Replacement Power Head for Taco 556-G2/G3, 557-G2/G3 and 5101-G2/G3 Geothermal Valves


Brand: Taco

Mfr Part#: 555-173RP

Availability: In Stock
Usually ships: within 1 business day
Qty Price
$77.95 / each
  • Description
  • Literature
  • Reviews (8)
  • FAQs

Taco 555-173RP is a Replacement power head for Taco Geothermal Series zone valves.

Taco 555-173RP is specially designed for high head, open system zone control. The unique end switch design permits control of the heat pump by the valve allowing movement of cold water into the coil before the heat pump starts. Reliable built-in Heat Motor, wax filled element and microprocessor-based actuator tab provide unmatched flow control and improve comfort and energy efficiency. Taco 555-173RP boasts both quiet and dependable operation. Manual open lever with twist-off head makes installation easy.


  • Power Head for Geothermal Zone Valves;
  • Easy twist-off design;
  • For Taco Zone Valves 556-G2, 557-G2, & 5101-G2;

Technical Specifications:

  • Parts Used With: Taco Zone Valves 556-G2, 557-G2, & 5101-G;
  • Application: Heating;
  • Voltage: 24v;
  • Depth: 2";
  • Max PSI: 125;
  • Wiring: 2 Wire Terminal Block;
  • Hertz: 60.0;
  • Temperature Range: 40-240F;


1 Year Head Warranty
Replacement Power Head for Taco 556-G2/G3, 557-G2/G3 and 5101-G2/G3 Geothermal Valves has an average 2.6 out of 5 rating based on 8 user reviews.
1 of 1 people found this review helpful.
It works, but not for long.
By Tom (from Idaho) on 1/2/2016
I just ordered my 6th power head. They last about 5 months.
Was this review helpful?  Yes / No
1 of 1 people found this review helpful.
A POS valve
By alan (from Jonesborough TN) on 4/25/2014
These go bad for me about every 6 months. I have two units - so I am ordering 4 a year right now. Does anyone make a better valve? These suck!
Was this review helpful?  Yes / No
1 of 1 people found this review helpful.
Too expensive and does not last
By (from Upton, MA) on 11/9/2011
This power head contains wax to slow down the value when closing to prevent pipe knocking but the value goes bad (freezes up) after 1 to 1 1/2 years of use and the geothermal system uses 2 of these. So I'm shelling out $70+ to $140+ every year or two.
Was this review helpful?  Yes / No
Long lasting
By Master refrigeration tech (from Quebec) on 9/27/2017
This head (orange) is meant to be instaled on geothermal ground water system wich be definition is pretty cold and will cause condensation. This condensation will sorten the life of this valve if it's not properly vented out. Do not use the brown head on geothermal since it's meant to be used on heating system.The main problem with this valve is the auxilliary contact, followed by an occasionnal defective coil.I've had some valve installed properly that lasted over 15 years.
Was this review helpful?  Yes / No
Always keep a spare.
By Jerry on 3/8/2016
Have replaced the head at least once per year for the 6 years on my heat pump. Valve works when the head works, but quits all at once. Wish there were an alternative.
Was this review helpful?  Yes / No
Longevity of Taco geo thermal valves
By Galen M. (from Lexington, SC) on 12/4/2012
Commercial hvac supervisor: Have a geo thermal heat pump open loop system at house. These valves prevent freezing water coils and protect compressor. They "prove" water flow so that a compressor does not start before water flow is "proven or established". They ALSO prevent hammer or pipe slam by opening and closing SLOWLY. Even if you have a two stage copeland compressor with 66% / 100% capacity, never remove this valve from stage one. Tips: These valves can collect fine sand or crud around the stem when installed in the horizontal position. When they do, the valve no longer closes completely. Not good. Taco says they can be installed in the vertical position and when you do, fine sand, dirt, crud will fall harmlessly down (we are talking of flow going from the top falling down, gravity, right?) I use a Whirlpool whole house water filter WITHOUT filter cartridge which catches sand but causes NO restriction to water flow.
Was this review helpful?  Yes / No
works great
By Gia (from PA) on 7/5/2011
I have this unit on my Geo Thermal Unit. It works great.
Was this review helpful?  Yes / No
Works fine but it doesn't last
By tbplan (from Springfield OR) on 6/30/2011
We use this in our 'pump 'n dump' geothermal heat pump system. I just ordered our third one. First one lasted 3 years, second one lasted 4 years. They work well, but they should certainly last longer. If there is an alternative brand it might be worth checking. But Pex has a great deal on this one. Hopefully third time is a charm!
Was this review helpful?  Yes / No
Indicate an email address where you wish to receive the answer to your question.
Enter numbers shown above without spaces. This step helps us to prevent automatic submissions.
The following was added to your shopping cart: ×

Forgot Your Password?

Enter your e-mail address below.
You will receive an e-mail
with password reset instructions.


Estimate Delivery Date & Cost

Ship to Zip Code:
Qty (Optional):