# AquaHot and Hydronic Heat Service: Cost, Hours and Process in Hacienda Heights AquaHot and hydronic heat service covers the boiler based systems found in diesel coaches, which provide both interior heat and domestic hot water from one heated glycol loop. Failures concentrate in the diesel burner, the circulation pumps, the electric elements and the glycol itself, which has a finite service life. ## Specifications - Price band: $750 to $8,500 - Shop hours: 3 to 35 hours - Turnaround tier: Systems and electrical - Insurance billable: no - Parts lead time: Burner nozzles, igniters and pumps 7 to 20 business days. Burner assemblies and heat exchangers 15 to 35 business days. - OEM brands: AquaHot, Aqua-Hot, Oasis, Webasto, Truma ## How hydronic differs from everything else in the coach A hydronic system heats a glycol and water mixture in a small boiler and circulates it through heat exchangers: fan coils in the living areas, a coil for domestic hot water, and on many coaches a loop to the engine block for preheating. One heat source, several loads, and a set of circulation pumps and zone valves in between. That architecture is why the symptoms are diagnostically useful. Hot water without interior heat means the boiler is working and a zone pump or valve is not. No hot water and no heat means the heat source is the problem. One cold zone means one circuit. You can narrow it substantially before opening anything. It is also why these systems reward a technician who understands them and punish one who does not. A coach with an AquaHot or an Oasis has a genuinely different heating system from a coach with a Suburban furnace, and a shop that treats them as interchangeable will change the wrong parts. - Diesel burner: nozzle, electrode, igniter, fuel pump and photocell - 120 volt electric elements, which many owners run exclusively at a park - Circulation pumps, one per zone on most configurations - Zone valves and their actuators - Domestic hot water heat exchanger, which scales over time - Glycol condition and level in the expansion tank ## The glycol nobody thinks about The glycol mixture is a consumable. It carries corrosion inhibitors that deplete, and once they are gone the mixture turns acidic and starts working on the aluminum and copper inside the system. Dark, sludgy glycol is not cosmetic. It is the fluid actively damaging the heat exchangers it is supposed to protect. Manufacturers specify a change interval, generally in the two to five year range depending on the system and the fluid. In practice, most coaches that arrive here have never had it changed, and a fair number have had plain automotive coolant added at some point, which is not the same fluid and does not behave the same way. So the first thing we do on a hydronic complaint is test the fluid. It is cheap, it is fast, and it frequently explains a slow decline in performance that the owner has been attributing to age. A flush and refill with the correct fluid is modest work and it protects a very expensive assembly. ## Burner lockouts, cost and hours A diesel burner that locks out is a safety control doing its job: it attempted ignition, the photocell did not confirm flame, and it stopped rather than continuing to spray fuel. Repeated lockouts trace to a fouled or worn nozzle, a dirty photocell lens, a degraded electrode gap, air in the fuel line, or a fuel pump losing pressure. Burner service is the routine work on these systems and it is what keeps them reliable. Nozzle, electrode, photocell cleaning and a combustion check with instrumentation, which is exactly why this is bay work rather than something to attempt with hand tools in a storage yard. The band on this page reflects a burner service at the low end and a heat exchanger or major component replacement at the top. Labor is 3 to 35 hours at the posted mechanical and electrical rate of $260 per hour, diagnosis is the in depth diagnostic tier at one hour and $285 credited against an authorized repair, and parts lead times are long: 7 to 20 business days for burner parts and pumps, 15 to 35 for burner assemblies and heat exchangers. Plan around that rather than being surprised by it. ## Not included - Chassis engine work is outside scope even where the hydronic loop is plumbed to the engine preheat circuit. - We do not service hydronic systems at a customer location. Burner setup requires shop instrumentation. - Seasonal readiness checks on a working system belong to our maintenance program. ## Questions **I have hot water but no heat. What does that tell you?** That the boiler is producing heat and the distribution side is not moving it. On a hydronic system the domestic hot water coil and the interior fan coils are separate loads on the same heated loop, so working hot water eliminates the burner and the elements and points at a circulation pump, a zone valve or the zone wiring. That narrows the job considerably before anything comes apart. **How often does AquaHot glycol need to be changed?** Manufacturers generally specify somewhere in the two to five year range depending on the system and the fluid. Most coaches that arrive here have never had it done. This matters because the inhibitors deplete and the mixture turns acidic, at which point the fluid is attacking the aluminum and copper it exists to protect. We test the fluid first on any hydronic complaint. **Why does my diesel burner keep locking out?** The control attempted ignition, the photocell did not confirm flame, and it shut down rather than continuing to spray fuel. Common causes are a worn or fouled nozzle, a dirty photocell lens, a degraded electrode gap, air in the fuel line, or a fuel pump losing pressure. Burner service with a combustion check addresses all of it and is the routine work on these systems. **Can I just run the electric elements and skip the burner?** Many owners do at a park, and it works for domestic hot water and light heating load. The elements cannot match the burner's output in genuinely cold weather, and a burner left unused for years develops exactly the problems that make it unreliable when you finally need it. Running it periodically is worth more than it costs. --- Source: https://ocrv.club/rv-service/aquahot-and-hydronic-heat-service OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887 Phone (949) 799-3387. Email info@ocrvcenter.com. Serving Hacienda Heights and the surrounding area. 18.4 miles, 24 to 38 minutes via SR-60 west to Fullerton Rd, then south to La Palma Ave. In shop work only. All estimates are priced and credited against an authorized repair.