Bad experience with Unico

[Ellenran]

I thought this thread was about someone having a bad experience with Unico. That's how I happened across it, and was surprised that Bryant, my installer, was also mentioned in the thread.
For the sake of others, I told my own experience with their equipment. Wish I had had the benefit of reading about problems with the unit before I signed on the dotted line.
I have not talked to Unico myself. Both my HVAC contractors have been in contact with Unico of course. I did ask Bryant for documentation of all we have gone through so I could give details to Unico in writing, but I have been unable to get that information from them. If I really believed it would make a difference, I would pursue it. I'm afraid it might be beating a dead horse.
I'm not wishing to hyjack the thread, but I AM answering questions. Should I not answer people's questions/accusations?
(As for the sizing of the unit, we told them in the future we would be finishing the full basement (permit pulled now) which adds another 1850 square ft, and above the detached garage another 650.)

[MM#7]

I thought this thread was about someone having a bad experience with Unico. That's how I happened across it, and was surprised that Bryant, my installer, was also mentioned in the thread.
For the sake of others, I told my own experience with their equipment. Wish I had had the benefit of reading about problems with the unit before I signed on the dotted line.
I have not talked to Unico myself. Both my HVAC contractors have been in contact with Unico of course. I did ask Bryant for documentation of all we have gone through so I could give details to Unico in writing, but I have been unable to get that information from them. If I really believed it would make a difference, I would pursue it. I'm afraid it might be beating a dead horse.
I'm not wishing to hyjack the thread, but I AM answering questions. Should I not answer people's questions/accusations?
(As for the sizing of the unit, we told them in the future we would be finishing the full basement (permit pulled now) which adds another 1850 square ft, and above the detached garage another 650.)

i'd call unico!

[coolwhip]

For what its worth, I have installed about a dozen Unico systems in large homes and historical buildings. I have not installed chillers that you have described in your posts though.
I would like to say that I have not had any problems with the equipment as long as preventative maintenance is maintained.

It sounds to me like the problems you are having are due to improper installation.

[tedkidd]

Ellen, you have a very interesting situation. What you are doing on the building side sounds great. That the HVAC side was addressed as a product rather than a solution is incredibly common. People routinely have the attitude; "Eh, over sizing only means equipment costs a little more."

There is a home builder in Massachusetts building net zero homes, which would be the next step for you. But getting the critical importance of good HVAC design and BALANCE will be the first step, and you can get much of that here.

Why don't you start a thread, it could be titled something like "chiller design for residential applications".

[Shophound]

Re: Ellen's residential chiller application. Question arises in my mind what thought process was behind choosing a chilled water approach for 3,000 square feet vs. split system DX, one system per floor.

Re: Ellen's situation directly; appears to be two problems. One: system design, and possibly structural/architectural design...HVAC can't keep up with heat gain. Two: high failure rate of parts that should not be expected to fail so soon after installation.

The passive solar aspect also piques my interest...how much is this penalizing the house during the hot months? And what exactly does this passive element consist of? Large areas of glass?

[Ellenran]

Thanks for all the ideas and suggestions.

I WILL contact Unico, but hope to go obtain copies of my records from both the HVAC contractors who have worked on the house's HVAC design and dealing with the many problems. It would be great if Unico would come out and see what we are dealing with. I'm thinking that Bryant DID bring a Unico rep out here before he switched out the chiller. I've been told we did not get a New second chiller, but a reconditioned one. How can you know?

I could send a photo of the house if that would help. The passive solar design has vertical (not slanted) windows, most with 3 ft. overhang but there is one section that still needs a trellis built. We utilize thermal shades on those windows right now as a temporary solar block. The house design was scrutinized by NCSU's Solar Center Dona Stankus, AIA, LEED AP Homes, LEED AP. She is a registered architect and the High Performance Building Programs Manager at the NC Solar Center in the College of Engineering at NC State University.

We went with a high velocity system because of wanting to save room for the ductwork (and remember we have SIPS so no using the exterior walls for ductwork either). We went with a water system to utilized the active solar system to help supplement the radiant heating in the floors. The radiant heat is fantastic. Love it.

[Shophound]

I could send a photo of the house if that would help. The passive solar design has vertical (not slanted) windows, most with 3 ft. overhang but there is one section that still needs a trellis built. We utilize thermal shades on those windows right now as a temporary solar block. The house design was scrutinized by NCSU's Solar Center Dona Stankus, AIA, LEED AP Homes, LEED AP. She is a registered architect and the High Performance Building Programs Manager at the NC Solar Center in the College of Engineering at NC State University.

We went with a high velocity system because of wanting to save room for the ductwork (and remember we have SIPS so no using the exterior walls for ductwork either). We went with a water system to utilized the active solar system to help supplement the radiant heating in the floors. The radiant heat is fantastic. Love it.

This place loves photos; always cranks up the conversation a few notches. Would like seeing a pic of your place if you don't mind.

With SIP construction, may I assume your roof is also formed by SIPs? I know some SIP designs only use them for walls and then build the roof conventionally using trusses or stick framing. Other designs use SIPs for everything, including the roof deck, which IMO if you're going with the SIP method is the smarter choice.

Hot water is used for radiant heating; may I assume it is redirected to fan coils for summer cooling (IOW the same treated closed water loop used for the radiant heating is also sent through the chiller in summer and circulated between various air handlers)?

Do you know what temperature the chilled water coming out of the chiller is, and what it is set for? Is there a buffer tank in the chilled water loop?

Is the attic in this house conditioned space?

[tipsrfine]

The only Unico chiller I've seen was back in my training days at school. I remember not liking the design of the double wall condenser coil due to it being too hard to keep clean. Any cottonwood trees around and that thing is done for pretty quick.

[Ellenran]

I attached some photos, hope you can view them. We built the house with centuries in mind. Stone is fake but a good imitation.

SIPS are 8 inches in roof, 10 inches on the flat roof terrace. Attic is all conditioned space (but not included in square footage since it's under 6 feet at the peak), they are just lofts for the kids bedrooms and the upstairs AH is up there, other AH is in basement.

I'll get the info on the chiller cold temps and other design elements from my HVAC guy, who I am hoping is coming SOON because my system is down again (its 95 outside). He tried to repair the leaking reversing valve last Friday, but I'm guessing the repair did not last and we are out of coolant. It is NOT cold now.

Chiller looks clean and no cottonwoods here.

[Shophound]

Nice photos.

My next question is...does this system, when it's not suffering from some form of component failure, nor is low on refrigerant, cool the house adequately on a hot day?

[Ellenran]

Yes, on normal days, with no failures, it cools sufficiently, we set it at 75 main floor, 77 upstairs. I'm sure it will help to get the trellis up over the livingroom windows. The only time it did not cool okay was when we had a large group (about 30 people) over on a hot day in the living room. I learned we need to chill the house a bit lower ahead of time when we anticipate a large crowd.

I remember asking Bryant about putting more outlets in the LR, but he was reluctant to do that, wanting to eliminate others (like the north MBR area) rather than add more. So he was acting like we were maxed out. He's hard to get a hold of, or I would chat with him more about it.

[Ellenran]

To answer the specific questions, yes the water from the Unichiller is
redirected to the air handler in the summers and does not pass through the
radiant flooring. In the winter, heated water from the Unichiller is
directed to pass only through the radiant flooring, though we have the
ability, if we wanted, also to pass it through the air handlers. The water
is chilled to 45 degrees and normally reaches that temperature. There is a buffer tank (standard size water heater is used for this). More specifically, the water from the Unichiller is pumped in a loop through the buffer tank. One injector pump then takes the heated or chilled water from this loop and circulates some of it into another water loop that passes through the air handlers. A different injector pump circulates some of the water from this main loop into another water loop that passes through the radiant floors.

[Shophound]

Thanks for answering my questions.

So, it seems your system is able to deliver on capacity in both heating and cooling modes when there are no component or functional issues with the system. Is that correct?

Now, another question. Did Unico make your entire system, or just the air handlers? Is the heat pump/chiller itself made by Unico, or others? Is this system a high velocity duct arrangement, with small ducts and outlets?

[beenthere]

http://www.unicosystem.com/Home/Prod...0/Default.aspx

[Ellenran]

Yes, this is a Unico Unichiller, all unico parts including the high velocity 2 inch ductwork/outlets.

I talked to Mitchell, our second HVAC guy tonight, and he said the 5 Ton unit is certainly NOT oversized, and that the Unico rep he talked to said it might be okay to add the basement to the system, if all zones weren't demanding a lot of cooling at once. Basement temp with no conditioning, after a 95 degree day (and weeks) is 79 (our kitchen was 87 at 6:00pm with no AC).

the photos by the way, are of the southeast, and west exposure.