Water Source Heat Pump

water source heat pump

water source heat pump
Geothermal heating, cooling gaining popularity
The technique uses water warmed in sunken tubes to create the source for heat. That heat, intensified by a condenser in a furnace-like unit, can provide forced-air heat, Radiant floor heating and even heat hot water.
What is the correct wiring for this thermostat?

Current thermostat doesn’t have letters, only numbers, so I’m having difficulty mapping the wires to fit the new Hunter 44550 thermostat. Thanks for any help you can provide! What I think the wires are, is in parenthesis.

Current wiring to a Peco TA158 Thermostat; numbers are on the unit, colors are the wires in the wall connected to the numbers posts.
Top Row
10 – Orange
11 – Empty
12 – Yellow
13 – Empty
14 – Black wired to Slot 1

Bottom Row
7 – Empty
6 – Red
5 – Brown
4 – Gray
3 – Purple
2 – Empty
1 – Black wired to Slot 14

New wiring posts in Hunter 44550 is:
RH –
RC –
G –
Y/Y1 –
W –
O/B –

HVAC unit is a Climatemaster Model No. VHS816 – Vertical Stack, Water Source Heat Pumps. In a condo, it’s both the heat and AC.

New thermostat is a Hunter 44550.


I’d rather you read from a site so here is a couple:

{Terminal name}, {color}, {function}
(R), Red, hot side of transformer.
(C) Common side of transformer (See B)
(Y), Yellow, Compressor activity (cooling or cooling and heating on a heat pump).
(W), (W1), (W2) White, “Heat” (gas burner, oil burner , electric heat, (auxiliary heat on a heat pump including defrost output from the outdoor unit to activate electric heat and turn on the AUX. heat lamp). Note: some thermostats require a jumper from “W” to “Y” for heat pump operation.
(G), Green, furnace blower fan. (needed for air conditioning, heat pumps and some electric furnaces). NOTE: on most thermostats the “G” and “Y” are connected together at all times when the fan switch is in the “Auto” mode!
(O), Orange , Energize to cool (used for reversing valve on heat pumps)
(B), Blue or Orange, Energize to heat (used on some systems, Rheem/Ruud is notorious for this).
(B) or (X), Blue, brown or Black, common side of transformer. Needed on some electronic thermostats or if you have indicator lamps. Do not confuse with (B) Reversing valve (energize to heat) above. York and Trane like to use (B) as common.
(E), blue, pink, gray or tan, emergency heat relay on a heat pump. Active all the time when selected, usually not used.
(T), Tan or Gray, outdoor anticipator reset.
Used on GE/Trane/American Standard and some Carrier Products.
(W2), Pink or other color, second stage of heat (may be same as (W) on heat pump or fossil fuel system).
(Y2), Blue or Pink, second compressor stage.
(L), Blue, brown, tan or gray service indicator lamp.
Numbers, see manufacture’s diagrams but can be stages of electric heat especially on York/Borg Warner/Coleman-Evcon, Frasier Johnson/ Air-pro.
(X2), Second stage of Electric Heat on GE/Trane/American Standard. See link above. Also used as indicator lamp or misc. contacts on other systems.


Hope this helps you out.

Trane’s Axiom Water Source Heat Pumps