Hello, Just looking for some thoughts on my installed design (now that it's too late to do anything about it)...I had a 2 ton WF Envison split system installed this past summer (May of 09). The unit (NDZ026A11AC) is in the crawlspace and the air handler (NAH026A0501R) is in the attic. There are two 200' vertical loops in the front yard, and I'm using the desuperheater. The house is approx 1200 sqft, and was recently remodeled - it's in pretty good shape already and I'm insulating the subfloor. Crawlspace is insulated. The system ran pretty good this summer (I'm in Atlanta...hot summers and moderate cold in the winter), but now that we're having some cold weather (in the teens last night), it seems to be struggling a bit. Pretty much running constantly to hold 69F. I received three quotes, and all were pretty much exactly the same, so I felt pretty good about the design. In browsing this forum, now I'm not sure if it's normal for the gear to run this much or not... Wondering if anyone sees anything interesting here. Thanks in advance.

One of our units is the same as yours (but with a horizontal closed loop). This is our first winter with this system too. We are in SW Virginia and are seeing our system run much more with lows in the mid teens and highs in the low 20's.

We have stopped setting back 2-3 degrees at night. It's easier for the system to maintain temperature than catch up. We have aux heat strips installed, but are using our propane fireplace since it is about half as expensive as electric heat per btu (for us) to assist the units/loop during waking hours. It's still early in the heating season and I don't want to use up all the heat in the ground. Our EWT's are about 39.2f.

Not sure what your design low is there, but if teens are about as cold as it gets then geo should run almost all the time.
To really answer your question we would need the manual J heat load calculations, then we could tell you how much it would run per hour at given temp outside.
Entering and leaving water temperatures might be interesting as well.
Joe

Thks for the comments...

Geome, agreed on the static temperature. It has been pretty tough for the system to catch up, so I'm probably going to leave it at 69F for a while to see how it goes. We have a 5kw heat strip, but not sure if it's been coming on. Also not sure what our water temps have been. Is there an easy way to tell from the unit, or does someone need to come out to measure that?

Joe, I'll look into the design low a bit. We're about as cold as we'd get at the moment though. I'd guess less than 20 days a year in the teens, and probably not many more where the daytime highs don't get above freezing.

I did go up in the attic and noticed that there was quite a bit of air noise. After looking I found several seams that were leaking for not being tight, and the underside of the unit was separated from one of the wall seams because it wasn't attached right. My guess is it's been pulling quite a bit of cold air in. I broke out the duct tape and cut it down the audible leaks quite a bit, but I'm going to have the installer come back out and check that out.

Thks.

water temps -

Downstairs compressor box has two smaller (desuperheater) and two larger (loop) water lines. A $14 Walmart meat thermometer with a separate probe can give a reasonably accurate reading.

First check the thermometer using a 3+" high cup filled with ice and just enough water to cover the ice. Thermometer should read close to 32.

Then strap the thermometer to a metal part of the loop line. Optionally use a bit of aluminum foil to improve thermal conductivity between probe and loop line. Insulate the connection with a bit of pipe foam or a small rag folded around it.

An air handler with leaky ductwork in a cold attic will lose quite a fraction of system heat - get that looked at.

I deeply dislike air handlers in uninsulated attics, even with good ductwork - a pricey but good fix is to seal the attic with sprayfoam insulation.

It would be nice to get a handle on actual vs design aux use.

Atlanta's bin shows 26 hours below 20* and another hundred or so below 32*.
It's a neat weather area where cooling load is 80% of peak heating need so a little judicious designed in aux. makes your unit right sized for heating and cooling both.
I'd guess it's running all the time because it's at peak load requirements.
That said, it'd be nice to know when auxiliary comes on.
Engineer has valid points as well.
Keep an ear on it and see if you have a balance point listed in design data offered up.
j

I think that the bulk of my trouble is related to the environment that the air handler is in, combined with some issues at the time of the install and some unusually cold weather at the moment. A tech came back out yesterday and verified the leaks at the seams and the issue with the dent near the door, and is going to come back to work on it. I think that ultimately I can use a combination of insulation and duct wrap to shore that up a bit.

My loop seems to be doing good....inbound is around 53F and outbound is around 47F. I probably would've been better to go with a radiant heat solution on the subfloor and skip the air transfer. My water heater may melt.

Thanks for the comments...I'll follow up with a status.

Posted By DecaturDawg on 05 Jan 2010 08:44 AM
I think that the bulk of my trouble is related to the environment that the air handler is in, combined with some issues at the time of the install and some unusually cold weather at the moment.

We are having 2 seperate conversations. You use the phrase "bulk of my trouble" when we are suggesting we're not sure you are having trouble.
Certainly ducts shouldn't leak into the attic, but other than that, without design info I have no reason to suspect the unit isn't working correctly.
J

What happened between 1/5/10 and 1/16/11?

DecaturDawg,

We apologize for not responding earlier, as we just found your post. We hope you have been in contact with your WaterFurnace dealer to discuss this matter. If our assistance is needed, please have your contractor contact our technical support staff, as we will be more than happy to work with you and your contractor to address your concerns.

WaterFurnace International, Inc.

I think DD is long gone...

I'm here. I just don't check this email account but about once a week or so.

The dented seam on the underside of the air handler in the attic was a real problem. The installer came back out and got that straight, but I found more leaks around the plenums on both sides of the main unit. I eventually just sealed up the seams using a combination of Great Stuff foam and foam board....I basically created another housing around them.

The system seems to be running fine at this point, but I'm not sure that it's generating the savings that I expected. If it performs for the duration of the warranty period w/o me having to spend much more money on it (a'la service calls), then I may get the savings down to match what I would have spent on a really nice standard heat pump.

Here's the last few years of December usage info. The unit was installed in May of 09. We were out of town all of last December (when the unit was sucking attic air) but the other months we were there for a comparable number of days. The comparison between bill months Jan 09 and Jan 11 is a positive one as it was much colder this last Dec than in Dec of 08, but my kwh usage was less this past year.

BillMonth MeanTemp Kwh Cost
Jan 08 48.94 1804 $174.43
Jan 09 51.87 1694 $163.77
Jan 10 39.32 1466 $144.13
Jan 11 39.87 1277 $135.80