6 gallon hot water heater only delivers 4 gallons

ehstars wrote:
Hello, I have a 6 year old Suburban SW6DE water heater which only gives me 4 gallons of hot water. This short change just started recently. The water gets heated to 135 degrees on either propane or electric, or both, but just doesn't deliver the whole 6 gallons. I have looked endlessly for leaks but no joy. The only thing that I see which might contribute slightly to this is my pressure relief valve is dripping a bit, about one drop every two seconds, more or less. But I doubt that would add up to two gallons in the 15 minutes it takes for the heating cycle to end, would it? Any advice would be great. Thanks.

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Closing.

I'm still wondering how the OP is measuring 6 gallons of hot water vs 4 gallons. After about 4 gallons, the output temp HAS to be reduced since you are replenishing the tank with unheated water. Regardless of how the intake tube and output tube is setup, it would still mix somewhat. So it would seem to be impossible to get 6 gallons of hot water out of a 6 gallon water heater UNLESS you drain it from the bottom and do not add any additional water to refill. Or am I missing something blatantly obvious (wouldn't be the first time, but...)?

wopachop wrote:
Was curious and google said 1 drop every 2 seconds is:
1.5 teaspoons per minute
15oz per hour
20 gal per week

So in a way a slow drip is roughly 1 standard 12oz can per hour.

One drop every 2 seconds is 30 drops per minute. In pharmacy we occasionally have to convert from drops to ml or ml to drops, and use 20 drops per ml as an average. (Every fluid varies with its viscosity, but 20 drops/ml is a workable average for aqueous solutions. Alcohol based elixirs would be a larger number of drops.) So, 30 drops per minute is 1.5 ml per minute, not 1.5 teaspoons.

That works out to 90ml (3 oz) per hour. Or 4 gallons per week. Still unacceptable.

Old-Biscuit wrote:
Cold Inlet diffuser (white) and Hot Outlet diffuser (black) are available for replacement on Suburban Water Heaters

Just disconnect water line.....then remove fitting screwed into tank.
Diffusers are replaced by pushing them in thru tank opening then held inplace via flange on end of diffuser and the fitting that is screwed back into tank

Suburban 171509...HOT (black) Diffuser
Suburban 171504... Cold (white) Diffuser





Atwood uses diffusers also but are NOT replaceable...factory installed
If Cold Inlet (points down) is broken off cold WILL mx with hot water and dilute it quickly
If Hot Outlet (points UP) is broken off Less HOT water will be available due to cold mixing with hot as it forces water out top outlet
Atwood doesn't even mention diffusers or have a real cutout picture of their tank components. Just a cartoon diagram

Thanks. I looked for that diagram and could not find it. I MEANT the cold water diffuser. That directs the input cold water DOWN to prevent premature mixing with the upper hot water. Doug

Cold Inlet diffuser (white) and Hot Outlet diffuser (black) are available for replacement on Suburban Water Heaters

Just disconnect water line.....then remove fitting screwed into tank.
Diffusers are replaced by pushing them in thru tank opening then held inplace via flange on end of diffuser and the fitting that is screwed back into tank

Suburban 171509...HOT (black) Diffuser
Suburban 171504... Cold (white) Diffuser





Atwood uses diffusers also but are NOT replaceable...factory installed
If Cold Inlet (points down) is broken off cold WILL mx with hot water and dilute it quickly
If Hot Outlet (points UP) is broken off Less HOT water will be available due to cold mixing with hot as it forces water out top outlet
Atwood doesn't even mention diffusers or have a real cutout picture of their tank components. Just a cartoon diagram

valhalla360 wrote:

dougrainer wrote:
Suburbans have a bent interior pick up tube(mounted on the interior hot exit fitting) that KEEPS Hot water flowing without getting the diluted cold water intake. IF that tube is knocked loose, the cold water coming in the bottom as it mixes with the hot water will dilute to normal hot water that would exit at the top. Things that can dislodge this tube

That helps a little but replace 2/3 of the water in the tank, you can expect it to be a mix of hot and cold water and the water coming out the tap will gradually get cooler.

This is just normal operation with a tank based water heater and why home based water heaters are typically 50-100 gal...if you replace 5-10 gal, you are only diluting with a small amount of cold water. In an RV, water is heavy, so they limit the size to typically 6 or 10 gal tanks and more than a quick shower or two and the water starts coming out colder because you've diluted with 50% or more cold water. It's just the nature of the beast.

Remember, he stated this problem just started recently. So, he has monitored the amount of hot water volume previously. Doug

dougrainer wrote:
Suburbans have a bent interior pick up tube(mounted on the interior hot exit fitting) that KEEPS Hot water flowing without getting the diluted cold water intake. IF that tube is knocked loose, the cold water coming in the bottom as it mixes with the hot water will dilute to normal hot water that would exit at the top. Things that can dislodge this tube

That helps a little but replace 2/3 of the water in the tank, you can expect it to be a mix of hot and cold water and the water coming out the tap will gradually get cooler.

This is just normal operation with a tank based water heater and why home based water heaters are typically 50-100 gal...if you replace 5-10 gal, you are only diluting with a small amount of cold water. In an RV, water is heavy, so they limit the size to typically 6 or 10 gal tanks and more than a quick shower or two and the water starts coming out colder because you've diluted with 50% or more cold water. It's just the nature of the beast.

wopachop wrote:
Was curious and google said 1 drop every 2 seconds is:
1.5 teaspoons per minute
15oz per hour
20 gal per week

So in a way a slow drip is roughly 1 standard 12oz can per hour.

Weeping T&P Relief Valve
As hot water drips out...cold comes back in IF on city water source (on pump system pressure would need to drop for pump to run and water heater pressure is going to be HIGH)
Water swells as it is heated.
Air pocket at top of tank helps control the possible increase in pressure when swelling occurs.
Loss of air pocket can allow higher pressure which can cause T&P to weep

Overheating can cause T&P to weep.....due to increase in pressure
Loss of T-stat/ECO--High Temp T-stat controlling heating can cause T&P to weep due to increase in pressure AND water temp

Debris/Calcium build up on T&P Valve seat can cause weeping

T&P POP open at 210*F/150 psi....weeping can happen at 125psi which can happen if air pocket is lost and t-stat has failed to control heat to 130*F

Was curious and google said 1 drop every 2 seconds is:
1.5 teaspoons per minute
15oz per hour
20 gal per week

So in a way a slow drip is roughly 1 standard 12oz can per hour.

Before you insult people, LOOK IN THE MIRROR. There is the dumb one. 180 degrees is NOT ANY RV Factory installed RV water Heater. As Old Biscuit pointed out, The MAX operating temp of any RV WH is the one EXT model that heats to 160 degrees, then has a mixing valve to drop the actual hot water output to 125 to 135. MOST RV water heaters have either a 130 or 140 MAX tstat. The 180 is when the Tstat FAILS and ONLY THE ECO is controlling the temp. KIND OF DUMB NOT TO KNOW THAT :B DOUG




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