System heat - Discussions and Snap Disc and such

[GypsyJo]

I asked a few days ago about my system heat but couldn't provide a picture of the switch yet.  I can't find any info on this anywhere in my manual and the techs don't know either.  When we were in the 20s shouldn't this system switch on if the switch is on?  

This is in my 2006 Monaco Camalot.  

Thanks

[Lloyd Caldwell]

This switch operates the heater in your water compartment.

[Larry Maida]

You appear to have a cold water pkg. The switch activates the sysrem. When its cold enough the sensor closes a disk and the system and light come on. It is usually a small heater in the water bay but can also be heat blabkets for the holding tanks. 

[cbr046]

The power switch should light when on.  All that does is enable the heater (and possibly heat pads) in the wet bay.  The light in my switch doesn't work but should be easily remedied through Amazon.

The System Heat lamp will light when the thermo-disc in the wet bay gets below temp (something like 35? 36? 39?) and goes out when it reaches 55F ish.  When this lamp is on the heater in the wet bay should be generating heat . . . . except there's a small poorly engineered underrated thermal fuse that keeps popping inside the heater.  A beefier replacement isn't available.  The light on my coach didn't work either but, again, Amazon to the rescue.  https://www.amazon.com/gp/product/B008OJ70R0/  The circuit can be tested by shorting the thermo-disc in the wet bay.  It's in there . . . . somewhere.

                ^^^This disc is for illustration only. ^^^

For those that are handy, the fuse inside the wet bay heater can be replaced . . . . but it'll just pop again.  I'm not sure if it pops on temp (184C) or current (20A) but I'm betting current.  It's a 300W watt heater that should draw 25A.  My plan is to split the 5 heating elements inside the box into a group of 3 and 2, each with it's own fuse.  That will solve the current part of the formula (hopefully it's not a temp issue).  Parts are on order.  Fuse - https://www.newark.com/thermodisc/g5a01184c/fuse-thermal-184-c-20a-250vac/dp/39T4439 and crimps - https://www.newark.com/amp-te-connectivity/323754/terminal-parallel-splice-crimp/dp/50F3313

The crimps are challenging to remove / install because of their thickness, but this is necessary for this high heat environment.  I use vice grips  with pressure top & bottom, like a football, to loosen the grip.  To install I'll put pressure on an edge to draw the crimp tighter, vs mashing the entire crimp. 

The switch and light can be pretty easily removed by getting a fingernail under the outline of the switch, then a small screwdriver and gently rocking it out. 

I hope this helps,

- bob

 

 

[GypsyJo]

13 minutes ago, Larry Maida said:

You appear to have a cold water pkg. The switch activates the sysrem. When its cold enough the sensor closes a disk and the system and light come on. It is usually a small heater in the water bay but can also be heat blabkets for the holding tanks. 

When it got down in the 20s it should have come on,  right?  But it never did.  

[Larry Maida]

Yes it should have. I would check the “disk” in the wiring. I understand there is a way to jump it to test and see if system comes on. If it does you need to replace disk. Someone said you can get on Amazon

[jacwjames]

11 minutes ago, GypsyJo said:

When it got down in the 20s it should have come on,  right?  But it never did.  

The light only comes on when it is cold enough for the heater to run in the wet bay.  It will depend on a lot of factors.  If you are running your furnace chances are it also has heat duct run to the wet bay which will warm the bay.  Also, if your tanks are full they act as a large heat sink that will take hours to cool down.

So watching for the light to come on is like watching a pot of water to start boiling.

I was on a trip last Nov and it got really cold, I was not plugged in and not even running my furnace.  I kept thinking the light would come on, even got up and checked several times.  Never did see it come on.  Finally when I started driving the next AM where I could see the switch/light out of the corner of my eye I saw it cycling on and off, temps outside were in the teens and when driving I'd say air infiltration made it cold enough.  When I stopped I used my thermo gun to check the water temp in the fresh water tank, it was +45F. 

Prior to the trip I had added tank heating pads to the system but never knew if they came on, so when I got back I added a separate light in the bedroom that comes on when the tank pads run.  Now at least I don't have to get out of bed😁

[GypsyJo]

3 hours ago, Lloyd Caldwell said:

Thank you.  I'll watch for this.  

 

[Tom Wallis]

I have an identical switch and light on my panel also. However, there are no heaters or blankets in my motorhome so I always assumed the switch and wiring were installed regardless if you had the optional cold weather package or not.

[jacwjames]

3 hours ago, Tom Wallis said:

I have an identical switch and light on my panel also. However, there are no heaters or blankets in my motorhome so I always assumed the switch and wiring were installed regardless if you had the optional cold weather package or not.

Probably,

Mine came with the small heater.  But in my passenger side rear electrical bay there was another relay labeled Cold Weather Package and looking at my wiring schematic it showed it as optional, it consisted of three heating pads. 

But I didn't have any heating pads. 

Last year as I was trying to solve another problem I found a coil of heavy wires in the black plastic wrap, did some testing ans sure enough, it was for the heating pads that were never installed.  It was controlled by the system heat switch but the power was supplied through a separate 30 amp mini breaker.  I added 2 heating pads under the fresh water tank and one straddling the black/gray tanks. 

So I bet if you do a little checking you may have the wiring harness for the heater in your wet bay. 

[Tom Wallis]

Thanks James, you could be right. In my case I installed a 500 Watt electric heater along with a WiFi thermostat in my wet bay. In my case the heat from it rises up and heats my plumbing and my tanks. So far I've haven't had any problems down to 5 degrees. But it kind of bugs me having a switch that doesn't do anything.

[Jerry Ellis]

Joanne,

I read through your posts and it's not clear to me if you're needing troubleshooting help, or just asking about the System Heat in general. With the power switch on, the heater in the wet bay will activate when the temperature inside the bay gets near freezing. Much like a furnace in a house, it will run until the thermostat shuts the system off.

Look in your wet bay for the heater. Previous posts have photos of what to look for and note that it may be tucked behind stuff. You might also have the heating pads. These look the same as a heating pad you'd buy at Walgreens.

The heaters sometimes fail and owners/technicians don't always repair things back to factory specifications so some of what we're describing might not look the same as what you find. I know this first hand.

Close up photos of your wet bay will help us help help you. 🙂

 

Jerry

 

 

[GypsyJo]

41 minutes ago, Jerry Ellis said:

Joanne,

I read through your posts and it's not clear to me if you're needing troubleshooting help, or just asking about the System Heat in general. With the power switch on, the heater in the wet bay will activate when the temperature inside the bay gets near freezing. Much like a furnace in a house, it will run until the thermostat shuts the system off.

Look in your wet bay for the heater. Previous posts have photos of what to look for and note that it may be tucked behind stuff. You might also have the heating pads. These look the same as a heating pad you'd buy at Walgreens.

The heaters sometimes fail and owners/technicians don't always repair things back to factory specifications so some of what we're describing might not look the same as what you find. I know this first hand.

Close up photos of your wet bay will help us help help you. 🙂

 

Jerry

 

 

Thank you.  I'll be checking that as soon as I get my coach back tomorrow.  

[brokenarrow1244]

I have the same system, when it is on the light will stay on, meaning you have supplied power to the small heater in the wet bay, when it lights up active, it means the weather has become cold enough to turn on the heater. I have only had the experience to see "active light" while in Utah. There was a freeze warning ay the rv park and I am glad it was working. However, the water pump is on the other bay behind the water heater mounted to the wall. It developed a crack and started to leak and required replacement. Some of the rvers put a 100 watt bulb in that area  to keep it warm enough . Sort of like chickens. If it is going to get cold just turn on power to it. If you want to inspect it, it is behind the dump valves across from the water hose.

[GypsyJo]

1 hour ago, brokenarrow1244 said:

I have the same system, when it is on the light will stay on, meaning you have supplied power to the small heater in the wet bay, when it lights up active, it means the weather has become cold enough to turn on the heater. I have only had the experience to see "active light" while in Utah. There was a freeze warning ay the rv park and I am glad it was working. However, the water pump is on the other bay behind the water heater mounted to the wall. It developed a crack and started to leak and required replacement. Some of the rvers put a 100 watt bulb in that area  to keep it warm enough . Sort of like chickens. If it is going to get cold just turn on power to it. If you want to inspect it, it is behind the dump valves across from the water hose.

The light has never been on as long as I've had the coach. I'll have to crawl in there and take a good look. 

Thank you 

 

[cbr046]

5 hours ago, GypsyJo said:

The light has never been on as long as I've had the coach. I'll have to crawl in there and take a good look.

 

We have a LOT of those style lights that don't work, including the lights inside switches.  Might be your light, not the circuit.   

- bob

[nvrtoofast]

Used mine this winter on the road. When switched, the light stayed on constantly. I have a small 6X6 heater in the wet bay. Left it on for cold days and nights. never froze up. The bays stayed fairly warm though with the furnace heat.
The system heat was a great "just in case" element for me.

[GypsyJo]

11 hours ago, cbr046 said:

We have a LOT of those style lights that don't work, including the lights inside switches.  Might be your light, not the circuit.   

- bob

Google point. I'll check that too. 

Thank you

Good grief.  I meant good point.  Sometimes auto correct is a pain.  

[saflyer]

On 3/5/2022 at 7:44 AM, Larry Maida said:

Yes it should have. I would check the “disk” in the wiring. I understand there is a way to jump it to test and see if system comes on. If it does you need to replace disk. Someone said you can get on Amazon

That would be great if I could access the snap disk without major disassembly of the wet bay. It took forever but the disk was finally located totally out of reach. Think I’ll test the bay heater before trying to get to the snap disk. Since the heater has a three pin connector I am assuming I can put 12v to two of the pins and ground to the third. Am I correct? Sounds like the fuse in the heater is a problem area, though. 
Ed          
’05 HR Ambassador 

[Happycarz]

My 08 (May 07 build) Camelot should be similar to your coach. When the system heat switch is turned on, power will be supplied to the fresh water heating pad and the snap disk. When temperature in the wet bay gets low enough, the snap disk closes the cube heater turns on, along with the light.
 
The cube heater has its own power and ground, dormant, just waiting for a signal from the snap disk trigger wire. When the cube heater comes on, the system heat light will come on. The light only comes on with the cube heater. The fresh water tank heating pad comes on with the switch and is not dependent upon the snap disk and the light does not come on with that, only the cube heater.

The wet bay and the snap disk have to be colder than the snap cold set point, somewhere around 35°.  You have a lot of mass there to cool down and with outside at 30°, the snap disk may still be above the set point.

If you can locate the snap disk, usually just behind the panel out of sight, pull it down and put an ice cube on it.  Make sure the system heat switch is on. The heater, along with the system heat light, should turn on.

In the picture below, the snap disk was just tucked up behind the panel with the other wires. It was not secured to anything and the bracket was loose flopping around. I removed the bracket, so yours might look like the picture of the one with the bracket.

 

[saflyer]

3 hours ago, Happycarz said:

My 08 (May 07 build) Camelot should be similar to your coach. When the system heat switch is turned on, power will be supplied to the fresh water heating pad and the snap disk. When temperature in the wet bay gets low enough, the snap disk closes the cube heater turns on, along with the light.
 
The cube heater has its own power and ground, dormant, just waiting for a signal from the snap disk trigger wire. When the cube heater comes on, the system heat light will come on. The light only comes on with the cube heater. The fresh water tank heating pad comes on with the switch and is not dependent upon the snap disk and the light does not come on with that, only the cube heater.

The wet bay and the snap disk have to be colder than the snap cold set point, somewhere around 35°.  You have a lot of mass there to cool down and with outside at 30°, the snap disk may still be above the set point.

If you can locate the snap disk, usually just behind the panel out of sight, pull it down and put an ice cube on it.  Make sure the system heat switch is on. The heater, along with the system heat light, should turn on.

In the picture below, the snap disk was just tucked up behind the panel with the other wires. It was not secured to anything and the bracket was loose flopping around. I removed the bracket, so yours might look like the picture of the one with the bracket.

 

Thanks. I think this might be epa response to my reply on this thread. 
 

I found the snap disk but it’s in a ridiculously difficult place to access. That is why I plan to test the cube heater first. Three wire connector so I assume wire is for heater power, one for 12v from the snap disk and one for ground. 
Ed

[jacwjames]

This is an older thread but wanted to update on my experience with system heat.  In the past we did not camp in colder weather but in 2021 I had a need for the system to work and wasn't confident it was. 

But I've been in Utah for the last + week and temps have been down to ~20F at night.  I do have the switch with "ON" indicator on my monitoring panel and I even installed a second light that I thought I'd be able to see come on at night.  The first really cold night I woke up at ~3AM and it was cold in the coach, I left a small space heater running but it wasn't keeping up.  So I turned on the furnace for ~1/2 hour and it cycled on/off.  For the nest several ours I slept with one eye open staring at the light in the bedroom, I never did see it come on.   I even got up a couple times to check on the monitoring panel, never saw that light come on.  I guess the old saying "A watched pot never boils" comes to mind. 

So the next morning when it got warm I checked on they system.  I bypassed the snap disc, the heater came on, and checked to see if the light came on and they did.  I then used a thermo gun and checked the fresh water tank temp on the back side, it was ~49F.  I then tested the snap disc by plugging it back in and resting an ice cube on it and it did start the heater, I did this several times.  So I confirmed the system was working.

So I moved one of my temp monitors from the Samsung refrigerator to back side of the fresh water tank so that I could look at the temps at any time.  This morning when I got up the basement wet bay temp was ~50F.  Now this morning I've seen both the monitor panel system heat and bedroom light come on periodically.   This morning @8:30AM the outside temp is 27F basement,  So I am starting to gain confidence in the system. 

Hope this helps others.

[Jerry Ellis]

I too went through a period where I was building trust in the System Heat. My experience was complicated by the fact that I was starting with a newly repaired system as it was busted and modified by the previous owner.

I used an indoor/outdoor thermometer placing the outdoor sensor in the wet bay to monitor things but might get one with the daily high/low recorder like this:

https://www.amazon.com/AcuRite-00424CA-Digital-Thermometer-Temperature/dp/B00WXIR94M/ref=sr_1_10?crid=2QNSIGD701G6M&keywords=thermometer%2Bhi%2Blow%2Boutdoor&qid=1697553740&sprefix=thermometer%2Bhi%2Blow%2Boutdoor%2Caps%2C69&sr=8-10&th=1

Jerry
2001 HR Scepter

[saflyer]

27 minutes ago, jacwjames said:

This is an older thread but wanted to update on my experience with system heat.  In the past we did not camp in colder weather but in 2021 I had a need for the system to work and wasn't confident it was. 

But I've been in Utah for the last + week and temps have been down to ~20F at night.  I do have the switch with "ON" indicator on my monitoring panel and I even installed a second light that I thought I'd be able to see come on at night.  The first really cold night I woke up at ~3AM and it was cold in the coach, I left a small space heater running but it wasn't keeping up.  So I turned on the furnace for ~1/2 hour and it cycled on/off.  For the nest several ours I slept with one eye open staring at the light in the bedroom, I never did see it come on.   I even got up a couple times to check on the monitoring panel, never saw that light come on.  I guess the old saying "A watched pot never boils" comes to mind. 

So the next morning when it got warm I checked on they system.  I bypassed the snap disc, the heater came on, and checked to see if the light came on and they did.  I then used a thermo gun and checked the fresh water tank temp on the back side, it was ~49F.  I then tested the snap disc by plugging it back in and resting an ice cube on it and it did start the heater, I did this several times.  So I confirmed the system was working.

So I moved one of my temp monitors from the Samsung refrigerator to back side of the fresh water tank so that I could look at the temps at any time.  This morning when I got up the basement wet bay temp was ~50F.  Now this morning I've seen both the monitor panel system heat and bedroom light come on periodically.   This morning @8:30AM the outside temp is 27F basement,  So I am starting to gain confidence in the system. 

Hope this helps others.

I just wish I could reach my snap disk. That would be so nice.

[jacwjames]

1 hour ago, saflyer said:

I just wish I could reach my snap disk. That would be so nice.

Mine was mounted up pretty high behind the white panel.   I was able get at it, take it loose, and move it down a little so it is easier to access.  

To test the system I have a male to male spad type connector so I just pull the wires loose and connect them together, and at that point the system heat and heater is working.  This time I used an ice cube to make sure the snap disc was working.   I had doubts so I actually have a new one coming that I can keep as a spare.