Pool dehumidifier

[tarz]

Got called to look at a Zephyr unit made by Dumont Refrigeration Corp. Unit is butchered. Anyone have experience on these? DP 1800 is the model. No books, schematics or anything that explains operation. Anybody have any literature on these?

[valvndamperguy]

How is it butchered: duct, piping, diffusers, remote condenser, controls?????

[baub]

Originally posted by tarz
Got called to look at a Zephyr unit made by Dumont Refrigeration Corp.

Dumont was bought out by Air Technology. http://www.airtechnologyinc.com/ATzephyrDetails.html
You can reach the tech dept. at 877 423 1865, ask for Jim Short.

I have one Zephyr, I installed about 20 yrs ago. I have maintained it up till now, and it can be a tough row to hoe. It has dehumid, cooling, re-heat, additional HW coil for room heat, and de-superheat coil for pool water heating. It wants a lot of regular attention, and a lot of KW that a succession of owners have found is tough to pay for. Kind of like a big, fancy boat.

Let me know if I can help out any more. Make sure your customer has deep pockets, especially if it is a private owner.

[tarz]

The butchering I mentioned was done to the wiring. Control and power has been cut and unit was made to run "fan only" by the inhouse maintenance guys. The desuperheater piping has also been removed and capped as they've installed a separate heater for the hot tub. I basically have to start from scratch with the wiring, that's how bad it is.There is a separate remote condensor and a separate gas furnace attached made by Reznor. There is a standard stat and a humidstat controlling this. Of course the mercury in the stat is blown out probably due to miswiring by inhouse staff. Without any literature whatsoever I'm not completely sure of the operation. When exactly are the remote condensor fans supposed to run other than the obvious call for cooling? I would think they would be off and the solenoid valves would be bypassing on a call for only dehumidification and not cooling and the pressure controls would be controlling the compressor. I haven't looked to see if the fans are separately staged. I'm assuming the juice is 22 but I can't even find the tag, haven't put gauges on yet though. The inhouse staff shorted out the gas valve and a few other components by jumping 120v to the 24v devices attempting to repair this beast. If someone would explain the theory of operation that would be helpful, schematics would be a great help as well. I checked the website, not much info. I haven't called the phone number yet but I might do that Monday. Sorry about the long post but this is a new animal to me. THANKS for any help.

[DeltaT]

First thing I would do, and this is what I do a lot of, is determine what the functions of the systems are. You can tell my looking at how the system is piped both in air duct and water piping.

Since it does not heat the hot tub anymore, does it still heat the pool water? Do the inline heaters in the duct still work? If so, they are the secondary form of air heat to maintain the poll room air temp.

The outside condensor indicates that there is an A/C mode. You can test the system just as if it were an A/C keeping in mind that anytime the compressor is running, dehumidification is taking place winter or summer.

The humidistat typically will energize the compressor so dehumidification takes place. The room thermostat energizes the compressor also but diverts the hot gas to the internal coil for heating which is located after the cooling/dehumidification coil and before the inline duct heater. If the system cannot heat the air then the second stage of the room thermostat will energize the inline duct heater for additional heat.

Any of this make sense. More info and I probably can help you.

[tarz]

The pool and hot tub both now have separate gas heaters located in mechanical room. I don't believe there are inline duct heaters other than a Reznor gas furnace between the dehumidifier and the ducting. The stat they now use is a single stage heat and cool. Good point on that though, I'm thinking a 2 stage stat would make more sense. 1st stage to bypass remote condensors and heat with internal coil and 2nd stage to kick gas furnace in if needed. Seems like a 2 stage heat stat would provide better overall dehumidification. I pretty much think I know how this thing works by looking at the piping,etc., but I want to make sure I'm not missing something. All the actual water piping has been capped so I don't have to worry about that. So a call from only the humidstat would energize the compressor in regular ac mode, utilizing the remote condensors. A call for cooling would do the same thing. A call for cooling from the stat and a call from the humidstat would also accomplish the same result. A call from the stat for 1st stage heat would energize the comp. and bypass gas to the internal coil for heat, a 2nd stage heat call would also energize the inline gas furnace for additional heat. Is all this correct?

[baub]

DeltaT has the operation right. On the one Zephyr I service, they want that de-superheater operating whenever the refrigeration cycle is operating. They have a water pressure switch that will shut down the refrigeration cycle if there is no water flow thru that part of the system. As I remember, the condenser inside the unit is sized assuming the de-superheater is operating. Also, the heat recovered is more valuable going into the pool water vs. outside.

Operating controls-

1) Humidistat- Controls the pump-down cycle on the refrigeration system. Simple on/off with some time delays in the control panel. System blower runs all the time.

2) T87F w/ heat/cool sub-base- In heating mode, AND WHEN THE HUMIDSTAT IS CALLING, discharge gas is directed to the internal condenser, right after the evaporator. Just like a de-humidifier. In Cooling, discharge goes to outdoor remote condenser. Just like a standard A/C.

3)T87F Heat only- controls the auxilary heat, in my case HW coil, in yours, the Reznor.

I strongly recommend contacting the individual I named above for a wiring diagram. Just don't rag on Zephyr or the POS you are trying servicehttp://www.stopstart.freeserve.co.uk/smilie/cheesy.gif. Also, there should be a wiring diagram adhered to the cover of the control panel. I would bet thats missing too, but if you look in the dark corners, you might find it.

Good luck, Brother!

[DeltaT]

tarz
This is your statement that gives me the most concern on the operations of your existing system.
All the actual water piping has been capped so I don't have to worry about that.

That being true, is the only heat rejection taking place directed out into the remote ourside condenser? Or is there a heat recovery valve that switches the hot gas from the compressor to another internal coil that is located past the dehumidification/evap coil?

[tarz]

There is a 3 way solenoid valve that blocks the flow of hot gas to the remote condensors and redirects it to a coil inside the unit located downstream of the evap. coil. There is no actual flowing water through this unit whatsoever, it's all been disconnected and capped. Does this mean that the internal condensor is now undersized for this system considering it was designed to heat water which would have provided additional heat rejection?

[baub]

Does this mean that the internal condensor is now undersized for this system considering it was designed to heat water which would have provided additional heat rejection?

From servicing just one Zephyr (for a long time), yes. How much, how little, I don't know.

[arthvac]

The Zephers that I have worked on used a desuperheater in front of both the reheat coil as well as the outdoor condensers. some also had pool water coils but not all of the early ones did. Does this unit have the bypass damper above the evaporator????? the early ones didn't.

The reheat coils would extract about 15% of total heat load the condenser sizes could be a little small if you are running room temps above 85. Best controls would be a room temp stat as well as a humidistat with the humidistat running the compressors and the temp stat for ac and the reznor reheat. I hope this helps. I custom manufacture dehumidifiers and small chillers if you have any other questions.

[DeltaT]

Originally posted by tarz
There is a 3 way solenoid valve that blocks the flow of hot gas to the remote condensors and redirects it to a coil inside the unit located downstream of the evap. coil. There is no actual flowing water through this unit whatsoever, it's all been disconnected and capped. Does this mean that the internal condensor is now undersized for this system considering it was designed to heat water which would have provided additional heat rejection?

This gets a little complicated since you have an outdoor condensor section which means and additional function of A/C.

One question first. Has the refrigerant piping to the condenser (that's what it is) that heats the water also capped off? If so that will affect the total amount of charge. It will still work but you will not be able to use the manufacturers amount of refrigerant. Let me know. It's important for another reason also.

There are 3 different directions the compressor hot gas can go because of your A/C option on this unit.

1) the hot gas is diverted to the pool water heat exchanger which is disconnected as you have said. This would happen for a call from the inline pool water return line thermostat on a call for pool water heat.

2) the hot gas is diverted to the internal coil down stream from the dehumidification/evap coil. This would happen for a call for heat for room air only.

3) the hot gas is diverted to the outside condenser. This would happen for normal A/C cycle on a call for room air cooling only.

Because you have the A/C function you probably have another diverting valve somewhere in the hot gas line.

Let me know if the refrigeration lines have also been capped off of the pool water heat exchanger and if you can find another dirverter valve in the hot gas line. Then we can go into the control system.

[tarz]

The refrigerant piping is all still intact. Just the water lines have been capped. There are dampers above the evap. coil that are manually adjusted. I'm about 100 miles from this project right now but I do remember another solenoid valve in the system, besides the solenoid valve that diverts gas to the remote condensors. Near the dormant water piping in the compressor section, there is what looks like a refrigerant receiver, this is where the 2nd solenoid valve is located. I'm thinking this was the water to hot gas heat exchanger because there is also capped piping coming out of it. The refrigerant system is still charged. On a call from the humidstat only, is hot gas diverted to the remote condensors or only directed to the internal coil?

[DeltaT]

"On a call from the humidstat only, is hot gas diverted to the remote condensors or only directed to the internal coil?"

That depends. Let's start out in a simple mode. You should find out why the pool water heat exchanger is capped off. There is only one way in which the pool water heat exchanger goes bad and that is a hole between the refrigerant section and the water section. If there is no hole, then the units should still be used for heating the pool water.

Winter: On a call for dehumidification the compressor is energized and the return air is dehumidified while going through the dehumidification/evap coil. That air continues on and through the reheat coil which is receiving heat from the compressor hot gas discharge.That air now supplied back to the pool room is usually not sufficient to heat the pool room AIR though.

On a call for ROOM air heat, the compressor is energized and the same happens as above except, usually, and an additional heat source (HW coil, in line duct heater) supplies the additional heat necessary to maintain set point via a 2 stage thermostat.

On a call for POOL water heat the above same happens except the 3 way diverting valve is positioned to allow the compressor hot gas through the pool water heat exchanger now. There is some sort of safety pressure or flow valve which will not allow this valve to switch to the pool water heat exchanger should no pool water flow be present.

Summer: On a call for cooling the dehumidification/evap acts like a straight A/C system but the other diverting valve switches the compressor hot gas goes to the outside condensors where there should be some sort of heat pressure control.

Remember, the fan must run all the time. And at any time for any reason in any mode (a call for pool heat, dehumidification, room air heat, or cooling) when the compressor is running, the system, by it's very nature, is dehumidifying. It's what is done with the compressor hot gas that indicates what mode the system is running in. Pool heat - hot gas to pool heat exchanger; Room air heat - hot gas to reheat coil; dehumidification - hot gas to reheat coil; A/C - hot gas to remote outside condenser.

Atart by troubleshooting each mode one at a time. Start with dehumidification, room air heat, pool water heating(if you reconnect the heat exchanger, A/C. Make sure only one control at a time has control of the system. So disconnect or reset the set points of the other controls not to call while only one control does. Example, humidistat calling but all other controls not. Make sense?

[tarz]

Yes, makes sense. I understand the operation completely now. Now wiring this thing shouldn't be a problem. Thanks to all that replied. As said many times before by many others, this website is a great learning tool. The wealth of information and experience on this site is priceless. Thanks again everyone for selflessly sharing your knowledge.

[DeltaT]

tarz
The controls also need to be addressed. Typically, withing the control department you will find a bunch of relays. Those relays set a mechanical priority to how the unit functions through it's factory wiring.

Typically, the unit funtions on this type of priority.

1) A call for pool heating over-rides any other call.

2) A call for dehumidification over-rides any other call except pool water heating.

3) A call for room air heating is last on the list and operates only after the above two have met their control set points.

If I were you I would attempt to work with the control wiring as you have found it UNLESS you have a clear set of control diagrams AND the control wire terminals are clearly maked as per the wiring diagrams. Then you can pretty well do what you wish.

Let us know how it goes. I love this stuff & the more complicated it is the funner it gets.

[zephyr man]

Tarz

You will be happy to know that we can help you out. Let us know what we can do.

The new Zephyr unit has a much cleaner internal component layout for ease of service. We even make installation and start-up simplier.

zephyr man

[dryguy]

Tarz and others,

There is another resource for techs working on Zephyr units. The former Service Manager for that line has started a business to support existing units in the field with technical help and replacement parts.

That contact is:

Maine Conditioning Company
Clyde Moody
Phone: 207-933-5770
Fax: 207-933-9740

Clyde is good people.

Good luck.

[zephyr man]

Tarz

Have you ever heard from anyone on the Dumont Zephyr dehumidifier? Give us a call. We purchased the engineering drawings etc... and then improved upon the complete system.