Atwood Water Heater Relay - Stuck Closed Again

[Traver8]

Hi All,

I am back again with a recurring problem that I am struggling to understand. Yesterday, for the third time in 6 years I had the relay for the electric side of my Atwood water heater stick closed. Fortunately, I was here and recognized the issue of very hot water pouring out of the temp/pressure relief valve and opened the breaker to shut it off.

I have not yet given anything a detailed look but have confirmed that with the 12VDC control switch OFF, I can close the breaker and hear the element start heating.

I have already ordered a new relay and will dig in again tonight and see what I can find.

Anyone out there have any theories as to what might be causing this? The last time was in Nov 2017 and my theory at that time was a poor connection on the 120VAC side had caused some local heating which caused the contacts to stick. I corrected the connection and replaced the relay at that time and all has been good until yesterday.

Details are:
2013 Jayco Jayflight
Atwood Gas/Electric water heater.
Stock Progressive Convertor
Dual 6V AGM batteries
Measured convertor output - 13.2VDC, AC ripple 2 mV

What else?

Thanks for your help.
Terry

See here for the Nov event discussion.

https://forums.trailerlife.com/index.cfm/fuseaction/thread/tid/29480209.cfm

[Wild_Bill_888]

Amazon has a 40 amp solid state relay for $10. Remote mount on a convenient heat sink.

[Chris_Bryant]

I’ve always thought that design was flawed. You should report it at https://www.saferproducts.gov/CPSRMSPublic/Incidents/ReportIncident.aspx

[Old-Biscuit]

Traver8 wrote:
To answer some of the questions,

I am using he Zettler AZ2280-1A-12D as sold by Atwwod.

Due to the tight space I have to crawl into, I don't think that I will be able to make too many measurements on the element. I will give that a shot though and see what I can do.

Thanks and keep the questions coming. I would like to get to the root of this.

Terry

Might want to try the Song Chuan Relay (does same thing as Zettler)
AC terminals are on opposite sides vs next to each other.
Might not generate as much heat as Zettler

(Suburban uses that relay in their DEL Models ---DC to trigger AC to element)

[Old-Biscuit]

Flute Man wrote:
To confirm the diagnosis, I would pull the relay and then ohm the contacts to verify that the Contacts are really stuck.
Jerry Parr

Relay uses DC to trigger AC to element
AC can NOT get to element unless Relay is closed

OP stated......
W/O DC ON the AC is still getting to the element.
Hence....relay is closed

[wnjj]

Is the relay mounted to a warm surface and if so could it be relocated?

Have you cut apart an old one to see if the contacts looked burnt? Otherwise perhaps the plastic casing is deforming slightly?

I had a micro relay that stuck on my Norcold fridge. When I cut it apart the contacts looked brand new so I don’t know why it did.

[Flute_Man]

To confirm the diagnosis, I would pull the relay and then ohm the contacts to verify that the Contacts are really stuck.
Jerry Parr

[Traver8]

To answer some of the questions,

I am using he Zettler AZ2280-1A-12D as sold by Atwwod.

Due to the tight space I have to crawl into, I don't think that I will be able to make too many measurements on the element. I will give that a shot though and see what I can do.

Thanks and keep the questions coming. I would like to get to the root of this.

Terry

[Old-Biscuit]

Which BRAND of Relay are you using?






Song Chuan Relay

Zettler Relay

[budwich]

measure the resistance of the heater / element which will give you how much current it is likely seeing (after some math). Then let the heater run a bit and do the same measurement again and see if there is any difference. Perhaps as the element heats up, it gets less resistive such that it results in more current... not enough to blow the fuse but enough to overheat the relay contacts to the point of "melt" after a number of runs / cycles.

side question, what is the part number of the relay?

[Traver8]

Link to the Nov 2017 discussion

https://forums.trailerlife.com/index.cfm/fuseaction/thread/tid/29480209.cfm