A blow-out plug is a short adapter with a Schrader air valve on one end and a male garden hose thread on the other, and it threads into the coach's city water inlet in place of the water hose. Air entering there follows the exact path municipal water takes: past the inlet's one-way check valve, into the cold manifold, out along the PEX runs to every fixture, and finally out of whichever tap is open. That is the entire mechanism, and it is why the inlet is the only correct entry point for air. Feeding the compressor into the gravity fill or the pump outlet drives air backwards through parts built to pass flow one way, and the check valve inside a SHURflo pump head will simply refuse it. The hardware list is short: a compressor with a working regulator and gauge, a quarter inch quick-connect coupler, and the plug. Everything that goes wrong on this job is pressure and order, not parts.
The limit is a component rating, not a rule of thumb, and it belongs to whichever part in the loop gives up first. Pentair's technical data sheet for the SHURflo Revolution 4008 lists inlet pressure as 30 PSI maximum, with the pressure switch shutting off at 55 psi and restarting at 40 psi. Suburban sits far above that: the relief valve on its Nautilus tankless heater is built to open at 145 PSI or 210 degrees, and cross-linked polyethylene tubing is rated well beyond anything a regulator will pass, so neither the pipe nor the tank is the limiting part. Truma goes the other way and states plainly that it does not recommend high-pressure air when winterizing the AquaGo. Manufacturers genuinely disagree here, and when they disagree the lowest published figure has to win, because the weakest component decides what the system tolerates. Set the regulator to 30 psi and the whole argument goes away.
A compressor tank sitting at 120 or 150 psi is not a setting, it is storage, and the regulator is the only thing standing between that stored pressure and a half inch PEX crimp. Hook a bare hose to a blow-out plug and the first thing that yields is usually a fitting the coach builder put somewhere unreachable, behind a shower surround or above a slide floor. The second is a toilet water valve, because a pedal-operated valve on a Thetford Aqua-Magic or a Dometic bowl seals against water pressure and its diaphragm was never asked to hold dry air at four times the system's working range. A pump pressure switch can be knocked out of calibration the same way. None of those parts are expensive on their own. The cost is that a weeping crimp behind a wall does not announce itself until the panel below it is soft, which is why the regulator is not optional equipment on this job.
The call almost always arrives in spring, phrased as water on the floor the first time the pump is switched on, or a hiss behind a wall that stops when the pump cuts out. The check order starts at the cheapest end: pressurize to 30 psi with the pump off and listen, then isolate the hot side at the water heater bypass valves to see whether the leak follows hot or cold. Next comes the toilet valve and the shower mixer, then the low point drains, then the pump head itself, because a switch that will not cut off mimics a leak convincingly. Left through a summer, a seeping fitting stops being a plumbing repair and becomes a floor.
Order matters more than technique. Drain the fresh tank and open both low point drains first, then close the heater off at its bypass valves and drain the tank separately by pulling the anode rod with a 1-1/16 inch socket, which is the method Suburban publishes in its own operation guide. A six gallon tank will not empty through a half inch line on air, and blowing through it only pushes hot side water back into the cold manifold. With the pump switched off, set the regulator to 30 psi and open one fixture at a time, starting with the one furthest from the inlet and working back: cold then hot at each, then the toilet, the outside shower, the ice maker line and any washer inlet. Run the whole circuit a second time, because water that clung to a horizontal run releases on the second pass and the first pass alone leaves it there.
For most Florida coaches the point of a blowout has nothing to do with ice. A snowbird rig parked from April to November holds warm standing water in dead legs the whole time, and warm wet plumbing is where biofilm establishes itself and where the rotten egg smell owners report in November comes from. Dry lines grow nothing, which is why emptying the system beats leaving it full even in Fort Myers. Freeze is a real second reason north of the peninsula: Tallahassee, Pensacola and the western panhandle drop below freezing every winter, the January 2025 Gulf Coast snowstorm put measurable snow on the ground there, and hard freezes reach inland as far south as the Gainesville and Ocala corridor. Owners heading north in March meet the same problem in Georgia and the Carolinas before they arrive.
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Call 888-759-1438Thirty psi. That figure is not a convention, it is the lowest published component rating in the loop: Pentair's data sheet for the SHURflo Revolution 4008 gives inlet pressure as 30 PSI maximum. Pipe and heater tanks tolerate far more, so quoting their ratings is misleading. The weakest part decides, and on almost every coach built in the last twenty years that part is the fresh water pump.
Not directly. Tank pressure is storage, and what reaches the coach is whatever the regulator passes, so the compressor rating is irrelevant as long as an adjustable regulator and a working gauge sit between the tank and the blow-out plug. A compressor with no regulator, or with a gauge that reads tank pressure rather than line pressure, is the setup that splits a crimp fitting behind a wall.
Yes, and you also have to drain it separately. Suburban's operation guide has owners close the heater off at its bypass kit and empty the tank by removing the anode rod with a 1-1/16 inch socket. Air will not move six gallons out through a half inch line, so a heater left in circuit stays full and quietly feeds water back into the cold side as soon as the air stops.
No, and we will not do it. Truma's own winterizing guidance says it does not recommend high-pressure air or antifreeze solutions on the AquaGo, and directs owners to the unit's drain sequence instead. The AquaGo is a heat exchanger rather than a tank, with a water operating pressure of 65 psi and internal passages that do not empty the way a straight PEX run does. Manufacturer procedure wins over habit.
For anything that holds water by design, yes. Air cannot clear a P-trap under the galley, lavatory or shower, and it will not empty the toilet bowl seal or the charge sitting behind the flush valve. The usual right answer is both methods: blow the supply lines dry, then pour non-toxic antifreeze into each trap and the bowl. That is a separate job from filling the whole system.
Usually yes, for water quality rather than freeze protection. A system sitting full and warm through a Florida summer is an ideal place for biofilm, and that is what the sulfur smell after storage generally is. Freeze matters too north of the peninsula, where the panhandle and north Florida see hard freezes every winter and an unprepared coach can split a line overnight.
Every figure on this page comes from a manufacturer document or a standards body, not from another repair site. Here is where each one comes from.
| Item | Price | What it covers |
|---|---|---|
| Service call | $299 | Includes the trip out to your RV and the first hour on site |
| Work past the first hour | Quoted after diagnosis | We tell you what it will take before we carry on |
| Parts | Quoted per job | Special-order parts may need a deposit before we order them |
| Written estimate | No charge | You approve the estimate before any work starts |
The service call covers the trip out to your RV and the first hour on site. Anything beyond that depends on what we find, and we quote it and get your approval before carrying on.
The price ranges on this page come from our own recent jobs across Florida, not from an industry average. What you pay depends on the rig, the parts it needs and what we find on site, so we give you a written estimate before any work begins and you approve it first.