Archive for the ‘Water Systems’ Category

Hot Water

April 21, 2015

indirect-hot-water

The other day, my son asked about swapping out his current hot water system to an electric hot water tank.

He currently has what is called an indirect hot water heater that uses a zone off his oil fired boiler to make hot water. (See diagram)

There were a number of reasons why he considered doing this.

First, he has electric solar panels on the roof of his house which have lowered his electric costs significantly, so he thought an electric hot water tank might save money.

Second, in the winter, he had issues with his existing system providing enough hot water when he needed it for his morning shower.

Lastly, in the summer, he felt it was not efficient for the boiler to come on and heat up boiler water so it could produce hot domestic water.

electrical-hot-waterHe thought that maybe a stand-alone electric hot water tank (see diagram left) could cost less, provide consistent hot water, and be more efficient.

He asked me what I thought.

Before I tell you what I told him, I want to point out that  there is no simple answer. There are many variables in determining the ‘best’ way to produce hot water.  Variables, like what kinds of fuel are available, what type of budget one has for the initial cost of the equipment, monthly usage cost, and annual maintenance cost.  Also, where he lives enters into fuel costs and availability of expertise in the various solutions.  Other variables are family size and  hot water usage or demands.

Finally, technology and efficiency standards are constantly changing so the answer depends on when he wants to make this change.

To compare heating options, I first need to define a term called BTU’s (British Thermal Unit).  A BTU is a measurement of energy and is defined as the amount of energy to raise one pound of water 1 degree Fahrenheit.  Or for those who are visual, one BTU is equal to burning one kitchen match.

I will limit this analysis to the most common fuel types.  If we look at just cost per BTU, natural gas is the first choice, followed by fuel oil and then propane and electric.

However, fuel costs are seasonal and they vary significantly over time and within the US.fuel-oil-costs

The chart on the above shows that  fuel oil costs for the past two years varied from $2.75 per gallon to over $4.00 per gallon.

 

If we look at propane prices over the past two years (below), we see a big spike to $4.00 per gallon in the winter of 2013-2014 and a leveling of costs in the winter of 2014 – 2015 to around $2.30 per gallon.Propane-costs

 

Natural gas is measured in cubic feet.  Prices fluctuate with demand, so it goes up in the winter time (see below)Natural Gas costCurrently, natural gas prices are very low.  In the last year, prices varied from a low of $9.49 to a high of $17.39 per thousand cubic feet.

Electric costs are measured in kilowatt per hour or kWh.  The costs vary seasonally and throughout the US (see below).  electric cost

The US average is 9.94 cents per kWh.  However, if you live in New England, where my son lives, the cost can vary from 15.94 cents to 20.45 cents, a significant difference.

To compare fuel costs to heat water, we need to determine the BTU’s in a unit of fuel.  Then we also need to take into account two efficiency factors. One is the efficiency of taking the energy in a unit of fuel to BTU’s. And the other is the efficiency to heat water with those BTU’s to the desired hot water temperature.

Below is a chart of the BTU’s in each fuel type and efficiency in converting it to BTU’s. This chart calculates the cost for a million BTU’s using the low and high prices throughout the heating season and various parts of the US.

Unit cost Cost per million BTU’s
BTU’s Units Low  High  Eff. low high
Natural Gas 1,028,000 mcf $9.490 $17.390 82% $11.26 $20.63
Oil #2 138,000 gal $2.900 $3.550 82% $25.63 $31.37
Propane 91,800 gal $2.400 $4.000 82% $31.88 $53.14
Electrical 3,412 Kw $0.098 $0.245 100% $28.84 $71.81

But we still have not made hot water. We only have cost per BTU. Let’s now apply the second efficiency factor to those BTU’s to make water. To get this efficiency, we need to know the input water temperature, the output temperature, the heat loss of the tank, the efficiency of the burners or elements, and heat transfer efficiency.

This can get complex.  However manufactures of hot water systems do provide this data for their equipment. To find it, read the specifications for the system or look for it on a tag that is normally attached.

For my analysis, I’ll simplify it and use the following percentages: fuel oil and gas efficiency hot water tanks are in the 60 – 65% efficiency range; electric hot water tanks are in the 90 – 95% range.

To compare costs for hot water, it really does not matter what we assume for usage, as long as we apply the same usage to the various fuel types. The data is valid for comparison purposes.   I will use 70 gallons of hot water per day for a family of four, input water temperature of 60 degrees, output temperature of 120 degrees which requires 16.3 million BTU’s per year.   The chart below shows the range of low and high annual cost.

Cost  1 million BTUs. Annual cost
BTU’s Units System Efficency low high low high
Natural Gas 1,028,000 mcf 0.62 $18.16 $33.27 $296 $542
Oil #2 138,000 gal 0.62 $41.33 $50.60 $674 $825
Propane 91,800 gal 0.62 $51.42 $85.71 $838 $1,397
Electrical 3,412 Kw 0.92 $31.35 $78.05 $511 $1,272

The bottom line is that for tank type heaters, natural gas is best.  Fuel oil is second best and propane and electric the most costly.

So, what did I tell my son?  Since, he already has a indirect system using his fuel oil fired boiler, the additional cost of getting hot water in the heating season is very small.  So, I told him that replacing his fuel oil indirect hot water tank with a classic electrical hot tank will not be a good idea. His solar power electrical panels may produce electricity cheap, but a hot water tank would exceed the capacity of his panels, causing him to extra kilowatts from his local electric company.

However I should also point out that there are newer technologies on the market.  Tankless hot water, or on demand, systems have been on the market for some time and electric hybrid heat pump hot water tanks are now available.   There are also solar heaters and drain-water heat recover systems.  These systems may offer cost benefits over today’s classic solutions.

There is no simple answer to what is the best way to get hot water.  Below you can find pointers to various websites that I used to answer my son’s question.  You can use them to get an ideal on how to determine the best answer for your own situation.

What is a BTU: www.businessdictionary.com/ and wikipedia.org

How much water average homes uses: http://www.oeic.us

Average electrical cost – www.eia.gov

Selecting a new hot water heater: energy.gov

To calculate cost of fuel to generate BTU’s: http://nepacrossroads.com/fuel-comparison-calculator.php

Average hot water usage and cost per year:  ugi.com

 

 

This blog was written by Fred Wilbur. Fred was an employee of Keith Specialty Store from 2005 – 2015 and today enjoys sharing information to help people have a better life.

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Submersible pumps – 2 or 3 wire?

June 1, 2011

Submersible Water Pumps, 2 or 3 Wire.  What is the Difference?

 Submersible pumps, the kind of pump that goes in your well or cistern, are available with two wire motors or three wire motors.  There is also another ground wire which is not counted, so if you look at the pump the actual number of wires will be three or four.  The two wire pump will have two black wires and one green ground wire.  The three wire pump has a black, red, yellow and green wire.

You are probably thinking, “That’s nice, but what is the difference to me?”  The main difference is the three wire pump uses a separate control box which includes a capacitor and relay to start the pump.  The control box is located inside your house or pump house.   The two wire pump does not use a control box.  Everything is built inside the motor of the pump.  All motors larger than 1 ½ HP are only available in the three wire version because you need the control box to start the heavier motors.  Most residential pumps are smaller horsepower.  Our top selling pump is just ½ HP.

Many years ago we sold mostly three wire pumps.  We believed that having a separate control box above the well would sometimes save people the time and expense of pulling the pump when they experience a problem.  If the problem is in the control box it is a simple and relatively inexpensive fix to replace the box, as opposed to pulling the pump and replacing the motor or whole pump.  This is the main advantage of the three wire pump.  Then, probably 25 years ago, a local plumbing contractor insisted he had far fewer problems with two wire pump systems.  We slowly shifted to selling more two wire pumps and our experience seemed to agree with the contractor’s observations.  Also, two wire pumps are less expensive, the wire used to install them is less expensive and the installation is easier because you do not have to wire through the control box.  Of the pumps we now sell, at least 90% of them are two wire.

Which size wire and breaker do I need for an electric water heater?

May 31, 2011

Which size wire and breaker do I need for an electric water heater? 

The wire and breaker size depend on which heating elements are in your water heater.  Find the watt rating  for the elements.  This rating is usually on a tag on the side of the water heater.  It is also printed on the elements.  You can find the elements on the side of the heater under a plate attached with one or two screws.

For elements up to and including 2500 watts, the minimum wire size would be 12 gauge.  With 12 gauge wire, use a 20 amp breaker or fuse.  For elements over 2500 watts you must use 10 gauge wire and a 30 amp breaker or fuse.   It is important to match the wire size to the correct breaker or fuse.  The breaker protects the wire from overheating.  You can use 10 gauge wire for lower wattage water heaters.  If you are running wire for a new water heater, it is a good idea to use 10 gauge so that you are covered for any water heater you might buy in the future.

You can find wire on our web site at: http://keithspecialty.com/elec.cable_wire.htm

Electric Hot Water Heater – Elements

May 14, 2011

How Do I Determine Which Element I Need for My Electric Water Heater?

 If you run out of hot water faster than you used to, have only lukewarm water or no hot water at all, it is possible that one of the elements needs to be replaced. How to accurately diagnose a faulty element is a topic of another post.  This post assumes you have already determined that you need new elements.  It discusses how to determine which element you need and how to replace them.

There are two types of elements found in the majority of water heaters:   a flanged element or a screw-in threaded element.  There are some other types on older heaters, but they are becoming very rare.

Flanged hot water element Flanged Element 

Screw in hot water element Screw-in Element           

Hot Water Element socket wrench Socket Wrench

                                                                    

Always turn off the power supply to the water heater and drain the water from the tank before working with the elements.  Most water heaters have two elements while some have only one.  The elements are located on the side of the tank behind a metal plate attached with one or two screws.  Remove the plate.  There will be two wires attached to the element.  Loosen the screws and remove the wires.  Don’t worry about remembering which wire went to each screw, it doesn’t matter.  It will now be obvious which element you have.  If you see four bolts, it is a flanged element.  Remove the bolts and pull the element straight out.  If you have a screw-in element, you will see a single large hex head on the element.  A 1 ½” deep socket can be used to remove the element or you can purchase an element socket wrench.

The wattage and voltage will be printed on the head of the element.  Some elements will have two different listings such as 3500W at 208V and 4500W at 240V.  Use the larger number when ordering.  You may want to replace both elements while you have the tank drained, even if only one is bad now.

Important reminder!  After installing the new element, always refill the tank with water before turning the power back on.  Open a faucet while you fill the tank to be sure there are no air pockets remaining inside the water heater.  Since elements are made to be submersed in water, they will burn out in seconds if you turn on the power to the tank before it fills completely.

 

Other informational sources:

  •  A diagram of hot water tanks – from HowStuffWorks.com
  • Good video on replacing an element.  Note: this video does not discuss filling the tank with water before turning on the elements.
  • Another source of how to change an element from Ehow.com

I just had city water installed and now my water heater leaks out of my relief valve!

April 25, 2011

You just had city water installed, and now your hot water tank is leaking out of the relief valve!  The following information will provide steps to help you solve the problem.

The first rule to remember is that as water is heated, it will expand.  Before getting city water you likely had a pump and cold water expansion tank in your house.  As the water heater did its job, the expanded water would push back the line into the expansion tank.

It is common after installing city water to have no expansion tank and a check valve installed in the new waterline.  When the hot water tank heats water, the expanded water has nowhere to go, thus building excess pressure and blowing it out of your water heater relief valve.

Expansion tank

Wilkins Expansion tank – item 41-300

The solution is to install a small expansion tank on the cold water line above your water heater.

We carry an expansion tank for hot water. It is our item # 41-300, a Zurn XT-8.  A tee fitting is required for the cold water line to go to a ¾ “ female pipe thread to accept the tank threads.  You will need enough room for the tank to hang.  It is advisable to have some support for the water line as well,  to avoid putting undo strain on it, causing it to break and create another problem.

relief valve

Relief valve

You may also want to replace the relief valve, our item 41-274, on your water heater as it may still drip after being opened by high pressure a few times.

Good article on expansion tanks from a code point of view: http://www.wvdhhr.org/phs/water/thermal_expansion2.pdf

Here is a link to Zurn’s installation document. for the XT expansion tank.

Can I damage my pump if I run out of water?

April 14, 2011

 If I run out of water, can it damage my pump?

 

Submersible pumps are more susceptible to damage than jet pumps.  Pumps are cooled and lubricated by the water flowing through them.  The impellers of a submersible pump will quickly begin to melt and fuse together when the water level drops below the intake screen of the pump.  Running without water even one time can cause the pump to lock up or seriously degrade the pump’s performance.  A jet pump may run quite awhile without damage but they can also overheat.  The impeller, diffuser, shaft seal or motor could be ruined.  Because this type of damage is not from a defect in the pump, it is not covered by the manufacturer’s warranty.

A low cut-off pressure switch will prevent damage in most situations but is not foolproof.  A better solution is to install an electric pump protection control.  The pressure switch turns off the pump when there is a drop in water pressure below 20psi.  The pump protector controls sense a drop in electric current as the load on the pump drops when the well goes “dry”.

The low water pressure switch is suitable as a little insurance for a well that doesn’t typically have a problem with water level.  We highly recommend the pump protector for low-producing wells.  If your pressure switch drops out, you will have to wait several minutes or more for the water level to recover, and then hold the lever on the side of the switch up until the pressure increases above 20psi.  The pump control is not only more reliable, it is also much more convenient.  The control has an adjustable timer which can be set from two minutes to an hour or more.  After the preset time, the control automatically restarts the pump.  It sure beats getting out of the shower soaking wet and trudging to the basement to lift the arm on the pressure switch!

 

 

Losing Water Pressure?

April 14, 2011

I am losing water pressure, how do I find the cause?

 

If you are connected to a municipal water company, call them.  If you have your own water source, read on.

If you notice the pump is coming on or the pressure reading on the gauge is dropping when no one is using water, there could be a leak somewhere in your system or a check valve might have failed.  Leaks can be in your house, underground or in the well.

Let’s check the easy things first – leaks in the house.  Look at each toilet in the home.  Lift the tank lid to see if the fill valve is stuck open and pouring water down the overflow tube.  Some fill valves can be taken apart and cleaned while others will have to be replaced.  It could be a bad tank ball or flapper allowing the water to leak from the tank into the bowl.  This will cause the water level to drop in the tank and the fill valve will open to refill the water.  Replace the flapper or ball.  It is also possible that an outside faucet wasn’t turned off completely or the garden hose has developed a leak.

If nothing was leaking inside the house, an outdoor source could be at fault.   Do you have a shut-off valve on the house side of the cold water pressure tank?  If so, turn it off and watch the gauge.  If the pressure is still dropping, the leak is between the tank and the bottom of your well or spring.  The leak could be a cracked fitting, a hole in the pipe, a loose hose clamp, a bad o-ring in the pitless adapter or a bad check valve or foot valve. If the water source is  a spring, replace the foot valve and the fitting.  If you have a well and the well head is underground, start digging.  If you have a well cap above ground, it will be easier to access.  Remove the well cap or well seal.  Listen for water spraying or hissing.  Look down the well with a flashlight for leaks around the pitless adapter.  If you do not see evidence of leaking pipes, you will have to pull the pipe out of the well.  For a single-line jet pump, check the pipe for holes or splits and replace the foot valve and fitting at the bottom of the pipe.  On a two-line jet pump system, check the pipe and pay special attention to the jet assembly (the piece that ties the two lines together).  Look for a hole in the jet assembly and check or replace all of the fittings.  Replace the foot valve.  For a submersible pump, check the pipe and the fitting at the top of the pump.  There is a check valve either just above the pump or built into the head of the pump.  Replace the existing check valve or add a new check valve above the pump.

Check the pressure on the well side again.  For jet pumps you will have to prime them by filling the lines with water.  Jet pumps will not work if there is air in the pipe.  Hopefully, the problem has been solved.  If there is still a loss of pressure you might have a leak underground.  Look for a wet spot in the yard between the house and the well which may indicate a leak.  If there is nothing obvious in the yard, the most likely spot for a leak is at the foundation where the pipe enters the house.  Dig this area first.  The next place to dig is along the outside of the well casing to the point where the pipe attaches to the outside of the pitless adapter.  If both of these areas are dry, the leak is probably somewhere else in the underground pipe.  Other likely areas are under sidewalks or driveways.  You may want to plug the pipe at the well or spring and do an air-pressure check to be sure the leak is definitely underground before digging up and replacing the existing pipe.

Pressure Tank – setting the pressure

April 1, 2011

How do I set the air pressure in my pressure tank?

The air pressure in the tank should be set according to the low cut-in point of the pressure switch.  Before setting the pressure, it is important to know what the low pressure cut-in is.  There are two ways to determine this.  The first is to find the pressure rating for the switch you installed. This is valid only if the switch has not been adjusted. If the switch was adjusted, the second method should be used, which involves observing the pressure gauge to see at which point the pressure switch turns on the pump.

view of the bottom of a pressure tank

The pressure switch rating is normally written on a tag that is inside the plastic cap covering the switch.  Typically this can be found on the inside of your pressure switch lid.  Before you remove the lid to see the label, you should shut off the power to the switch at the main circuit panel.  To remove the lid, loosen the screw on the top of the pressure switch cap.   Look inside the cover to read the pressure range. The first number is the low pressure  cut-in  pressure.

label inside pressure switch cover

The label on the left is a 30 – 50 pressure switch. Look under the PSI column:  ON/I is the low pressure cut-in pressure, the OFF/O is the high pressure cut-off pressure.

This is the factory setting of the switch when purchased. However, since the switches have adjustment screws, it is possible the switch settings have been changed.

If the switch has been adjusted or you cannot find the rating on the switch, you need to observe the pressure gauge to see when the switch turns on.  You will need power turned on to do this.   Observe  the pressure gauge as you allow water to run in your sink or washing machine.  As the gauge decreases, make a note of where the pressure is when the pump switch activates the pump. This is the low pressure cut-in point. Continue to watch and note the pressure where the pump switch shuts off.  This is the high pressure cut-off point.

Once you have determined the cut-in pressure you can set the tank pressure.  To do so, shut the power to the switch (and pump) off and completely drain the tank of water.  It is important to drain the tank completely before checking and setting the pressure in the tank. If you do not, the pressure will not be set correctly.

There is a valve stem which is usually on the top of the tank under a plastic cap.  With an air pressure gauge, check the air pressure just as you would on a car tire.  It should read 2 to 3 pounds less than the low pressure cut-in pressure.   If the pressure in the tank is not set correctly,  you may then either add or release air as needed.

If you are using a  30-50 pressure switch, the low pressure cut-in point is 30 psi.  Set the tank pressure at 27 or 28 psi.  Once you have the pressure in the tank set correctly, you can turn the pump back on.  Don’t forget to close the boiler valve you opened to drain the tank.

Microns and Water filters

March 7, 2011

What does the micron rating mean on a water filter cartridge?

A micron is one millionth of a meter or about 0.0000393 inches. The average

5 micro filter

Item number 33-036

thickness of a human hair is 100 microns. A filter cartridge with a 5 micron rating will remove all particles 5 microns or larger from the water. Five microns would be 0.0001965 inches in diameter. A 20 micron filter will filter particles of 0.0007864 inches or larger while allowing smaller particles to pass. For particles of rust, sand or dirt that are easy to see, a 10 or 20 micron filter would be appropriate. For very fine particles, choose the 5 micron filter. Use of a small micron filter when large particles are present will shorten the life of the cartridge.

Other valuable information can be found at the links below:

“A grain of sand is anywhere from 75 to 150 microns, so a 50 micron water filter should be good enough to handle your sediment issue.” – blog.waterfilters.net (3 of 10 posts about water filteration)
“Turbidity is a measure of the cloudiness of water, often the result of suspended
mud or organic matter, and may sometimes indicate that the water is contaminated with Cryptosporidium or other pathogens.” – heartspring.net
“We’re all made of more than 70% water. As our exposure to environmental pollutants increases, so does our need for filtered, healthy water. Your tap and bottled water can contain pollutants … “ – waterfiltercomparsions.com

We carry many of the common filter supplies on our web site.

Check out our web site entries.