt meter home with me, so I used my clamp on ammeter to measure the current in the power cord going to each pump. Sure enough, as the picture shows, 10 amps. Bad power factor? It must be, I can imagine a motor that would be that inefficient. Power factor is something that can be fixed, some Saturday when I have a little tinkering time.

Regardless, the first result of 1115 watts holds, so that is the load we will have to calculate for. Their are two pumps in the system, so the total possible load will be 2230 watts when both pumps are running.

I am looking for a somewhat unique operation. What I want to do is power the pumps with the solar panels if possible and have the electrical grid available as a backup. Included in this would be some amount of reserve power in case the pumps need to run when the batteries are discharged and the grid is not available. This will give me the best of both worlds, using the PV panels to off set our electrical use for the pumps and providing a back up power source for the pumps when the grid fails.

Xantrex makes the DR 2424 inverter that has a battery charger built into it. This will work well in this application with a few external control devices to connect the grid power to the battery when the battery voltage indicates a 50 percent discharge state. It has a continuous rating of 2400 watts with a 6500 watt 5 second surge capacity, which is needed when starting motors.

The battery bank size needs to be calculated. This is going to be quite large because of the inefficient motors. I will use the basic 1 hour time unit for calculations. To run the pumps for one hour will require that the inverter provide 2230 watt/hour. The inverter is 96 percent efficient, therefore, 2230 watts x 1.04 = 2320 watts from the battery bank.

To convert this to Amps, divide by the battery bank voltage, which will be 24 volts, so 2320/24= 97 amps. Therefore, to run both pumps for one hour will require 97 Amp/Hours (Ah) of storage. However, the pumps do not run continuously, rather, they cycle on and off. The old main sump pump was never on for more than 50 percent of the time, even during heavy flooding. Often times it was much less, more like 10 to 20 percent of the time. Pump number one is in the same position as the old main sump pump, so I will assign a 50 percent duty cycle to that unit. Pump number two is on the other side of the basement, where it seldomly runs. I will assign a 15 percent duty cycle to that unit. To properly calculate the duty cycle we need to divide the total load by the number of pumps, then calculate the duty cycle load for each pump. Both pumps running will draw 97 amps. Divide 97 by 2 = 48.5 amps. 48.5 amps x 0.50 percent = 24.25 amps and 48.5 amps x 0.15 percent = 7.28 amps. Therefore, add the two pumps together and the amp hours (Ah) under average conditions is 31.5 Ah.

I would like the system to run autonomously (without input from the grid or solar panels) for 48 hours. 48 hours x 31.5 Ah = 1512 Ah. I would like to operate the battery bank so that in never exceeds 70 percent discharge voltage, so 1512 Ah x 1.3 = 1965 Ah battery bank storage capacity.

I would like the batteries to be charged by two 150 watt solar panels. This will require the solar panels, mount, and charge controller. I want the PV panels to operate at maximum efficiency, so I will be using a passive tracking mount and an MMPT (Maximum Power PoinT) charge controller. Both of those items will increase the amount of power from the PV array by about 25-30% each.

Finally, I would like the batteries to be disconnected from the inverter and recharged when they reach the 50 percent discharge voltage, which will require something with a low voltage disconnect relay. Here are all the parts:

Total cost $4,118.00

This system qualifies for both State and Federal tax rebates. The Federal tax rebate is 30 percent of the cost, capped at $2,000.00 and the New York State rebate is 25 percent of the cost capped at $5,000.00. Apply those rebates to the total cost:

0.30 x $4118 = $1,235.00

0.25 x 4118 = $1029.50

Therefore, $4118 – 1235.00 – 1029.50 = $1853.50 final cost for the whole backup system.

Hmmm, looks like I found a good candidate for my Federal tax refund coming in May. The contractor offered a back up system that consisted of a separate battery powered pump that was rated at 1/2 the pumping capacity of the main pumps and ran for 12 hours. The cost of that system was $1,000.00. I believe my system is much better than what they proposed.

Diagram:

pv powered sump pump backup system diagram

Click on picture for higher resolution version.

Popularity: 12% [?]

Feb 29 4 comments
Interior, Structure

Basement Wet? or Basement Dry?

It has been about four days since the AmericanDry Basement people finished their work here, but it is looking good.

Before:

basement before waterproofing

After:

Basement after french drain installation

I am working on the solar/battery back up system plans.  There was a battery back up pump system offered with the system, but I think I can do better for about the same cost.  What I want to do is have a 2120 Ah battery bank and a 2400 watt inverter connected to 300 watt or greater solar panel.  This will operate on solar power most of the time.  If the battery bank drops below 50 percent discharge level, it will switch to the AC grid power to power the pumps and recharge the batteries.  This will give me about a 30 percent reserve (in case it attempts to switch back to AC power during a power outage).  The idea is to provide back up power and offset some of the power used by the pumps.  I will also run the Solar Hot Water system off of this set up.

The grid seems to be pretty reliable around here.  The longest outage was for about 10 hours after we had a tornado touch down about 1/2 mile away.  Other than that, we have had perhaps two or three other outages of about 2 hours or less.  It helps that we are only about a mile away from the sub station.

I will do a separate post on how I sized that system and other considerations for the design.

Popularity: 8% [?]

Feb 26 12 comments
Interior, Structure

How to water proof a basement, Part II

The contractors came back this morning and stayed until the job was finished, which was quite late. Here is what they did today:

  • Placed the ADS drainage pipe in the trenches they made yesterday
  • Placed two drainage basins in opposite corners of the basement
  • Installed two Zoeller 1/3 HP M53 cast iron effluent pumps, one in each basin
  • Piped the pump outputs to the existing sump pump drainway
  • Filled the trench with gravel
  • Drilled weep holes in the base of the cinder block walls
  • Placed plastic drainage mats against wall and around the footings
  • Patched the floor where the trenches were opened with 5000 PSI concrete
  • Used “Super Slurry” (a mixture of KIM and Portland cement)on the walls and patched all the horizontal and vertical cracks in the walls

Here are some more pictures:

4 inch perforated ads drain pipe place along the inside of a foundation footing

4 Inch Perforated ADS pipe placed along the footing.

footing drainage trench filled with gravel

Drainage trench filled with gravel.

plastic drainage mat placed against block wall

This is a plastic drainage mat placed against the cinder block wall. Each row of cinder block cells had a weep hole drilled in the bottom of it. This plastic mat ensures that any water collecting inside the cinder blocks drains out and is conducted to the under slab footing drain. The bottom 24 inches of each wall had a coating of “Super Slurry” applied to repair water damage to the cinder blocks.

basement sump with zoeller m53 pump

Basement sump with Zoeller M53 cast iron effluent pump. These pumps are designed for rugged service and can pass solids up to 1/2 inch.  Each sump has a high water alarm which will go off if the pump malfunctions.

sump basin in corner of basement

Finished corner sump with cover removed.  The covers were put in place before the contractors left.

basement drain floor resurface

All of the trenches were resurfaced with 5000 PSI concrete.

floor drain in front of stairs

They even installed a floor drain in front to the stairs that lead to the BILCO doors.

Needless to say, they were here quite late completing all this work, leaving around 10 pm. They did a great job cleaning up all the mess and carting away all the rubble and debris.  We have a written warranty (the only kind there is) that states the floor will be dry for as long as we own the house (provided there is power for the pumps).  This warranty is transferable to the next owner.  I would say the American Dry Basement is pretty confident that this system will work.  I will post an update in a few weeks and let you know what I think.

I am going work on a solar electrical system to power these pumps. I think that would be the best way to back up the system in case the electricity ever goes out. Also, these pumps will likely be running often and I would like to off set some of that electrical use with the solar PV system.  I don’t want our de-watering efforts to drive up our electric bill.

Popularity: 8% [?]

Feb 25 3 comments
Interior, Structure

How to water proof a basement from the inside out, Part I

I knew this would take longer than one day, in spite of what the sales man said. The American Dry Basement crew showed up here around 9 am and got right to work. I drained out the solar tank and moved it out of the way, along with the two water filters. One thing to note: It appears, upon inspection of the pipes, that the water filters are doing a great job getting rid of the iron in our well water. The pipe coming from the well has a good coating of orange rust on it, the pipe leaving the water filter is perfectly clean.  I’ll have to do a separate post on that later.

The contractors are very thorough, covering all of our stuff piled in the middle of the basement with plastic. Even though the floor was covered in water, the jack hammer still created some concrete dust.

American Dry Basement contractor using jack hammer

They began by jack hammering around the perimeter of the basement floor, leaving several connectors in place. This created a pretty good size trench. It was good to see the footing and know that it was poured correctly. There is hope after all. After all the concrete was jack hammered, the debris was loaded into 5 gallon buckets and carried upstairs to the truck. They will get rid of all that waste material for us by taking  it to a recycle center in Danbury, CT.  There it is ground up and reused, which is nice. The 5 gallon buckets were used on the return trip to carry number 2 gravel downstairs.

American Dry Basement installation work drainage trench

Another view:

American Dry Basement work

Looks like a mess and that water is cold.  I don’t envy these guys one bit, they are earning every penny we are paying them.

Before they left for the day, a Zoeller M53 effluent pump was dropped into one corner to get some of the water out.  Then they can install the perforated pipe and drain basins.  We will have two drain basins and two pumps, one on either side of the basement.  They will be back tomorrow to finish the job, so check back for more pictures.

This whole thing is happening so fast I have not had a chance to draw it out.  When I have the opportunity, I will draw out some details and get a parts list together.

Popularity: 7% [?]

Feb 24 4 comments
Interior

The basement water proofing prep work

I spend a good part of yesterday prepping the basement for the contractors to come and work on it.  I had to move everything that was near the walls so they would have room to work.  I tried to give them as much room as possible, however, in some areas all I could manage was 3-4 feet.

basement before waterproofing

The things that I have not moved yet are:

  • The solar storage tank.  When I did this project, I connected everything with pipe unions.  In theory, it should be pretty easy to drain the tank, loosen the union and move the tank out of the way.
  • The backup hot water tank.  Same as the solar tank, all plumbing connections have unions.  I will have to remove the electric from this tank, this is on a flexible whip.
  • Water filters.  Operate the bypass valves and use the quick disconnects.  Also pretty easy
  • Water tank.  I hope that I can avoid moving this if at all possible.  The pressure tank plumbing connections have unions like all the other plumbing fixtures.  This also has the wiring for the well pump pressure switch.  If I remove all of this, the house will not have any water until they are done.  That is not the end of the world, but it is inconvenient.

The sales guy said they can work around the furnace and oil tank.  Good thing, that.  I have no intention of moving either of those.  There is still a large amount of water on the floor, which I was told, would not be a problem to work in.

Popularity: 3% [?]