large ac for church

patrickr

greetings.  since I'm a general contractor I've never gotten to "go to the wall" for help.  I've followed Dan for years, preach quality work to my crew and subs, and my trucks sport dead men bumper stickers.  my question involves replacement A.C. at a church i volunteer at.  the dead unit is a 50 +year old ammonia absorption unit that died from lack of use and scale build up.  now the bean counters are talking about putting in five 5 ton single phase compressors.  this means a new 600 amp panel, 175' runs for power and line sets to each unit, tieing into 5 blower units, etc.  shouldn't we be looking at a natural gas absorption unit (25 ton) and reusing the existing lines?  the gas, lines, power for pumps, etc. are existing.

Empire_2

50 Plus years?

If it were me, I would replace everything if for nothing else, to assure there are not other issues with existing Components and the like.    I would feel better starting from scratch, and still use new chiller, but add more control for staging up or down during the peak and off peak hours.  This type of job would be a great opportunity to introduce injection techniques with Primary/Secondary set up with redundant pumps.  Since it is a church, Am I wrong in thinking it for a large common area?  OR is some of the chilled water going to not only the church comm. area, but also to office space.......?



I think there is a wide open opportunity to save a lot of money as far as energy savings, but I think they're going to have to bite the bullet. 



Mike T.

patrickr

gas chiller vs. gas driven compressors

i appreciate the idea of replacing everything.  But it's not in the budget.  And we won't need to have staging options.  The use is all on or nothing and then only 5 to 7 times a year.  we live in a temperate climate and only need the A C in the afternoon or evening for a special service.  (Funerals are bad enough without sitting in a hot humid building)  otherwise we can hold the temp. with ventilation fans.



Does anyone have an opinion on gas chillers vs. gas driven compressors?  what should i stay away from?  50 years from now someone will be looking at what we choose now.  i'd like for them to think that we've done our homework



thanks again.



patrick

707-254-0995

TonyS

Robur makes excellent units

I installed a few Robur units and maintained quite a few of them for the local gas company. They have to be serviced every year by a QUALIFIED certified installer. They can be hard to find. But as your unit testified, life span always exceeded 30 years. Someone that visits this page just installed one of the new heat pump units and posted some pics a few months ago. I would go to Robur.com and see if you can get some ideas. They kinda faded away on residential installs because of the upfront price and because the gas companies now sell electric a/c (who would have thought that 20 years ago) but it could very well be just what your looking for.

Jim Bergmann_2

mini split

I would highly consider a few mini splits. You could most likely get away with a lot less tonnage because you eliminate the duct losses. We did a large church with a 25 ton calculated load with less than 1/2 of that. It cools very well. The cost was about 1/3 of the ducted system. Fujitsu, or Mitsubishi will help you size the equipment.