Old Servel gas A/C

[ct_hvac_tech]

My aunt, who bought her house in 1977, is finally thinking about replacing her furnace and A/C this spring.

I got to thinking about this system after she was talking to me about it, because I had not even been in her house since I was 8 years old, but I remember the system rather well.

The furnace was this dark grey gas unit, and I think he name was Brentwood....It is the only furnace I have ever seen with that name on it. I think the name was actually on a label with some kind of logo that was a light blue oval with the name inside of it.

What I always remember more than anything was the A/C. I was always curious how the system worked, but I never have gotten to work on one, and I don't even really see any units like this around anymore.

The condenser was a big blue thing that was made by Servel.

Here are a few things that I always had questions on, but never really knew anyone that could anser them.

1 She had to have a company come out every spring to service it and start it - she said that the original company told her that during the winter when it was not being used, it shut itself off inside and needed to be restarted in the summer. Ever hear of such a thing?

2. The WEIRD sequence of operation. When the thermostat called for cool, the indoor blower started, but the condenser did not start for about 3 minutes after the call for cool. I figure maybe this was a delay on make control, but here is where it gets strange:

When the thermostat satisfied, the indoor blower stopped right away, but the outdoor condenser unit continued to run for about 3 minutes after the thermostat satisfied. I never did understand why.

3. The unit never cycled from the time it was new. She said she had to keep the thermostat at 68 because the house just would not stay cool if she had it any higher. If she let it run 24/7 the unit would keep running until 2 in the morning when the house finally got down to temp, but once it started back up, around 7 or 8 in the morning, it would just keep running all day and into the night.

She said it ran that way from the day it was installed. So, could this mean that the unit was never charged properly from the start? Or is gas A/C just not as fast to cool as electric A/C?

I would love to hear from guys who worked on these - did you like them, were they hard to work on, were they good units, ETC.

[Catpower]

If it's been running since 77 it must be a pretty good unit.

It's an absorbsion chiller, it was power by gas and they were a pia if they wanted to be. Sometimes oever the season they can get uncondesables in the "tower" that you had to vent.

They used annhydrous ammonia for the absorber, so everthing in the outdoor unit is steel.

If you change it make sure you have some strong backs to help move the unit as they are heavy as hell.

[pecmsg]

Come on CT, you’re the one with the camera. Post some pic of this dinosaur!

[HeyBob]

The Brentwood was made by Lear Sigler, always rotted out just above the burners, usually right over the pilot.

The Arkla Servel unit wasn't bad to work on, my Dad did a lot of them, I stay away from amonia..........

[t527ed]

the utility company around here did the work on them so the only time i ever saw one was to tear it out.

they were some heavy sum b!tches.......

[timebuilder]

I have a friend in Harrisburg who has one. I did some searching around to find a guy that used to work for UGI who knows absorber chillers. He comes out and does the startup and shutdown for her, and he is very reasonable. If it doesn't have a compressor, I'm lost!

Thew unit works great. She checks the water once in a while, and she's good to go!

[dougvhvac]

Pulled one out when I first got in the trade, very unusual unit. We had been warned about the ammonia being 'bad' stuff, certainly worth remembering if you end up working on it or removing it. The condenser was so big and so heavy, we hired a crane to lift it out of the backyard. He couldn't get his outriggers all the way out, started to tip once the weight was fully on the boom. Then he made a mistake, backspooled the cable and hit the brake just before it came back to ground. Bent the boom, made for a very unhappy crane operator. Might be easier to turn it into a garden shed than remove it.

[DeltaT]

Gas companies pushed them really hard in the 60's and 70's. They are absorbsion chillers and not a typical condensing unit. When the TStat called for cooling the Servel took a while to produce chilled water so hence the delays.

The thermostat actually lit up a burner(s) inside the Servel, which heated up the chemicals inside the sealed chamber that caused the cooling effect. Once cooling started there was also a small chilled water pump that pumped the chilled water to the inside cooling coil. So the lines run into the home should be water lines and not refrigerant lines.

Two big problems. Sometimes while operating or sitting over the winter the salt brine and the other chemicals would separate and a technician had to go through a process to get the thing to cool again.

Second problem is the design temp of the chilled water was not as good as a DX system in removing humidity. And most of those systems, including the large commercial ones, were sold and installed on the East Coast where humidity is a big part of the comfort picture.

The complications and the initial install costs pretty well did them in.

If you find any technical info, pictures or sales brochures a few of us on this board sure would like to see them.

[Milk man]

the utility company around here did the work on them so the only time i ever saw one was to tear it out.

they were some heavy sum b!tches.......

I helped take a couple out. Broke in the boss's new pickup one morning with one. Squated it (little baby truck) and left huge scratch marks in the bed.

The other one the foundation company used a bobcat to move it. I told them I'd cut it away from the house but would not hook it up again. The HO was buying a new system anyway.

[madhat]

I used to work on them under a guy named Brian West way back when. Had me do everything accept the ammonia side. A big problem with them is people dumped automotive antifreeze in them, since they were open to the air it would foul, and coat everything with a slime. Brian West had a solution he made up himself, it's been too long to remember what it was. I do remember mixing Methyl alcohol with it, because it was so dangerous. A properly tuned system would actually out cool and dehumidify better than a Compressor system due to the coolant tank and lower than refrigerant temperatures, and the fact the whole coil was at a colder more even temperature.

[cbh04]

I def. remember the slime! wash out the chiller barrel n drip tray, might've been the original double row condenser coils, and you had to wash between them, but ya couldn't split em, but there was a bout a 1/4" spacing so it could be done. Remeber venting off the noncondensables into a bucket of water oh so slightly!!! didn't want that hose whipping round! generator would get sooted up because the burners would get fouled, that had to have been asbestos in there! well, at least it was wet then. Once ya knew them, they were pretty easy.

[madhat]

ct_hvac_tech, Does your Aunt live up north? I have relatives that live in upstate New York, they cool their houses with city water, the water is pulled off the main thru the regular house meter, thru the cooling coil, especially made for potable water. Then thru a small bronze pump, another meter and back into the main downsteam. The water authority is happy to have them temper the water, of course they don't need much cooling.

[Milk man]

ct_hvac_tech, Does your Aunt live up north? I have relatives that live in upstate New York, they cool their houses with city water, the water is pulled off the main thru the regular house meter, thru the cooling coil, especially made for potable water. Then thru a small bronze pump, another meter and back into the main downsteam. The water authority is happy to have them temper the water, of course they don't need much cooling.

Is the water cheaper to use than electricity?

[madhat]

They pay close to nothing for the water returned to the system, mostly it's just to maintain the meters, under ground lines and connection points. Also the system water line is a big loop and a lot of houses already have a smaller loop with water flowing in and bypassing the meter and back to the main. I understand this is to prevent freezing and if they have a problem they can still supply water.

[ct_hvac_tech]

I def. remember the slime! wash out the chiller barrel n drip tray, might've been the original double row condenser coils, and you had to wash between them, but ya couldn't split em, but there was a bout a 1/4" spacing so it could be done. Remeber venting off the noncondensables into a bucket of water oh so slightly!!! didn't want that hose whipping round! generator would get sooted up because the burners would get fouled, that had to have been asbestos in there! well, at least it was wet then. Once ya knew them, they were pretty easy.

Sweet! Do you by chance have any info on how they worked?

Also, does that sequence of operation I described make any sense?

[DeltaT]

Sweet! Do you by chance have any info on how they worked?

Also, does that sequence of operation I described make any sense?

Back in the 60's & 70's there were tons of info and sales stuff showing how these simple machines worked. There has to be some of that stuff still around. I'd check with the local gas company first with anyone who is over 50.

I'm sure someone in the gas company kept the sales/technical items in stock somewhere at the office or home.

They were very simple with basically no moving parts cept the water pump. Three chemicals were inside the sealed chamber. A NG burner was below the sealed chamber and heated the chemicals. As the chemicals rose through the chambers they went in different directions according to their specific gravity. One removed the heat. The other chemical(s) caused a refrigeration effect and chilled the water that was sent into the house.

Everyonce in a while for no apparent reason the chemicals would stick together so service had to be provided.

Do a search on EBay too for anything to do with these systems. Back in the days there literaly were tons of sales/technical items showing how they worked internally.

[oroy54]

Pat, as far as the A/C and heating is concerned. Back in the mid 60's the city of Rosenberg, Texas would offer free natural gas to anyone who would take roots there. The Serville unit's would of been a God send. Now lets go meet some Mexican girls.

[blabath]

I used to work on a Servel Unit installed in a local bank about 15 years ago. The only thing I ever had to do was remove the non-condensables, relight the damn pilot once or twice a year and clean the surface dirt off of the cabinet when I was washing the condensor coil on the DX unit next to it. I went to work for a Union mechanical contractor and the bank could not afford the higher labor rate. Later they hired another local contractor to replace it, I meant to get the old Servel to take to the UA training center but I lost track of it.
As I recall, and it's already been said here, the unit did a great job, was basically bullet-proof, and lasted forever. I'm pretty sure the only reason it got changed out was because the local guy had no idea what it was.

Here is a picture illustrating how it worked....

[woody19]

I worked on absorbers from 25 ton Arklas to 650 ton Carrier units. They used lithium bromide as the solution. Only worked on a couple smaller units with ammonia and didn't care too much for them. Taught classes for So. Cal Gas Co. on how to service those that they installed. Actually enjoyed working on them. Thought I'd never hear anything about them anymore and threw out all the manuals I had about six months ago.