FHP/Bosch Model & Serial Number Decoder: Identify Your Water-Source Heat Pump
Every FHP and Bosch water-source heat pump carries two identifiers on its data plate: a model number that spells out the series, size, voltage and cabinet style, and a serial number that encodes the month and year it was built. Both are readable once you know the code — no lookup software required. This guide covers FHP's original 2006-era nomenclature, which the Bosch-era model strings still follow for their first 14 characters.
Finding the data plate
The model and serial numbers are printed on the manufacturer's data plate, usually mounted on the cabinet exterior or just inside an access panel. Have both numbers in hand before you call for parts or service — the model number tells us what the unit is, and the serial number tells us how old it is.
Decoding the serial number (build date)
On FHP/Bosch units, the first letter of the serial number is the year of manufacture and the second letter is the month. The remaining characters are the unit's production sequence number and don't need decoding.
First letter — year built
Each letter was reused on a 23-year cycle, so it maps to two possible years. I, O, and Q are skipped in the sequence.
| Letter | Newer cycle | Older cycle |
|---|---|---|
| A | 1994 | 1971 |
| B | 1995 | 1972 |
| C | 1996 | 1973 |
| D | 1997 | 1974 |
| E | 1998 | 1975 |
| F | 1999 | 1976 |
| G | 2000 | 1977 |
| H | 2001 | 1978 |
| J | 2002 | 1979 |
| K | 2003 | 1980 |
| L | 2004 | 1981 |
| M | 2005 | 1982 |
| N | 2006 | 1983 |
| P | 2007 | 1984 |
| R | 2008 | 1985 |
| S | 2009 | 1986 |
| T | 2010 | 1987 |
| U | 2011 | 1988 |
| V | 2012 | 1989 |
| W | 2013 | 1990 |
| X | 2014 | 1991 |
| Y | 2015 | 1992 |
| Z | 2016 | 1993 |
Second letter — month built
| Letter | Month | Letter | Month |
|---|---|---|---|
| A | January | G | July |
| B | February | H | August |
| C | March | J | September |
| D | April | K | October |
| E | May | L | November |
| F | June | M | December |
(There's no letter I in the month code either, and September is J.)
Worked example
Serial DC0123456 breaks down as: D = 1997 or 1974, C = March — so this unit was built in March 1997 (or March 1974). The letter alone can't tell those two cycles apart; the model family is usually the tiebreaker, since most of the R-410A series in FHP's lineup didn't exist until decades after the older cycle. If it genuinely matters which decade, FHP/Bosch customer service can confirm from the full serial.
Coverage note
This decoder comes from FHP's own factory documentation and its year table runs through Z = 2016. Bosch has not published an updated version of this table for serials built after that point — if your unit is newer, treat the model number and any install paperwork as the more reliable source of age.
Decoding the model number
FHP's 2006-era model string uses up to 14 characters and follows one of two layouts depending on the product type.
Vertical, horizontal, split, and water-to-water units
Example: EM031-1VTC-FLT
| Position | Field | What it means |
|---|---|---|
| 1–2 | Series | Refrigerant + product line (see table below) |
| 3–5 | Nominal capacity | Thousands of BTU/h — divide by 12 for approximate tonnage |
| 7 | Electrical configuration | 0 = 115/1/60 · 1 = 208-230/1/60 · 2 = 277(265)/1/60 · 3 = 208-230/3/60 · 4 = 460/3/60 · 5 = 575/3/60 · 8 = 220-240/1/50 · A = 380-415/3/50 |
| 8–9 | Cabinet configuration | VT = vertical · HZ = horizontal · CF = counterflow · CS = condensing section / water-to-water · AH = horizontal air handler · AV = vertical air handler |
| 10 | Water coil | C = copper · N = cupro-nickel |
| 12 | Water connection location | F = front · S = side |
| 13 | Return air location | L = left · R = right · B = back (VT only) · F = front (VT only) |
| 14 | Supply air location | T = top · F = front · R = rear · S = straight-thru · E = end blow · B = bottom |
So EM031-1VTC-FLT reads: Energy Miser (R-22), 31,000 BTU/h nominal (~2.5 tons), 208-230V/1-phase/60Hz, vertical cabinet, copper water coil, front water connections, left return air, top supply air.
Console series
Example: CA009-1ULC-XXX
| Position | Field | What it means |
|---|---|---|
| 1–2 | Series | CA = console, R-410A slope top · CS = console, R-22 slope top |
| 3–5 | Nominal capacity | Thousands of BTU/h |
| 7 | Electrical configuration | 0 = 115/1/60 · 1 = 208-230/1/60 · 2 = 277(265)/1/60 · 8 = 220-240/1/50 |
| 8 | Control options | U = unit-mounted console controller (CUC) · R = remote thermostat · S = master/slave operation |
| 9 | Water connection | L = left · R = right |
| 10 | Water coil | C = copper · N = cupro-nickel |
What each series actually is
| Series | Trade name / refrigerant | Type & size range |
|---|---|---|
| AP | Aquarius II, R-410A | Water-to-air, 2–6 tons |
| AU | Decorative-cabinet ES variant, R-410A | Water-to-air, 2–6 tons |
| CA | Console, R-410A slope top | In-room water-source heat pump, ¾–1½ tons |
| CS | Console, R-22 slope top | In-room water-source heat pump, ¾–1½ tons |
| EC | Aquarius, R-410A | Water-to-air, ½–30 tons |
| EM | Energy Miser, R-22 | Water-to-air, ½–30 tons |
| ES | EnviroSaver, R-410A | Water-to-air, 1½–6 tons |
| EV | EnviroMiser, R-410A | Water-to-air, 1½–6 tons |
| GS | Geo-Saver, R-22 | Water-to-air geothermal, 1½–6 tons |
| GT | Geo-Thermal, R-22 | Water-to-air geothermal, ¾–6 tons |
| MB | Modular Air, R-22 | Large water-to-air, 30–60 tons |
| WP / WH | Water-to-water, R-22 | No blower or air coil — load and source water coils only, ~1½–35 tons |
| WW | Water-to-water, R-410A | No blower or air coil — load and source water coils only, 2–35 tons |
A note on newer Bosch-era models
Current Bosch-branded units (BP, CA, LM, and the rest) use a longer, 40-character model string, but the first 14 positions still follow this same FHP scheme — series, capacity, and electrical configuration read the same way. If you're working from a modern Bosch data plate, the series prefix and capacity digits above still apply.
Still not sure what you're looking at?
Send us your full model and serial number and we'll confirm the unit and pull the right parts — genuine FHP and Bosch OEM components, in stock and ready to ship.
Frequently Asked Questions
Where do I find the model and serial number on an FHP or Bosch water-source heat pump?
On the manufacturer's data plate, usually mounted on the cabinet exterior or just inside an access panel.
What does the first letter of an FHP/Bosch serial number tell me?
The year of manufacture. Each letter was reused on a 23-year cycle (I, O, and Q are skipped), so a single letter maps to two possible years — the model family is usually the tiebreaker.
What does the second letter of the serial number mean?
The month of manufacture, A through M (skipping I), following the standard month-letter table.
Do newer Bosch-branded units use the same decoder?
Yes. Current Bosch units use a longer 40-character model string, but the first 14 positions still follow this same FHP scheme for series, capacity, and electrical configuration.
How do I know which decade my unit was built in if the serial letter is ambiguous?
The letter alone can't distinguish the two 23-year cycles. Use the model family as a tiebreaker — most R-410A series didn't exist until decades after the older cycle — or contact FHP/Bosch customer service with the full serial number.
What's the highest year covered by this serial number decoder?
This decoder comes from FHP's own factory documentation and its year table runs through Z = 2016. Bosch hasn't published an updated table for serials built after that point, so for newer units treat the model number and install paperwork as the more reliable source of age.
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