I am considering installing a GSHP and I am trying to obtain more information about Climadry and how it compares to using a separate whole house dehumidifier with respect to cost, efficiency, and maintenance. I live in North Carolina and my house is about 1800 ft2, relatively tight (1500 CFM50), and well insulated (R21 walls, R5 windows, unvented attic and sealed cralwspace). Is Climadry recommended for my area? Does anyone have experience with owning/installing such a system? Does it make sense to get a unit with ClimaDry or is better to try a season without it and install a separate whole house dehumidifier. Thank you in advance!

i opted not for the climadry even though i had the option to get one for a tremendous price. with climadry you give up the option for the cupro nickel coated coils and that i wanted. also it seems to be a tricky system to regulate if you read here you will see someone had it and the climatesmaster support was pathetic at best. so if you do not need it save the bucks.

A properly sized (read as not over-sized as is most typically the case when HVAC contractors select the unit size) two stage heat pump will greatly improve dehumidification. I don't see why you would need separate dehumidification in NC. Another thing that can aid in dehumidification is one of the new heat pump water heaters if it is located within the conditioned space.

I have to agree that CM support on climadry is non existant.
j

In general I like the idea of having fewer mechanical units in the home, so in this respect if I do need a dehumidifier, ClimaDry sounds appealing. However, its steep cost ($2500+) seems to be higher than a high efficiency dedicated dehumidifier. It also seems to require running in stage two, which for a 2ton unit (what I am being recommended), would consume more than 1kWh. An Ultra-Aire 70 in comparison consumes 600wh. I guess I would have more maintenance costs with the separate dehumidifier, so ultimately there may not be that much of a difference. When ClimaDry is running, however, the GSHP will also generate some hot water (unless my EWT is too low and all the heat would need to be dedicated to dehumidification).

The lack of support and positive experience reports with ClimaDry is discouraging. None of the installers in my area that I spoke with have any experience with it and it seems that installing it properly is not something that can be done just by following intuition.

Based on the load calculations my house cooling load is aroung 1.5 tons, however, the heating load is higher (Raleigh, NC is still in a heating dominated climate), so I must go with a 2 ton dual stage system, which I hope will not be oversized in the summer.

If I do install a separate dehumidifier at a later stage, can that dehumidifier's controller turn on the GSHP's fan if the GHSP is not running but dehumidication is needed?

Thanks for the replies. This forum has been extremely helpful.

I got my 2-ton CM unit late last winter, ordered with Climadry. It has the cupro-nickle core. The house is new, superinsulated, and very tight. The total conditioned space is around 3700 sqft, plus or minus. Even so, the unit is considerably oversized for cooling. I haven't had the Climadry feature in use yet, but that isn't because it doesn't work. There were relatively few days when the house needed cooling this past summer, given the nature of the house and how slowly it gains heat in hot weather. However, humidity was an issue, and the only way to get that down was to use the unit for A/C. We had to be very careful not to run it too long, as that would overcool the house, and we'd have to suffer higher humidity for a quite a while until the temperature climbed up a bit. Having Climadry operable would have been wonderful.

Here is my problem. The system is open-loop, standing column well design. Per CM's installation guidelines, the water valve installed was a slow-opening Taco Heat Motor Zone Valve. Also per CM's manual, the Y1 line from the thermostat was run through the valve, then on to the heat pump via the end switch on the valve, so that the water would be flowing when the compressor came on. This wiring is a big problem for a unit with Climadry, because the thermostat could be calling for action by signalling on either Y1, DH, or both. Both lines have to go to the unit eventually, but neither should be used to control the operation of the valve.

I believe the correct way to wire up the water valve for a unit with Climadry is to have the unit's DXM control board issue the signal to the valve, not the thermostat. This can be done in the case of a water valve that turns on without delay, as for a closed loop system, by using connection "A" on connector block P2 on the DXM board to drive the valve; this connection is powered from the compressor relay contactor.

For an open loop system using a well pump, where the use of a slow-opening valve is useful for avoiding water hammer, the situation is different. First, the water valve should NOT be a heat motor zone valve; those are too slow to open, taking over a minute and a half to open when starting cold (by my own testing and testimony of others). Fortunately, Taco has another valve, their Zone Sentry, and it is available with metallurgy suitable for well water operation. It opens in about six seconds after the capacitor is charged, which may take a few seconds or less to a maximum of 20 seconds the first time, per their specs. Next, the DXM board has two accessory relays, either of which can be configured via DIP switches to be used for "Water Valve - Slow Opening." However, the first of these two relays must be used for "Reheat Option - Dehumidistat," leaving only accessory relay 2 available for the water valve. When configured this way, the compressor relay is delayed for 60 seconds after the accessory relays are activated.

If I had to do things over, I'd just pay the couple hundred bucks for the replacement valve and wire it to accessory relay 2, as above. Being cheap, I ran the problem past my brother, who does circuit design for a living. He designed a "simple" circuit board that could be built with about $30 in small parts. It's function is to take both the Y1 and DH lines from the thermostat, activate the present water valve if either signal is active, and upon receipt of the signal from the valve's end switch turn on a pair of relays to pass Y1 and DH on to the heat pump. I've been mounting and soldering the parts for this circuit in spare time, for use mainly next summer. I'll post something when I get it working. If I screw that up, I'll replace the valve and wire as described above and pass on that result alsol.

I think the designers of the DXM board knew what they had to do for Climadry, but somewhere along the way CM's documentation on how to wire for an open loop system fell short. Their experts weren't much help over the phone. The local distributor, while they hadn't provided a unit with Climadry before mine and hadn't realized there would be a wiring problem either until I brought it to their attention, at least understood the situation after I explained it.

Aydan,

a two stage 2T should work well for you in Raleigh. There shouldn't be humidity issues.

Avoid the Climadry for reasons already cited.

However, 1500 CFM50 ain't all that tight for 1800 SF. Consider expending some time and effort to bring that down. Reducing air leakage helps with both humidity and heating / cooling load.

If you absolutely, positively have to have a separate dehu, duct it so it can operate independently of the main system else it will expend considerable effort drying out the main system coil between compressor runs. Ultra-aire units are well regarded, but I've cleaned up after a couple problem installs.

Note also that central dehus aren't cheap to buy or operate and that they add considerable cooling load.

A heat pump water heater may be a good fit for you - it can be a twofer - cheap hot water along with cooled and dried air around the HPWH