aqua hot has 1 zone that blows cold air only, the fan is working fine

[LaMonte Monnell]

I just had my Aquahot on and running the heater. I checked each zone and the one under the frig is blowing cold air only. What would cause this, clogged water line going in to register? The rest are all very warm air coming out of them! I have front, lr side,under frig, bathroom, and bedroom(5 zones).

[Joe Rhea]

LaMonte
How many zone pumps do you have on the unit?
Joe Rhea

[LaMonte Monnell]

heck if I know Joe. I have five locations that the hoses go thru the fan housings for the heat to come out of. Heat is ok from four.

[Joe Rhea]

How many thermostats do you have?
One stat per zone pump. If like mine two stats, one for the front of coach and the other for the bath and aft cabin.

[Steve Huber Co-Admin]

Lamonte,
If your 01 Contessa is like mine, it probably has a Hydro-Hot 500. There are 2 circulation pumps. Check to see that both are working by looking at the status indicator on the control unit near the Hydro Hot. I suspect both are working since you have heat coming out of all but one register. Also verify the Heating Zones lights are Green. The system has 2 heating loops; 1) Living and Kitchen area,  2) Bath and Bedroom area. Remove the offending register grill and see if the  hoses feeding the heat exchanger are both hot. If one is hot and the other just warm or cool, you may have a blockage at the exchanger. If both hoses are cool, anti-freeze is not getting to the exchanger and the blockage / kinked hose is somewhere between the circulation pump and the exchanger.
Steve

[Fred Brooks]

   Hi Lamonte, The model Aqua hot you have is notorious for sticking check valves just above the circulation pumps. After sitting idle for 2-3 months, the  anti-freeze may get a little "gummy" around the check valves. These check valves are gravity closing type and require a fair amount of internal pressure to push them open. Here is how you do the test to prove the check valve is stuck: turn on the aqua hot diesel and set the T-stat to 75 to 80 degrees. When you start to get heat out of the heat exchangers, go to the aqua hot unit and touch the copper pipe just below the check valves (these are located just above the zone pumps) then touch the copper tubing above the check valves and see if it hot also. The offending check valve will be hot below and cool above. Next take a small hammer and tap the check valve and it will open and wash itself clean with hot coolant. If the check valve will not open then you will have to change it.
   Hope this helps, Regards, Fred

[Steve Huber Co-Admin]

Fred,
Wouldn't a bad check valve cut off anti-freeze flow all the heat exchangers in the loop? Since LaMonte has only 1 heat exchanger in his living/kitchen loop that isn't heating and the others on the loop are OK it would seem that the check valve is not a factor. What am I missing??
Steve

[Fred Brooks]

   Yes you are correct, I was thinking the galley was on a dedicated circuit.
    Regards, Fred

[Joe Rhea]

I have not figured out where the return air comes from on the blower under the frig. I would guess the basement. If the lines going to the coil is warm or hot the problem would be return air to cold ( leak from the outside ). The air off of my coil is not extremely warm compared to the other coils.

[Steve Huber Co-Admin]

Joe,
The air used by the heat exchanger should mainly come from through the front grill. If you remove the grill you will see that the heat exchanger is set back a bit from it and that there is no sealed path from the exchanger output to the grill. The fan  in the heat exchanger blows air from this space under the reefer. If you are getting air that is cooler than the other registers, either you have a leak to outside air under the reefer or a partially plugged input line. See if there is a temperature difference in the temperature of the input and output heat exchanger lines compared to another heat exchanger in the same area (kitchen / living area).
Steve

[Chuck Calhoun]

I just encountered the same problem. One of the small wires that connects the circulating pump was broken. Remove the cover on the hydro-hot and check to see if the both circulating pumps are operating. Good luck.