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Aqua Hot front zone not heating


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A few months ago I noticed my AH 600D front zone was blowing cool air. All other zones working properly.  The unit was serviced about 12 months ago and had been working well for over three years. Serviced every year for past three years.

  1. No faults shown on control board. Indicator lights on and glowing green. 
  2. I have the original circulation pumps and the pump for the front zone (circulation pump #3) is spinning, but a bit noisy. 
  3. Couch side supply line feels cool to the touch before and after check valve, while other zone lines are warm.
  4. Tapped the check valve several times without success. 
  5. Tried heating on 50 amp and diesel burner, no difference.
  6. Did re-set on five button CCC thermostat, but no change.
  7. Fluid level in AH expansion tank is good.
  8. I opened the outlet hose connection on the circulation pump, thinking it might be air locked. Fluid leaked out but was only a trickle.
  9. I swapped the engine preheat circulation pump with the front zone pump (circulation pump 3), thinking the pump was bad. Swapped pump spinning but still no heat.

    Anything else I can do before taking it to the dreaded RV dealer?

2008 Dynasty Squire 

Edited by Pduggs
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From what you describe it seems that the check valve is stuck or corroded closed.  If you replaced the pump and it still didn't work, it seems the loop to the front is blocked.  I had a friend that had to replace his check valve as all the tapping in the world wouldn't loosen it.  You could try bypassing the check valve to see.  Just an idea.

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That’s a good idea. The thing is the hose coming out of the circulation pump and running up to check valve is cool to the touch and soft. If it were a closed check valve, wouldn’t this hose be hot and firm?

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Paul, it sure sounds like the check valve.  What else could it be?

It wouldn't hurt to install a new one.  Cold weather is coming on and the dealer service is backed up for some time.  

Chuck, yes a propane furnace will work just fine. However, the Aqua Hot provides unlimited hot water and can run from 120v electric, diesel (150 gallons onboard), or will even produce heat from just driving or running the main engine.  Also, the heat is different from a propane furnace.  Propane superheats the air and dries it out where as the Aqua Hot does not.  Much easier on the skin and lungs.  It's one of those things that you don't know what you are missing until you use it.  

Edited by vito.a
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Your #8 comment has me confused.

Having trouble visualizing at what point you are checking for flow. After the pump or check valve?

Actually a cold hose is exactly what I would expect. Seems like the pumps are flow oriented not pressure so soft doesn’t surprise me.

I would for sure find a qualified Aquahot hot guy if you take it in. Regular RV service departments are likely give you an appt weeks out and then throw their hands up when you finally get a turn. This is not meant as a slam on dealers, by the way.

 

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53 minutes ago, Pduggs said:

My front zone isn’t working, but all the others are and I still have unlimited hot water.

If you can swap the pumps, you are certainly qualified to swap or eliminate the valve, if only for a test. I would also consider swapping the zone hose to an other zone and eliminate blockage/kink in the plumbing that way, whatever is easier.

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26 minutes ago, Fonman said:

Your #8 comment has me confused.

Having trouble visualizing at what point you are checking for flow. After the pump or check valve?

Actually a cold hose is exactly what I would expect. Seems like the pumps are flow oriented not pressure so soft doesn’t surprise me.

I would for sure find a qualified Aquahot hot guy if you take it in. Regular RV service departments are likely give you an appt weeks out and then throw their hands up when you finally get a turn. This is not meant as a slam on dealers, by the way.

 

Thanks for your response.
 

The pump outlet hose is the vertical hose running from the pump to the check valve. This hose is not hot, nor is the hose after the check valve. The hose between the pump and check valve IS hot on the other two house heating zones, as are the hoses after the check valve. 
 

This is why I didn’t suspect the check valve. But as others have stated, it’s easy to replace that valve or bypass it just to make sure. 
 

Regarding dealers, I’ve not had a good experience with them, not that I’ve used that many. If anyone knows a good AH shop or technician, please let me know. 

26 minutes ago, Ivan K said:

If you can swap the pumps, you are certainly qualified to swap or eliminate the valve, if only for a test. I would also consider swapping the zone hose to an other zone and eliminate blockage/kink in the plumbing that way, whatever is easier.

Thanks for your response. I will replace the check valve. 

When I swapped pumps I carefully examined the pump inlet and outlet. Both were clean. 

I must have a blockage somewhere. The check valve is the most likely culprit. 

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John Carrillo is one of the best Aqua Hot technicians.  He helped me last year with an intermittent issue.  His shop is across the street from the Aqua Hot factory.  

He also has good pricing on parts.  

https://heatmyrv.com/

CONTACT JOHN CARRILLO   (970) 518-3085

Heat My RV
8245 W I-25 Frontage Rd Unit #5
Frederick, CO 80516
jcarrillo@HeatMyRV.com

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If you have a blocked check valve, it would be full of cold coolant when4the pump started. If the hose is blocked, the heated coolant cant enter the hose to heat it.

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1 minute ago, JohnC3 said:

If you have a blocked check valve, it would be full of cold coolant when4the pump started. If the hose is blocked, the heated coolant cant enter the hose to heat it.

Yeah that makes sense. Thanks. 

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As mentioned I would disconnect the circulator output hose and put a short section of hose on the pump into a bucket and see what happens. Likely the valve unless you just replaced the fluid. I think that would be the only way it could be airbound unless the fluid got real low and sucked in air through the overflow reservoir 

7 hours ago, Chuck B said:

I never have been a Aqua Hot fan because it is a over a $10,000 option.  Then there is the annual maintenance cost.  My two floor ducted furnaces keep us just as warm.  We always had hot water from our hot water heater.  Chuck B 2004 Windsor

How does this help the OPs issue???  Propane fired furnaces certainly are not problem free either. 

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55 minutes ago, Chargerman said:

As mentioned I would disconnect the circulator output hose and put a short section of hose on the pump into a bucket and see what happens. Likely the valve unless you just replaced the fluid. I think that would be the only way it could be airbound unless the fluid got real low and sucked in air through the overflow reservoir 

How does this help the OPs issue???  Propane fired furnaces certainly are not problem free either. 

That’s a good idea. Thanks. Do you know the pressure of the fluid?

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5 minutes ago, Chuck B said:

True, but a lot less expensive.  JMHO,  Chuck B 2004 Windsor

Agree. Fortunately, besides regular maintenance mine has been problem free in the 7 years we’ve owned it. 
 

I don’t know the fluid pressure but I would guess around 10 lbs at operating temp  

Edited by Chargerman
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Paul,

What part of Florida will you be heading for? We are in New Hampshire but heading back home to Florida on the 13th.

When I changed out coolant back in 2015 my front zone lost the ability to heat but the bathroom and bedroom zones worked fine. Turns out that I had an air lock in the front zone somewhere. After driving it to a service center in Anchorage AK for some service, when they finally got around to checking why the front zone wasn't heating, it was working as it should. SO driving it must have shaken out any air that may have gotten into that specific loop.

Edited by Dr4Film
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11 minutes ago, Dr4Film said:

Paul,

What part of Florida will you be heading for? We are in New Hampshire but heading back home to Florida on the 13th.

When I changed out coolant back in 2015 my front zone lost the ability to heat but the bathroom and bedroom zones worked fine. Turns out that I had an air lock in the front zone somewhere. After driving it to a service center in Anchorage AK for some service, when they finally got around to checking why the front zone wasn't heating, it was working as it should. SO driving it must have shaken out any air that may have gotten into that specific loop.

We have driven about 500 miles since this issue began, without anything changing. A drive to Florida via the Carolinas might do it though. 
 

We will be in the Tampa area most of the winter, with 30 days over by Jupiter. 

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