Pentair UltraTemp Heat Pump

The UltraTemp is Pentair's heat pump for pools and spas. Pentair currently lists seven models, from the 110 to the 140C, including three that heat and cool and a quieter 120Q. All of them have a titanium heat exchanger, 2 in. plumbing, and dual thermostats for a pool and a spa. The manual says to expect about 1°F an hour from a properly sized unit, and that heat pumps are meant to hold a temperature, not to heat fast like a gas heater.

Every current UltraTemp is a TradeGrade product, sold through dealers, pool builders and service companies. That decides the warranty: two years, ten on the compressor and a lifetime on the heat exchanger, from a dealer and professionally installed. Bought online, it's far less.

What the rating becomes in cooler air

Pentair rates every UltraTemp three ways: at 80°F air and 80% humidity, at 80°F air and 63% humidity, and at 50°F air. The water is 80°F in all three. The 50°F figure is the one to size on for spring and fall, and it's 61 to 64 percent of the headline number on the current models, always at a COP of 4.0.

• UltraTemp 110: 110,000 BTU/hr, falling to 70,000 at 50°F
• 120 H/C: 125,000, falling to 80,000
• 120Q: 127,000, falling to 80,000
• 140: 145,000, falling to 90,000
• 140 H/C: 140,000, falling to 85,000
• 140 H/C Active Defrost: 138,000, falling to 84,000
• 140C: 140,000, falling to 85,000

The heat/cool models rate slightly below their heat-only counterparts, and the brochure gives the 120 H/C and 140 H/C 71,000 BTU/hr of cooling at COP 4.1.

The manual's tables also cover the 70, 90 and three-phase 120C, which aren't on Pentair's current list; the 70 and 90 keep 67 percent at 50°F. Its specification table has a plain 120, with exactly the ratings the brochure gives the 120Q, while its parts list names only the 120Q.

Defrost, and the Low Ambient Temp alarm

Around 50°F air, the UltraTemp may need to defrost, and only if Defrost is enabled in the service menu. The manual describes a passive cycle. When the refrigerant sensor reads below the defrost point, the compressor stops and the fan keeps drawing air over the coil for about 15 minutes. If the refrigerant warms enough, the compressor restarts. If it doesn't, the unit shuts down with a LOW AMBIENT TEMP alarm.

That alarm isn't a fault. The manual's fix is to wait for the ice to melt or the air to warm. Ice building up on the coil is a different matter. The manual's causes include Defrost being disabled, blocked air flow, sprinklers and low refrigerant, and its advice is to shut the unit off and let the ice thaw.

Pentair also sells a 140 H/C Active Defrost, 462032. Its name is the only description Pentair gives: the manual doesn't cover it and the brochure only lists its ratings.

AutoSet is gone from newer units

Pentair's product page still calls AutoSet a standard feature. It lets the heat pump start the filter pump 1 to 4 hours after the time clock shuts it off, check the water temperature, and heat if needed, repeating until the clock runs the pump again. The manual and the kit's own instructions say heat pumps built after May 9, 2022 don't have it. The AutoSet accessory kit, 473603z, adds the contactor back. The kit is also what Extend needs, the feature that restarts the pump to finish a heating cycle the time clock cut short.

Flow and plumbing

• Flow: at least 30 gpm. A built-in flow control valve handles up to 120 gpm. Above that, or with a pump over 2 HP, add a manual bypass valve, because the manual says excess flow will damage the heat exchanger.
• More than one heat pump: plumb them in parallel, with 30 to 100 gpm each. A gas heater or solar goes in series.
• Pressure: 50 psi maximum working pressure.
• Connections: 2 in. PVC unions come with the heat pump. Cool water goes in on the right, heated water comes out on the left.
• Condensate: thread the included hose barb into the drain outlet in the base before first start, and run a 5/8 in. garden hose away from the pad. Expect 3 to 5 gallons an hour while it runs.

The water pressure switch is set at 1.5 psi at the factory. The manual says to adjust it only if the heat pump won't run with good flow or won't stop when the pump does. Adjustment may be needed if filter piping runs 3 ft or more above the top of the heat pump. If the heat pump sits more than 6 ft below the pool surface, the manual calls for an external flow switch. A very short return run can give too little back pressure. Its fix is a directional fitting or elbow where the return enters the pool, then a check that flow is still above 30 gpm.

Where it can go

• Outdoors only, on a flat pad pitched no more than 1/4 in. per foot, and if possible level with or slightly above the filter pad.
• Clearances: 24 in. at the front, 12 in. on the other sides, and 5 ft above it if it's under a cover or overhang.
• From the pool: at least 5 ft from the inside wall, unless a 5 ft solid fence or other permanent barrier is between them. Canada requires 3 m.
• From the house: at least 6 in.
• Sprinklers: keep them off the unit. The manual says they can void the warranty, and well water sprayed on the coil leaves mineral buildup.
• Roofs: don't put it where a roof without gutters sheds water onto it.
• Anchor clamps: recommended everywhere, and required in Florida under Florida Building Code 301.13. The bolts and concrete anchors aren't included.

The electrical side

The single-phase models run on 208 to 230 V. The 110 through the 140 H/C want a minimum circuit ampacity of 42 or 43 A, a 50 A recommended fuse and 70 A at most. The 120C and 140C are three phase. The manual says voltage below 208 V may damage the heat pump and void the warranty. Wiring goes through watertight conduit to the compressor contactor, with a disconnect in sight of the unit. The bonding lug on the left side takes 8 AWG solid copper, or 6 AWG in Canada.

Automation: an IntelliTouch or EasyTouch on software 1.11 or later can run the heat pump over RS-485, using the optional four-wire cable, 520199. Any other system connects by relay to the pool, spa and common spade terminals on the back of the control board. Either way, the heat pump won't heat above 104°F or cool below 45°F.

Alarms on the display

The manual's alarm list, with what each one means:

• HIGH WATER TEMP: water above 107°F
• LOW WATER TEMP: water below 40°F
• LOW WATER FLOW: the water pressure switch is open
• REMOTE POOL/SPA: the pool and spa remote inputs are both on at once
• WATER THERM SHORT or OPEN: the water temperature thermistor circuit
• SUCTION TH SHORT or OPEN: the defrost thermistor circuit
• LOW AMBIENT TEMP: too cold to run, or a defrost that didn't finish
• BROWNOUT: low 24 V supply to the control board
• HIGH REFRIG: the high pressure switch is open
• LOW REFRIG: the low pressure switch is open
• SERIAL COMM LOST: no message from the automation system for 2 minutes
• FIVE ALARMS: five faults within an hour. It resets itself after an hour, or at the ON/OFF button

The timers are worth knowing before calling anyone. After water starts flowing there's a 1-minute sensing delay. After that the fan starts, and the compressor waits another 5 minutes. A compressor that isn't running in the first six minutes is working as designed.

Water chemistry

The manual's table: pH 7.4 to 7.6, calcium hardness 200 to 400 ppm, cyanuric acid 30 to 50 ppm, total dissolved solids under 2,000 ppm, and no copper. Total alkalinity is 80 to 100 ppm with calcium, lithium or sodium hypochlorite, and 100 to 120 ppm with dichlor, trichlor, chlorine gas or bromine. The manual says poor water chemistry may damage the heat pump and void the warranty.

The table has no line for salt. Salt pools run their salt alone above 2,000 ppm of dissolved solids: Pentair's own IntelliChlor manual asks for 3,600 ppm. Neither document says how the two fit together, so ask Pentair before relying on the warranty in a salt pool.

Winterizing and upkeep

Winterizing: turn off the power at the breaker, shut off the water, and disconnect both unions so the heat pump drains completely. Cover only the top. The manual says not to wrap the sides in anything that holds heat or moisture. It also says failing to winterize properly voids the warranty. In spring, reconnect the unions and bleed the air out at the filter. Check for leaks before turning the power back on.

Every year: clean the air coil with a garden hose without bending the fins, and never with a pressure washer. Keep plants trimmed back and the top clear. Pentair wants a professional service once a year.

A leak test: if water keeps draining from the base more than an hour after the heat pump stops, or it drains more than 3 to 5 gallons an hour while running, the manual suspects an internal plumbing leak. Condensate has no chlorine in it, so test the water.

Parts

Pentair publishes two UltraTemp parts lists, and they don't agree.

The manual's list, on pages 32 and 33 of the 2023 installation guide, is the newer one. It's the one this page follows. It covers the current models, including the 120Q, and the LG compressor kits Pentair uses now. Its French and Spanish versions carry the same part numbers.

The separate parts list is two pages from Pentair's parts catalog, and older by its file dates. It lists Emerson compressors, the heat exchangers and straps for units built before January 2017, and a contactor and main harness for units built before December 2014. Its header lists the item numbers it covers, and those don't include the 120Q or the Active Defrost model. It also covers 50 Hz units and the 90I and 100I. None of those are in the manual's specification table, so their parts are left out of the list below.

For a unit built from 2017 on, start with the manual's numbers. For an older one, the separate list has the heat exchanger and straps it needs. Pentair's compressor conversion kit instructions cover replacing an Emerson compressor with an LG one, but they give no kit number. Neither list covers the 140 H/C Active Defrost.

The two lists disagree on these parts:

• Expansion valve for the 110: 473787 in the manual, 473999 in the older list
• Compressor isolation kit: 476232z against 473736
• Compressor blanket: 475230 against 475231Z
• Union O-ring: 355330 against 071426
• Black pan head screw: 470198 against 474198
• Item 26 screws: square drive, 475263 and 475264, against Torx, 470161 and 474197
• Harness 473732: three phase in the manual, single phase in the older list
• Bolt 473745: 1.75 in. in the manual, 2 in. in the older list

The manual's troubleshooting table also names an expansion valve head, KT-45-ZGA, for a stuck valve whose head rattles, though it isn't in either list.

Where Pentair's documents disagree

• AutoSet. The product page calls it standard. The manual and the kit instructions say units built after May 9, 2022 don't have it.
• Online purchases. The warranty page gives one year, parts only. The UltraTemp product page says a TradeGrade product sold online gets 60 days.
• High water temperature. The alarm list sets HIGH WATER TEMP at 107°F. The troubleshooting table says 108°F.
• Cleaning the coil. The same paragraph tells you to flush the coil with compressed air, then says compressed air can damage it.
• Height. The manual's drawing gives 45.5 in. for the 110 through 140C. The brochure gives 44.5 in., and 48.2 in. for the 120Q.
• The 120 and the 120Q. The manual's specification and dimension tables list a 120. Its parts list names the 120Q, and so do the brochure and the product page.
• A conversion. The manual gives about 1°F an hour as "(-17°C)". A 1°F rise is about 0.6°C; −17°C is the temperature 1°F.

Buying it

Buy an UltraTemp from a Pentair dealer and have it professionally installed, or the warranty shrinks to a year, parts only. Keep the installation paperwork: the warranty runs from the installation date, and the control board keeps warranty hours and cycle counts that can't be reset. If you're also replacing the pump and filter, buying all three from one dealer on one invoice, and registering with the bill of sale, can qualify for Pentair's three-year bundle warranty.

For how the UltraTemp compares with gas, see pool heater types compared. If one has stopped heating, pool heater not heating walks through the checks before any of these parts.