Waterfurnace pond-loop winter problems

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02-02-2011, 06:53 PM
Treepmeyer

Waterfurnace pond-loop winter problems

Last May I installed a 5-ton Waterfurnace for my 3000 sq.ft. home with a pond loop. The pond is 6ft deep and 120'x60'. We live in southwest Michigan (hort. zone 6a). Cooling last summer was great, no problems at all. This winter is a disaster. The system goes into "fault" mode almost every day, sometimes more than once per day, and we can't get the temperature above 66 degrees. When the system is in the "fault" mode the compressor is turned off and the auxiliary electric heat runs by default. I shudder to think what my electric bill will be.

This autumn I got concerned about whether the system would heat enough in the winter and asked my dealer whether I should install a supplementary ground loop - he said no, we should be fine. I unfortunately did not know enough to turn the desuperheater off and I left a windmill-driven bubbler in the pond. The dealer's service man said that I should turn them both off (I did) but no improvement. He said that the coils are probably encased in ice and we may just have to wait until warmer weather melts the ice. Does this sound right? Is this system functioning correctly? Thanks
02-02-2011, 07:19 PM
acwizard

The dealer sounds correct as far as the coils are incased in ice. This will surely decrease your capacity. I think you are going to have to install some form of groundloop which is below the frostline. The available energy that you can transfer into your home is proportional to the temperature and energy that is available in the loop.
02-10-2011, 04:39 PM
WF_Inc

Treepmeyer,

Under an ice cover in the winter, ponds can maintain approximately 39oF throughout. This is due to the density characteristics of water. Water has a maximum density at 39oF. As water becomes colder the density increases, thus the colder water falls to the bottom. The water closest to the ground is then warmed and rises. This creates a natural convection current of constantly rising warmer water and falling colder water. When the water approaches the freezing point its density decreases significantly and the icy water will then rise and insulate the convecting water below. This is why pond aerators should never be used in cold weather.

WaterFurnace International, Inc.
02-11-2011, 07:48 PM
junkhound

6ft deep

pretty shallow;
what is the frost depth where you are?
how deep is your loop? How thick is the ice on the pond"

If near the bottom and frost depth higher than 4 ft or so it would take 6000 hours to freeze the entire pond solid, by that time it is summer. However, if loop higher than frost depth, you 'may' have ice, otherwise, like WF implies due to convection currents, iced loop unlikely.
02-20-2011, 08:34 PM
notquiteamish63

pond loop issues

A couple of simple questions before assuming the worst.
1. Are your faults "waterflow or low pressure"?
2. Did the installer check the freezepoint of the solution in your loop and what is the incoming temperature of your loop? Unless the loop is coming in below 26 degrees or not protected to 15 degrees, you should not be getting the above faults. Incoming temps this low hurt efficiency a lot but should not be faulting the unit. Incoming temps below 26 degrees are definitely a problem.
3. Don't want to miss the easy one. Did they set your system to closed loop?
4. Another possibility for a waterflow fault is if the unit is running a little low on refrigerant. Have them check this also. good luck.
02-20-2011, 09:50 PM
dunkman

We set our closed loop systems to 20-22% glycol, that'll protect you down to 17-20 degrees freeze protection. If your loop was encased in ice you should be seeing frost on the well pipes in the house.
03-10-2011, 06:27 PM
mstrblstr3

Thats a puddle not a pond

This sounds like a case of to little pond for to big of a loop.
I put a loop in a pond three times as deep and I have still been seeing really cold entering water temps. I think that the design of the pond loop needs to be tweaked because I added two extra coils to my loop just because cost wasn't a big issue.
I'm not confident that a pond at this depth would accomadate any size loop. And I definitly think that the bubbler taxed the whole loop system beyond recovery for this heating cycle.
Hopefully your geo contractor will work with you to resolve this issue. He probably was going on your information of the ponds depth, because I know that I rarely will measure a ponds depth if the homeowner seems to know the dimensions
03-10-2011, 06:44 PM
can2man

Quote:

Originally Posted by notquiteamish63

A couple of simple questions before assuming the worst.
1. Are your faults "waterflow or low pressure"?
2. Did the installer check the freezepoint of the solution in your loop and what is the incoming temperature of your loop? Unless the loop is coming in below 26 degrees or not protected to 15 degrees, you should not be getting the above faults. Incoming temps this low hurt efficiency a lot but should not be faulting the unit. Incoming temps below 26 degrees are definitely a problem.
3. Don't want to miss the easy one. Did they set your system to closed loop?
4. Another possibility for a waterflow fault is if the unit is running a little low on refrigerant. Have them check this also. good luck.

I agree these questions have to be answered first. We use ethanol up here and my last two calls were incorrect mixture. Loops are running cold this year. I live in a hor. zone five and we never put in a lake loop unless we get 8 feet. The good news is if it turns out to be not enough loop then it can be fixed without digging.
03-13-2011, 09:04 PM
mstrblstr3

Insulation?

Quote:

Originally Posted by Treepmeyer

Last May I installed a 5-ton Waterfurnace for my 3000 sq.ft. home with a pond loop. The pond is 6ft deep and 120'x60'. We live in southwest Michigan (hort. zone 6a). Cooling last summer was great, no problems at all. This winter is a disaster. The system goes into "fault" mode almost every day, sometimes more than once per day, and we can't get the temperature above 66 degrees. When the system is in the "fault" mode the compressor is turned off and the auxiliary electric heat runs by default. I shudder to think what my electric bill will be.

This autumn I got concerned about whether the system would heat enough in the winter and asked my dealer whether I should install a supplementary ground loop - he said no, we should be fine. I unfortunately did not know enough to turn the desuperheater off and I left a windmill-driven bubbler in the pond. The dealer's service man said that I should turn them both off (I did) but no improvement. He said that the coils are probably encased in ice and we may just have to wait until warmer weather melts the ice. Does this sound right? Is this system functioning correctly? Thanks

I can't imagine how your furnace wouldn't keep your house above 66 if you were decently insulated. Do you know what that situation is like. Rent a hopper from lows and blow it in whereever you can. Also check to see if your third stage heat dip switch has been switched off. There are some instances where a little backup heat will be cheaper than a taxed loop.