Tank type electric water heaters—hard to beat.

Super Insulated Water Heater

Me in my water heater

Everyone that knows me, knows I spend a lot of time in my basement playing with my water heater.

I have always been skeptical of the claims made about different types of water heaters and I have never had anything more than anecdote to sort out any truth of these claims.

About 6 months ago I bought an electric meter to install on the water heater so I could keep track of exactly how much electricity it uses.  This takes some of the extrapolation and guessing out of equation.

What I am writing here in no way clarifies everything but it clearly demonstrates the whole topic needs to be revisited by people with more money and testing facilities than I have.

Some of this inquiry is in answer to advertising by on-demand water heater manufacturers that would have us belief tankless-type heaters are god’s gift to water heaters and that tank type heaters are no longer a viable way to heat water. 

There are lots of pros and cons to both types.

It is my premise, if water heaters came with a LOT more insulation than is currently required, they can remain competitive in cost to operate and certainly in cost to install. 

The initial costs and maintenance costs associated with tankless water heaters is still considerably higher than tank type heaters–and lets face it, they are as complicated as under the hood of your car.

An interesting thing happens when you install an electric meter on your water heater.  It becomes very difficult to use hot water “normally.” This is because of the nagging little voice in the back of your head that questions whether you are wasting hot water while you are doing the dishes, doing the laundry, taking a shower or washing the cow.  That said, the ratio should remain similar even if the numbers end up somewhat higher.

Meaningful numbers can still be found when comparing operating costs of an off-the-shelf heater compared to one that is super-insulated.

About two months ago, my heater died.  When I replaced it, I replaced it with another tank type heater that was 15 gallons smaller than the previous heater.  I decided I would monitor costs for a period of time prior to super insulating it.  The tank comes insulated to R-13.  I would ultimately insulate the tank to R-40.

My installation is further complicated by a re-circulation loop.  I also wanted to determine the operating costs of the loop.  Just how much did it add to water heater operating costs?  In addition I wanted to see performance differences of keeping the tank and loop at 135° F and 120° F.  I suspect I could have gotten better numbers if I monitored for a whole year or several years, but I was merely looking for hints of the truth.

Super Insulated Water Heater

Insulated to R-40

At 135° F, the operating costs of the loop resulted in an additional 15 cents per day.  The loop operated for 15 minutes an hour between 6am and 10 pm. 

The loop with super insulated lines and tank also results in having a larger volume of hot water sitting in the tank waiting to be used.  The hot water circulating to the bottom of the tank mixes with the incoming cold water reducing the amount of time it takes to bring all the water up to the set temperature. 

If power is lost, I still have a tank full of hot water for a couple of days.  With the tankless you immediately have nothing.

My loop is a thermosiphon loop (no pump) and has a timer with an electronic valve to control how much it operates.  The loop to the kitchen and back to the water heater is approximately 88 feet and insulated to R-20.  I consider this cost per day to operate the loop as insignificant.  The cost is mostly offset by the savings related to not wasting water.

After insulating the tank to R-40, the per day costs to heat water to 135° F averages 92 cents per day.  Prior to insulating the tank, the average daily cost was about $1.20.  This is approximately a savings of 24%.  This results in a payback on the $152.00 cost to install the R-40 insulation of 1-3/4 years.  Over the 20 year life of the water heater (typical of my area) that could be a savings, at current electrical rates, of $2060.00.  This is the cost of more than 5 water heaters based on the $400.00 cost of my recent water heater purchase. 

I know of no comparable way to get this kind of savings with a tankless water heater and of course initial costs are much higher with the tankless.  Maintenance costs over 20 years is going to be close to the savings of the super-insulated tank type heater.  Keep in mind that estimates of cost to operate tankless water heaters do not include increased costs to maintain re-circulation loops.

I realize no one is likely to do their water heaters what I did to mine to achieve these numbers. 

This exercise is to expose the silliness of what we currently require of manufacturers. 

Manufacturers could certainly add insulation to R-40 (or higher) at the time of construction much cheaper than I can do it in the field.  This seems like a no brainer if we are serious about conserving energy. Of course this only applies to electric water heaters that can be heavily insulated at the sides, top and bottom.

Another factor that comes into play, is that the size of the tank can be much smaller, which even further reduces annual costs to operate the heater. It also deals with possible problems with replacing larger heaters that would be bigger if insulated to R-40.  There is no reason standby-costs on a tank-type water heaters can’t be brought under 50 cents a day–probably under 30 cents a day if the tank is 40 gallons or less.  With a super insulated tank, a 40 gallon tank should be more than adequate for a family of four.

When are we going to start requiring manufacturers to install more insulation on their heaters?

Temperature behind the insulation

The temperature of the tank behind the added insulation is 100° F

Charles Buell, Real Estate Inspections in Seattle

Confused About Attic Ventilation?

Builders, roofers, insulation contractors, homeowners and home inspectors are seemingly dazed-n-confused about attic ventilation.

Lets first discuss what the purpose of ventilating the roof is.  The primary purpose is heat reduction.  With the ventilation necessary to accomplish this it will also remove very minor amounts of moisture that may find its way into the space as well.  Its overall purpose is NOT TO REMOVE MOISTURE.  We want to reduce heat to reduce cooling loads and improve indoor comfort.

One can find an endless number of articles on the web about the solution to moisture issues in attics being to add more ventilation.

While I think a lot of these answers are only accidentally correct, when someone says moisture issues in the attic are a “ventilation issue,” I think they are missing the big picture and may result in the wrong solution to the problem.  These solutions too often make things worse.

Sure the ventilation can be wrong in terms of “amounts,” or it can even be completely missing.  It is interesting, because attic ventilation can actually be completely missing and the issue might still not happen at all.

I think it is safe to say, having too much upper ventilation would be worse than none at all, because it will increase depressurization of the lid.  This will lead to even more house air (which is at higher pressure) pushing its way into the attic.

So ventilation may need more balancing of intake and exhaust, but that alone will not correct the issue.

What the house needs is proper air sealing more than ventilation correction. 

Of course in the context of any air sealing the attic, it would be a good idea to adjust the ventilation to industry standards.  This is typically 50% upper  and 50% lower spread around the sides.  As long as that upper level does not go above 50% it is fine.  40% upper and 60% lower is fine as well.

You can get ventilation horribly wrong per code recommendations, and if you get air sealing correct, the attic will behave itself.

This attic had 15% upper ventilation and 85% at the eaves and this is what it looked like 33 years later.  (R-60 cellulose, raised heel trusses, and who even knew about spray foam in a can back then?) (As a side note:  the shingles on this roof were white 3-tab, over no underlayment and lasted 30 years with no sheathing damage—even at the eaves.) 

You can get ventilation perfect per code recommendations, and if you get air sealing wrong, the attic can go horribly wrong.

This is a 15 year old attic with perfect 50/50 ventilation.  (R-38 white fluffy, conventional framing)

It is more accurate to say this is an air bypass issue than a ventilation issue because the issue cannot be corrected by just focusing on ventilation.

This is where power vents become “snake oil” and can make the condition radically worse.

To illustrate the problem, I pose a question?  How much do I need to increase attic ventilation to fix a roof leak?

I think most would agree you fix a roof leak by fixing the roof.

The same is true for too much moisture in the attic from indoor sources–you exclude the moisture as necessary–you fix the moisture bypasses.  This is accomplished with proper, adequate air sealing and in some areas this will include vapor barriers.  The vast majority of moisture finding its way into attics is from air bypasses—not vapor diffusion.

This air sealing can be difficult in older homes and should be automatic in newer homes.

One of the biggest hurdles to overcome is that roofers are not air sealing experts and many insulation contractors are also not on board with the science of it all.  As a homeowner, you need to make sure the roofer and builder and insulator you hire knows how these systems play together.  You will also need to find a home inspector or building performance professional to help you sort it all out.

Charles Buell

Real Estate Inspections in Seattle

 

Simply EXHAUSTED!

Most bathrooms have exhaust fans in them—or should.

Bathroom Exhaust fan cap

Bathroom Exhaust Fan Cap

Most modern codes (Washington State) require exhaust fans even if there is a window that can be opened. If we do not control moisture levels in our bathrooms, it can not only have a detrimental effect on the bathroom itself, it can also create moisture issues for the rest of the home.  We all know how useful it can be to change the air in the bathroom even if water is not involved.

Who is going to open their window every time they take a shower when it is cold outdoors? Not me.  If you were to do this, you might be surprised at how well it works to lower the humidity in the bathroom, even if it is cold and rainy outside.

Now that I have convinced you of the necessity for bathroom exhaust fans, we need to make sure they are working when we turn them on. Just because the thing shakes, rattles and rolls, does not mean that it pulling any air from the room. Simply turning the fan on is no test of its function.

There are many ways to determine if the fan is pulling any air; and many ways the function can be compromised.

1. The biggest way the function of these fans is compromised is that the user does not use them!

I know this is in the “DUH” category—but it is painfully true.

People need to be taught to turn these fans on, and to leave them on for a set amount of time. Typically I recommend that they be installed on a timer that can be set for various amounts of time and that after showering they be run for 60 minutes. This amount of time can be cut drastically if one raises the temperature in the bathroom itself before taking a shower. Air that is 75 to 80 degree F can contain a LOT of moisture—considerably more than 65 degree air. To the point, even without the fan running, the bathroom mirror may barely fog up if it is hot enough. If you raise the bathroom temperature to 80 degrees F, take your shower, then turn the exhaust fan on for 20 minutes, everything will likely be hunky-dorie in terms of adverse moisture conditions in the bathroom.

We have all taken hot steamy showers in cold bathrooms without fans and then have seen the condensation on the mirror and walls. This can be very damaging to the home (especially modern tight houses), promoting mold/fungal growth on the wetted surfaces. Most bathrooms do not have a “localized” means of heating the bathroom previous to taking a shower, making this not an option. In that case it is best to run the fan the entire time you are showering and for an hour afterwards—assuming the fan is functioning properly.

2. The fans are so noisy they do not get used.

Yes, if every time you take a shower you have to listen to the roar of a jet engine, or feel the house being shaken apart, or make the neighbors complain, there is a good chance the fan will not be used at all.

3. There is no space under the bathroom door.

Many times I see bathroom doors so tight against carpeting that no air can be pulled in under the door to replace the air that the fan is attempting to exhaust. Again, with this installation, no/not enough moist air is removed from the room, making the fan non-functional.

4. There is something restricting the flow of air from the fan to where it terminates at the exterior.

This can be caused by many things—things your home inspector will be looking for. Perhaps the fan motor is running but the squirrel cage has lost its squirrels. Perhaps the damper in the fan unit is stuck closed. Perhaps the vent pipe is crushed, or the end of the vent pipe or outlet of the unit itself is covered with insulation. Perhaps the vent cap damper at the exterior is stuck–maybe blocked with wasp’s nests, paint, debris or other restrictions. Maybe the missing squirrels are living in the vent pipe.

So how does a homeowner test to see if the fan is functional?

Well of course there is sophisticated testing equipment that can be used, but there are less scientific means of determining some degree of function.

1. The paper test.

The paper test can be done on the unit itself—all openings of the fan unit should be fully covered however. Covering only a portion of the opening may not tell you that the air is moving into the unit and then right back out the uncovered part of the cover. If the fan is too high to get to, or the cover is too complicated to cover, you can place the tissue paper right along the bottom edge of the bathroom door on the floor. If the tissue scoots across the floor when you turn the fan on, all that air is going somewhere—and shows that the fan is moving air. (As a side note, if the fan is running and forcefully holding the tissue paper in place, this is a good time to close the bathroom door if it is open.  All of these tests should be done with the bathroom door closed and because if the tissue paper falls off or starts to fall off you will know you have inadequate clearances under the door.)

2. The wet finger test.

If you don’t have any tissue paper you can use the wet finger test. This is kind of like testing to see which way the wind is blowing. You will feel your finger get colder as air is pulled under the door and attempts to dry your finger.  If you feel a good draft with a dry finger, that is an even a more confirming test.

3. The business card test.

If you don’t have a wet finger (it is surprising how resistant people can be to putting their fingers in their mouth) or tissue paper, you can stand up a business card on the floor up against door. It should tip over when you turn the fan on.

While not very scientific, these methods of testing will give you some general information as to function of the fan—at least enough to tell you whether it might be a good idea to have the vent evaluated further. For the best results with this “testing,” make sure that windows are closed during testing and throw a towel or rug over the forced air heat register. These openings can affect how much air is moved from the room—especially the window (The ductwork typically has so much friction losses that it is not often a factor).

Now go back and look at the picture at the top of the post. Can you predict, based on the picture, whether the bathroom exhaust fan moved any air from the room?

Perhaps not so obvious, the screen is keeping the damper closed.

By Charles Buell, Real Estate Inspections in Seattle

If you enjoyed this post, and would like to get notices of new posts to my blog, please subscribe via email in the little box to the right. I promise NO spamming of your email! 🙂