Hot Water Tank vs Fresh Water Tank

Nomad Mike · 06-22-2015, 03:55 PM

How do I know if the hot water tank has enough water to turn on the electric heat? I know I can pull the relief valve to see if it has water, but what is the relationship between the fresh water fill level and the hot water tank fill level?

So I have 1/3 tank of fresh, does that mean I have a full hot water tank ie ~20 fresh and 10 hot? The specs say I have a 93 gal fresh water tank with hot water tank included. From looking at diagrams the hot fills at the same time it is supplied to the taps with cold and since the pump supplies the hot water pressure, I should be fine at that 1/3. But how low is too low in the fresh tank before I need to cut off the hot usage?

t55watson · 06-22-2015, 04:02 PM

If you have water, tank or hose, and water comes out the hot water side of any faucet you are good to heat it. Tank gal. has no effect on amount of water in heater except when tank is empty.

mel s · 06-22-2015, 04:13 PM

Quote:

Originally Posted by Nomad Mike

How do I know if the hot water tank has enough water to turn on the electric heat? I know I can pull the relief valve to see if it has water, but what is the relationship between the fresh water fill level and the hot water tank fill level?

So I have 1/3 tank of fresh, does that mean I have a full hot water tank ie ~20 fresh and 10 hot? The specs say I have a 93 gal fresh water tank with hot water tank included. From looking at diagrams the hot fills at the same time it is supplied to the taps with cold and since the pump supplies the hot water pressure, I should be fine at that 1/3. But how low is too low in the fresh tank before I need to cut off the hot usage?

Nomad Mike
The amount of water in a RV fresh water tank has little to do with the amount of water in the RV water heater tank, (unless the fresh water tank is empty).
To determine if my water heater tank is full when I'm using water tank water, I open a hot water faucet and run it until only water comes out, (no air).
Same when I have pressurized water from an outside source, (like a campsite faucet).
Mel
'96 Safari

Nomad Mike · 06-22-2015, 04:50 PM

Thanks for the help, so I don't have to worry about the electric element if I have water running from the hot side of my sinks.

J Birder · 06-22-2015, 04:59 PM

Quote:

Originally Posted by t55watson

If you have water, tank or hose, and water comes out the hot water side of any faucet you are good to heat it. Tank gal. has no effect on amount of water in heater except when tank is empty.

That is not always true. If the hot water tank was bypassed for winterizing, and the valves are still in the bypass position, then (cold) water will come out of any of the Hot water faucets, but the hot water tank will still be empty.Turning on the heat would not be a good thing to do.

Joel

schrederman · 06-22-2015, 05:07 PM

I ALWAYS open the pop-off valve on my water heater to be sure it's full before turning it on. I replaced a friend's water heater last year. He turned it on with no water in it and the tank cracked... not good... expensive... and that was with no labor cost. Yes... he's that good of a friend...

mel s · 06-23-2015, 07:50 AM

Quote:

Originally Posted by J Birder

That is not always true. If the hot water tank was bypassed for winterizing, and the valves are still in the bypass position, then (cold) water will come out of any of the Hot water faucets, but the hot water tank will still be empty.Turning on the heat would not be a good thing to do.
Joel

J Birder
Correct

If the water heater has a bypass and IF the bypass valves are not set correctly no water will fill the water heater tank, (but water will flow out of the hot water faucets).
I should have stated that in my previous post, (#3 in this thread).

Sorry
Mel
'96 Safari

macgyvr · 07-22-2015, 09:47 AM

So if the bypass is on, you'll have water in both the hot water and cold water side of the faucet?

My bypass selector is a bit misleading and I'm not sure if I'm in bypass or not.

In one selection I have water out of both sides...in the other selection I have water out of only the cold water side...nothing from the hot side...

Which is the normal selection...no need to bypass it.

My water heater is only running for 20-30 seconds and shutting off, I'm wondering if somehow I'm not getting water into the water heater and the water heater doesn't like no water and it is shutting off the gas.

mac 'not hot' gyvr

Nomad Mike · 07-22-2015, 10:14 AM

You should get water out of both hot and cold always. If your in bypass, the cold water supplied either by your pump or a city connection will skip the hot water tank but enter the hot water line. When the bypass in not on, water will enter the hot water tank and exit into the hot water line.

I found this drawing somewhere on this forum:

mel s · 07-22-2015, 10:15 AM

Quote:

Originally Posted by macgyvr

So if the bypass is on, you'll have water in both the hot water and cold water side of the faucet?
My bypass selector is a bit misleading and I'm not sure if I'm in bypass or not.
In one selection I have water out of both sides...in the other selection I have water out of only the cold water side...nothing from the hot side...
Which is the normal selection...no need to bypass it.
My water heater is only running for 20-30 seconds and shutting off, I'm wondering if somehow I'm not getting water into the water heater and the water heater doesn't like no water and it is shutting off the gas.
mac 'not hot' gyvr

macgyvr
I don't think that any RV water heater knows if it has water in it or not.
Me thinks you have a "electronic control board problem".
Most RV repair shops have a board tester... (and many test boards for free).

Remove your control board... take it in and and have it tested.
Mel
'96 Safari

macgyvr · 07-28-2015, 07:24 AM

Thanks for the replies.

So I had replaced my ect, tstat, thermocoupler, and that other diode overload thingy (that's a word right?). The dang water heater was running 10-30 seconds and shutting off.

I wasn't getting water off the hot water side on one of the two bypass selections, turned out to be the normal selection.

I did however have water in the water heater when I pulled the drain plug. I did not having anything coming out of the relief valve at the top.

So after a bunch of searching via google and this site, I pulled the plug again on the hot water heater. Only about a gallon of water drained out.

I determined that the one way coupler on the water line was broke and only letting water drip in. The water heater was turning on but as we know hot air gets hot faster than water, so the water heater was over heating and the ect, tstat was doing its job and shutting the water heater off.

So I stood on my head, pulled the water heater partially out and took the coupler on the bottom of the water heater off. It was in fact broken. I pulled the guts of it out, stood back on my head to put it back together.

The water now flows to the hot water heater and to my faucets. The water heater fires up and works. We had hot water this weekend.

I also figured out that this water heater is not the original to the coach (dated 2007). Not to surprising since the coach is 14 almost 15 years old. It does have two hoses coming off that look like they go into the cooling system of the coach. I didn't think that Diesel pushers had the motoraid...I don't know how to turn it on to use it either, not sure if someone added it on or what.

Regardless, we have hot water, wife happy.

mac 'happy wife, happy life' gyvr

wa8yxm · 07-28-2015, 04:30 PM

If fresh water has enough for the pump to suck and bypass valves are not in bypass mode hot water tank has water (enough) in it.

I'm in S.E. Ga. it's 5:30 the fresh water tank IS hot water

Seroiusly accidently turned off hot water the other day.. Did not matter, Morning shower was well within comfort zone.

cbeierl · 07-28-2015, 04:48 PM

Quote:

Originally Posted by macgyvr

... I didn't think that Diesel pushers had the motoraid...I don't know how to turn it on to use it either, not sure if someone added it on or what....

Many (most? all?) of the Winnebago diesel pushers have motoraid heating the hot water tank (but not a house heater in the rear of the coach as many gas models have).

rgreen45 · 07-28-2015, 09:47 PM

Quote:

Originally Posted by macgyvr

Thanks for the replies.

I determined that the one way coupler on the water line was broke and only letting water drip in. The water heater was turning on but as we know hot air gets hot faster than water, so the water heater was over heating and the ect, tstat was doing its job and shutting the water heater off.

So I stood on my head, pulled the water heater partially out and took the coupler on the bottom of the water heater off. It was in fact broken. I pulled the guts of it out, stood back on my head to put it back together.

I hope you replaced that check valve ... the thing you called a one way coupler. It needs to be there.

macgyvr · 07-29-2015, 12:10 PM

Quote:

Originally Posted by cbeierl

Many (most? all?) of the Winnebago diesel pushers have motoraid heating the hot water tank (but not a house heater in the rear of the coach as many gas models have).

It's odd, because the manual for my coach (01 Winnebago Journey), says that diesel pushers don't have it, only the gas models.

Quote:

Originally Posted by rgreen45

I hope you replaced that check valve ... the thing you called a one way coupler. It needs to be there.

Not yet. Saw it was broke and that I could get the guts out. I see mixed reviews on this site about having it. Some folks have run without them for years. I didn't have time to get a new one when I found the problem. When I'm not against a trip (like I was last week and it's not 90 degrees) I'll probably replace it when I winterize this fall.

mac 'always something' gyvr

cbeierl · 07-29-2015, 03:55 PM

Quote:

Originally Posted by macgyvr

It's odd, because the manual for my coach (01 Winnebago Journey), says that diesel pushers don't have it, only the gas models.
...

Perhaps that's referring to the 'motoraid' rear cabin heater that's on some of the gas models but none of the diesels.

Nomad Mike · 07-29-2015, 09:40 PM

Quote:

Originally Posted by macgyvr

It's odd, because the manual for my coach (01 Winnebago Journey), says that diesel pushers don't have it, only the gas models.

Not yet. Saw it was broke and that I could get the guts out. I see mixed reviews on this site about having it. Some folks have run without them for years. I didn't have time to get a new one when I found the problem. When I'm not against a trip (like I was last week and it's not 90 degrees) I'll probably replace it when I winterize this fall.

mac 'always something' gyvr

Quote:

Originally Posted by cbeierl

Perhaps that's referring to the 'motoraid' rear cabin heater that's on some of the gas models but none of the diesels.

Here is a Youtube video of a 2001 Journey 36LD that has both water heater and room Motor Aid. It is spelled this way in my manual and the brochure is all one word.
My 05' Journey manual and brochure both mention having Motor Aid:

cbeierl · 07-29-2015, 09:52 PM

Quote:

Originally Posted by Nomad Mike

Here is a Youtube video of a 2001 Journey 36LD that has both water heater and room Motor Aid. It is spelled this way in my manual and the brochure is all one word.
My 05' Journey manual and brochure both mention having Motor Aid:

The video is incorrect--The 'Engine Heater' switch is for the engine block heater (120V AC) which is something completely different. I'm not aware of any Winnebago diesels with Motor Aid room heat.

Nomad Mike · 07-29-2015, 10:33 PM

Quote:

Originally Posted by cbeierl

The video is incorrect--The 'Engine Heater' switch is for the engine block heater (120V AC) which is something completely different. I'm not aware of any Winnebago diesels with Motor Aid room heat.

Yea, after I posted that I looked at my engine block heater and it is labeled the same and doesn't say Motor Aid or room heat.

But, that 2001 has Motor Aid water heat via a switch? I have no switch in mine, maybe it is all the time on my unit?

cbeierl · 07-29-2015, 11:22 PM

Quote:

Originally Posted by Nomad Mike

Yea, after I posted that I looked at my engine block heater and it is labeled the same and doesn't say Motor Aid or room heat.

But, that 2001 has Motor Aid water heat via a switch? I have no switch in mine, maybe it is all the time on my unit?

That salesman doesn't have a clue what he's talking about. The water heater switch is the 120V AC switch for the electric element in the water heater. Motor Aid for the water heater is always on.