Refilling Aqua-hot after fluid loss

[Mike Sulley]

Hi all.  Hope you are all out enjoying the summer on the road.

I spent a good part of this last winter learning about my Aqua-hot AHE 100-01S Sr # 047.  A very primitive early model.  No fancy mentoring or control bells and whistles.  But I got it operational thanks to the help from people on this forum.  Thank you all so much.

While doing the yearly maintenance, I replaced the old diesel lines as well as the Racor filter.  Unfortunately, I replaced the clear tubing going to the boiler fluid recovery bottle with an inferior brand of hose.  It worked for the first couple of trips, but eventually sheared off at the connection below the radiator cap and vented off some quantity of boil fluid.  And now the diesel burner won't fire up.  I did as suggested here and replaced it with glycol compatible silicon hose.

So my first question is how is the easiest way to refill the lines going to the heat registers on the floor above the basement?  I assume they are now empty and full of air.  I have refilled the boiler tank and recovery bottle.  Can I jumper the zone relays to engage the zone circulation pumps to refill them or is there an easier way?

Secondly, I pulled the diesel burner to inspect it for black carbon sooting.  It appeared fine so I reinstalled it.

I also checked the diesel control thermostat ( 190 degree F - blue dot) and it has no continuity.  I assume this would shut down power to the burner and needs to be replaced.  I do have continuity on the high temp shut down thermostat.  And the AC heater side thermostats seems to work fine.

Would greatly appreciate any and all comments.

Respectfully,
Mike Sulley

[Eric Maclean Co-Admin]

Mike
If you turn the thermostat to the heat position and turn up the thermostat high enough to trigger a command for heat the system will close one of the zone relays which in turn will operate that zones circulation pump with it running keep the boiler toped up the zones should fill .

The blue dot thermostat is the diesel control thermostat it is a 190*F thermostat it is intended to open and turn the diesel burner off at 190*F and close automatically when the boiler temp drops back down,If it is open at temperature below 150*F the unit is bad and should be replaced.

While your there check the high limit thermostat for continuity it should have continuity it only opens if the system overheated temperature above 230*F
Some of the older high limit thermostats had a small button on them to reset them .

If you use a jumper wire to by pass either of the two diesel thermostats only do it to test for proper operation to see the burner come to life , DO NOT operate the system with either thermostat by passed for any more than a short time as this could lead to a dangerous over heat /pressure situation.

Hope this helps
Eric

[Mike Sulley]

Hi Eric,  Thank you for your response.

I had tried turning on the diesel burner and turning up the thermostats to no avail this last week while camping.  The weather was mild and we ended up mostly using the A/C.

Today I opened up the Aqua-hot cases as stated in my first post and checked it out.  Out of curiosity, I turned on the diesel burner today and it fired right up.  Pleasant surprise.  I checked the voltages at all four control thermostats with respect to the brown ground wire and was surprised to see 12volts at all four control thermostats.   I have always left the breaker on the electric heat while it is plugged in while in storage.  So it was still hot when we arrive at the camp grounds about 30 minutes later.

I am still learning about the aqua-hot heating system every time it acts up.  In retrospect, I had turned on the 120v water heater back on as soon as we arrived at the camp grounds.  I tried to start the diesel heater an hours or so later.  I am now wondering if because the weather was so mild and the boiler tank was already heated to 190 F or so, the diesel burner never got a signal to ignite.

Would appreciate your thoughts.  And again, thanks for all your help.

Sincerely,
Mike Sulley

[Eric Maclean Co-Admin]

Mike
Your right on the electric thermostats are set at a higher temperature 198*F than the diesel thermostats 190*F and of course if the temperature is above the cut in point of the diesel thermostat say 160* or 170* the diesel won't run .
The system is set up with the 1650 watt electric element to maintain 198*F and under light loads that is enough but if you run extended showers or a moderate heat demand the electric can't keep up as the temperature in the boiler drops below the diesel cut in point the diesel burner will cut in to supplement the electric and give you an extra 50,000 BTUs of heating power .
It's ok to leave your diesel switch on all the time for this reason however I shut mine down when I travel as the coaches engine loop will heat the boiler
As well to the engines thermostat setting usually 180*F which would keep the Aquahot burner running to heat the engine.
I also shut it down when camping in close proximity to other campers so the diesel fumes don't bother anyone.

Did you manage to get boiler fluid back through all the heating zones?

Hope this helps
Eric

[Mike Sulley]

Eric ,

Thank you for this additional information.  I will change some of my storage procedures to reflect this new information.  Like turning off the electric heat breaker while in storage, utilizing the engine heat to warm the Aqua-hot tank while traveling,  and being more aware of when I really need to fire up the diesel burner.

 For the first couple years of RV ownership, I kept the coach in warm storage, but no 50 amp shore power was available.  Apparently the previous owner left the Aqua-hot burner switch in the on position.  I did notice that every time I started the coach, I would notice the smoky diesel smell of the Aqua-hot coming on.  So when the Aqua-hot started giving me problems.  I performed the yearly maintenance, but didn't know how to start up the diesel burner.  I hadn't noticed the placement of the start switch.

I think I was able to fill all the heater loops.  I used my IR thermometer to track the process of the heated fluid through each line.  So I think I am good now.

Thanks again for your help.

Respectfully,
Mike Sulley

[David Ciotti]

You could use one of those air duster cans to cool off the thermostats so the heaters will kick in and circulate the fluid through the heater cores.  If you turn the can upside down a cool blast of air/stuff comes out of the can.  You will only need a short blast (a second or two) to cool down the thermostats.