The post previous to this was about water heater Deadband.  This post is related in that it shows us another way that deadband affects use of hot water and the safety concerns posed by deadband.

Very high water temperature

How difficult can it be to figure out what the water temperature in a home is?

In the State of Washington, Licensed Home Inspectors are required to report when the water temperature is above 120 degrees and then advise the client that the recommended high temperature is 120 degrees Fahrenheit.

What I have found, over and over again, is that if I take the temperature reading at the kitchen—-where I start my inspections—it might read 118 degrees F and falsely be led to think that the temperature is OK.

Because most kitchens have mixing valves, I know that sometimes the temperature might actually be a little higher than that—so I know I am going to check it somewhere else too.

After the kitchen, the next part of the inspection usually moves to the highest level of the home.  The idea is that you want to test all the plumbing from the highest level and then down to the  lowest level so that by the time you get to the crawl space it will be flooded by all the leaking so that you might not even have to do the crawl space.  Of course this is meant tongue-in-cheek—but you get the idea.

Lots of bathrooms—at either the tub or the vanity—may have faucets that are not mixing valves so that it is easier to get an accurate temperature reading at those locations.  That said—lots of newer tub and shower fixtures have mixing valves with anti-scald features which again prevents accurate temperature readings.  Regardless, I usually check the temperatures at this bathroom and the temperatures are usually consistent with the reading (or very close to it) that I got at the kitchen.

By the time I have gone all through the other levels of the home and finally get to the basement (if there is one), I often find the laundry sink which almost always has separate faucets, I know I can get a good temperature reading there.  I take the temperature and all of a sudden it is 130 degrees Fahrenheit.

At first you scratch your head and say, “How can this be?”

The answer is that “time has gone by”—-perhaps an hour or two or three.

When the inspector arrives at the inspection, the water heater has been sitting idle and has been cooling off.  Because there has been no demand for hot water it may have cooled all the way down to its low point—the temperature at which the thermostat would normally kick in and start heating the water.  However, these simple thermostats operate the best with a pronounced change in temperature for them to kick-in.  The temperature of the water might go even below the normal kick-in temperature.  During the normal everyday operation of these thermostats, the temperature differential is likely between 5 and 10 degrees but can vary up to 25 degrees—the difference between whether a baby gets scalded or not.

These swings in temperatures are especially true of vacant homes.

The moral of this story is that it is best protocol to take the water temperature later in the inspection than it is to take it right at the beginning of the inspection—for the most accurate indication of what the temperature actually is.

In the end, it is not difficult to figure out the temperature—but the best protocol must be followed.

***

Charles Buell, Real Estate Inspections in Seattle

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If you are thinking that this post is about the Grateful Dead Band, I am sorry to disappoint.  It is  “loosely” about Jack & Jill in the shower—-but not about them being in the shower together—if they showered together this would not happen.

I have done many posts about conditions related to water heaters—this is but another.

This one may be a bit “technical” but it will hopefully help explain a condition that occurs all too often in homes.

Water Heater “DEADBAND”

The question varies, but it usually goes something like this.  Jill asks, “How come some times there seems to be plenty of hot water for both me and Jack to take showers—-and other times there is not?”

Well Jill, it is probably due to “deadband.”  While deadband can be an issue with gas water heaters it is very common with electric water heaters.  You see, the thermostat on your water heater has a range at which it turns itself off and turns itself on (Jill could not help but think about how this might apply to her and Jack in other more interesting ways).  It is this “range” that causes the problem (how true, how true, thinks Jill).  Some water heaters are worse than others (DEFINITELY true, thinks Jill).

Let’s say that Jill starts out with a fully heated water heater at 120 degrees Fahrenheit.  She takes a nice leisurely, relaxing shower and uses most of the hot water—-but not quite enough to get to the low point of the thermostat to make it kick back on to heat more water.  Now Jack comes along an hour later (after the lazy butt sleeps in)—all set to take a nice long hot shower (Jill is thinking cold shower)—-only to run out of hot water as the thermostat finally kicks in to heat more water.

To simplify things, I have drawn a little graph to help visualize the basic concept.

A visual of how deadband happens

So what is the solution?  There really isn’t one that doesn’t involve keeping the heater at higher than safe, recommended temperatures (120 degrees Fahrenheit).

Keeping the heater at higher temperatures (so that there is more water to dilute) also means that the thermostat’s low range is always going to be higher than what is a satisfactory temperature for a nice long shower.  Installing tanks with more storage capacity is another solution as well.

Perhaps the best solution would be to install what is called a “tempering valve.”  This is a clever device that allows you to have the water heater set at say 130 degrees Fahrenheit and mixes a little cold water into the stream whenever you use hot water so that you don’t ever get more than 120 degree water out of your faucets.  This also protects the heater from the growth of bacteria in the tank that is encouraged or maintained by 120 degree water.

Sounds like Jack will be in plenty of hot water now—no more cold shower treatment.

***

Charles Buell, Real Estate Inspections in Seattle

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