Author Topic: Hot Water Not Lasting Long - Hydro-Hot HHE-500  (Read 18256 times)

RebeccaKlein

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Hot Water Not Lasting Long - Hydro-Hot HHE-500
« on: December 02, 2015, 07:05:36 PM »
This is my first post so let's see how this goes ?!?!  We have owned our coach for about 9 months now and have traveled about 8000 miles.  I recently started having issues with the Hydro-Hot Water Heater.  It seems that the hot water for shower and or dishes is very short lived.  The water does not go all the way cold but is luke warm. 

Prior to my purchase the previous owner replaced a Webasto Burner with a rebuilt one.  This was done in October of 2014.

Any suggestions would be appreciated. 


Karl Welhart

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #1 on: December 02, 2015, 07:30:57 PM »
Welcome to BAC.  I assume that you have the diesel mode turned "on".  If that is true, you should get constant hot water after a few minutes.  There could be several reasons if you are not.  The simplest could be the mixing value needing to be cycled, cleaned or replaced. 

The other could be the shower facet in the service bay have the knobs in the on position.  The can also cause your problem.  It also could be the circulation pump is bad and needs to be replaced.

If your exhaust is burning clean (no smoke) and the diesel burner system is working properly, then the Webasco unit should be OK.  Not sure why it would have been replaced with a re-built unit.  Has your unit been service lately?

Good luck,
Karl and Nancy Welhart, F36017
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RebeccaKlein

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #2 on: December 02, 2015, 07:40:57 PM »
Thank you for your reply. The Diesel and Electric switches are both in the on position.  The unit is burning clean. My heat is working great.  It seems like it is just the hot water in both the shower and the kitchen. 

According to the previous owner the coach was completely serviced just prior to our purchase.  I have all the receipts and records from work he had done but not work done from the owner prior to him.  I believe he owned the coach for 2 years and did substantial work to recondition it. 

RebeccaKlein

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #3 on: December 02, 2015, 07:44:33 PM »
I did check the service bay and all Hot water knobs are in the on position. 

Marty and Suzie Schenck

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #4 on: December 02, 2015, 09:07:02 PM »
Rebecca, Try going to www.rvhydronicheaterrepair.com and join that forum (it's free). Roger Burke is a wealth of information and sells parts at a discount. He is an Aqua Hot trained tech. Marty

David T. Richelderfer

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #5 on: December 02, 2015, 09:45:49 PM »
I'm betting on the mixing valve being the problem.  If the diesel burner is working and the inside furnaces are providing good heat, then what else could it be?  The common thread between the sink and shower, but after the diesel burner and furnaces, is the mixing valve.

If you do a search on "mixing valve," then you will find several references to things to try before replacing it.  For example:
http://beaveramb.org/forum/index.php/topic,3719.msg28614.html#msg28614
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Joel Ashley

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #6 on: December 02, 2015, 10:00:20 PM »
I have to agree with David;  your symptoms are almost classic mixing valve.  At least it's one of the first things to check - I've never had to do it personally, but previous discussions here have advised that just rotating the handle for it can free it up so it mixes the proper proportions of hot and cold again.  I'm not sure that access to the handle is always particularly easy though;  I've never tried to locate ours. David's link should help.

Joel
« Last Edit: December 02, 2015, 10:04:16 PM by Joel Ashley »
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RebeccaKlein

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #7 on: December 02, 2015, 10:01:27 PM »
 Thank you all so much.  I will look into the references provided and will post the fix. Thanks again.

Jerald Cate

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #8 on: December 02, 2015, 11:13:38 PM »
Rebecca,

Look for leaks around the Hydro-hot system.  I had a problem similar to yours this past summer and found a loose connection on the back of the Hydro-hot unit.  I guess it loosened up from road vibrations, tightened it up and everything was fine.

Stan Simpson

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #9 on: December 04, 2015, 03:47:49 AM »
The other could be the shower facet in the service bay have the knobs in the on position.  The can also cause your problem.

When you say your hot water knobs are all on, I think you misunderstood this part of Karl's post. He means the shower knobs for the outside shower, not the knobs that are on the water manifold. If I misunderstood, I apologize.

Stan
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Fred Brooks

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #10 on: December 04, 2015, 01:19:25 PM »
               Hi Rebecca, If your coach has a faucet in the water bay and a hand-held sprayer, here is what happens sometimes. You go and dump your holding tanks and turn on the faucet to use the sprayer for clean up. If the faucet is not turned off, it allows the hot and cold water to mix together and give you warm water in the shower. Hope this helps, Fred
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Orman Claxton

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #11 on: December 04, 2015, 03:56:34 PM »
There is also the stir pump

David T. Richelderfer

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #12 on: December 04, 2015, 06:27:58 PM »
Circulation pump?  Stir pump?  Different pumps or same pump?  On my Aquahot (AHE-100-02S) the picture documents the middle pump of Circulation Pumps A, B and C [NOTE: all three pumps are here documented as circulation pumps] is the "Stir pump/Circulation Pump B."  Regarding Pump B, as quoted from the manual:  "The stir pump circulates the antifreeze and water heating solution within the Aqua-Hot boiler tank in order to ensure even-heating of the solution.  To accomplish this, the stir pump draws the solution from the supply port of the tank and deposits it back into the return port of the tank, after circulation through heating loop number 2.

Soooo... do these three pumps do the same thing, but for different zones?  Do they each act to stir the solution through the boiler tank AND circulate that solution through their respective zone of responsibility?  If so, then any one of the Pumps A, B and C would stir the solution and thus the water would be stirred and nearly equally hot around the area of the boiler tank.  Now, if any of the interior furnace fans are working well, then the Circulation Pump for those heating zones must be working well.  This again points back to the mixing valve as being the likely problem.

I would note my discourse here is based upon the Aquahot unit in my coach, not necessarily the unit in the coach upon which this thread was started.
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Bill Sprague

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #13 on: December 04, 2015, 08:01:28 PM »
We had the HHE-500 in our '04 Monterey for 12 years.  Although it was a grand adventure with lots of good trips and rallies, the Hydro-Hot was my most disliked system.  When it worked, it was nice.  When it didn't.....  "Hate", "anger" and "frustration" come to mind.

My guess is that the stir pump is in need of replacement.  Now for the rest of the story.....

The HHE-500 is a relatively small version of the various models.  It uses a smaller coolant tank than the more expensive models.  In order to get the smaller tank to function it has to have a working and dedicated stir pump.  It is very small and the original has a weird magnetic drive between the motor and delicate impeller.   In our twelve years the stir pump was expensively replaced twice.

We had symptoms similar to the OPs at about year three.  The first replacement was done by Beaver Coach Sales after they guessed failures of two other component$, including the Mix Valve.  With some destructive dis-assembly of the first pump it was clear that the impeller had broken in to small pieces.  It was "old and brittle".  Because of the magnetic drive, the motor ran fine and confused the diagnosis. 

In two out of the last three years we owned it, the hot water reliability was very strange.  For a shower, we would have to turn on the diesel, run and run water long enough so the system was at full output.   Then, if you stayed alert, you could adjust the shower as necessary to keep from burning or freezing.  Taking an electric shower was out of the question.  I had forgotten the repair from 7 years earlier.  If I had, I might have replace the stir pump myself. 

During the two or so years of frustration, three different techs tried to trouble shoot it.  With intended humor and a smile, Orman was one of them.  We were at Quartzsite.  The assumption was that if the hose coming out of the stir pump was hot, it was pumping properly.  Orman used his new (at the time) IR gun and measured the temperature of the outlet hose.  I used my finger.  We agreed it was very hot.  Roger Burke's trouble shooting guide suggests the same thing by saying if it is hot to the touch, it is probably working.   (Note that Orman did not ask for any payment since nothing appeared to be in need of repair.)

At 7 Feathers 1 or "BAC(k) to the Future" a well known tech did a full service.  I'm momentarily forgetting his name, but he was there as the available AquaHot service tech because Orman could not attend.   He did a complete and routine annual service.  Nothing could be identified as broken.  Hot water reliability still sucked.

At the Ale Trail rally, John Carrillo was in town a few days before the FMCA rally.  John used to work at the factory.  He now has his own service company.  At Jerry Carr's request, he came to our rally a couple of days and serviced several Beavers.  When it was our turn, I explained our frustration.  John explained that a complete and through trouble shooting procedure would be needed.  Everything would have to be measured and tested.   He included the idea that it was not possible to test the stir pump and if EVERYTHING else tested OK we would have to agree to GUESS that the stir pump needed replacing.  What the heck!  It was only money!  I won't list all that John did because it would require even more typing.  It took about 90 minutes to adjust, adjust, measure and clean everything.   Everything testable passed the test.  John ended up putting in a new, improved version of the stir pump.

I all but hugged John!  The 12 year old Hydro-Hot functioned like it was brand new and continued to do so until we sold it.  It was the stir pump again!

After John left, I hooked up the "broken" stir pump and it would pump water out of a bucket!  I had assumed the failure to be the same as the first one and expected the impeller to be in pieces.  I took it apart and the impeller was fine.  The cause of the two years of crappy showers and luke warm water in the kitchen was the magnet in the drive was "tired".  It was not so tired as to prevent a little coolant to pass and heat the hose for Orman to measure as hot, but it was too tired to pump enough to sufficiently circulate the coolant in the tank. 

My happiness in the RV experience improved dramatically when we kissed the Hydro-Hot goodbye!  Based on a quick price check, I think I can buy two new water heaters for the motorcabin for what I had to pay John to fix the stir pump in the motorhome!

Dick Simonis

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Re: Hot Water Not Lasting Long - Hydro-Hot HHE-500
« Reply #14 on: December 04, 2015, 08:26:48 PM »
Just as an FYI, if your pumps made by March (most likely the case) all the parts should be available for repairing the pump.  I've had to overall several March pumps in a past life and it was a rather simple process once the correct parts were identified.

The magnetic coupling does indeed fail almost as often as the impeller.