AquaHot Repair in the Cold....Of Course When Else Would It Fail
I’ve learned a lot from this forum, so would add to it my latest repair “notes”.
So, woke up a couple of days ago with temp getting low. Bottom line: AquaHot 400D burner (diesel) not igniting. Dang-it been meaning to get to that fuel nozzle. That was my first thought, but no worries as I had one ready to go. Changed out fuel filter a couple weeks ago just had not got around to tackling “that thing”...you know, the burner. Not too worried but just waiting on warmer weather. Well, now is the time and it is not getting warmer (CO).
Anyway, took off burner, changed nozzle, check the probes, cleaned the flame sensor and reinstalled. Still no ignition. Ok, now to reading the the manuals, again.
Found you could check many of the sensors with simple resistance check so did that. Discovered the Control Thermostat was bad. Sweet! Found the part at my RV store so ready to go. Read the manual on replacement process and said to drain the AquaHot system of the boiler antifreeze. Ok, back to RV store to pick up 6 gallons of the antifreeze—read somewhere that you should periodically flush that anyway, so not an issue.
Temp 20deg and wife said windchill made it 2deg...yep, feeling that.
Decided to tackle job anyway. AquaHot installed a ball valve under the removable cover (thanks for that) but did not leave tube long enough hose to get outside the bay (you guys). Back to HD to get a connection to extend hose. Ok, all good. Drained the system (about 6 gallons) and replaced the Control Thermostat. Now, to refill system. Mind you, manuals said to refill via the drain valve (Installation Manual). Now, that did not make sense and I did not have snazzy enough hand pump or connection to do that. So, I decided to use the expansion canister.
I added antifreeze up to the Full Hot line and opened (depressed) the air release valve and gravity did the rest. Repeated this process until 5.5 gallons had been added—took about 1 hour. I noted that occasionally, antifreeze would come out of the air valve, but I just waited a few minutes then continued the process until it was done—guess fluid needed time to seep in all the crevasses. Along the way noted the Low Tank Level Cutoff light went from Red to Green. Took about 1 gallon beyond that.
So lessons learned:
1) there are 3 manuals that each have good tidbits of info in them: installation, service and parts.
2) takes about 6 gallons of boiler antifreeze to replace fluid in a DX3 with a AquaHot 400D
3) easy check of thermostats should be first line of troubleshooting the system
4) get the connections you need installed ahead of time for the drain extension—you will eventually need it and it is just one more thing not to have to think about.
5) you can use combination the expansion canister and air release valve to refill the system with boiler antifreeze
There you have it...hope it helps.
2019 DX3 RB