System Heat where does it get the heat?

[CapnDean]

My 2008 Camelot 42PDQ is parked in the barn with 50 Amp power to it.    We are in for some unseasonably cold weather this coming weekend.  I am in Gulfport MS and we seldom see temperatures in the teens for more than a day or two.   We are anticipating high teens for 3 days.  Ill run a space heater inside the coach to keep the house above 50 degrees.   I plan to turn on "system heat" which I understand is the basement heating system that keeps my water tank from freezing.   Do I need to set my AquaHot to electric heat in order for System heat to get heat?  Or does it have it's own strip heat or other source?

 

 

[Ivan K]

I don't know if you have heat pads for the tanks but I would leave the AH at least on electric to protect it plus it heats the basement and likely a heating register down there, ours does.

[jacwjames]

If you have heat pads they recommend that they not be used if the tank is empty, at least the ones I installed last year had this warning. 

Last year I did not winterize my coach since I had just built a garage to park it in, left it plugged into 50 amp and ran the system heat.  I do not have aquahot.  The heating pads easily kept the tanks ~45F.

This year I decided to winterize the coach so drained the water lines and tanks.  I turned the system heat off but also pulled the fuse for the heating pads to be on the safe side.   

[Dbircky]

“System Heat” is a cube heater in the wet bay that is behind the white plastic cover.   It is turned on by the switch and controlled by a snap disc.   When it’s about 40 degrees IN THE WET BAY it should kick on.  There is a fan you can hear when standing outside by the bay door.    I put a few pieces of styrofoam insulation inside the door to help hold the heat in.  

[Tom Cherry]

46 minutes ago, Dbircky said:

“System Heat” is a cube heater in the wet bay that is behind the white plastic cover.   It is turned on by the switch and controlled by a snap disc.   When it’s about 40 degrees IN THE WET BAY it should kick on.  There is a fan you can hear when standing outside by the bay door.    I put a few pieces of styrofoam insulation inside the door to help hold the heat in.  

The system heat is a brown space heater.  If your pump is like mine, there is a panel in the bay next to the wet bay.  You can remove it and look inside.  The system heater is behind the tanks.

WORD OF CAUTION.  There is a high failure rate on these heaters. There is a file as well as at least 2 topics.  Basically, i would NOT depend on it.  The units had a catastrophic failure in the 2006/7 time frame and a NON TESTED thermal fuse was added…..totally a poor design,  they work for maybe a few cycles on or off….then the heat load builds up.  BINGO WORTHLESS.  This was a known issue and Frank McElroy and myself investigated and came up with a permanent, safe fix.  Odds are…yours, if it ever was used….failed.  

IF you have the AquaHot system as an option, it is the best.  The temperature of the thermostat is around 45 DF and it works great.  PROBLEM…your barn.  Carbon Monoxide.  The 15 amp electric element is 1/10 the BTU as the diesel is.  Since you have 50 amp power….I would try this…

Depending on how cold it gets in the barn, run the Heat Pumps for a few days and get the MH thoroughly heated up to maybe 50 - 55 DF.  IF there are no animals in the barn, you COULD set up an exhaust fan and have a 20” floor fan running to ventilate the structure.  Buy a cheap 110 VAC CO2 monitor and plug it in somewhere in the barn.  Put a chair there and run an extension cord and dangle it from the back or the chair or back.  It needs to be around “seat height” off the floor.  That is your INSURANCE a policy.

set the AH to 45-50 DF and run the diesel burner and turn on all the furnaces.  You have a dedicated AH zone in the same area as the cargo or system heater.

the other option, instead of the AH is to blow out the plumbing, including the washer dryer (you cycle and spin it for a few minutes).  Remove the filter housing and dump it and leave the filter out and then totally open, one at a time, each faucet, low point drain, icemaker, toilet….especially those with a wash hose.

Put a trouble light or 60 watt incandescent light rear the flush valves of the toilet.   Also a trouble light in the wet Bay Area. Close the doors.

Buy a bottle of RV antifreeze.  Drain your tanks.  Then close the valves.  Dump a pint or so of RV antifreeze in each drain.  You can open th W/D and dump it in and cycle using the DRAIN cycle.

If you have a Sanicon, use it and get the RV antifreeze in it.  Drain the fresh tank.

That’s my take…..  NOW….comments…

Sun or thermal radiation that heats during the day, blinds up, helps keep it warm.  You space heater, assuming an electric is the same wattage as electric element.  The diesel is 10X more BTU than one of them.  Daily cold soaking without some heat will lower the “functional Mass temperature” of the motor home.  That makes it more prone to damage.  But keep it heated to 40 or even high 30’s will radiate heat to the bays.  
Supplemental spot heat in critical areas will help.

I used the compressed air blow out and RV antifreeze for years in a gasser stored outside with no power…

[waterskier_1]

I'll add that the "System Heat" runs off 12 VDC, and draws up to 30-Amps.  If the main engine alternator is not running, you should be shore power or solar (daytime) or it will quickly drain your battery. 

  - Rick N 

[Dbircky]

Tom, these things are unicorns for sure.   My cube heater is light tan and works fine.   I found the snap disc was mounted on the floor and both terminals were corroded.   I replaced it and it keeps the bay toasty.   Checked it this morning after writing the prior post and it was 46 in the wet bay with the temperature in the barn of 18.  Granted it’s out of the wind. 

[Tom Cherry]

45 minutes ago, Dbircky said:

Tom, these things are unicorns for sure.   My cube heater is light tan and works fine.   I found the snap disc was mounted on the floor and both terminals were corroded.   I replaced it and it keeps the bay toasty.   Checked it this morning after writing the prior post and it was 46 in the wet bay with the temperature in the barn of 18.  Granted it’s out of the wind. 

You have located the “tan unicorn”.  NOW…a question for you.  Did you have on the AquaHot ON.  In mine, as well as countless others, you will never see the System heater on as the AH comes on earlier and then the temp never drops below the ON temp of the system thermostat.

NOW….if you have the AquaHot there is either a big control box with a dial on it in the rear wet bay or there is a FLOOR mounted Thermostat.  TYPICALLY, the thermostat for the system (tan) heater is suspended in the ceiling of the bay.  SO…if you see a hanging snap disk thermostat, then that is for system heat.  Monaco wimped out and went to a cheap snap disk and screwed it into,the floor for my AH….even though the wiring calls for the nicer dial ones.  

The only way to know if your heater works, assuming you have an AH is to NOT have on the AH….and then use a remote thermostat….like for an indoor/outdoor thermometer or physically peer inside the bay from  the access panel and feel the air flow and make sure it is HOT….just passing this on….

My only alert was that we usually have (here and on the original Yahoo site) a rash of “my heater don’t work”.  That is also true on the other sites.  Whether there is a 10% or 90% failure rate, we have no idea.  When I spent a lot of time on the phone with the final “function” test lady as well as the one who did repairs, she told me none of the older heaters ever come back in for repair and they have so many now and it is always the safety “thermal” load….that spoke volumes.  

The fuse was not rated nor had the right heat rise and such for the way the heaters “internal” thermostat works.  The hanging exterior one just “calls for heat” or turns it on.  But there is a separate internal thermostat that cycles it on and off to prevent overheating or a meltdown.  Instead of addressing that control board, a “too HOT” ONE TIME thermal fuse was installed.  When it blows…it has to be replaced. It was never tested. Frank set up a “lab” experiment that was almost an exact mock up of the bay. He then measured temps and chose a fuse with better temp range while still providing the same safety.  The one shot thermal was a mandate from the company’s legal person…..and added based on reading a chart and never tested.

The fan will run but the interior heating element cycles on and off.  Many folks have found it only blew cold air and were reluctant to depend on it.  An older one was more reliable, but could get too hot.  As long as yours works and you know it has, if it’s a newer one, the higher fail rate….then that’s all we can say.

The high failures lead to many different fixes and one shot “substitutes”….most of which eventually failed,  The approach that Frank used was a true “properly”, we feel, reliable fix.  Many abandoned them and bought other brands as they were frustrated with the “this works” experiments.

Not questioning your situation, just want you to know this is the history and the reliability is highly suspect….

[Dr4Film]

My previous Windsor had the optional Winter Package installed. That package was basically a System Heat switch which activated a set of tank heat pads located under each tank. It also powered up a circuit that goes to a Snap Disc located in the service bay that once the temperature in the bay reached its set point and closed the Snap Disc then the Road Pro 180 Watt Heater would turn on heating up the service bay until the temperature rose to the set point of the Snap Disc which would then turn off the heater. As the temperature fluctuated the heater would come on and off as needed.

[96 EVO]

6 hours ago, Tom Cherry said:

 

set the AH to 45-50 DF and run the diesel burner and turn on all the furnaces.  You have a dedicated AH zone in the same area as the cargo or system heater.

 

May or may not have a AH heat exchanger down below. 

It was an option. Mine never came with one.

[Tom Cherry]

55 minutes ago, 96 EVO said:

May or may not have a AH heat exchanger down below. 

It was an option. Mine never came with one.

According to both the 2008 HR Scepter and 2008 Camelot owners manuals and wiring diagrams, with the AquaHot system, there is a “wet bay” heater as standard.  Monaco (HR also) offered a “cold weather package”.  That was an electric heating pad for the fresh tank.  If you have the AquaHot, you are supposed to have a wet bay register or heater.  It may be different on your controls, but mine is isolated from the furnace mode….in that it will come on,if the thermostat is calling for heat in the bay.  The ONLY caveat is that the AH must be on ….either or both Diesel or Electric.

SOME models of the upper end AH, used in say a 2007 Dynasty, required that the Bedroom “Furnace” on the Thermostat was on…or in Furnace mode….in addition to the AH switch(es) being on.  For whatever reason the 450 I have will supply anti freezing protection without any zone being in “furnace”.

Have you pulled the plate to get to your water pump and shined a light in there.  Mine is located sort of behind the 12 Heater.  It would be in a Devil of a place to service…..but it works great and I never see the “system” light on as it comes on first

[96 EVO]

I don't have one Tom.

This is C&P from page 150 of my owners manual.........

Aqua-Hot Bay Heater (Optional): The optional Aqua-Hot includes a heat exchanger in the basement that operates when the Aqua-Hot is on and temperatures drop below 45° F.

[Tom Cherry]

1 minute ago, 96 EVO said:

I don't have one Tom.

This is C&P from page 150 of my owners manual.........

Aqua-Hot Bay Heater (Optional): The optional Aqua-Hot includes a heat exchanger in the basement that operates when the Aqua-Hot is on and temperatures drop below 45° F.

I think we are saying the same thing,  if you do NOT have an AquaHot hydronic heating system, then you have a propane furnace….and the 12 System heater is the freeze protection.

From what you said, I assume no AquaHot, which was an option…..and it included the additional register for the wet bay and is described in the section for “optional AquaHot” system.  is that correct?

That was my point to CapnDean @CapnDean, the OP.  If he has the optional AquaHot system, he has a standard or additional AH register in the wet bay.  If he does NOT have an AquaHot system and has the Propane Furnace, as I assume you do, then the 12 V DC heater is the only Freeze protection.  Due to the high failure rate, it is a liability,  

In addition, if the temp is staying that  high in the bay and he has the AquaHot and the burner and/or electrical was ON….then the AquaHot would come on automatically, assuming it is wired like the 2009….  Thus the System Heat or Service (12 VDC) never comes on….

Hope this clears it up and makes sense….

Thanks….

 

[96 EVO]

I have a (broken down) Aqua Hot. It came with no wet bay heat exchanger!

I know where it would be installed in the bowels of the wet bay, but it's not.

[CapnDean]

Okay so system heat is 12v strip heat in the wet bay.    That’s what I needed to know.    Thanks all for your responses. 
 

To contend with the upcoming cold weather I have parked the RV in the barn, set up a small space heater inside the house and turned on the Aqua hot to electric heat and turned on system heat.   I think this will do because:

Gray tank is empty, Black tank is empty with 5 gallons fresh water in the bottom.

my barn has sides, but the north end is wide open (no doors).   I believe that I am set up to handle a few days cold.    I will report if anything failed me.

[Frank Bergamo]

If it were me, I would turn on the diesel burner. Better to be safe than sorry later. JMO.

 

[Tom Cherry]

53 minutes ago, CapnDean said:

Okay so system heat is 12v strip heat in the wet bay.    That’s what I needed to know.    Thanks all for your responses. 
 

To contend with the upcoming cold weather I have parked the RV in the barn, set up a small space heater inside the house and turned on the Aqua hot to electric heat and turned on system heat.   I think this will do because:

Gray tank is empty, Black tank is empty with 5 gallons fresh water in the bottom.

my barn has sides, but the north end is wide open (no doors).   I believe that I am set up to handle a few days cold.    I will report if anything failed me.

FWIW.  Your electric AH may not handle the heat load.  BUT….you might be OK.  The one register or radiator is small….in comparison to the rest of the system.  Remember the 10:1 ratio.  The THING I think you ought to know…and you may know it….is this.

The System Heat will only come on when the AH can’t handle the load…..as in the electric can’t keep up.  You said it was 46.  MY BET….if you had been out there around 5:00 AM, you probably would not have seen the “IN USE” for the System Heat come on.  If the small unicorn heater was needed, then the IN USE light comes on.  The AH register will cycle on and off….and the electric probably kept up with it.  46 is a bit low….when we got into the low 20’s and I had NOT winterized….I kept the Diesel running…..and set the thermostat to 50.  I always had 55 on he remote probes….in both the fresh and the wet bay.  My fresh tank is up front….so no residual heat get there….it was just the radiant heat getting into the water tank area.

My advice….or word of caution.  UNLESS you see the IN USE light ON and turn off the AquaHot and let it cool down, you have NOT tested the tan unicorn.  My tiny bet would be….if you have used it a few times….it has a bad fuse and is broken.  Sending it back to the factory is futile.  Frank and I wrote a white paper on how to fix it and there have been, to the best of our knowledge…..no failures.

So..I would want to verify that the standard tan Unicorn heater works,  it took 3 minutes to pull mine and a two second hook up….assuming the thermostat was good….which I had seen the IN USE or IN Service light…..all the heater was doing was blowing cold air….as the thermal fuse to the heater element was blown…..as most do…

That’s my take and hands on experience.  Depending on it and it being broken or untested could be a costly experience…..

[waterskier_1]

Depending on the configuration of plumbing components, and the location of the Aquahot the vent may not BFF in the service bay.  On my 05 Exec, my water pump, manifold and water filters are on the curb side.  That is where the Aquahot vent an thermostat for basement heat are located.  My Service Bay is street side (obviously) and does not have a dedicated Aquahot vent, but the heat travels across the bay.  My Exec didn't come with the electric System Heat option.  I added one to my Dynasty, too help heat the Service Bay, but found I didn't use it.  I always empty all holding tanks, water hoses and sewer (Sanicon) hoses before freezing.  I travel with the water system winterized with antifreeze, and done winterize until I get to warm weather.  I end up doing this several times a year - I'm not a full timer, and live in Colorado.

  - Rick N

[Tom Cherry]

12 hours ago, 96 EVO said:

I have a (broken down) Aqua Hot. It came with no wet bay heat exchanger!

I know where it would be installed in the bowels of the wet bay, but it's not.

Totally weird.  but this is Monaco.  Mine is hidden.  Not installing the wet bay unit would also have included not running lines or the wall (nicer) or floor (snap disc) cheap thermostat. Are you the original owner?  If someone removed the register or blower module, then wonder if the heat exchanger lines are still there?  

I pulled the 2007 Scepter manual.  It shows the standard bay heater in the text and layout.  So, that was not an early 2008 running change.  

If it ain’t there….it ain’t there,,but someone  sure went to a lot of trouble to remove something…..

Hope  you get your broken down system functional again….and when it does, wonder if the lines going to that zone are still there.  The diagram shows the bay heater as a daisy chained plumbing loop….so the heat exchanger loop would have had to have a “pipe” installed for continuous flow and functionality….

 

[96 EVO]

2nd owner.

Can't see the original user removing the bay heater as the AH burner is the one item (going by the hour meter), he used a lot.

No signs of a unused coolant loop down there either. I'm guessing yours enter the bay on the curb side?

I'm guessing you don't read the C&P I quoted from the manual to mean...... The Aqua Hot bay heater is an option?

Edited December 20, 2022 by 96 EVO

[waterskier_1]

Depending on the configuration of plumbing components, and the location of the Aquahot the vent may not BFF in the service bay.  On my 05 Exec, my water pump, manifold and water filters are on the curb side.  That is where the Aquahot vent an thermostat for basement heat are located.  My Service Bay is street side (obviously) and does not have a dedicated Aquahot vent, but the heat travels across the bay.  My Exec didn't come with the electric System Heat option.  I added one to my Dynasty, too help heat the Service Bay, but found I didn't use it.  I always empty all holding tanks, water hoses and sewer (Sanicon) hoses before freezing.  I travel with the water system winterized with antifreeze, and done winterize until I get to warm weather.  I end up doing this several times a year - I'm not a full timer, and live in Colorado.

Aquahot literature recommends using Zone 2 (of the Aquahot - not the Dometic thermostat inside) which is often also the bathroom zone.  Do you have an Aquahot register in the bath?  

  - Rick N

[96 EVO]

3 minutes ago, waterskier_1 said:

  using Zone 2 (of the Aquahot - not the Dometic thermostat inside) which is often also the bathroom zone.  Do you have an Aquahot register in the bath?  

  - Rick N

Two.

One in the bathroom, one in the toilet room.

[waterskier_1]

1 minute ago, 96 EVO said:

Two.

One in the bathroom, one in the toilet room.

That sold be the same loop that the basement heat souk be on.  The zone valve is controlled bypass the basement terms, and tye fan(s) are either on a Domestic thermostat or fan switches.  If you have the Aquahot boiler heated by either electric or diesel, you may feel the registers warm, even without the fans on, since tye temps outside are usually lower than inside, and that  Aquahot zone is its zone pump running. 

  - Rick N 

[96 EVO]

I have a 3rd heat exchanger in this loop in the bedroom.

Never felt any of them warm without the fans starting up.

[waterskier_1]

How many zone pumps do you have on your Aquahot?  Typically there are 4, and sometimes 3.  One for tye salon area, one for the basemen/bath, and one for the bedroom, and one for engine pre-heat.