Atwood water heater problem solved...I think!

[HabsOnTheRoad]

I think I may have finally solved the temperature swing problem with our Atwood on-demand water heater. The problem was that when you take a shower and get the temperature just right, it would go cold after about 30 seconds. You wouldn't have to crank the handle over to the hot side and it gets too hot and then feather in the cold water. You get another 30 seconds of decent temperature water. The result was screams coming from everybody in the family as they are taking showers! No bueno! The kids could not take a shower by themselves with this issue. They would either get scolded with hot water or a blast of freezing cold water!

Some research and talking with Atwood (and a lot of trial and error) revealed that we needed to have more water flow (not more PSI), as the water heater will not kick on until there is at least 1.5GPM flow rate.

First thing I did was to buy a Valterra high flow water regulator with a built-in PSI gauge. That seemed to make the issue better, but still didn't fix it completely. I then placed a 1 gallon jug in the shower and timed how long it took to fill it up with the factory shower head. It was inadequate. So, off to Lowe's we went and bought a 2.5 GPM showerhead. That seemed to help a little bit more, but still didn't solve the problem.

So the real issue is that when you mix the hot and cold water to a comfortable temperature, the flow rate on the hot side is not reaching 1.5 GPM. The fix is to turn down the thermostat (red knob on the lower right portion of the water heater housing, accessible via the outside of the RV) on the water heater to only 1/4 from the minimum setting so that the shower knob is pushed over to the hot side almost completely for a comfortable temperature, resulting in more like 2 GPM on the hot side. I hope that makes sense. We just had a test shower run and it seems to have fixed the problem.

Will report back later if the problem crops up again.


https://habsontheroad.com
2017 Berkshire XLT towing a 2012 CRV

[HabsOnTheRoad]

Just took a shower and never had to move the knob once! This is so exciting! I think I may have solved the problem.


https://habsontheroad.com
2017 Berkshire XLT towing a 2012 CRV

[wmtire]

Excellent. Thanks for sharing.

[BandJCarm]

Congrats. I gave up and replaced mine with a conventional. Just too cantankerous for me.

[pearly44]

Atwood On-Demand water heater = Another example of the corrupt RV industry foisting an unproven, untested, inadequate solution upon an unsuspecting RV public. All of these things should be replaced at no charge.

[Bama Rambler]

Excellent diagnosis. I read about the flow requirement before, but you got into the details of how to do it. Thanks much.

[pearly44]

Originally Posted by HabsOnTheRoad

I think I may have finally solved the temperature swing problem with our Atwood on-demand water heater. The problem was that when you take a shower and get the temperature just right, it would go cold after about 30 seconds. You wouldn't have to crank the handle over to the hot side and it gets too hot and then feather in the cold water. You get another 30 seconds of decent temperature water. The result was screams coming from everybody in the family as they are taking showers! No bueno! The kids could not take a shower by themselves with this issue. They would either get scolded with hot water or a blast of freezing cold water!

Some research and talking with Atwood (and a lot of trial and error) revealed that we needed to have more water flow (not more PSI), as the water heater will not kick on until there is at least 1.5GPM flow rate.

First thing I did was to buy a Valterra high flow water regulator with a built-in PSI gauge. That seemed to make the issue better, but still didn't fix it completely. I then placed a 1 gallon jug in the shower and timed how long it took to fill it up with the factory shower head. It was inadequate. So, off to Lowe's we went and bought a 2.5 GPM showerhead. That seemed to help a little bit more, but still didn't solve the problem.

So the real issue is that when you mix the hot and cold water to a comfortable temperature, the flow rate on the hot side is not reaching 1.5 GPM. The fix is to turn down the thermostat (red knob on the lower right portion of the water heater housing, accessible via the outside of the RV) on the water heater to only 1/4 from the minimum setting so that the shower knob is pushed over to the hot side almost completely for a comfortable temperature, resulting in more like 2 GPM on the hot side. I hope that makes sense. We just had a test shower run and it seems to have fixed the problem.

Will report back later if the problem crops up again.


https://habsontheroad.com
2017 Berkshire XLT towing a 2012 CRV

After reading the Atwood tech doc, this was one of the first things we tried. Problem is that by turning the modulator valve to the left, you are effectively lowering the temperature of the hot water. I found to get any sort of consistency in the shower, I had to turn the hot water almost all the way on which resulting in the modulator valve being turned almost all the way down. This worked, sort of, until DW started complaining about the luke warm water at the kitchen sink.

[jcowles3]

Tankless heater work on temperature differential so the warmer water comes in the less you need to heat it up, thus low setting on tstat but if its cold then you need more delta T... and yes use little to no mixing water!


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[Tbonz]

FYI..I built my own regulator ...go to Lowe's or Home Depot and get a while house regulator and adapt it to fit water faucet and hoses...full flow but regulates pressure. I do not have the water heater you do but this regulator is grand..Total cost about $70. But worth it

[joet19711]

Originally Posted by jcowles3

Tankless heater work on temperature differential so the warmer water comes in the less you need to heat it up, thus low setting on tstat but if its cold then you need more delta T... and yes use little to no mixing water!


Sent from my iPhone using Forest River Forums

And.. when you are in colder temperatures and the incoming water is colder you will be turning the modulator up towards the max and then you can go play the "hit the red high temp reset button" all the time. and if your little black plastic tube that comes off the pressure switch and protrudes thru the cover gets blocked up with dirt, bugs, etc. you can go and mess with that. I have been fighting with since July.
Bad design all the way around by Atwood.

[Phil57]

I wrote up a similar fix last week. You need to keep the flow rate up. I can turn my temp outside to max and still have a lot of adjustment inside. I stopped using a water regulator as I haven't had a need for one. I do carry it just in case. I am running two shower heads to keep the flow rate up. Two is not the best as the shower is small. I'm searching for a hi flow shower head.
As for the black tube it's an easy fix. Turn it so it is inside the compartment and cover the hole with tape. It's a two minute fix. Hardly something to get all hostile about. I am very happy with the Atwood. It is working almost Perfectly.

[HabsOnTheRoad]

UPDATE ON WATER HEATER ISSUE:

I got a call from Jerry at Atwood about my water heater issue (difficulty maintaining enough flow on the hot side for the water heater to kick on). He said there has been a recall issue for the mixing valve and that it's about a 10 minute swap. The new valve only requires 1 GPM in order to kick on. To know if you have the updated part, there should be a scold warning sticker near the thermostat. Ours does not have that sticker. You can also provide would your water heater s/n and they can confirm if you need the new part.

I will report back after we have had the replacement performed.

I'm glad to hear this may be the solution to our problem, but I'm frustrated that we weren't informed of the recall when I first called Atwood and when I called the service department of the dealer we bought it from.

(I posted this update in another thread as well because there were two different discussions about it)


https://habsontheroad.com
2017 Berkshire XLT towing a 2012 CRV

[gordonsick]

I'm surprised that the Atwood requires a 1 gallon per minute flow rate to turn on the heater.

I'm pretty sure that the flow rate from my shower (I measured it) is only 1 gallon per minute, after mixing in some cold water. Thus, my Girard Gen II works fine with a flow rate of less than 1 gallon per minute.

Maybe it was an illusion that the Atwood was an upgrade from the Girard.

–Gordon

[QueenD]

Originally Posted by BandJCarm

Congrats. I gave up and replaced mine with a conventional. Just too cantankerous for me.

Wow you mind me asking the cost to replace.

[Phil57]

Originally Posted by QueenD

Wow you mind me asking the cost to replace.

If you have a Atwood you can get it working very easily. Remove all of the water restrictions from the shower head. That is the white plastic things in the end where the hose attaches. Also out side turn the black hose to the inside and cover the hole. The new models have done just that except they cover the hole with glass. If anything is in that black tube the heater will not work.

[dcheatwood]

Makes sense. Wonder why some have issues and some don't. Glad you solved yours.

[Oscarvan]

You can get the Atwood to fire. As Phil said, removing flow restrictors can get you above the threshold.

The problem with the thing is that the flame height changes with flow. Picture a little squirrel sitting there controlling the throttle. So when you turn the shower a little cooler, the hot water flow goes down a little, and the squirrel adjusts, more than you asked for. Problem is that with our plumbing installation the hot water travels 40-50 feet so there's a lag. (About a minute). So you in the shower are constantly chasing the temperature which ranges from scalding hot to purple cold.

On edit.... one of the solutions is to have a split faucet. IOW, the hot full on, and stays full on. Modulate temperature with the cold side without affecting the hot flow. That would improve it, although there would be some change in flow because the change in cold flow would change the total pressure to the hot water heater, whether on pump or regulated external water supply.

[Phil57]

Oscar I will check but I don't believe the flame or more correct the BTU output changes with water flow. Again I'm going off memory. Also the 50 seconds for hot water was in the kitchen. My shower is hot in about 25 seconds. I get absolutely no fluctuation in temperature. I can honestly say I wouldn't trade my water heater for anything else.

[Oscarvan]

Originally Posted by Phil57

Oscar I will check but I don't believe the flame or more correct the BTU output changes with water flow. Again I'm going off memory. Also the 50 seconds for hot water was in the kitchen. My shower is hot in about 25 seconds. I get absolutely no fluctuation in temperature. I can honestly say I wouldn't trade my water heater for anything else.

If the BTU output does NOT change with water flow fluctuations it follows that the temperature HAS to change.....

Same heat into more or less water..... right?

As far as times...... remember our layouts are different. Hot water in shower for me is tank to pump, well in front of right rear wheel, then to water heater, all the way in rear right side, then to manifold, midship left side, then to shower, all the way in rear left side.

[Phil57]

I don't think mine has any less travel. I have a rear bath and a water manifold as well.