Commissioning, particularly in the case of a single system supporting four zones, should have included verifying adequate airflow into (and out of) each room as well as ensuring that the unit has proper external static pressure.

The phrase "necessary suction" means nothing to me. "Suction" simply does not figure into ductwork design.

Use of building cavities, attics or crawl spaces as return plenums has its weaknesses, mostly associated with air quality, and infiltration, but such arrangements normallly provide plenty of airflow.

I am skeptical to the point of utter disbelief that an air distribution retrofit so deep so as to incorporate 4 zones in place of one would somehow fail to contemplate return air paths in the course of installation.

I wouldn't be overly concerned about energy cost until a bit more time has passed

Your concern is that part of the return duct uses the wall cavity? This isn't a problem as long as the other aspects are OK.

I don't understand why they are blaming the RA system for anything. The only time it causes trouble for geo is when it is undersized.
Balance problems are usually on the delivery side.
Was your previous system gas or elec?
j

First of all, thank you, thank you, thank you for your responses. I will try to provide some more information to help you better understand the issues. The concerns were raised by the geothermal company's staff who identified issues with the return system after going into one of our walls while doing some ductwork. I would've never known otherwise, and I'm glad they pointed out their concerns without simply patching up the wall and saying nothing. I give the employees credit for this - although the sales person/part-owner I dealt with initially seemed troubled by his employees sharing their concerns with me. He said they are perfectionists and often identify problems that aren't worth worry about. I don't think this is a small issue, but I'm trying to look into further. When this owner came back later with this lead engineer, that person also expressed concerns about our return system and said it should be repaired, but seemed to indicate we should share responsibility for their repair.

Essentially, during installation they modified some of the ductwork and return ducts directly around the unit, but it is the remainder of the house that raised concerns. So, what test should/could they or another company run to see if things are working adequately? By the way, it's not just that the return ducts use the wall cavities, but that the wall cavities are not enclosed. If I recall their explanation, usually when the return system is tied into a wall cavity, the space between the 2 studs/joists leading to the wall/floor return is enclosed or runs fully to the wall. In our case, the central wall where our return runs up through has no separation - in other words airflow is not restricted to between only 2 studs/joists, but the entire length of the home is wide open within the inner wall. I hope that better explains the situation. Should they have been able to identify this type of an issue prior to bidding/contracting the job and thus should their installation include the necessary updates? If they failed to contemplate return air paths early on, should I now be required to pay more to get the unit functioning fully (assuming it is not - and perhaps it is)?

I'm not sure that they initial checked the airflow into and out of each room (but they may have), and I know they haven't done that since installation. Do third-parties provide this type of analysis so as to get an independent assessment of the system they installed? Perhaps I could call Waterfurnance and see if they have someone to recommend. On that note, the company I used was listed as a GeoPro on the Waterfurnance website.

My previously system was all electric - a heat pump. The outside unit was 15 years old and the inside unit was 29 years old (original with the house). It still worked, but since we just moved in and knew we would have to replace it soon, we figured we do it right away. It would seem there should be a huge difference in performance between a brand new geothermal system and that old system.. By the way, I am in PA just outside of Philly for climate references.

Any further insights or recommendations would be greatly recommended? Assuming they should be responsible for making any further improvements (and let me know if you don't think they should), are there any industry resources I should reach out to if I get resistance from them? Thank you again!!!

you are sayihng there are no 2x4 or 2x6 studs in the interior walls or ceilings. how did they do the dry wall then. maybe i am reading this incorrectly. but forgive , if i am , as i also live in pennsyltucky like you do. about 100 miles north of you and also doing the same thing as you.

There are 2x4 studs in the interior of the walls and ceilings. We live in a rectangular shaped single family house. The walls I'm referring to that contain the returns are the within the interior/central walls that separate the foyer and front living room from the dining room and kitchen in the back. This is the area where the staircases to the basement and to the 2nd floor also are located. Well, rather than a wall that might be 4 or 6 inches thick like the exterior walls, sections of these interior walls have much large hollow spaces (almost like soffits) that were large enough for the installer to step into when he cut a hole in the wall to investigate. They're about 2-3 feet deep. So while there are studs around the edges upon which the drywall is attached, it's opened up such that if you steped inside you could walk between several studs. Thus the area where the returns are is not blocked or sections off between only 2 studs, but may run in area large enough for 4-6 studs. I hope I'm explaining this right - this is definitely not my area of expertise.

Soooo........?
Inadequate R/A is a problem. Yours appears to be adequate.
We can discuss whether or not to change it and who should pay for it all day, but it will not fix your problem.
Again trouble is on the delivery side.
j

So do you suggest I have an energy audit completed by a third-party to check whether there is trouble on the delivery side? Is there some other evalution that can be completed to accurately assess the system. Of course, it's getting warmer around here so I don't know if that makes it harded to evaluate. Thanks again!!!

some rooms get hotter or colder than others.

So this is the only symptom you have? Sure, you could hire someone to better balance the registers - but most people do it themselves.

The symptons are that 2 rooms in particular - the family room on the first floor and the master bedroom on the second floor - are significantly colder than other rooms. The family room has it own zone, because it is on a stone slab and has no second floor above it, and this room seems to have a lot of trouble getting up to a reasonable temperature (i.e. 68), and it's called for Aux - although they set the system up not to kick Aux on easily. But I'm concerned that one or two rooms are going to be keeping the system running higher (i.e. second stage) all the time, whereas other areas of the home seem not to even require heating. Also, each of the remaining 4 rooms on the second floor seem a bit warmer or cooler than the others (there is no sense of uniform comfort - which was part of what I was led to believe would occur).

Please note that I wouldn't have known there was a potential return issue unless they pointed it out. In other words, I'm just relaying what they (as apparent experts) are telling me. There are 4 people involved so far - the 2 installers, the lead engineer and the business/sales person. Of these 4, the 3 technical folks (all but the salesperson) acknowledge that my returns are problematic and will likely impact comfort/performance. So they acknowledge a problem exists - the issue is whose responsibility is it at this stage. As I mentioned, the electric bill didn't seem less the first month. Thanks!

If the rooms still perform badly with their interior doors open, then the problem is likely NOT a return duct issue

There may be a system wide return shortage.

TESP (Total External Static Pressure) across the unit and comparison of actual vs design supply air flows to the problem rooms are two bits of data required to assign a cause.

The skeptic in me suspects they may have screwed up the supply ductwork and are fabricating a scapegoat outside their scope of supply. Ductwork is the least well understood and most often fouled up aspect of HVAC systems.

Actually, the family room and the master bedroom is much much better when the doors are open. With the doors closed there is a significant difference (i.e. much colder and the system seems to be working harder) than with the doors open.

Thanks for directing me to the two bits of data required to assign a cause. I will look into these further and it will be helpful to have them on hand when I speak to the company next.

I'm not sure that they screwed up the supply ductwork, since their installers identified the return issue before even completing the supply install. In order words, they hadn't yet had the chance to see how the unit would perform when the issue first surfaced, but they suspected the problem based only on their observations. Again, I think it was good of them to point it out instead of just closing up the wall and saying nothing. I think it was more a case of they saw the problem and said "Oh crap, we never expected this" and now don't want to be responsible to make the improvements necessary to get the full benefits of the system. The contract is rather vague as you can see from my original post (they are to provide all ductwork and tie it into each individual zone - but are not very specific beyond that). I think this cuts in my favor, since they are the experts and should have either limited what they would cover in the way of ductwork improvements should such issues arise or should now be responsible. But I am certainly interested in your thoughts. Shouldn't they have been able to perform some test in advance to identify this potential issue, since it seems that inadequate ductwork/returns are very common? Thanks again!

Certainly few people understand that supply and return registers should to be balanced right down to the room level. Very common to see a supply register closed and yet the return is wide open - this creates a vacuum in the room that causes a lot more air infiltration from outside.

OK - that's good information sufficient to adjust my earlier guesswork. That very much sounds like a return air problem. The system will struggle to provide comfort and conditioned air losses to both infiltration and exfiltration will be high.

Another tool to quantify return problems is to measure pressure differences between rooms with closed doors. Presently, that test is rarely done - takes a manometer accurate out to thousandths of an inch WC. I believe Energy Star certificatio will start requiring that test beginning in 2012.

Thank you jonr and engineer (and joe for the earlier feedback)!!!! I will certainly look into both balancing and measuring the pressure differences. The big question still remaining - when this type of issue is identified during an install to an existing home, is it understood to be part of the service to provide the necessary return improvements? I recall reading an earlier post on this forum that indicated many installers (including the one making that post) are careful taking job for older homes versus new construction for the very reason that they often can't tell fully what they're getting into. That leads me to believe they are assuming the risk by taking on such a job. Thoughts???

Not sure if this helps, but as I write the temperature outside is 43 degrees. Of the 4 zones, (1) upstairs hallway thermostat setpoint is at 70 and it's not calling for anything (although the master bedroom is certainly 4-5 degrees colder even with the door open); (2) the first floor dining room therm setpoint is 68 and it's not calling for anything; (3) while the first floor family room (which is a build out on a stone slab - original and not addition) therm setpoint is 68 and it's calling for Stage 2 with the door open. I didn't check the basement zone, but keep it to only about 65 since I'm not down there much. Anyhow, when it's colder I often find that the entire unit is kicking on for just that one room, which is independently zoned since we all recognized it was much colder prior to the geothermal install. It would be much, much worse (perhaps not even reaching 68) if the door was closed. Another thing to mention is that there are 3 supplies and 1 return in the family room, but the largest of the supplies comes down from the master bedroom above (not directly above, since the bedroom is over the garage that sits in front of the family room). Thus only the 2 smaller supplies that go under or just above the slab (not sure which) are on that zone. Since that third supply register is not operating unless the upstairs kicks on - which is not as often since heat rises - the family room is making use of at most 66% of its supply ducts (and probably less since the 2 that are zoned are the smaller ones). I asked during the install about the possibility of zoning the master bedroom and the family rooms together given this odd ductwork and because they are the two coldest rooms (even though they are on 2 different floors), but they indicated that it would be difficult and require opening up some walls. I certainly wouldn't mind that if it worked. By the way, the family room is about 20x22, which is the largest room on the first floor, and contains a door to the kitchen, a sliding double glass door (new) to the patio/yard, a double window (all windows throughout house are new) on one wall and a fireplace with 2 smaller windows on the other wall. The last wall is where the return is and the one supply duct from upstairs and this wall is shared with the garage. Do you have any thoughts on zoning these 2 rooms together given the ductwork or any other thoughts given this info?

On a final note, when the home was originally built the large return near the ceiling in the upstairs hallway was placed almost directly above a supply vent near the floor in that hallway. Unfortunately, the installers also put the thermostat in between them, which must make it difficult to get an accurate reading of the entire 2nd floor. Their solution was to close the supply register in the upstairs hallway, saying that even if they moved the thermostat the return would just be sucking back much of the air provided by the supply below. Any thoughts on a solution to that one?

Again, thank you very much thus far - this has been a tremendous help!!!

the entire unit is kicking on for just that one room, which is independently zoned

But they probably didn't size the ducts/vents in that room (or always allow some flow to other rooms) to handle the full output of the unit. If so, that would be bad design that would cause inefficient operation. You might be better off with a well balanced all one zone system.

The geothermal company didn't do any modifactions to the ductwork except in the basement around the unit. So they are essentially dealing with a bad design from when the home was built about 30 years ago. Even when we had only one zone the family room and master bedroom were colder (and they were made aware of that fact). We were hoping the zoning would help - hence having the family room zoned all it's own. We are scheduled to meet with them next week to hear their proposals, so please feel free to share any additional insights that might help in my preparing for this meeting. Thanks for all of your help thus far.

A neighbor mentioned yesterday he had someone insulate the ductwork in his crawlspace and now his bedroom in the NE corner of the house is much warmer. So perhaps sealing and insulation (if outside the conditioned space) shoud be considered as well as the design.