Skip to main content ↑ ↓
Topic: Aqua-Hot Maintenance "Fun" (Read 502 times) previous topic - next topic

Aqua-Hot Maintenance "Fun"

Got around to doing some basic work on the aqua-hot.  Ours is a 431/12 which is a AHE-100-02S as near as I can determine.

In our 2000 the AH is located mid ship, in the middle of the main storage bay.  First task was to simply clean up the inside of that compartment which had 25 years of soot, grime and gunk.  Once done with that I removed the AH access cover which only had a couple of screws holding it in place, the other screws were in the bottom of that bay.

20241119_141654.jpg With the access cover off, I noticed the magic silver Webasto box was not attached to the head, it was simply sitting in the base as its mounting bracket was gone.  Moving on I disconnected the Webasto cables, loosened the nuts on the (2) swing arms so I could pull back the burner head.

With the burner back and rotated away, I got to see some goodies.  First up, a dead mouse towards the back, along with the requisite turds.  With the mouse removed, I found (3) polytube 90 degree bend supports lying in the far right corner, no idea why they were removed and left there.  I also found one of the relay clips lying in the base pan.  Last was the cover edge trim. It was intermingled with the wire harness which must have fallen off at some point.

Back to maintenance: cleaned the photo disk / sensor, cleaned the combustion / swirler, new nozzle, adjusted the electrodes, cleaned the heat transfer tabs.  Replaced the head, reinstalled the edge trim, relay clip and bend supports.

20241119_160926.jpg 20241120_121726.jpg I went to replace the radiator cap, and it literally fell apart in my hand.  The relief tab broke off, then the cap came off.  I had to pick out all the bits and then finally removed the spring and seal.  Cleaned it all off and put on a new cap. I've never seen anything like that. Who knows how old that was.

Next, there will be fuel filter and radiator flush/fill; given the cap I don't think the fluid has been changed in a long time.

Couple of questions!

  • Who is Rudy's yoga instructor?  Getting in position to loosen/tighten that rear swing bolt was something!
  • On the face of the burner, where the flame sensor disk is located, there are (3) bullet style connectors.  The plastic insulators are shot,  I taped  over them for now.  Are those just standard connectors that I can splice or should I get a new cable?
  • The loose Wabasto box is concerning.  Looks like the bracket is available as P/N WPX-362-107 ~$15.  Is there some obscure reason why that bracket was removed that I'm missing?

Thanks!
2000 / 36' / U320 / WTFE
WildEBeest / "Striving to put right what once went wrong"

Re: Aqua-Hot Maintenance "Fun"

Reply #1 –
Quote from: steve –

Couple of questions!

  • Who is Rudy's yoga instructor? 
Namaste'

And I am VERY glad he didn't show me the latest dead mouse found in the belly of the Beest.  I've seen enough to last me for a while.
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Aqua-Hot Maintenance "Fun"

Reply #2 –
Quote from: steve –
The loose Wabasto box is concerning.  Looks like the bracket is available as P/N WPX-362-107 ~$15.  Is there some obscure reason why that bracket was removed that I'm missing?
Steve, A number of years ago, after replacing the silver control box several times with rebuilt boxes, I decided that the box being mounted against the burner motor was overheating the electronics inside the box. I detached the box and moved it outside the AquaHot housing. Over time this didn't seem to make any difference. So when I finally bit the bullet and bought a new black box, I moved it back to its original spot. Thankfully I had saved the metal mounting plate.

Something like this may explain the missing mounting bracket.

(Incidentally, I have so far been very pleased with the modern black plastic control box.)
Jan & Richard Witt
1999 U-320  36ft WTFE
Build Number: 5478 Motorcade: 16599
2011 Jeep Wrangler Unlimited w/Air Force One
Jan: NO5U, Richard:KA5RIW
The selected media item is not currently available.

Re: Aqua-Hot Maintenance "Fun"

Reply #3 –
Quote from: Jan & Richard –
, after replacing the silver control box several times with rebuilt boxes, I decided that the box being mounted against the burner motor was overheating the electronics inside the box. I detached the box and moved it outside the AquaHot housing.


Same,  I remember a conversation about this somewhere and moved my box also.

2000 GV320 4010 build #5712  2019-?
1999 Bounder 2000-2008
Bardstown, KY
🥃The Bourbon Capital of the World🥃

Re: Aqua-Hot Maintenance "Fun"

Reply #4 –
Morning Steve,  being 5 ft 8 in and 160 lbs makes getting in there and laying on your side a little easier.  But still not fun.

Your heater model is 431/12 unless stated differently on label on heater.  My 03 is a 431/12, which are the best heaters AH made, in my opinion.  Metal pumps and Watt mixing valves are long lived but no longer used.

Mounting the Control Unit, silver box, onto the burner is fine or any place else is too.  I have left the stainless cover off of the burner area of my heater, stored it.  This lets the heat escape into the bay away from the box.  A new Aqua Hot 300 901 solid state encapsulated control unit, with pig tail plugs, is only $1029 from AH.  A rebuild box is fine too.  But a black plastic box made in the Ukraine that does not have the pig tail plugs the new AH box does is very suspect and rarely long lived.

You are most welcome to call if I can be of any assistance.  It is not rocket science so I believe you will do fine.  The only thing I can suggest that many folks do not know is as follows:

1). Tighten the nozzle once, loosen it 1/4 turn and tighten it a second time to seat the threads into the nozzle tower.

2). Torque spec for the J-bolts that hold the burner to the heater is 20 inch-pounds, not foot-pounds.  So for all men, that means "SNUG", not tight.  Breaking off the tabs on the heater means taking it all apart, bearings and all, to replace the housing.

3). With a new service and nozzle on the burner, run and fire the burner ONCE per month or more year round, no excuse not to.  This keeps fresh diesel on the nozzle so the fog spray pattern remains constant.  You can go 2 or 3 years between services, maybe even 4 years.  Leave it off for weeks on end, plan to service the burner.  Watching the exhaust pipe while firing determines the need to service.  Clean and clear exhaust, good to go.  Visible vapor or smoke, service needed.

We are snug this morning in 40 deg temps with our AH cycling on and off just fine.  All the very best.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Aqua-Hot Maintenance "Fun"

Reply #5 –
Quote from: Rudy –
A new Aqua Hot 300 901 solid state encapsulated control unit, with pig tail plugs,
To clarify my earlier post, the new control box that I am very satisfied with is the solid state encapsulated unit. I guess I used an inaccurate description.
Jan & Richard Witt
1999 U-320  36ft WTFE
Build Number: 5478 Motorcade: 16599
2011 Jeep Wrangler Unlimited w/Air Force One
Jan: NO5U, Richard:KA5RIW
The selected media item is not currently available.

Re: Aqua-Hot Maintenance "Fun"

Reply #6 –
Richard, the Ukraine box is shaped like the silver box and is black plastic.  Very pleased for you having the 300 901 control unit
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Aqua-Hot Maintenance "Fun"

Reply #7 –
Thanks Rudy,

Any thoughts on this one, or is it not something we need to address further?

Quote from: steve –

  • On the face of the burner, where the flame sensor disk is located, there are (3) bullet style connectors.  The plastic insulators are shot,  I taped  over them for now.  Are those just standard connectors that I can splice or should I get a new cable?
Learn every day, but especially from the experiences of others. It's cheaper!  - John C. Bogle

2000 U320 36' non-slide / WildEBeest Rescue
2003 U320

Re: Aqua-Hot Maintenance "Fun"

Reply #8 –
Please call me.  7 one 3.  8 one 8. 3234
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Aqua-Hot Maintenance "Fun"

Reply #9 –
Rudy,  thank you very much for taking the time to walk me through the details, much appreciated  ^.^d
2000 / 36' / U320 / WTFE
WildEBeest / "Striving to put right what once went wrong"

Re: Aqua-Hot Maintenance "Fun"

Reply #10 –
Quote from: steve –
Rudy,  thank you very much for taking the time to walk me through the details, much appreciated  ^.^d

Steve, were they the same as butt connectors?
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Aqua-Hot Maintenance "Fun"

Reply #11 –
The connectors for the flame sensor are round bullet connectors.  You twist them to break the friction and pull them apart.

The plastic coverings get hard and crack off over time due to heat.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas