I am desperate to find documentation for this unit I am the not so proud owner of a Tetco Model WR26-G Water to Water heat pump which I bought from Arit now bankrupt. After 2 years of fighting with Tetco to get some documentation I managed to get the wiring diagram. This allowed me to get the unit working in the heating mode. I have the Tara Loop with 3 750” slinky loops buried between five and fifteen feed deep. I am using a 38 gal water heater as a buffer and mixing tank and 3 (Taco 009 variable speed pumps set on low) pumps running the main circulation pump between the tank and heat pump and one for each zone of the radiant floor. For heating and for cooling the water is away from the floors and diverted to fan coils. I am getting a pressure drop across the cold water (source loop side) of about 2 psi and across the Compressor side of about 3 psi. and about 9 deg F rise across the unit. Have heated water to 114 deg F. which is way hotter then I will need for my application. I am having a problem with the cooling mode. I currently have the heating cooling changer over valve being terminal “O” being energized by terminal W1 which means that the valve is activated at the same time the compressor is. I am wondering if I should hoop it to terminal “R” which would have it constantly energized (activated when ever we make the switch from heating to cooling, Because now when I try to start the unit in cooling mode it activates the high pressure safety lockout, within 1 or 2 seconds. Any idea as to why this might be happening. Thanks Glen

Does the unit have an electronic control panel? If so a company by the name of ICM makes most of them and they are similar.
Mine has an "R" terminal which is the 'Hot' 24v but..........it also has an "REV" terminal which is the connection for the Reversing Valve, switches from Heat to Cool. The valve is energized by an ambient temperature sensor in series with the power to the panel, ie thermostat.

The Reversing Valve operates as best I can tell in the Heat Mode as Normal with the Cool Mode switched by the solenoid (only a two wire solenoid).

Maybe yours is similar.

Is the diagram you have clear enough that you have the HPS wired correctly? If the machine is truly being locked out from high pressure it should run for about a minute to pressurize, certainly longer than 2-3 seconds.

On my panel the NO safety switches for HPS & LPS have a separate terminal but internally they are simply in series. Other safetys such as a FreezeStat if supplied/equipped are in series w/ HPS external to the panel.

Dick

Glen,  I'm just a novice with this, but I have 2 Tetco water to air units.  This may or may not be the same with your unit.  When my thermostat is set to cool my soleniod is engergized all the time.  Wired to O on my unit.   If you are using the prewired plugs from Arit you might want to verify they are wired correctly.   I had two wires miswired from one side of the plug to the other.  Good luck, Steve

Switched terminal “O” to energize from terminal R always hot from instead of W1 and cooling is up and running. Still need documentation to modulate the flow thru the unit, and set the high and low compressor pressures. With a pressure drop table I have not clue as to flows through the unit but on the domestic side it is way more then the 4 gal min and the loop side I am running a lot of water as well

If you have a ball type valve on the discharge side of the pump that circulates through the heat exchanger you can throttle it to get a higher exit temp/ delta-T. If it is line size you won't get much effect until it is ~30% open. You can run it that way.

Within reason take what you get on the ground loop. Current draw is almost constant w/ fractional HP pump motors.

Compressor pressures aren't adjustable and will vary w/ loop temps. HPS is NC & fixed to open @ ~500 psi for R410. less for R22. LPS is similar and opens below about 20 psi. My controller has a 2-minute delay in LPS (only) before activating lock out.

Tetco has made a living selling to newbies and DIYs (though not a good living apparently). Pros here will sometimes seem unhelpful with problems like this making folks think we don't help or like DIYs. Not true, it's simply too late in the game to ask for internet advice. We might have helped with design or equipment selection but can't help clean-up a mess once too many mistakes are made.
Too much we don't know to help with your heat pump woes, but it sounds like you are on the fast track to equipment failure.
I suggest getting a pro in.
If you didn't meet one while you were shopping, you can check igshpa for someone near you.
They might charge a little to sort this out for you, but it will cost much more after a part or two is damaged.
Good luck,
Joe

Steve: Thank you for the information your unit and mine are designed to use the same 4 wire thermostat so knowing that your reversing valve is always hot when cooling is selected on the thermostat confirms my controls. Bergy: Because of the type of fan coils I am using I have two sets of controls one for heating and one for cooling I also use ball valves redirect water from the floor to the fan coils. During the changeover the O terminal is controlled by a switch. craigb93: The only information I have is for another tetco model which says to hook up gages to the High and Low side and adjust water until I get 250 to 270 psi on the high side and over 53 psi on the low side. I would feel a lot better IF I had the specifications for the WR26 Joe: I would happily get a pro out, but then what can he do. He would need the same information I am trying to find. I also live in Arizona the wild west. it is hard to find anyone with any knowhow to fix anything. Only the contractors are lienced and the people who do the work are in the country illegaly.

Here is a link to a Mollier Diag for refrigerants.
http://www.xtremesystems.org/forums/showthread.php?t=100451

You can have an idea of your pressure ranges with a $9 electronic meat thermometer.

From the numbers you quoted I'd say they were for an R22 machine.  IF you really have  a r410 machine just work accordingly.

Here are the specs for FHP units. They are not your unit but your values will not be much different. It will give you a feel for where you stand given your darth of other info.
http://www.fhp-mfg.com/newpdfs/WP_WW/WP_Spec.pdf. Look for the chart of water flow versus pressure drop.