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John97
Over The Hills And Far Away
Premium
join:2000-11-14
Spring Hill, FL
kudos:1
Reviews:
·Bright House
·ooma

1 edit

Not enough hot water - house has 2 WH connected together.

My new (to me) house has two hot water heaters. Both are 40-gallon electric "lowboy" style. Since we moved in about a month ago we've had insufficient hot water. My realtor got me a home warranty as part of the deal, so instead of investigating/dealing with it myself - I put a call in for it. They sent out a plumber. One of the units was original to the house, over 25 years old. The other one is newer (7-8 years old) as it's predecessor had been replaced. The units are located in different parts of the house.

We've been unable to take more than a 5-10 minute shower. Filling the jetted tub for a bath is out of the question. The ancient unit was located closer to my master suite. The plumber replaced it, which seemed to be the logical thing to do - all things considered.

During the replacement, he figured out that the two units are "somehow" connected together because there was a T-connection with a second pipe running up into the attic on both the hot and cold sides. The pipes for the other water heater come out of the attic, which leads to the conclusion that the two are connected together. There is so much (loose blown-in) insulation in the attic, that it's going to be tough to see exactly how the pipes are run.

So after the replacement, we still have insufficient hot water. I took a good look at the other water heater tonight. Now, I haven't located my multimeter since we moved. It's probably in a box in the garage somewhere. I'm going to borrow one from work tomorrow and test the elements. But, the top part of the unit feels warm, and the bottom feels cold.

I suspect that that water is first drawn from what is now the "older" unit and that one has a bad lower element.

In case I am mistaken, anything else I should look for? I plan on calling the plumber back out, but would like to have some sort of idea what is going on before I do, so that this doesn't turn into an ongoing mess.
--
So put me on a highway, and show me a sign.
And take it to the limit one more time...


AnonEEMouse

@bhn.net
The lower element is for keeping the water warm, the top element is for heating water as you are using it I believe, so both will never be on at the same time.

Could it be possible one waterheater services one half of the house and the other the other half?

When I installed my new W/H I replaced 2 low boys in parallel with a single low boy and a thermostatic mixing valve. It allows me to set the hot water heater at 150F and the valve at 120F, I get more H/W than if the tank was set at 120F alone.

Bob4
Account deleted

join:2012-07-22
New Jersey
reply to John97
said by John97:

I suspect that that water is first drawn from what is now the "older" unit and that one has a bad lower element.

That's a good possibility. But check the thermostat settings first. The top one should be set to a lower temperature than the bottom one. e.g., top:120, bottom:130.


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to John97
The typical showerhead has a gpm rating of about 1.5-3 so even at 3 gpm's you should have enough hot water for 12-14 minutes. That's at full hot so when you mix in 40% cold water now you have a 20-22 minute shower. Add in the fact the water heat should be making new hot water and a 30 minute shower isn't out of the question. Reduce the 3 gpm head to 2 gpm's and now you have a 45-50 minute shower. If you can't get that the water isn't hot enough so either the thermostat on the water heat is too low or it's not heating the water correctly.

We have a tankless water heater hooked to a 50 gallon water heater. That's unlimited hot water!
--
IF YOU FIND ANY MISTAKES IN MY WORK...Please consider that they are there for a purpose. I try to please everyone and there is always someone looking for mistakes!


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
reply to John97
Dip tube(s) broken?

Bob4
Account deleted

join:2012-07-22
New Jersey
reply to Bob4
Other possibilities are a broken thermostat, a broken dip tube, or the hot and cold pipes are backwards.

And here are the markings for a typical electric water heater thermostat:

"dot" 110 degrees
"Hot" 120 degrees
"A" 130 degrees
"B" 140 degrees
"C" 150 degrees
"Very Hot" 160 degrees


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom

2 edits

1 recommendation

reply to John97
The Home Warranty sent out a plumber and you still don't know what the problem is? If the plumber couldn't fix it or even identify the cause of you problem then you should ask the Warranty Company for a new one who is more knowledgeable.

From the number of and different answers here it's evident you aren't going to resolve it here.

You need an experienced and knowledgeable plumber.


John97
Over The Hills And Far Away
Premium
join:2000-11-14
Spring Hill, FL
kudos:1
Reviews:
·Bright House
·ooma
Thanks for all the replies.

I do have low-flow water-saving showerheads. I replaced all three showerheads in the house the first week I was here because a) they were all beat, and b) the house has a septic system - so I want to do what I can to minimize water usage.

Even with the low-flow showerhead the hot water only lasts between 5-10 minutes.

I am going to give the warranty company a call today after work and lay this all out to them, to see what they say.

--
So put me on a highway, and show me a sign.
And take it to the limit one more time...


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to John97
Increase the water temperature. It should never be below 140F in a tank anyway. Hotter water will give you more warm water. If scalding seems to be an issue install a mixing valve at the output. Should be around $50 in parts and 1hr of work for a plumber who knows what he is doing.


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom
reply to John97
said by John97:

Thanks for all the replies.

I do have low-flow water-saving showerheads. I replaced all three showerheads in the house the first week I was here because a) they were all beat, and b) the house has a septic system - so I want to do what I can to minimize water usage.

Even with the low-flow showerhead the hot water only lasts between 5-10 minutes.

I am going to give the warranty company a call today after work and lay this all out to them, to see what they say.

It sounds to me that your lower element(s) may not be working. That would account for the very limited amount of hot water. It doesn't take much for the upper element to heat the water (at the top of the tank) and cut off. More than half way up the tank the water will be very cold.

Normally unless you dray a lot of hot water the bottom element does 90 percent of the heating. The top element basically is to provide hot water as long as possible if the temperature at the tank top drops to actuate the top element and turn off the bottom element.

I have mine set at 120 degrees and it's plenty of hot water for my wife and I to shower for as long as we want.

kherr
Premium
join:2000-09-04
Collinsville, IL
Reviews:
·Charter
reply to John97
Time to invest in an instant hot water heater. You'll be able to fill your tub and take showers to your heart's content. You will also no longer have to pay for storage. I know when my heater dies (at least 15 years old) that's what I'm going to look into.

Also you should NEVER turn the stat over 120. There are many, many codes that state this, and it's for a reason.


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to John97
My wife refuses to allow me to turn the water heater down to 120. She insists it stay at 140. Given that's an option on the water heater there's no reason not to use it. If a water heater was meant to be run only at 120 they wouldn't make it configurable.
--
IF YOU FIND ANY MISTAKES IN MY WORK...Please consider that they are there for a purpose. I try to please everyone and there is always someone looking for mistakes!


toby
Troy Mcclure

join:2001-11-13
Portland, OR
reply to John97
said by John97:

We've been unable to take more than a 5-10 minute shower. Filling the jetted tub for a bath is out of the question.

With your 80 gallon combined, that still might be an issue unless..... you fill the tub at a slower rate, 25%, give the heater time to run as you are filling it. Simple really, we have to do it too.


cdru
Go Colts
Premium,MVM
join:2003-05-14
Fort Wayne, IN
kudos:7
said by toby:

With your 80 gallon combined, that still might be an issue unless..... you fill the tub at a slower rate, 25%, give the heater time to run as you are filling it. Simple really, we have to do it too.

Your average bathtub holds 50-60 gallons of water. If you can't get a tub full of hot enough water out of 80 gallons of water heating capacity, something is wrong.


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to John97
Even at that your assuming they do 100% hot water. No one is going in 120-140 degree water so there is at least some cold to get it down to 100-106 so a single 40 gallon has enough to fill a 50-60 gallon tub.
--
IF YOU FIND ANY MISTAKES IN MY WORK...Please consider that they are there for a purpose. I try to please everyone and there is always someone looking for mistakes!


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom
reply to Draiman
said by Draiman:

My wife refuses to allow me to turn the water heater down to 120. She insists it stay at 140. Given that's an option on the water heater there's no reason not to use it. If a water heater was meant to be run only at 120 they wouldn't make it configurable.

160 degrees is an option also so why not use it? Why heat water just to have to add cold water to temper it down to a tolerable temperature to use?


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to kherr
said by kherr:

Also you should NEVER turn the stat over 120. There are many, many codes that state this, and it's for a reason.

You mean BELOW 140.
There are many, many codes that state this all over the world, except in US where lawyers can get scalded if they manage to hold their hands under hot water for 10 seconds.

scooper

join:2000-07-11
Youngsville, NC
kudos:2
reply to John97
Have you tried turning the water off to first one of the heaters, and then the other, to see if each is providiing hot water ? Also to check which one is providing hot water to what faucets. This should be something you can do without a plumber.

As others are saying - either 40 gallon heater should be enough to do your entire house. Something is not right about your setup.


Raphion

join:2000-10-14
Samsara
Reviews:
·Verizon FiOS
reply to Bob4
said by Bob4:

Other possibilities are a broken thermostat, a broken dip tube, or the hot and cold pipes are backwards.

Definitely check this. Connecting the water heater backwards is an easy mistake for a spaced out plumber, and will result in nearly zero usable hot water. If plumbed backwards, so that water is drawn from the "C" port, the "hot" water is being drawn from the very bottom of the tank, through the dip tube. So you'd be drawing cold water, while plenty of buoyant hot water is floating in the tank above the denser cold water that you're drawing.

Water should go in "C" and come out "H", this way, cold water is injected at the bottom of the tank, and hot water is drawn off the top.


LazMan
Premium
join:2003-03-26
canada
reply to Draiman
said by Draiman:

My wife refuses to allow me to turn the water heater down to 120. She insists it stay at 140. Given that's an option on the water heater there's no reason not to use it. If a water heater was meant to be run only at 120 they wouldn't make it configurable.

Smart wife...

»en.wikipedia.org/wiki/Legionellosis

It's an option to stab yourself in the eye with a pencil. I don't suggest doing that, either.


BillRoland
Premium
join:2001-01-21
Ocala, FL
kudos:3
reply to John97
I have a 10 year old AO Smith 40 gallon electric tank heater and I can tell you right now something is bad wrong with your setup if you can't take more than 5-10 minute shower. Considering you had one tank replaced and it didn't help all that much, the next step in my mind would be figuring out how the tanks are actually plumbed. 80 gallons of capacity should give you plenty of hot water.


toby
Troy Mcclure

join:2001-11-13
Portland, OR
reply to cdru
said by cdru:

said by toby:

With your 80 gallon combined, that still might be an issue unless..... you fill the tub at a slower rate, 25%, give the heater time to run as you are filling it. Simple really, we have to do it too.

Your average bathtub holds 50-60 gallons of water. If you can't get a tub full of hot enough water out of 80 gallons of water heating capacity, something is wrong.

Mine is a large jetted bath that holds more than 80 gallons. Tis why.


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to Jack_in_VA
said by Jack_in_VA:

said by Draiman:

My wife refuses to allow me to turn the water heater down to 120. She insists it stay at 140. Given that's an option on the water heater there's no reason not to use it. If a water heater was meant to be run only at 120 they wouldn't make it configurable.

160 degrees is an option also so why not use it? Why heat water just to have to add cold water to temper it down to a tolerable temperature to use?

You only need to heat the water to 140 to kill bacteria and you only need as much hot water as you can use. Heating it more then you need is pointless unless you like throwing money away. It doesn't matter what setting you use you still have to add cold water to temper the water down period end of story.

Example to 102 with 40 gallons:
120 to 102 = 15% or 6 gallons cold water = 46 gallons total
140 to 102 = ~27% or 11 gallons cold water = 51 gallons total

If you want to fill a bathtub with around 50 gallons of water which option would you pick?
--
IF YOU FIND ANY MISTAKES IN MY WORK...Please consider that they are there for a purpose. I try to please everyone and there is always someone looking for mistakes!


Jack_in_VA
Premium
join:2007-11-26
North, VA
kudos:1
Reviews:
·Millenicom
reply to LazMan
said by LazMan:

said by Draiman:

My wife refuses to allow me to turn the water heater down to 120. She insists it stay at 140. Given that's an option on the water heater there's no reason not to use it. If a water heater was meant to be run only at 120 they wouldn't make it configurable.

Smart wife...

»en.wikipedia.org/wiki/Legionellosis

It's an option to stab yourself in the eye with a pencil. I don't suggest doing that, either.

How many people have documentated cases of acquiring it from a water heater? How many do you know? You are more likely to get it from your windshield washer fluid than a water heater.

a ubiquitous aquatic organism that thrives in temperatures between 25 and 45 °C (77 and 113 °F), with an optimum temperature of 35 °C (95 °F)

n 2010 a study by the UK Health Protection Agency reported that 20% of cases may be caused by infected windscreen washer systems
Adding an antibacterial agent to the automobiles' windshield system's reservoir is also recommended

Bob4
Account deleted

join:2012-07-22
New Jersey


Draiman
Let me see those devil horns in the sky

join:2012-06-01
Kill Devil Hills, NC
Reviews:
·Verizon FiOS
reply to John97
Keep your tank at 140 and install a thermostatic mixing valve to get it down to 120 if that's all you want. You should have one of those installed to bring it down to 106 anyways if you are so worried about burns from hot water. Even 120 degree water can cause 3rd degree burns it just takes a few seconds longer.
Expand your moderator at work


Chinabound
Premium
join:2002-12-21
Antioch, IL
kudos:3
reply to Draiman

Re: Not enough hot water - house has 2 WH connected together.

said by Draiman:

Keep your tank at 140 and install a thermostatic mixing valve to get it down to 120 if that's all you want. You should have one of those installed to bring it down to 106 anyways if you are so worried about burns from hot water. Even 120 degree water can cause 3rd degree burns it just takes a few seconds longer.

You are wrong.

"Most adults will suffer third-degree burns if exposed to 150 degree water for two seconds. Burns will also occur with a six-second exposure to 140 degree water or with a thirty second exposure to 130 degree water. Even if the temperature is 120 degrees, a five minute exposure could result in third-degree burns."
»www.accuratebuilding.com/service···aph.html

By the way - learn to use the correct reply button.
Expand your moderator at work

Automate

join:2001-06-26
Atlanta, GA
reply to Chinabound

Re: Not enough hot water - house has 2 WH connected together.

Third degree burns are very severe. According to Wikipedia they can result in "Scarring, contractures, amputation" »en.wikipedia.org/wiki/Burn

The point is even a 1st or 2nd degree burn is very painful and should be avoided.

The same site you quotes says
"Each year, approximately 3,800 injuries and 34 deaths occur in the home due to scalding from excessively hot tap water. The majority of these accidents involve the elderly and children under the age of five."

and

"The CPSC notes that a thermostat setting of 120 degrees Fahrenheit (49 degrees Celsius) may be necessary for residential water heaters to reduce or eliminate the risk of most tap water scald injuries. Consumers should consider lowering the thermostat to the lowest settings that will satisfy hot water needs for all clothing and dish washing machines."