A real fix for Acadia compressor failures

David Friedman

I am an MSEE and ran engineering at Computervision in Bedford Ma. for 16 years and consulted after that for many years.

I put a Halowell Acadia Heat pump in my retirement home in Laconia Ma based on its outstanding specs and rather mundane technology which in my opinion was not at all pushing the state of the art.

My unit failed - and I started researching why - and was able to quickly:

1. Realize that the compressor failures that drove the company out of business were the fault of the start circuit used.
2. I quessed based on technical similarities between T-89 and T-81 compressors that the basis for the error was Bristols suggested method of starting for the newer T-81 line which as you know uses two motor directions for two levels of compression.
3. An earlier implemantation of the Acadia called the ACHP worked fine - but used the T-89.
4. The T-89 was speced to use "kickstart" two wire devices KSTS xxxx
which had no issues.
5. But Bristol insisted that the t-81 be started using a complex arrangement of two dual contact power contactors by GE and two potential relays by GE. The problem which developed either due to the GE contactors being open and thus prone to environmental contamination, or due to the fact that each contactor in the circuit uses one contact to close L1 to R or S depending on motor direction, and uses a second contact to select and later of course drop out the potential relay.
6. What happens is that when the second low current contact (it only handles the potential relays coil current of about 30 ma.) drops the potential relay - perhaps low level arcing occurs and the contact fails open. The next start cycle and the comporessor is subject to destruction since the start cap won't drop out.
6. I have designed - but not tested - a new start arrangement which goes back to the KSTS 2 wire method of puttiing the potential relay directly across the R to S of the motor. I have calculated what potential relay is needed given the Bristol spec which presumes a 3 wire potential relay circuit. Plugging the specs of the GE potential relays used gave me information by to compute the R to S voltage during start at the specified Bristol start cap disconnect times. Connecting this potential relay with the recomended Bristol speced start cap will create a totally viable starting system and eliminate totally the failing mechanism of the Bristol inspired circuit used in the acadia.
7. I have to beleive that there are other AC or Heat pump systems that use the T-81 and my guess is that they may have the same problem.

Post if you have any relavent comments.

beenthere

A potential relay opens itself up.

__________________
How many times must one fix something before it is fixed?

David Friedman

Given the Bristle dual relay/dual contactor circuit - these potential relays never lived up to their pootential and did the job the were designed for reliably.

Joke or not. About 30 Milllion in product sales are on the verge of being Dinasoar'd due to these potential relays not being allowed to to what they wanted to do - namely remove the start cap.

Caps exploded, compressors burned up, literally causing fires in some Acadia's.

I found the problem and fixed it and now want to get the word out. Do you know any HVAC guys that installed Acadia's. If so you can help out by telling them to read my Post and then get the fix next week after the part comes in I need to get up and running so I can claim victory.

The fix is just choosing the right 2 wire start system for the Bristol compressor (T-81) used. The original ACHP's used a virtually identical compressor (T-89) which was speced by Bristol using rectorseal kickstart parts (KST series specifically designed for the T_89 line)

I used the explicit voltage values speced by Bristol for staring the T-81 using 3 wire setups and different potantial relays for each side of the motor - and was able to find a potential relay by GE and configure a simple 2 wire "kickstart" using the compressors designated start cap.

Something is fixed when the underlying physics and electrical theory is applied using good engineerng jugement. I feel my 45 years years of professional experience as a design engineer and engineering manager with a BSEE , a MSEE , and a MS in management qualifies me to have a good chance of fixing something so that it stays fixed!!!!!

beenthere

I know of a few contractors that installed them. And I know of a distributor that still has several Arcadia's still in stock that they won't sell.

If your fix is as you say, "the answer", why aren't you contacting Arcadia with this info, as they are still sort of in business(they got 3 people answering phones, and no one making anymore units). then the 3000 units installed in the military base housing could be fixed.

__________________
How many times must one fix something before it is fixed?

David Friedman

Hallowell is totally out of business. Assets are up for sale by bank. I got involved when my own unit failed after company no longer existed and made contact to some of the abandoned customers and a few HVAC contractors still trying to help people. I dug into my failure and found it to be result of Bristol/Hallowell adoption of a Bristol brainstorm called a dual contactor/dual relay circuit unique to the T-81 TS compressor and found an alternative modeled after "kickstart" two wire starter.
I am:
1. Waiting for parts to repair my unit since my compressor didn't pop (but would have if I kep tryiing to use it)
2. Trying to form a real organization of HVAC groups plus me to act as a solid techincal service support group - hopefully working with F.W. Wells who is stocking spare parts.

All of this is moving very quickly since I first took an ohmeter to my system and starting researching how my failure compared with the multiple horror stories I gathered - and "Necicity is the mother of invention - came to my aid" only two weeks ago.

I would love to contact the service group for the military base but don't have any idea of where or who they are.

Please tell the HVAC guys you know to directly contact me via the blog - or via direct e_mail/telephone. (David Friedman - 978-505-5581) dafried70@gmail.com

And please help me contact the service group for the military base if you know how,

David

David Friedman

"Been there" states 3000 were at military base which was Hallowell's largest customer and mosst visible failure - but that is not true.

There were about 1000 at that one place - and 2000 more sold individually and through distributers like F.W. Webb.

Any one with info as to haw to contact any and all Acadia owners please contact me via either this blog - a smaller Google blog on Acadia's - and or directly.

dafried70@gmail.com 978-505-5581

beenthere

Your right, they advertise 2000 units at the military base. Don't know if all 2000 were installed though.

__________________
How many times must one fix something before it is fixed?