2 Gallons of Hot out of 6 Gallon Hot Water Heater

[Larry-NC]

Originally Posted by 5picker

The thermostats are not adjustable so you can't 'bump' them up.

They do make one or two different degree 'stats so you could see what you have and see if you can get a hotter one.

Be sure to check the things that have been mentioned. (hoses reversed, outside shower, etc.) It's also possible the dip/mixing tube inside the tank fell off or is faulty somehow mixing the cold into the hot at a much higher level in the tank.

Here's what it should look like when looking in the removed anode bung...

I wasn't even aware that there was a dip tube. You would think it has minimal effect since cold enters near the bottom and hot exits near the top. Maybe it reduces turbulence a little, encouraging laminar separation.

But I did find a different picture in the SW6DE Repair Manual, a cutaway view. This might make it easier to visualize. I wonder if you could knock the dip tube off by poking around through the anode rod opening. They seem to be directly opposite.

[BMullins46]

OP says he does NOT have a shut off button on his shower. Since he is an experienced camper he has some valid concerns about the water heater operation. I would question his testing methodology however. He needs to listen to those have mentioned the mixing of the cold incoming water with the hot water in the tank. Secondly how often would you use straight hot water in the quantity he tested? Taking "navy" showers is what we do and suggest to anyone who has similar issues like the OP.

I would suggest he consult with the service department at his dealer and if necessary contact the manufacturer of the water heater for suggestions on how to solve his problem.

[MR.M]

Originally Posted by SmackIt

I appreciate the advice from everyone.

The water is coming from the fresh water tank, it's probably about 45-50 degrees. The outside temperature is 75 degrees. These are very normal warm conditions, it's not like the hot water heater needs to work that hard.

2 gallons from a six gallon tank is not normal. Especially considering I'm plugged into 30 amp shore power with 2 full tanks of propane. The water heater is running in dual electric/gas mode. I'm giving it a minimum of 30 minutes, but generally 60 minutes to recover between these tests.

All plumbing is correct in its routing and function... if I was running a test of a 2 gallon water heater, I would say everything is normal.

I never ran out of hot water on my Jayco, it was scalding hot, and you had to add cold to the hot water stream to avoid getting burned. Even with a "full" 6 gallon tank on my new Surveyor, I can almost stand putting my hand in the direct hot water stream at full hot. It's a little painful, but definitely wouldn't cause a severe burn.

How do you bump the hot water heater temp up on the Suburban SW6DE? If the above comments are true about the cold water diluting the heat after only 2 gallons of use, I need to have much hotter water sitting in the tank.

1st if the hot water coming out at first is hot , then most likely getting a mix of cold in from somewhere . check the outside shower .
2. you will never get 6 gallons of hot water out of a 6 gal tank . but you should get 4 to 4.5

3 running both electric and gas will heat things up quicker but will not make it last longer

4 your could have a weak T-stat no way to increase temp replace T-stat

5 have you ever drained and flushed the tank ? maybe in order

6 do you have a check valve on the hot out of the tank ? if so it could be bad and or the valve is not closing off completely and needs replaced


7 get an on demand water heater

[BikeFlagAZ]

Originally Posted by tomkatb

Another thought.

If your outside shower valve or shower is on with the hose end off. That causes issues like this.

Best to read the post before responding.
“ I do not have an outdoor shower.”

[Paul Dershem]

Originally Posted by TriGlide

We don't turn on our hot water heater unless we need it. It heats up in about 10 to 15 min max and we have never ran out of hot water when showering or doing dishes ever. After we finish we then turn it back off until the next time we need some.

Same here - because we are very conservative with water consumption in general, and especially when washing dishes and showering (we take "Navy showers"). We've never run short of hot water. During warm weather, we typically have hot or very warm water available at the tap even after the water heater has been off for several hours.

When we first got our trailer, we only got luke-warm water because I didn't have the winterizing valves in their correct positions.

[awellis3]

Originally Posted by SmackIt

Why am I only getting 2 gallons of hot water?

Well, I've read all the responses and I don't believe anyone has suggested checking that the tank is filling all the way. If you have a large air pocket displacing a gallon or two of water, that would cause your problem.
Have you opened the relief valve to verify the tank is full?

[Larry-NC]

Originally Posted by awellis3

Well, I've read all the responses and I don't believe anyone has suggested checking that the tank is filling all the way. If you have a large air pocket displacing a gallon or two of water, that would cause your problem.
Have you opened the relief valve to verify the tank is full?

Naah, that can't be it. Hot water exits near the top. Any air in the heater below the hot water exit will be expelled the first time you turn on the hot water. It happens that way every spring when you refill the water heater.

[wmtire]

On the outside of the water heater near the top, there is a black rubber cover that may have the word reset on two round circles. This cover is over your two separate thermostat assemblies.

When you remove this rubber cover, the thermostat assembly on the left (black wires) is to your electric heating element heating mode

The one on the right (red wires) is to the propane/dsi heating mode.

The thermostat assemblies are bolted up to the side of the tank and sense the temperature thru the tank wall.

You may want to check and make sure they are tight and snug against the tank wall and nothing was messed up during manufacturing assembly. For future reference, These two thermostat assemblies are what you replace to change the operating temp of your water heater. The original thermostats operate in the 130 degree range and you can purchase higher limit one's in the 140 degree range

Fyi, don't touch the thermostats electrical connections by accident if you have power going to either while you check.

[D W]

Personally, I don't see a problem here. You run 2 gallons of pure hot water out of the water heater and then another gallon while at the same time replacing water in the water heater with ~45°F water, it's going to cool the water heater temp. That's a no brainer.

I mean who actually takes a shower, washes dishes or their hands with straight hot water?

[SmackIt]

Originally Posted by D W

Personally, I don't see a problem here. You run 2 gallons of pure hot water out of the water heater and then another gallon while at the same time replacing water in the water heater with ~45°F water, it's going to cool the water heater temp. That's a no brainer.

I mean who actually takes a shower, washes dishes or their hands with straight hot water?

Given the inability to up the temperature of the 6 gallons held in the tank, I'm forced into a pretty quick depletion of comfortable warm water. I assume most people are showering between 95 ~ 110 degrees. A comfortable shower with this unit is tap positions at 85~90% hot and 10~15% cold. My Jayco was about 50/50 for a comfortable shower temp.

[TitanMike]

Originally Posted by SailorSam20500

Just an outside possibility. While doing your kitchen sink test, grab the top pipe and make sure the hot water is coming out there and cold is, in fact, going in the bottom. Could be that the pipes were hooked up backwards. A possibility since the pipes aren't color coded pex.

I'll second this suggestion. The more I think about it the more it makes sense.

As I've always understood, hot water will rise and the cold will stratify along the bottom of the tank (to a point anyway). If Cold is entering at top it will diffuse rapidly in the Hot that is being drawn from the bottom.

As you said, no color coding so maybe an installation error??????

[Herk7769]

It appears to me like the valves are turned 90 degrees out for use.

The valves are like a T inside and with the valve handles pointed at the heater you are defeating the valve by allowing cold water to enter the hot water line through the bypass hose.

Turn the valves so they aline with the water hoses (not the bypass hose) to use hot water and away from the tank to bypass.

[youroo]

Originally Posted by Herk7769

It appears to me like the valves are turned 90 degrees out for use.

The valves are like a T inside and with the valve handles pointed at the heater you are defeating the valve by allowing cold water to enter the hot water line through the bypass hose.

Turn the valves so they aline with the water hoses (not the bypass hose) to use hot water and away from the tank to bypass.

If you are trying to say the Valves in his 1st post are in the wrong position for Hot water while camping ,that is a false statement! Youroo!!

[nomad297]

First — have you actually measured the temperature of the hot water and timed it and recorded the temperatures at different time intervals as you are measuring the volume of hot water? This is where you always start when diagnosing the performance of a water heater.

With residential plumbing and water heaters, when a specific amount of hot water is required for a household, the water heater is sized using 60% as the factor for the amount of hot water you will get from any specific size of tank-type water heater without considering water that is heated during recovery. So, a 50-gallon water heater will provide about 30 gallons of hot water and a 75-gallon water heater will provide about 45 gallons of hot water. A 6-gallon residential water heater will provide about 3-1/2 gallons of hot water. All top inlet/outlet residential water heaters use a dip tube to send the cold water to the bottom of the tank so it doesn’t mix with the hot water at the top. The cold water “pushes” the hot water up to the hot outlet. Basically, all tank-type water heaters are filled with cold/warm water in the bottom half and hot water in the top half.

I work on residential and commercial water heaters all of the time, and it is very rare when I need to drain the tank to replace the drain, the lower element or the gas control valve. I shut off the water supply to the tank, then open up a faucet or something else at or below the level of the top of the tank for a little while, then close it to create a slight vacuum in the tank. Once I have done this, I can do a quick replacement with minimal water escaping the water heater. I do this with my bare hands because the water at that level in the water heater is not hot. Sometimes it is cold, but usually it is just slightly warm, but it is never hot. This is something I can do with confidence because I know the bottom half of the water heater does not contain hot water.

RV water heater tanks aren’t shaped like residential tanks, so the difference of the 3-1/2 gallons of hot water you will get from a 6-gallon residential water heater and the lesser amount you get from an RV tank could be due to this — just a thought. I doubt your water heater is hooked up backwards because there is a check valve on the hot side that wouldn’t allow the tank to fill if it was hooked up this way. Also, your dip tube may be missing/snapped or it may be installed upside down causing the cold water to mix higher in the tank than it should.

Assuming you have a properly working thermostat, I bet if you let your water heater heat completely, let it settle for about 15 minutes, then turned off the water supply, removed the T&P relief valve from the tank, then siphoned the top 60% of water from the tank, you would end up with about 3-1/2 gallons of hot water.

Bruce

[Herk7769]

Originally Posted by youroo

If you are trying to say the Valves in his 1st post are in the wrong position for Hot water while camping ,that is a false statement! Youroo!!

OK, if you say so. Just trying to figure it out like everyone else.

[NavyLCDR]

I take a Navy shower when camping, usually with both electric and propane on the water heater. During the rinse phase I have plenty of hot water, more than is really needed. Just out of curiosity, why has nobody else conducted the same experiment as the OP and check just exactly how much pure hot water they get? I would, but I am winterized now.

I'm thinking double check the plumbing at the water heater. If the cold is going in the top and the hot is coming out the bottom, that is likely the problem. Or the internal tube on the cold water inlet that should be directing the cold water inlet to the bottom of the tank.

[eye95]

Originally Posted by Herk7769

OK, if you say so. Just trying to figure it out like everyone else.

My understanding is that the valve handle (of a properly installed valve) should point in the direction of the water flow. If this is the case and if the valve handles are properly installed in the pictured water heater, then the valve handles are pointed in a way that indicates the water will flow through the heater and not through the bypass piping.

[nomad297]

Originally Posted by NavyLCDR

why has nobody else conducted the same experiment as the OP and check just exactly how much pure hot water they get?

His experiment’s method is flawed and will not provide accurate results.

Originally Posted by NavyLCDR

I'm thinking double check the plumbing at the water heater. If the cold is going in the top and the hot is coming out the bottom, that is likely the problem.

I really doubt this is the problem. If this was the case, the hot side check valve would either have to be missing or broken. Plus, he would be getting much less hot water than 2 gallons.

Bruce

[nomad297]

Originally Posted by eye95

My understanding is that the valve handle (of a properly installed valve) should point in the direction of the water flow. If this is the case and if the valve handles are properly installed in the pictured water heater, then the valve handles are pointed in a way that indicates the water will flow through the heater and not through the bypass piping.

The direction of the lever does not have anything to do with the direction of the flow. The direction of the lever only indicates which part of the valve is open. With the three-way valve, this might be a little confusing, though. The valves in the picture are positioned correctly for proper operation of the water heater.

Bruce

[NavyLCDR]

Originally Posted by nomad297

His experiment’s method is flawed and will not provide accurate results.

Flawed experiment or not, if someone else was to do the same experiment and post back that they also get 2 gallons of pure hot water out of the their 6 gallon tank then it would provide proof to the OP that his system is normal. I'm just not going to go out and undo my winterization to do it for him.