Raypak 206A / 266A / 336A / 406A Digital Heater: Diagnostic Order and the Parts That Actually Wear

The Raypak Digital atmospheric series — 206A, 266A, 336A and 406A, sold in copper (C suffix) and cupro-nickel (X suffix) exchanger versions — is probably the most common gas pool heater on American equipment pads. It is also one of the most forgiving to diagnose, because the digital control tells you which circuit interrupted the sequence. What it does not tell you is why, and that gap is where parts get replaced for no reason.

This guide walks the heater in the order the controller itself walks it: power, water, call for heat, ignition, combustion, heat transfer. Along the way it separates the components that wear and can be replaced aftermarket — the tube bundle, the Unitherm governor and bypass, headers, refractory, stack — from the gas-train and safety components that must come from Raypak. The 207A/267A/337A/407A low-NOx siblings share almost everything below except the blower and its air switch; where they differ, it is called out.

What the display is telling you

On a call for heat the Digital control proves water flow, then runs the ignition module through trial for ignition, then monitors two high-limit switches and a rollout fuse while it fires. A fault interrupts that chain and the display shows a short code. Read the code as a side of the heater, not a shopping list.

Set points and time windows are as published in Raypak's service literature; treat the numbers as design intent rather than something to measure to the degree.

Two codes deserve a warning up front. ROL means combustion products came out where they should not — a blocked exchanger, collapsed refractory or a vent problem — and the heater has shut itself down to protect the cabinet and everything around it. It is not a nuisance trip. Find the cause before pressing anything. And HL1/HL2 are almost never the switches. They are the heater telling you that heat is being made faster than water is carrying it away, and the answer is on the water side.

Prep and safety

Power off at the breaker — not just at the heater's switch — and close the manual gas cock upstream. Let the heater cool before opening the jacket; after a high-limit or rollout event the exchanger, headers and stack are hot for a long time. If the heater sits below pool level, isolate it before pulling any drain plug or the return header.

Then do the two-minute pad check before opening anything: pump running and primed, filter pressure against its clean baseline, heater-loop valves fully open, variable-speed pump schedule high enough to deliver the heater's minimum flow during heat calls, water level above the skimmer throat. The controller only knows the pressure switch is open. It cannot tell a dirty filter from a failed switch, and it will report both as PRS.

Power and controls

Verify supply voltage at the heater's terminal block and the transformer output before chasing any downstream fault; a heater fed from a tired GFCI or an undersized run will throw intermittent board and ignition faults that look like component failures. If the display is dead, dim, or the buttons need two presses, the membrane pad and the board are the suspects — both OEM parts. The switch decal membrane 009492F for the 206A–406A and R185B–R405B series is the exception: it is the printed overlay, not the electronics, and can be renewed when the legends have worn off or the surface is cracked and letting water in.

Two small items in this area are ordinary aftermarket parts: the rocker switch 009493F and the poolstat cover and lock 009505 that keeps the controls out of the weather and away from curious hands.

Water side: PRS, HL1 and HL2

PRS — pressure switch open. The switch closes when inlet pressure proves the pump is pushing water through the exchanger. Check in order: pump running, filter pressure, valves, baskets, water level. If the heater sits well above the pool, the switch may need its setting confirmed against the manual rather than replaced. Only after every flow cause is eliminated does the switch itself — an OEM part — come under suspicion.

HL1 / HL2 — high limit. Same starting point: flow. If flow is verified, move inside the heater. On this platform there are three internal reasons water stops carrying heat away at the rate the burner is making it, and all three are aftermarket work.

The Unitherm governor. This wax-element valve sits in the inlet/outlet header and holds the exchanger at operating temperature by recirculating part of the flow until the water warms up. Its job is to stop cold pool water hitting hot copper — which condenses flue gas on the fins, soots the exchanger and eats the tubes. When the governor sticks, the exchanger either never comes up to temperature (sooting, condensate dripping out of the stack) or is starved of flow at the wrong moment (high-limit trips on a pool with perfect flow everywhere else). It is the first internal suspect on any repeat HL1/HL2. The 006719F governor fits the 206A through 406A and the 207A–407A low-NOx units as well as the R185A–R405B series; the 006720F governor plug seals its port in the header.

The internal bypass. Working alongside the governor, the bypass balances how much of the pump's flow goes through the tubes and how much goes straight to the outlet. A bypass that has eroded or stuck open lets too little water through the exchanger and the limits trip; stuck closed and the tubes see the full pump flow, which erodes the copper. The 006715F Capron bypass kit covers the 206A–406A and the R-series; 062235B is the bypass valve for the 206A and 266A atmospheric units.

The headers. The polymer return header 006707F (supplied with gaskets, for the 206A–406A and R185A–R405A) and the header baffle kit 006826F are where scale and flow damage show up first: a warped header face, a baffle that has broken free and is rattling in the water passage, a gasket that weeps at the joint. If the header is off for any other reason, replace the gasket set rather than reusing it — the 006713F o-ring gasket fits the 206A, 266A and 336A and the R185A–R405A.

Ignition: IGN

IGN means the ignition control ran its trial for ignition and did not prove flame; after repeated attempts it goes to hard lockout. Work from the outside in: gas supply pressure at the valve under load (a supply that reads fine static and sags when the burners light is a classic), pilot or igniter operation on a call for heat, flame-sense wire and ground clean and tight, ignition module output present. Every one of those parts — gas valve, pilot assembly, igniter, ignition module, flame sensor — sits inside the appliance's gas train and certification boundary, and we do not manufacture or supply them. If the diagnosis lands there, the part comes from Raypak. The one item near the pilot that is ours is the 306692 pilot mounting bracket, a piece of formed steel that holds the pilot at the correct position relative to the burners on the IID units; it bends, corrodes and gets lost, and replacing it does not change how the heater lights.

Combustion and rollout: ROL

A rollout trip says flame or hot gas came back out of the combustion chamber instead of going up through the exchanger. The causes are physical, and you can see them with the top off: fins bridged with soot or scale so gas cannot pass, refractory panels cracked, crumbling or fallen into the burner tray, a bird's nest or a collapsed stack. On the atmospheric units a strong downdraft at the stack top can also roll flame; on the low-NOx 207A–407A a blower that has lost speed does the same thing and usually shows FAN first.

Refractory is a normal wear item and aftermarket work. The 010088F left and right refractory panels and the 010089F tile set cover the 206A, 266A, 336A and 406A; the front and rear sets are per model — 010090F for the 266A, 010092F for the 406A — and 010079F is the refractory retainer kit for the 207A–337A low-NOx units. Handle new refractory with gloves and do not let it get wet before installation.

The stack top is the other combustion-side wear part. Outdoor stack tops rust through, get crushed, or are simply missing when the heater arrives on your route; size by model — 009834 6-inch for the 206, 009835 7-inch for the 266, 009836 8-inch for the 336, 009837 9-inch for the 406 — and 009838 is the 6-inch indoor top for the 206 and 207. The thermal fuse and rollout switch themselves are safety devices and stay OEM.

On the low-NOx siblings, the 010042F combination air blower kit for the 207A–407A is a normal aftermarket part: a blower that will not start or has a rough bearing is a motor replacement, not a gas-train repair.

Heat transfer: the tube bundle

Everything above eventually leads here. The finned copper tube bundle is the part that wears out a Raypak, and it wears in three recognisable ways:

• Scale inside the tubes in hard water. The tube wall runs hot because the water is insulated from it; you get HL1/HL2 on a heater with good flow, and the fins look clean.
• Erosion and pinholes from low pH, high sanitizer, or excessive flow past a failed bypass. The exchanger drips inside the cabinet, the refractory below it goes soft, and eventually water runs out of the burner tray.
• Sooted, condensate-damaged fins from running cold — a stuck governor, a pump that only runs at low speed, or a heater used for short spa calls in winter. The fins are black or green and bridged; the heater is slow and throws rollout codes.

A lightly scaled bundle can sometimes be acid-flushed once. A bundle that is pitted, leaking, or has lost fin area is a replacement, and the replacement must match the original in three ways: model, header type, and material. Copper (C suffix) and cupro-nickel (X suffix) bundles are not interchangeable, and Raypak changed header designs during the run of these models — check the data plate and the manufacture date before ordering. The bundles we make for this family:

When the bundle comes out, the water chemistry or flow condition that killed it has almost certainly damaged the governor and bypass as well. Replace the governor and inspect the bypass at the same time — putting a new bundle behind a stuck governor is how you get called back in a year for the same leak. Renew the 006721F drain plug and the 005264F rear drain plug and cover while the exchanger is out; both are cheap, both are brittle by the time you meet them.

What is aftermarket work and what is OEM-only

We wrote a longer piece on why gas-train and safety components should stay with the equipment brand. For this heater the line falls here.

OEM-only: gas valve, pilot assembly and pilot tubing, igniter and ignition module, flame sensor, both high-limit switches, the rollout switch and thermal fuse, the water pressure switch, the water thermistor, the low-NOx air pressure switch, the control board and its membrane keypad electronics, and the ASME pressure relief valve. Every one of these either meters gas, proves flame, or exists to shut the heater down when something has gone wrong, and its failure mode is part of the appliance certification.

Aftermarket work: tube bundles, the Unitherm governor and its plug, bypass kits and valves, headers, baffles and header gaskets, refractory panels, tiles and retainers, stack tops, drain plugs and covers, the combustion blower on low-NOx units, and the cabinet and control-side hardware — switch decal membrane, rocker switch, poolstat cover and lock, jacket top 010048F, tie-down bracket 11636, sensor wells 006805F and their retaining clip 300203, the sensor adapter 006714F, and the pilot mounting bracket. These are sealing, structural and flow components. They scale, they corrode, they crack, and replacing them does not alter how the heater proves flame or shuts itself down.

That split is also where the economics of the repair sit. Switches, sensors and igniters are inexpensive OEM items a truck carries a few of. The tube bundle, governor and refractory are what decide whether a twelve-year-old 406A is worth saving, and where an aftermarket price turns "replace the heater" into a one-visit repair.

Cross-reference table

Where a Raypak number differs from ours, it is listed; most parts in this family carry the Raypak number itself.

The complete list of parts that fit each model is on the Raypak 206A, 266A, 336A and 406A model pages, with the low-NOx 207A and the R406A alongside.

Sourcing

POOLPOINT manufactures the tube bundles, governors, bypass kits, headers, refractory, stack tops and cabinet hardware above factory direct for US distributors, service companies and online sellers. MOQ starts at 50 pieces per SKU, mixed cartons are accepted to reach it, and private label is available. We do not supply gas-train, ignition or safety components for any heater, and will say so if asked. Request a quote for wholesale pricing on the parts we do make.