Is my Aqua Hot malfunctioning or my wall thermostat?

[Bigdogracing]

We were on 50amp service all weekend and used the AH for hot water and heat.  First night, the heat seemed to be blowing fine, until about 2am- then walked up cold and it was 50 degrees inside but cold air was blowing, not warm/hot any longer.  I did check the AH and all lights were green, appeared to be no red lights/errors o the display panel.  Ended up using electric space heaters rest of the night.  Same thing happened the next night- seems like too works fine for awhile but then at some point when the trio stat reaches temp and $@#!s off, when it comes back on, no heat, only cold air.  Thoughts?  Anything I can self trouble shoot?  I plan to call AH on Tuesday but have time tomorrow too check things out.  I cannot get in for service until April…. Thanks in advance.

Oh, we already checked the fluid level of the AH and its fine per the manual.

Edited December 31, 2023 by Bigdogracing

[Frank Bergamo]

Is your diesel burner on? The electric element by itself will not keep up when the temperature drops.

Edited December 31, 2023 by Frank Bergamo

[Fasthobie16]

High temp thermostat button not resetting? Are you getting hot exhaust outside after your restart the diesel burner?  Hope it’s not the  controller.  Expensive piece to replace.  

Edited December 31, 2023 by Fasthobie16
Spelling

[Bigdogracing]

14 minutes ago, Frank Bergamo said:

Is your diesel burner on? The electric element by itself will not keep up when the temperature drops.

Oh, no we were running on 50 amp electric only-  thats not enough?  So you can have both the diesel and electric switch on at same time>. Which one takes precedent?

[vito.a]

Turn your Aqua Hot diesel burner on. 

[Bigdogracing]

8 minutes ago, Fasthobie16 said:

High temp thermostat button not resetting? Are you getting hot ehaust outside after your restart the diesel burner?  Hope it’s not the  controller.  Expensive piece to replace.  

We haven’t used the diesel option for it yet we had 50 amp electric so opted to use that vs burning diesel, if that makes sense.

[Jetjockey]

Diesel and electric can be on at the same time. They have separate high limit switches but are both controlled simultaneously on and off by the common  control thermostat .

All green lights on the circuit board will not necessarily indicate the circuit board is doing its job.  Those green lights only indicate heat is being called for,which heating zone are active and which pumps are called to be running.The diesel or electric side can work independently of one another in the case either fails.
 You might try tapping on the circuit board housing. I have seen that solve the problem temporarily or for quite sometime. There are transistors on that board which control the diesel burning and electric heating function and can become intermittent or just plain weak. I experienced this several times in a year or so..   it makes one to think other components are at fault . Replace burner controls three times to think I had the problem solved only to find out it was the circuit board . All three if the suspect burner controls tested good on later investigation. 
Depending on model,w your aquahot may have only one electric burner at 1450 watts. That is not much for a large motorhome. You might try feeling the aquahot for warm to determine if There is any heating going on.

 

 Your diplomat may be new enough to have dual electric burners at much higher wattage.

Edited December 31, 2023 by Jetjockey

[Tom Cherry]

1 hour ago, Bigdogracing said:

We haven’t used the diesel option for it yet we had 50 amp electric so opted to use that vs burning diesel, if that makes sense.

 

Lets put it another way.  Look at your Aquahot Plate Data. I have the AHE450, which was used on the "LOWER FOOD CHAIN" MH's, not the Dynasty.

AC or Electric element specifications....  15Amps = 1,650 Watts = 5,630 BTU per HOUR....

Diesel Burner Specifications =                                                         56,000 BTU PER HOUR...

Basically, the diesel burner has TEN (10) TIMES the heat output as the Electric.  The Electric is OK, in MOST cases, for domestic HOT WATER.  BUT, your Heat Pumps will put out MORE heat that the Electric will. SO, when your Heat Pumps are NOT adequate to keep the MH comfortable and your NEED more HEAT, you MUST TURN ON THE DIESEL and run the Aquahot (FURNACE).

That's how it works.... 

NOW, your's may be different...but the Electric has been 15 Amps or 1,650 Watts for a LONG TIME.  Your Diesel burner may also different....but most likely it is in the same ball park....and will be in the 56,000 range.  This is straight from the Specifications page of the Owner's Manual, around Page 2....check your manual or look at the Plate on the Aquahot....

BTW....so you don't worry about draining your Diesel Tank.  A Gallon of Diesel fuel is 138,700 BTU's.... The Burner (mine above) is rated at 56,000 BTU/Hour.  So, divide 56,000 by 138,700.....that is  0.40 Gallons PER HOUR....  You did not list your Length so you may have 2 HVAC's and an 8KW Onan....at 50% load, the Genny consumes 0.43 GPH....the 10KW, ironically is the SAME...0.43.  SO, you are consuming the same fuel for the Aquahot as your Genny...assuming a 50% Load...

EDIT....Based on Ivan's response....mine, or at least the LOW ENDS have the SAME THERMOSTAT....so when the temperature of the "BOILER" drops below the set point and BOTH switches (Diesel and Electric) are ON...  THEN BOTH the Electric element and the Diesel Burner will come on.  BUT at a 10:1 ratio....guess who carries the load. You CAN only turn on the Diesel at night...which many of us do. BUT, obviously if you are only on 30 Amp service, then you may have issues as you do NOT have a LOT of power.  Remember....on a 50 Amp Service, you have Line 1 and Line 2 for a TOTAL of 100 Amps of electricity...but the 30 AMP is only ONE LINE....the Dogbone splits it...so you have 3.3 TIMES the current on 50 Amp than you do on 30...  The OLDER AH's used to have two different thermostats (electric and Diesel and the Electric was lower...so it had the "opportunity", if the demand was low...to heat up the boiler without the Diesel firing.  That was dropped....don't know when, but the 2009 units like mine us the SAME Thermostat...  WHICHEVER or BOTH are on....that heat source is activated. Thanks to Ivan for a good point.

Hope this helps...

[Ivan K]

1 hour ago, Bigdogracing said:

Oh, no we were running on 50 amp electric only-  thats not enough?  So you can have both the diesel and electric switch on at same time>. Which one takes precedent?

Also, depending on your AH model, both electric and diesel system may be controlled by the same tank mounted thermostat or by separate thermostats with different trigger temps. In our case, diesel kicks in if electric can't keep up and the fluid temp drops enough to start the burner to help out. I keep both switches on in cold weather or for showers if we have hookups.

[Bigdogracing]

1 hour ago, Ivan K said:

Also, depending on your AH model, both electric and diesel system may be controlled by the same tank mounted thermostat or by separate thermostats with different trigger temps. In our case, diesel kicks in if electric can't keep up and the fluid temp drops enough to start the burner to help out. I keep both switches on in cold weather or for showers if we have hookups.

Than you so much! As usual y’all are super helpful and a wealth of knowledge!  We will start using the diesel option when its that cold!  Happy New Year!

 

1 hour ago, Tom Cherry said:

 

Lets put it another way.  Look at your Aquahot Plate Data. I have the AHE450, which was used on the "LOWER FOOD CHAIN" MH's, not the Dynasty.

AC or Electric element specifications....  15Amps = 1,650 Watts = 5,630 BTU per HOUR....

Diesel Burner Specifications =                                                         56,000 BTU PER HOUR...

Basically, the diesel burner has TEN (10) TIMES the heat output as the Electric.  The Electric is OK, in MOST cases, for domestic HOT WATER.  BUT, your Heat Pumps will put out MORE heat that the Electric will. SO, when your Heat Pumps are NOT adequate to keep the MH comfortable and your NEED more HEAT, you MUST TURN ON THE DIESEL and run the Aquahot (FURNACE).

That's how it works.... 

NOW, your's may be different...but the Electric has been 15 Amps or 1,650 Watts for a LONG TIME.  Your Diesel burner may also different....but most likely it is in the same ball park....and will be in the 56,000 range.  This is straight from the Specifications page of the Owner's Manual, around Page 2....check your manual or look at the Plate on the Aquahot....

BTW....so you don't worry about draining your Diesel Tank.  A Gallon of Diesel fuel is 138,700 BTU's.... The Burner (mine above) is rated at 56,000 BTU/Hour.  So, divide 56,000 by 138,700.....that is  0.40 Gallons PER HOUR....  You did not list your Length so you may have 2 HVAC's and an 8KW Onan....at 50% load, the Genny consumes 0.43 GPH....the 10KW, ironically is the SAME...0.43.  SO, you are consuming the same fuel for the Aquahot as your Genny...assuming a 50% Load...

EDIT....Based on Ivan's response....mine, or at least the LOW ENDS have the SAME THERMOSTAT....so when the temperature of the "BOILER" drops below the set point and BOTH switches (Diesel and Electric) are ON...  THEN BOTH the Electric element and the Diesel Burner will come on.  BUT at a 10:1 ratio....guess who carries the load. You CAN only turn on the Diesel at night...which many of us do. BUT, obviously if you are only on 30 Amp service, then you may have issues as you do NOT have a LOT of power.  Remember....on a 50 Amp Service, you have Line 1 and Line 2 for a TOTAL of 100 Amps of electricity...but the 30 AMP is only ONE LINE....the Dogbone splits it...so you have 3.3 TIMES the current on 50 Amp than you do on 30...  The OLDER AH's used to have two different thermostats (electric and Diesel and the Electric was lower...so it had the "opportunity", if the demand was low...to heat up the boiler without the Diesel firing.  That was dropped....don't know when, but the 2009 units like mine us the SAME Thermostat...  WHICHEVER or BOTH are on....that heat source is activated. Thanks to Ivan for a good point.

Hope this helps...

 

Than you so much! As usual y’all are super helpful and a wealth of knowledge!  We will start using the diesel option when its that cold!  Happy New Year!

1 hour ago, Jetjockey said:

Diesel and electric can be on at the same time. They have separate high limit switches but are both controlled simultaneously on and off by the common  control thermostat .

All green lights on the circuit board will not necessarily indicate the circuit board is doing its job.  Those green lights only indicate heat is being called for,which heating zone are active and which pumps are called to be running.The diesel or electric side can work independently of one another in the case either fails.
 You might try tapping on the circuit board housing. I have seen that solve the problem temporarily or for quite sometime. There are transistors on that board which control the diesel burning and electric heating function and can become intermittent or just plain weak. I experienced this several times in a year or so..   it makes one to think other components are at fault . Replace burner controls three times to think I had the problem solved only to find out it was the circuit board . All three if the suspect burner controls tested good on later investigation. 
Depending on model,w your aquahot may have only one electric burner at 1450 watts. That is not much for a large motorhome. You might try feeling the aquahot for warm to determine if There is any heating going on.

 

 Your diplomat may be new enough to have dual electric burners at much higher wattage.

 

Than you so much! As usual y’all are super helpful and a wealth of knowledge!  We will start using the diesel option when its that cold!  Happy New Year!

Edited December 31, 2023 by Tom Cherry
Duplicates on the posts....cleaned up into ONE post with the Quoted Links not duplicated

[96 EVO]

18 hours ago, Ivan K said:

Also, depending on your AH model, both electric and diesel system may be controlled by the same tank mounted thermostat or by separate thermostats with different trigger temps. In our case, diesel kicks in if electric can't keep up and the fluid temp drops enough to start the burner to help out. I keep both switches on in cold weather or for showers if we have hookups.

Yeah, they eliminated that feature before they made my 450-D circa 2007 ☹️!

All the models they make now, when the tank thermostat calls for heat, both sources are starting simultaneously, if you have both switches turned on.

[Dr4Film]

For those Aqua-Hot owners who haven't read your owners manual, it clearly states early on in the manual that the Diesel Webasto Burner is your PRIMARY heat source and your Electric Assist is your SECONDARY heat source.

The 600D model with two high wattage electric heating elements may keep up with demand during cold weather depending on the temperature outside and the temperature of the incoming shore water. However, even that manual clearly states that the Diesel Burner is the primary and the electric assist is the secondary.

Also, the recommended procedure is to ALWAYS run your diesel burner at least ONCE per month especially when you have been using ONLY the electric assist. This is to ensure that the diesel system stays in good working condition.

[Bigdogracing]

Thank you- I don't have the AH manual but found where I could finally download it! 

[Lenny D]

The diesel side does not use that much fuel. I've had my AH running (both electric and diesel) since the end of September 23' .. I had a full tank of fuel when I parked in March 23' .. (02 Windsor - 40') .. I start my motor once a month. Since I started using my AH I've used up maybe 1/8 of a tank. I'm parked in New Jersey. With that said, for 1 month (October) my control board failed and I lost the diesel side so In was running just in the electric. No way it could keep up with the temp drops .. I was also using the heat pumps on my Penguin II roof units to supplement but they stop working when the temps drop below 30 degrees .. We also used electric space heaters to compensate when needed (I found the oil heaters to work the best) .. Once the diesel side was repaired we had good heat but I noticed the hot water was running out too quickly. I had the tech come back and he was going to replace a thermostat inside the AH unit as well as the tempering valve .. Thats when I noticed I was getting a steady drip under the coach from the AH unit. ended up ascertaining that the tank inside the AH was leaking from most likely the copper tubing. My unit is older. The copper tube is on the outside of the tank .. All the research I did showed other AH owners with the same model as mine, I have a model 431/12 which is identical to the original 100-01/02 that was replaced by the previous owner, were showing leaking from corrosion where the clips that hold the tubing to the take oxidize and eventually compromise the copper. . . So, I cancelled the thermostat and tempering valve replacement and now am waiting for a rebuilt tank to be shipped and installed .. We had to rob a bank to pay for the parts and labor but such is the life we chose and love. AH's are fantastic ... when they are working. . Some friends think it might be time to sell .. I disagree. If I still had a stick and brick I certainly wouldn't sell if my furnace or hot water heater went down.   

I believe once you start using your diesel and electric together you'll be nice and toasty. We keep our thermostat at 71 degrees .. I like it warmer, at 72* and the wife likes it cooler 70* .. The age old husband / wife cage match .. lol. . Best of luck getting to the bottom of your AH issues and safe travels. 

LD (The Breeze) 2002 Monaco Windsor 40PBT

[DBRV.0]

As I re-read @Bigdogracing's initial entry, it seems that his problem is that heating stops.  He doesn't say that heat is insufficient.  I'm sure he appreciates, as well as I appreciate, the comments regarding preferred heat source.  I don't have the knowledge, but perhaps someone can guide him in getting his problem fixed?

[Dr4Film]

9 hours ago, DBRV.0 said:

As I re-read @Bigdogracing's initial entry, it seems that his problem is that heating stops.  He doesn't say that heat is insufficient.  I'm sure he appreciates, as well as I appreciate, the comments regarding preferred heat source.  I don't have the knowledge, but perhaps someone can guide him in getting his problem fixed?

Re-read his very FIRST sentence in his initial post. That explains it all.

Basically, hot air (aka heat) blowing fine from the heat ex-changers followed by cold air blowing. Simple explanation, boiler fluid too cold. If you don't have the diesel burner on so that the primary heat source can maintain the boiler fluid at temperature, you are going to end up with cold air and cold water. The secondary heat source simply cannot keep up with the demand by itself.

[DBRV.0]

2 hours ago, Dr4Film said:

Re-read his very FIRST sentence in his initial post. That explains it all.

Basically, hot air (aka heat) blowing fine from the heat ex-changers followed by cold air blowing. Simple explanation, boiler fluid too cold.

I understand your interpretation, and I hope your are right.  Mine is that cold air blowing means cold fluid, and cold fluid means no heat source, not just minimal heat source. 

A 50 degree interior is mighty cold, but one item missing was a statement of what the outside temp was.  I also don't know his AH system and how much electric capacity it may have.  I have noted with our 600D on electric only, I can keep the interior in the mid-60s on nights that drop well into the 30s.  Electric only is not what I want, but what I have to currently work with.

Edited January 4 by DBRV.0

[Tom Cherry]

22 hours ago, Lenny D said:

The diesel side does not use that much fuel. I've had my AH running (both electric and diesel) since the end of September 23' .. I had a full tank of fuel when I parked in March 23' .. (02 Windsor - 40') .. I start my motor once a month. Since I started using my AH I've used up maybe 1/8 of a tank. I'm parked in New Jersey. With that said, for 1 month (October) my control board failed and I lost the diesel side so In was running just in the electric. No way it could keep up with the temp drops .. I was also using the heat pumps on my Penguin II roof units to supplement but they stop working when the temps drop below 30 degrees .. We also used electric space heaters to compensate when needed (I found the oil heaters to work the best) .. Once the diesel side was repaired we had good heat but I noticed the hot water was running out too quickly. I had the tech come back and he was going to replace a thermostat inside the AH unit as well as the tempering valve .. Thats when I noticed I was getting a steady drip under the coach from the AH unit. ended up ascertaining that the tank inside the AH was leaking from most likely the copper tubing. My unit is older. The copper tube is on the outside of the tank .. All the research I did showed other AH owners with the same model as mine, I have a model 431/12 which is identical to the original 100-01/02 that was replaced by the previous owner, were showing leaking from corrosion where the clips that hold the tubing to the take oxidize and eventually compromise the copper. . . So, I cancelled the thermostat and tempering valve replacement and now am waiting for a rebuilt tank to be shipped and installed .. We had to rob a bank to pay for the parts and labor but such is the life we chose and love. AH's are fantastic ... when they are working. . Some friends think it might be time to sell .. I disagree. If I still had a stick and brick I certainly wouldn't sell if my furnace or hot water heater went down.   

I believe once you start using your diesel and electric together you'll be nice and toasty. We keep our thermostat at 71 degrees .. I like it warmer, at 72* and the wife likes it cooler 70* .. The age old husband / wife cage match .. lol. . Best of luck getting to the bottom of your AH issues and safe travels. 

LD (The Breeze) 2002 Monaco Windsor 40PBT

Comments on "FUEL USAGE" are like.... YOUR MILEAGE MAY VARY. I quoted the published rates of fuel based on BTU/HR of the Diesel Burner and also the BTU/Gal of Diesel. We have a member near me that does NOT winterize and uses his AH and HP and he reports the same thing...  You will NOT use a LOT of fuel...but you have to BE AT THE MH to turn it on and off as needed...  I choose to winterize and NOT keep running back and forth to storage...

BUT, if you have it where you can go out once a day and adjust or keep check on it, then the Diesel you burn over a winter will be minimal...

SUPPOSEDLY, there is an HOUR meter on some of the AH that tells you the ON TIME (Cumulative) for the burner.  One of our members records that. BUT, the fuel usage per hour of operation that I stated are good numbers....one just has to look at the Burner Capacity of their AH and do the math....  YES, if you leave on the Electricity, it helps...but remember, it is almost a 10:1 ratio of Diesel to Juice....  That is why the electric will allow you to shower....unless you have a gang....then you will hear the scream, as my GD did...."TURN ON THE DIESEL" when her GM washed dishes as well.  Pretty astute for a 10 YO GD...so I started using the diesel during "shower time"....

[96 EVO]

1 hour ago, DBRV.0 said:

I understand your interpretation, and I hope your are right.  Mine is that cold air blowing means cold fluid, and cold fluid means no heat source, not just minimal heat source. 

A 50 degree interior is mighty cold, but one item missing was a statement of what the outside temp was.  I also don't know his AH system and how much electric capacity it may have.  I have noted with our 600D on electric only, I can keep the interior in the mid-60s on nights that drop well into the 30s.  Electric only is not what I want, but what I have to currently work with.

DBRV, your newer AH, like mine, will shut off the blower fans when the boiler fluid gets cool, then restart them when it heats up.

From what I've read, the older units would leave the fans on. So, you could get cool air blowing from the heat exchangers.

[DBRV.0]

48 minutes ago, 96 EVO said:

DBRV, your newer AH, like mine, ...

Actually, the P. Owner said he chose to replace the AH a year before I bought it.  I've had it a year, so yes, it is a newer AH, maybe newer than you knew.

Nice to see that the AH control box in the basement has some nifty features, including a Diagnostic mode which shows every pump status, a Test mode for manually control of features, water temp, and some other things.  AH seems to call it 'Reporter 2".  PO said replacement cost $10k.  Ouch.  Diesel heat didn't work when I bought it and I haven't diverted enough of my time to investigate the AH, as well as to improve diesel quality.  Maybe this week.  I found a couple of excellent tutorials by Darren on YT channel 'My RV Works'.

[amphi_sc]

My current usage scenario: It's presently 37° outside, I'm on 30 amp service, my AHE100-03S is on electric only, heat source has now switched to AH furnace not heat pump. Bedroom & bath are comfortable 68°.  Front salon is cooling down with that thermostat turned off, bedroom door is closed.  I don't care at night, no need to heat the front. From the current draw I find the Electric element in AH is running and will be all night.  Hot water heat floor fans cycling on for about a minute every 5 or so and are blowing warm air.  But I also have a small cube heater on low drawing 7 amps in the bedroom.  By morning it'll still be comfortable inside and if I don't get up until 8:30 - 9:00 ish I'll have warm water for a shower and front heat pump can warm up the front salon by the time I'm dressed. Admittedly shower mixer will be full hot drawing water from basement tank ... Shower will still be comfortable for me but definitely not scalding hot ... and shower head volume turned to about 2/3rds full flow.  By the way I can hear the neighbor's propane furnace running about 4 minutes out of every 5.

Tip:  Let the front cool off, close the BR door, supplement heating needs with a small cube heater, draw water from on board tank as it is warmer than the fresh water hose.

It works for me.  YMMV

Edited January 5 by amphi_sc

[DBRV.0]

On the topic of tips ... here's another.  If you wish to allow your RV to cool down at night but you want to remain warm, consider what we have done.  We were gifted with an electric 'throw' blanket big enough to cover just the top of a double bed.  It was designed to shut off after a couple of hours, but that was enough to convince us to buy a mattress-cover electric blanket with separate controls for each side, and could stay on all night.  We now turn the electric on an hour before retiring.  When we crawl in, it is all nice and toasty, while everything has minimal heating overnight.

[Dr4Film]

Great tip but with a word of caution for those that have a MSW Inverter. Electric mattress pads and blankets don't play well with MSW Inverters. In those cases, one can only use them while on adequate shore or generator power. Then make sure to disconnect them from the outlets BEFORE switching power sources or shutting down 50 amp service from shore or generator.

[DBRV.0]

3 hours ago, Dr4Film said:

... a word of caution for those that have a MSW Inverter

Good to know.  Mine happens to be Magnum pure sine.  It would be interesting to understand why some things, like blankets, have an issue with modified sine, as well as symptoms that indicate a problem - like non-functional, or other control issues such as lack of temperature stability.

Edited January 5 by DBRV.0