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BrandonD 11-01-2012 07:50 AM

Poor hot water performance
Hi guys,

We bought a house last April and aren't overly impressed with the hot water heater. We are a family of three but we all like our extra long hot showers. The water gets plenty hot enough but doesn't last very long. Sometimes it can run out in a 20min shower with no other hot water usage. We have a 50 gallon Marathon, model MR50245 B (electric). I am not sure if our tank is undersized for our demand or if one of the heating elements is bad. I also am not sure how to tell how old the water heater is to know if I should just bite the bullet and replace it before it leaks.

A bit of other possibly useful information: when we moved in we wanted to replace the entire private well treatment setup. It was very poor before and tasted horribly. Our raw water has an extremely high iron content. When we replaced the softener and filters we were informed that the new soft water will start to 'clean' the pipes and water heater from the previous sediment caused by the poorly treated water. We were told to drain and refill the water heater occasionally when our hot water started to smell again. Sure enough, when I did there was quite a bit of brown water coming out when I first opened the drain and quite a bit when it started to slow down.

What do you think my next steps are? Is my tank undersized or could it be just a heating element? I am comfortable taking the heating elements out, but is there a way I can test them to see if they're bad? Like a continuity test? I have not checked the thermostats on either of the elements yet, but increasing the temperature wouldn't really fix the problem of running out of hot water would it?

Thanks for any tips and pointers. I'm pretty handy (enough to troubleshoot this and replace the water heater if necessary anyway).

joecaption 11-01-2012 07:57 AM

The serial # will tell you how old it is.

BrandonD 11-01-2012 08:14 AM

Thanks joecaption. Google'd it and it looks like I have one from November 2001. Should I look at replacing it or can I still get some good years out of it if it turns out I just need to replace one or both heating elements? It is out in the garage so I am not overly concerned about damaging any belongings from a leak but it's always good to replace something on your schedule, not its own.

joecaption 11-01-2012 08:24 AM

My guess is the average life of most water heaters is about 15 years.
A lot deppends if someone took the time to drain the soilds out of the bottom of the tank at least once a year, which almost no one ever does.

To make it simple for my little pea brain I change all the smoke detector batterys and drain some water out of the tank at the same time on the same date.

concretemasonry 11-01-2012 10:12 AM

The serial number can be very misleading when it comes to real age. Often dealers and distributors will buy an excess of units when there are discounts and just store them. Too often, in warehouses, newer heaters are stored in front of existing heaters and never get rotated out. Indoor storage does not affect the operation since it has never been used.

I had a new heater installed that was 3 years old when it was actually put in service.


DannyT 11-01-2012 11:36 AM

sounds like the lower element is not working. probably burned out. the other possibility is one of the thermostats is bad but the element is what i would check first. if you have 240v at the lower element then the element is bad. if you aren't comfortable working around 240v call a plumber. when it is repaired make sure to flush the tank out at that time if you decide to fix it.

BrandonD 11-03-2012 07:33 AM

I tested both elements yesterday evening with the three tests Joe linked to and found and they both passed all three tests. The thermostats were set extremely low so I increased them to half way on both. The top one ranged from low to high and now it's in the middle (medium), the bottom one was quantitative up to 170 degrees and it's now at 150 I believe. Our showers when we got home last night were fine, but that was relatively low on our typical demand scale, so we're yet to see if this solved our problem. Does setting them at half way sound reasonable or should I take another step in troubleshooting? Perhaps the lower element is under performing because of our previous extremely hard water?

The water heater actually has a timer wired but I took a look at the dial and there's no jumpers/brackets/whatever they call them so it just runs 24/7. Might Google the model number online and see if I can find the parts online to get it on a schedule.

Daniel Holzman 11-03-2012 09:38 AM

The topic of hot water running out too fast comes up frequently on this forum, check some of the threads. In your case, you say you get 20 minutes of hot water, and you say you have a 50 gallon tank. If your water heater is set to 120 degrees F (pretty common), and you take a shower at close to 120 degrees, then your are essentially running unmixed hot water.

The average shower is somewhere around 2 gallons per minute, of course they vary, but you can easily measure the flow by putting a five gallon bucket in the shower and timing how long it takes to fill. Let's say you have a 2 gpm showerhead. Then in 20 minutes, you will have used up approximately 40 gallons of hot water, so at that point you start to get a mix of cold and hot water from your heater. No conventional water heater is going to heat water up fast enough to replace used up hot water.

So it is entirely possible that your heater is working just fine, you simply need a larger tank. You could replace the heater with say an 80 or 100 gallon heater, or I suppose you could add a tank in series. However, an 11 year old heater is probably near the end of its design life, and most likely worth replacing.

ddawg16 11-03-2012 10:30 AM

20 Min shower? Really? I thought 10 min was a lot.

I think Daniel's assesment is pretty accurate based on my research into the subject. I had to asses my water heater setup for my 2-story addition....number of people did not change....but added 2 more bathrooms. I was considering going with tankless....but being that I'm on gas....and the size of my heater and it's recovery rate....I'm ok.....(and we don't take long showers)

For comparison...I have a 50 Gallon gas heater heater....which has a 1st hour rating of 83 basically (as I understand it), it is supposed to supply 83 gallons of hot water in one hour. Also note that I have my water turned down to about 115 deg (kids) and the longest shower is maybe 10 min....and we use low flow shower heads

Since your on electric.....a tankless unit would be a good option for you.....that would end your hot water limit....(but I wouldn't want to pay your electric bill)

BrandonD 11-03-2012 11:53 AM

1 Attachment(s)
Since adjusting the temperature on the thermostats I've since seen the pipes entering/leaving my water heater rise out of the shell. I realize by increasing the temperature I increased the pressure in the tank. I've attached a picture. I knew the pipes rose because the black rubber ring around each of pipes was lifted from the tank instead of seated as in the picture. The right pipe was close to 1.5" up! Is this normal?

Alan 11-03-2012 12:21 PM

Hold the phone here.

You have a 50 gallon "MARATHON" water heater. (plastic)

A normal showerhead puts out 2GPM.

Reading the first hour rating on your marathon water heater, you will find that it actually puts out less hot water in the first hour than the capacity of the tank, where the opposite is true for it's "steel cousins".

At two gallons per minute, and a 20 minute shower, I don't find it completely off base that you would run out or come close to running out. (what is the wattage rating on the elements?)

We put an 80 gallon marathon in for a customer at their request, and we went back several times to check it, because they couldn't fill their soaker tub with it. Everything checks out, except that it just doesn't put out as much hot water as a steel tank.

Alan 11-03-2012 12:23 PM


Originally Posted by ddawg16 (Post 1043803)
Since your on electric.....a tankless unit would be a good option for you.....that would end your hot water limit....(but I wouldn't want to pay your electric bill)

Only if you want to add a separate 200A service to your home. :eek:

Canucker 11-04-2012 11:52 AM


Originally Posted by ddawg16 (Post 1043803)
Also note that I have my water turned down to about 115 deg (kids)

dawg, put a mixing valve on to lower the temp. Lowering the temp to that range gives Legionella a perfect breeding ground, of which kids, elderly and people with depressed immune systems are more susceptible to catching. It becomes airbourne from the shower heads or aerators, and you breathe it in, thats how its transmitted. Bonus to using the mixing valve is that you get a longer supply of hot water. Cheers :)

BrandonD 11-11-2012 07:33 PM

Thought I'd follow up. Like I said in my last post the elements tested out OK but I adjusted the thermostats slightly. Since then we've had no hot water problems. Concerned about the effects on our electric bill, I signed in to check out our smart meter where you can see consumption reports. The average has stayed the same so I think we're in good shape.

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