Joe/Masoud: how should the water valve be wired for a Climatemaster Tranquility 27 with Climadry, for an open loop installation? CM's installation info says to run the Y line from the thermostat to the slow-acting water valve. When the valve is fully open, the end switch is closed, and the signal is passed on to the heat pump. Mine presently is wired that way, and in normal operation (heat or cool) everything works well. The two of you worked together last summer to resolve Masoud's problem with Climadry, so I figure you ought to know what I need.

The thermostat I selected for zone 1 here was the CM ATP32U04, which has dehumidification control. Per CM's info, tstat line DH is connected directly to the H terminal on the DXM board. When the temperature setting in COOL mode is satisfied, but the humidity is higher than the humidity setpoint, my understanding of the device is that it sends only the DH signal. CM's info on "Climadry Sequence of Operation" treats this as "Reheat Mode" and the unit will turn on cooling by itself. If the tstat is signalling both cooling (Y1/2) and dehumidification (DH), cooling overrides reheat mode until the temperature is satisfied, after which the unit will continue to operate in reheat mode if there is still a call for dehumidification.

In either mode, cooling or dehumification, the compressor must run, and so there must be water flow. If there is no call from the tstat for cooling but there is a call for dehumidification, how will the water be turned on? Needless to say, I can't get Climadry to work in my installation; it quickly shuts down with fault code 2 (HP), due to there being no water flow.

I get the impression that CM's documentation is missing something for open loop installations with Climadry. I suspect that control of the water valve in such an installation must come from the DXM board and not be tied to the Y signal from the thermostat, since the tstat may at any time send signal over Y, or just DH, or both. If this is so, how is it done? I've looked at the DXM board and its wiring diagram, but nothing leaps out at me. What am I missing?

Something niggling in the back of my mind that climadry was for closed loop only.
flow centers are activated with compressor contactor.
solenoids are usually activated with thermostat.
j

CM says in their latest info that Climadry units made before April 5, 2010 must have freeze protection to 20 F. That would have precluded use of Climadry with open loop before then. I spoke with someone at CM last year, and it seems they resolved the issue of freezing damage to the Climadry reheat coil that could occur under some circumstances.

In my installation, the water valve is a Taco 5101G Heat Motor Zone Valve, wired into the Y1 wire from the thermostat, according to Figure 21 in CM's IOM:A (under Electrical - Low Voltage Wiring). I suspect CM didn't consider Climadry with open loop and the need to get water flowing when only the DH and O lines from the ATP32U04 tstat are activated. I think I'll have to call them again. I had hoped someone here had run into this.

Edit: on your and Masoud's posts from a year ago, I note that you checked antifreeze level after getting him squared away, meaning he has a closed loop system and wouldn't have the water valve setup I do.

There is a different board for climadry, you will simply have to run down signals and have a second isolated taco actuator. A simple isolating relay would do.

I thought I'd update readers with more information on the subject. I'm still not where I need to be, but I think I'm getting close. On further reading of the CM IOMs, it does seem that the design of the DXM board provides a way to turn on the water valve and delay compressor operation to give the valve time to open, without relying on interception of a line from the thermostat. Implementation details have to be worked out.

On the DXM board there are two "accessory relays." DIP switches are used to configure "personality" of these relays. One configuration for either is "Water Valve - Slow Opening." When the relay is configured this way, the DXM board turns on the relay 60 seconds before turning on the compressor relay. On my board, the first accessory relay is configured for "Reheat Option - Dehumidistat" and the outputs are in use accordingly. The other relay is at present not used.

CM's documentation covering low voltage wiring says that an external solenoid valve should be used on ground water installations to shut off flow to the unit when the compressor is not operating. A simple fast-open valve actually could be driven from the "A" output of the DXM board, as it is powered when the compressor relay is activated. However, CM suggests the use of a slow-opening valve to reduce water hammer, and one of their diagrams shows interception of the Y1 line from the thermostat by a Taco. When the valve is fully open, the end switch is used to pass Y1 on to the DXM board. Nothing is said in that section about how that wiring will not be suitable for a unit with Climadry, when there may be a signal from the DH output of the thermostat without a signal on Y1. I think that in time CM will have to update their documentation to cover wiring of the water valve more thoroughly.

Also in the low voltage wiring section is CM's statement that slow closing water valves take approximately 60 seconds to open, with very little water flow before 45 seconds. This was the basis for my thought that all I have to do is activate the water valve from the second accessory relay, that the built-in 60 second delay before the compressor came on would be sufficient. Now I see that 60 seconds won't be long enough for the Taco 5101G valve I have (it was in the list of parts in the proposal from the region distributor). This series of valves from Taco are "heat motor zone valves," which work by electrically heating a wax, which expands to force open the valve. Yesterday I ran a timing test twice on my valve. The first time, with the system having been off for a while, took 87 seconds for water flow to begin. I shut it off, waited 5-7 minutes, then turned up the tstat again. This time it took only 55 seconds, reflecting only partial cooling of the wax in the valve. I think the longer time would be more typical of what will be needed, since the wax typically will have cooled longer.

I still think that the right way to drive a slow-opening water valve in a unit with Climadry is from the DXM board and not from the thermostat. Further, the use of a slow-opening valve probably is a good idea, and that in turn means using the second accessory relay to provide the timing delay. However, it also means that the present heat motor zone valve is far too slow for the purpose and that I have to replace it with something that opens in much less time. One possibility is a Taco "Zone Sentry" valve. Their documentation on the valve says the valve opens in about five seconds, after a capacitor charge time of up to 20 seconds (usually less). Other specs seem ok. I'm hoping for comments on this or any other suitable valve.

Can you break the 24v from the board to the compressor contactor to drive the Taco valve (2) then (3) to the contactor? I am assuming the controls are like most other heat pumps..

Adam

Climadry adds a PC board that interacts with the thermostat independantly.
I confess Dick, having only seen one of these, I don't have a great picture in my minds eye.
I'm still to meet with masoud sometime in the future, I will refresh my memory on the schematic.
Meanwhile how bout a time delay on Y between the climadry and main boards. They are inexpensive and adjustable (sounds like 30 secons will do).
j

Adam, I wondered about that, since that is the logical solution to having the water running before the compressor comes on. Ultimately that is the last 24v line that is powered, regardless of how many other 24v signals might have triggered the chain of events. The brown and yellow wires from the contactor terminals CC and CCC on the board are 18 gauge, same as the rest of the wiring connecting to the board. I don't know if there is any problem regarding the 24v power draw of the compressor relay vs the current carrying capacity of the contacts on the end switch of the Taco valve. I also don't know if there might be any problem with timing issues on the DXM board if it expects certain things to be happening within a certain amount of time after it thinks the compressor has come on. I'll have to read more about the board, its operation, diagnostics, and self-protection strategies for the unit.

In the "DXM Controls" section of the manual (IOM:K, p. 520), there is this description of the Low Pressure Switch: "The Low Pressure Switch must be open and remain open for 30 continuous seconds during a compressor "on" cycle to be recognized as a Low Pressure fault. If the low pressure switch is open for 30 seconds prior to compressor power up it will be considered a low pressure (loss of charge) fault. The Low Pressure Switch input is bypassed for the initial 120 seconds of a compressor run cycle." If it's looking at refrigerant pressure before the compressor runs, then the pressure at the measurement point must be adequate without the compressor actually running. I don't know if delaying actual start of the compressor for 90 seconds or more by running the relay line through the water valve would eat up too much of the 120 seconds the board give the compressor loop to get up to speed.

There also is a check on the water coil temperature. A fault will occur if the temperature is below the selected low temperature protection limit setting AND the temperature is rising at less than 2 degrees per 30 seconds. This checking is ignored for the first 120 seconds of a run cycle. While eating up 90 seconds by the water valve delay might otherwise be of concern, I don't think this is a problem because the water temperature wouldn't be low in my case in the first place.

I don't see any other time-based checking, but I suppose there could be something undocumented.

Joe, I'm not clear on what you mean about "on Y between the Climadry and main boards." I don't see any separate board for Climadry (but I haven't looked for one). I don't see any indication of a separate one on the wiring diagram for a unit with Climadry, although the connections to the three-way valve and its controls do appear on that diagram. Anyway, I wouldn't think that routing a signal from the DXM to any part of the Climadry circuitry through a delay device, if the DXM board activates the compressor by itself anyway.

There has been some back and forth email between me, the regional distributor, and CM on this issue. So far the replies from CM relayed to me haven't been very satisfying or detailed, although the last one did say that Taco heat motor zone valve is quite slow and a faster valve might be required, with no quantification. That got me to actually measuring the time to open and the realization that the "60 seconds to open" phrase in their low voltage wiring section is misleadingly low. They did make this suggestion: "If they want to try current valve, wire "A" on DXM P2 terminal strip to #2 on Taco valve. #1 on Taco valve to "C" on DXM P2. "A" on DXM energizes with a compressor call." That surprised me, as it would have no delay at all between compressor start and the start of the valve-open process, and seems most likely to lead to a high pressure fault before the water valve opened.

I think I'll run that suggestion about running the line to the compressor relay through the water valve by CM, although I suspect the answer will be it could lead to a Low pressure fault, and that my only hope is to have a faster water valve. Does anyone have anything to say about the Taco "Zone Sentry" valve for this purpose?

I wouldn't think I'm the only installation to run into this issue of water valve operation with open loop (well water) and Climadry. Someone out there must have worked this out, and I would have thought CM would know "everything" about what to do. The regional distributor said mine is the first they ordered with Climadry, so maybe that says something.

My experience was no one who knew anything about climadry was available to talk to-ever. Though some pretended they were.
If you don't have a seperate climadry signal then operating y through the end switch of of your water valve is fine and will not cause LP faults.
j

I'm sorry I did not respond earlier and can't help now. Dick, I'm not familiar with Climadry running on an open loop.

Regards,

Masoud

Aug 10, Dick: "In my installation, the water valve is a Taco 5101G Heat Motor Zone Valve, wired into the Y1 wire from the thermostat,"

On second thought, PERHAPS this helps. In my case Climadry (2008, and probably now too) only works in stage 2. Y1 does not light up on the fan board when Climadry is running. Y2 does.

Regards,

Masoud

Thanks for the comment, Masoud. I had seen that before, about Climadry and stage 2. My unit was mfg this past winter. I won't know what it does until I get it working. I have two options for proceeding, it seems. One is to buy a replacement valve for the Taco 5101G and have the second accessory relay on the DXM board operate it, and not have the Y1 line from the thermostat run through it. The one I would get also is a Taco, but in their "Zone Sentry" series. They have a special version of it for open loop systems, with different metallurgy. The special one isn't on their web site, and is less than a year old; Taco gave me the part number as V075T2B1ZA024Q4A1. It uses a small motor running off a capacitor charge to open and close; open time is six seconds after capacitor charge time of less than 20 seconds.

The other option I have is to work with the valve I have, and use some custom circuitry to do what I need. My brother is a EE, and he's outlined what I need. He says the handfull of parts are cheap, totaling maybe 20 bucks. Basically it would send a 24 vac current to the valve if either Y1 or DH is output from the thermostat. On receiving the signal back from the end switch on the opened valve, it would use that to turn on a pair of relays to pass the two lines from the thermostat on to the heat pump. I'll let everyone know which I use.