Kind of a long story so I'll try to be brief. 2013 Forest River (Salem) TT. 6 gallon DSI water heater. Twice after taking delivery the electric side of the water heater stopped working and has now been fixed and is functioning for the time being.The problem is my water runs cold after about 3 gallons of straight hot water is put into the tub. With only the gas side working I was told by the dealer that was the problem. Well, now both sides are working and it's no better. So, I know this sounds like a dumb question but is there some reason I'm only getting 3 gallons of hot water from a 6 gallon tank? I've had the same setup (6 gallon DSI) in a previous TT and it lasted way longer. I know RV showers aren't like home but I can barely get through a shower (military style) and hardly have any hair to rinse. It just seems like something is wrong. I know with a home water heater the dip tube can cause the kind of problem I'm having. Do RV water heaters have dip tubes? I'm try to be sure my expectations are in line and getting some information from others before I go back to the dealer.Thanks for any info.

How long do you keep it on before you run it?

Double check the bypass. It may not be completely closed. We

Could be bypass valve at WH being open (mixing cold water with hot)Could be outside shower knobs on (only turned off with button on handle) mixing cold with hotYES RV WHs have dip tubes on hot out and cold inlet.Missing Dip tube on cold inlet would cause more cold to be mixed with hot in WH tank. As you use hot the cold would pour in upwardly vs downward.Drain WH and with a strong pin point flashlight look thru drain hole for a black plastic piece laying on bottom of tank. That would be a dip tube that has fallen off.

I believe that some of the water heaters on newer rigs come with a "mixing valve" which would tend to give you colder showers ... worth a look.

did you open pressure relief when you put water in the heater to burp it

Problem with water heater or not? | Good Sam Community

12 Replies

nomad297
Explorer
Mar 27, 2014
Old-Biscuit wrote:
PRV...........very common acronym in RV speak for 'pressure relief valve' on WH.

Very rarely will you see it referred to as a T&P (more common of an acronym in the real world) :B

Might be cause the 'temp' is forgotten about opening at 210*F

I never thought of that. Being a plumber, I am set in my ways with its terms. Maybe now I understand why so many people call into my office saying the PRV on their water heater is leaking. The girl who takes the calls always writes up the tickets that way, too, and I always shake my head, knowing they really mean the T&P. maybe I have more RVing customers than I thought.

Bruce
Old-Biscuit
Explorer III
Mar 26, 2014
Yes there is something wrong!

You know something isn't right.....your other trailers WH didn't run out and it was same size.

Have you check the posted suggestions?
Bypass valve/outside shower valves AND if 'dip' tube has fallen off?
mtofell1
Explorer
Mar 26, 2014
Thanks everyone.... I really appreciate all the replies. To answer a couple questions, it's on plenty of time before I use it. It's reached what ever temp it's going to and has shut off. This has been ongoing through probably a dozen attempts so it's not just a random case of me not letting it heat up enough.

The RV has been winterized and de-winterized twice and it still behaves basically the same so I don't think it's a matter air being trapped and I've never seen water flowing from the TPR valve.

It's covered by a warranty so I don't really care why it isn't working. I mainly just want to know if something is wrong? Should I be getting more than 2-3 gallons of hot water before it goes cold?

Does anyone else bathe kids in the tub? I can barely get 2" of water in the bottom of the tub and it goes ice cold so I have to think something is wrong. Heating up pots of water on the stove is getting old :)
Old-Biscuit
Explorer III
Mar 26, 2014
PRV...........very common acronym in RV speak for 'pressure relief valve' on WH.

Very rarely will you see it referred to as a T&P (more common of an acronym in the real world) :B

Might be cause the 'temp' is forgotten about opening at 210*F
nomad297
Explorer
Mar 26, 2014
Old-Biscuit wrote:
mikeh449 wrote:
did you open pressure relief when you put water in the heater to burp it

Why do you 'burb' it thru PRV?
Open a faucet to expel air in system.

WH tank is designed to have an air pocket in top of tank so that the air can be compressed when the water is heated (water can't be compressed----pressure increases---PRV leaks)

Ok now...let's keep our plumbing acronyms straight. A PRV is a pressure regulating valve. A T&P is a temperature and pressure relief valve.

Bruce
Old-Biscuit
Explorer III
Mar 26, 2014
mikeh449 wrote:
did you open pressure relief when you put water in the heater to burp it

Why do you 'burb' it thru PRV?
Open a faucet to expel air in system.

WH tank is designed to have an air pocket in top of tank so that the air can be compressed when the water is heated (water can't be compressed----pressure increases---PRV leaks)
nomad297
Explorer
Mar 26, 2014
Old-Biscuit wrote:
Could be bypass valve at WH being open (mixing cold water with hot)

Could be outside shower knobs on (only turned off with button on handle) mixing cold with hot

YES RV WHs have dip tubes on hot out and cold inlet.

Missing Dip tube on cold inlet would cause more cold to be mixed with hot in WH tank. As you use hot the cold would pour in upwardly vs downward.

Drain WH and with a strong pin point flashlight look thru drain hole for a black plastic piece laying on bottom of tank. That would be a dip tube that has fallen off.

Old-Biscuit knows his plumbing. Good job.

Bruce
mikeh449
Explorer
Mar 26, 2014
did you open pressure relief when you put water in the heater to burp it
ksg5000
Explorer II
Mar 26, 2014
I believe that some of the water heaters on newer rigs come with a "mixing valve" which would tend to give you colder showers ... worth a look.
Old-Biscuit
Explorer III
Mar 26, 2014
Could be bypass valve at WH being open (mixing cold water with hot)

Could be outside shower knobs on (only turned off with button on handle) mixing cold with hot

YES RV WHs have dip tubes on hot out and cold inlet.

Missing Dip tube on cold inlet would cause more cold to be mixed with hot in WH tank. As you use hot the cold would pour in upwardly vs downward.

Drain WH and with a strong pin point flashlight look thru drain hole for a black plastic piece laying on bottom of tank. That would be a dip tube that has fallen off.