AQUA HOT HEAT EXCHANGERS

We have a 2005 Beaver Monterey, and recently discovered a leak in the basement heat exchanger.  We were losing the Aqua Hot boiler antifreeze due to a leak in the heat exchanger coil.  This coil is 6-8" long, 6" wide and 2.5' thick.  Does anyone know where I can find a replacement coil? 
I'm currently using an electric heater in the basement, and have bypassed/removed the unit and removed the coil.  But I have not had any luck finding any parts for the heat exchanger unit.  I've replaced the 12v fans on several of them, this is the first one I've had troubles with leaks.  Aqua Hot doesn't include them in their parts list.

Click the Resources button above and scroll down the menu to RV parts & salvage.

Here are a couple of sources

https://www.aquahotpartswarehouse.com/collections/heat-exchanger-parts

http://www.parts.rvhydronicheaterrepair.com/Heat-Exchangers_c13.htm;jsessionid=B3AEDE34DE5C4EB037986A65BE845B37.p3plqscsfapp003

I have not used either if these personally, I keep them on file "just in case".

ken

Check with Roger Berke on his Hydronic Heater Forum.    My County Coach has an Aqua Hot 450D but the heat exchangers used by CC were from Heater Craft.  You might contact Heater Craft and see if they have what you need. 

I have a similar exchanger in my wet bay.  It has no fan and I suspect you could actually use a small automotive heater core in its place.  You might take the exchanger to a radiator shop and see if they can get you a heater core that is of similar size. 

I wish I would have known sooner, I just gave all of mine away from when I replaced them about 7 years ago.  Monaco used their own heat exchangers which were a metal housed design with two pancake fans.

I couldn't figure out why the heat exchanger fans were so much quieter in my friends Newell compared to our Monaco until I started some research and discovered that Monaco heat registers were different than the actual Aqua-Hot ones.

I replaced all of mine with the Aqua-Hot Cozy III heat exchangers and had all of my old ones on the shelf until I cleaned out my shop to move a couple of months ago.  I advertised them for sale and got no takers and ended up giving them away to someone on another forum.

Here is a link to the Cozy III heat exchangers from Aqua-Hot but I would check with Roger Berke as I am sure his prices are lower, plus to support a fellow RVer.
https://www.aquahotpartswarehouse.com/products/cozy-iii-heat-exchanger


Mike.

Thanks for the feedback from all so far!  Unfortunately I had already been to all of the links listed, with the exception of the ones listed by Tom in the "RV parts & salvage" links list on this site, and found nothing similar to what was installed in my RV.
I believe that I probably have something similar to the one Mike described, a metal housed design, but with only one pancake fan.  There are several units like this in my Beaver, this is the first time I've ever had a leak in the coil itself.

I found a similar one from Heater Craft, but the ports were at a 90 deg angle.  I still need to contact them to see if they can change the port orientation.

I'm going to check out Roger Burkes "Hydronic Heater Forum" next.  If I can't find any used identical replacement then I'll have to go with '2dalake's advice and try to find a small automotive heater core to use in its place.  I might also take the leaking exchanger to a radiator shop and see if they can repair it, or maybe get me a heater core that is similar size.  It has to be close to fit in the original metal housing.

One things for sure, with an RV, nothing's EASY!!!

Jim and Coe said:

Thanks for the feedback from all so far!  Unfortunately I had already been to all of the links listed, with the exception of the ones listed by Tom in the "RV parts & salvage" links list on this site, and found nothing similar to what was installed in my RV.
I believe that I probably have something similar to the one Mike described, a metal housed design, but with only one pancake fan.  There are several units like this in my Beaver, this is the first time I've ever had a leak in the coil itself.

I found a similar one from Heater Craft, but the ports were at a 90 deg angle.  I still need to contact them to see if they can change the port orientation.

I'm going to check out Roger Burkes "Hydronic Heater Forum" next.  If I can't find any used identical replacement then I'll have to go with '2dalake's advice and try to find a small automotive heater core to use in its place.  I might also take the leaking exchanger to a radiator shop and see if they can repair it, or maybe get me a heater core that is similar size.  It has to be close to fit in the original metal housing.

One things for sure, with an RV, nothing's EASY!!!

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I'd try the radiator shop.  My father owned a radiator shop for 30 years and I worked there summers and weekends while in high school.  I got pretty good at radiator repair.  If the exchanger is copper tubing with aluminum fins, the leak is in the tubing.  Unless the thing is leaking in many places, it can probably be repaired pretty easily. 

We did just that, we took it to the nearest radiator shop and they fixed it up for us!!
I'll put it back together and have it up and running again in no time now.  Thanks everyone for their help.
Jim and Coe

Hi!  Darryl & I (Lois) are relieved to find thorough discussions on Aqua Hot.  We have purchased a 2001 Safari Serengeti.  The dealership replaced the Aqua-Hot system when we purchased it, as they found the unit was leaking.  This was Dec 2015.  It wasn't until early this winter (2016) that we discovered that the diesel burner doesn't fire.  We've watched ZMotorsports wonderful YouTube videos (hey!  You're a blessing, Friend), and printed out the detailed service manual, and Darryl is a life-long maintenance worker, including boilers, so he has become familiar with what works and how to maintain the Aqua-Hot.  However, we just can't get the diesel burner to fire up.  The 110-V side of the unit works.  The diesel side works to the extent that it runs and goes through the purge cycle, but it just doesn't light.  When it is going through its purge cycle, the indicator light inside the coach is not on.  The electric side comes on, but not the diesel.  The wiring and hoses have been checked for leaks and to confirm that they're securely fastened.  Lots of searching and research has found no discussion on this problem of not being able to start up the diesel side of the Aqua-Hot.  Are there any sources of information, or advice that anyone can help us with?  Thanks so much!  Darryl & Lois

I can't help much with your problem (perhaps Mike will see this), but like the generator, the Aqua Hot is usually set up to not run (get fuel) below 13/ to 1/4 tank of diesel. This probably isn't your problem, but thought I'd mention it.

Burner not firing could be, as previously mentioned, that the fuel level is low. But it could also be either the fuel pump or the control board.

ken

DAL-Snowbirds said:

Hi!  Darryl & I (Lois) are relieved to find thorough discussions on Aqua Hot.  We have purchased a 2001 Safari Serengeti.  The dealership replaced the Aqua-Hot system when we purchased it, as they found the unit was leaking.  This was Dec 2015.  It wasn't until early this winter (2016) that we discovered that the diesel burner doesn't fire.  We've watched ZMotorsports wonderful YouTube videos (hey!  You're a blessing, Friend), and printed out the detailed service manual, and Darryl is a life-long maintenance worker, including boilers, so he has become familiar with what works and how to maintain the Aqua-Hot.  However, we just can't get the diesel burner to fire up.  The 110-V side of the unit works.  The diesel side works to the extent that it runs and goes through the purge cycle, but it just doesn't light.  When it is going through its purge cycle, the indicator light inside the coach is not on.  The electric side comes on, but not the diesel.  The wiring and hoses have been checked for leaks and to confirm that they're securely fastened.  Lots of searching and research has found no discussion on this problem of not being able to start up the diesel side of the Aqua-Hot.  Are there any sources of information, or advice that anyone can help us with?  Thanks so much!  Darryl & Lois

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Thank you very much for the compliments and I am glad you have found the videos helpful.

As to the unit's diesel burner not firing, there are several items it could be.  I have attached a link to the service manual for the AHE-100-02S which I am pretty sure your model is based on your coach year, however, I could be wrong.  You will need to look for the model # on your specific.
http://www.aquahot.com/eSource/ecom/eSource/staticpages/documents/AHE-100-02S%20Service%20Manual%20Rev.%20B%209-27-2011.pdf

Unfortunately on these older units, like mine, you don't have a control board with indicator lights like the newer models.  For testing you have to do it old school with a meter but it sound like Daryl being a maintenance mechanic this should be no problem.

The fuel pump you are hearing is actually the blower motor as the fuel pump is mechanically driven off of the blower motor.  The fact that this blower motor is running tells you that the switch to the control board is functioning at least.  Once the blower motor begins to run to purge the air from the combustion chamber as well as primes the fuel system, then it will send a signal to the coil and fuel solenoid.  Once the fuel solenoid opens and the coil ignites the fuel, the photocell (flame sensor) should detect the flame and turn the coil off to cease the sparking.  The fuel will continue to burn until the Klixon (thermistor) reaches its desired temperature and then it closes the fuel solenoid and continues the cool down period and purge cycle.

Have your husband remove the cover and while you turn the switch on he should hear the blower motor engage, which then drives the fuel pump.  Within a few seconds he should hear an audible sparking from the coil.  If he does not he should then dig in deeper and ensure there is power going to the igniter coil by using a VOM and verifying.  Again, this has to be done old school but quite easy with a meter.  If power is NOT getting to the coil, it could be a relay that is sticking or bad.  If power is getting to the coil but the coil is not sparking it could be either the gap is set incorrect (there is a gage on the side of the blower motor to set up the igniter to specification) or it could be a bad igniter coil. 

If the coil is igniting the fuel but then shutting down it could be the photocell not seeing the flame and shutting it down on a fault. 

After running these test it should be evident where your problem lies.  If the unit is not sparking I am going to suggest looking closely at the igniter distance first as this will be cheap to address and no parts required.  Then look to the coil and test it.  I have seen these igniter coils act up intermittently but generally when they fail they fail open and do not spark.

Hope that is helpful and enough to get Daryl pointed in the correct direction.

But again, before going through all of the above, do as Ken mentioned and ensure you have well over a 1/4 tank of diesel fuel.  The pickup for the Aqua-Hot and genset both are designed to not pickup fuel if the tank gets below 1/4 of a tank.

Mike.

Thanks so much Mike!  The tests you described will help us troubleshoot the issue.  Because the motorhome dealer replaced our Aqua-Hot unit a year ago, we have a 400-D, which sounds like a newer model, and I found a detailed manual online, but THIS firing issue isn't discussed.   (We do have plenty of diesel.)  We will report back once Darryl has fixed it, to help others  Right now, our new Baby is getting the slides re-aligned.  We feel that the past owners really didn't know how to maintain the unit, based on various things that Darryl has had to repair, and the two slides are way out of alignment.  Our other limitation is not being able to find any documentation on the electronic panel above the door.  (YIKES, she says in a tremor voice).  There's so much we can't see and don't know.  We did get the Motorhome "manual" from Monaco, such as it is, but it really doesn't explain the "workings" of the unit much at all.  We would love even some more detailed documentation for a Safari that is CLOSE in age - we think that will at least help us to understand a bit more.  Thanks All!  Lois & Darryl

My problem is not heating the aqua hot system but rather getting heat from the floor heat exchangers. I have plenty of hot water, the electric element works as required, the system fans work, both low and high, for the exchangers but not heat. I place the thermostate to highest temperature level, still no heat from the exchangers.  I need help.

Welcome to the RVForum Subchaser. You should go into your profile and enter the year, make and model of your RV. It helps others troubleshoot any problems you may be having.

Is the RV new to you, and is this a new problem, or a recurring problem? Are you plugged into shore power when this happens, on battery power or both? Do your AC units have heat pumps? If they've got heat pumps, your thermostat may be selecting heat from them first, which would explain why you're not getting heat from the floor vents. In our coach, that's controlled by a setting in the thermostat, but yours may be different.

Kev

Kev,
Thanks for your response, still working on my profile.  I have 2002  Beaver Monterey which I am confident have heat pumps.  Where do I find the switch, if any, to set the thermostate for heat over air.  Someone suggested the setting could be on he roof units themselves.???

Where do I find the switch, if any, to set the thermostate for heat over air.  Someone suggested the setting could be on he roof units themselves.

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If I understand your question correctly, it's likely one of the several modes on the thermostat itself. There might be Heat, Furnace, Cool, Fan only, perhaps another mode, and the labels might be slightly different. Note that if the outside temperature is below about 40?, then you may not get a lot of heat out, and somewhere not far below that they'll possibly no longer operate.

The above was certainly true in my 2007 Beaver Patriot Thunder, and is also true in my current 2016 Newmar Ventura.

I have the "mode" on heat, the fan on auto and the temperature set to the max heat.  If this unit only provides heat above the 40 degree it is not a very good heater.  I  carry electric ceramic heaters which require shore power or I must run the generator for them to work.  Certainly the aqua hot heat system must be more efficient than 40 degrees or above?

Heat pumps are not part of the Aqua Hot. They are devices (usually on the roof) that can switch between being air conditioners and heaters, and the physics are such that much under 40? they don't do much. The Aqua Hot (may be Furnace on the thermostat) is hot water heating (hydronic) and there are generally heat exchangers next to the floor (I think these are what you mentioned in your first post). My Beaver's A.H. had a heat exchanger under the center of the dash, under the kitchen sink, in the bathroom and bedroom, in the basement and another (I forget where). Each heat exchanger has a fan that blows across the exchanger.

Your rig is a little older than my Beaver was, but I had a fault/control panel for the A.H. just inside one of the outside bay doors, opposite the water bay. This board showed each loop/each exchanger and had fault lights next to each, along with reset and something else.

If you were getting heat from the heat pumps you'd be getting heat from the air conditioning ducts. Otherwise it's just the Aqua Hot. If no exchangers give heat then it may be the thermostat or perhaps wiring somewhere.

So there may be confusion about terminology in some prior posts here.

In any case, if Mike (zmotorsports) sees this thread he might help, but I've pretty much exhausted my knowledge here (yup, I don't know much).

Here is a site that is all about Aqua Hot with a monitored tech. You can join for a small fee, but it is way worth it, in my opinion.  http://www.rvhydronicheaterrepair.com/