On Mon, Aug 03, 2009 at 05:58:11PM -0400, Patrick Shoemaker wrote: > I think you'll find that to get a propane/NG generator installed on a > commercial building rooftop, you'll be looking at $10k minimum using > even the cheapest Generac air-cooled units. You'll need a roofing > company to come out and modify the roof to provide a mounting surface > for the generator, that will probably be the biggest cost. Getting > management comfortable with modifying a $300k roof membrane could be an > issue as well. Then getting gas to the unit from the building's gas > supply will require a plumbing contractor, permits, inspections. Then > the electrical hookup- more permits and inspections and a licensed EC.
Also add a $1-3k for a good auto transfer switch. Maintenance such as oil changes and testing can also run a couple hundred a year in labor and materials, so that adds up over the life of the backup power solution. We've also seen propane delivery companies forget to keep the tanks full due to the unpredictable propane usage. And we've had weather so bad, propane trucks couldn't refill till spring if they wanted to. I am a big fan of whole building generators though. It's warm and fuzzy to keep a building going like normal when nobody else has power. I certainly understand the need for planning power consumption to scale with needs and growth. We consider power consumption in almost every equipment purchase or upgrade. Many upgrades decrease power consumption, like newer managed switches or newer PC hardware, making site runtime better. > I just got a quote for qty 8 110AH 12v AGM batteries for a new site: > $1500 including shipping. > > A note on the Generac air-cooled generators. They break. All generators > break. The key is routine testing and PM. The generac air-cooled models > don't have any provision for automatic alarm reporting. So when a > battery dies or gas valve sticks or spark plug fouls or whatever, you > won't know about it until a manual site inspection or the power goes > out. The better generators (and the Generac liquid cooled models) have > contact closures or RS232 interfaces to report these conditions to your > site monitoring system, in turn notifying you back at the NOC. > > > Patrick Shoemaker > Vector Data Systems LLC > [email protected] > office: (301) 358-1690 x36 > http://www.vectordatasystems.com > > > Tom DeReggi wrote: > > We also use the triplite APS inverters with good quality Gel cell. > > Actually, > > we got a good 15 years out of the existing C&D batteries, because we > > inherited them from Teligent days :-) > > But new, qty 4- 12V 150AH batteries in series for about 3500watt and decent > > run-time is $1400. + $800 for replacement inverters. (The Triplites worked > > really well, but about half of them died by the end of eight years. We > > matched good inverters with good pre-existing batteries and vice versa.) > > So > > our thought was.... Why not buy a $2000 generator for the run-time and > > load, > > and then several smaller UPSes for infront to cover the surges, power > > conditioning, and monitoring? Ones that keep running even when batteries > > short out. Part of the reason we are investigating is that we now have > > duplicate need of devices to power. Some are AC devices like PC routers. > > Some are 20-24VDC w/AC adapters. Some are new licensed gear running on 48V. > > Cost is increased having long battery run time on both seperate AC and DC > > backup power subsystems. And how do we plan for load growth? How many new > > radios installed will be AC or DC? Unlicensed versus Licensed? We really > > dont know in advance. There is a lot of power waste going from AC to DC to > > AC to DC. > > > > The thought was... If long run time was accomplished by the propaine > > generator, both DC and AC battery subsystems could be installed with lower > > cost lower run-time batteries. We'd still need to account for max watts > > growth for each subsystem, but we could way reduce AH requirements for both > > subsystems. > > > > Or am I making this to complicated, and better just sticking with batteries > > :-) > > > > Chris Erikson's idea on solar panels sounded interesting. Although, I bet > > my > > ruthless roof rights people will try to charge me a monthly colo fee for > > them :-( > > I wonder if I can make the solar panels look like rain/weather shields :-) > > > > Tom DeReggi > > RapidDSL & Wireless, Inc > > IntAirNet- Fixed Wireless Broadband > > > > > > ----- Original Message ----- > > From: "jp" <[email protected]> > > To: "WISPA General List" <[email protected]> > > Sent: Monday, August 03, 2009 12:11 PM > > Subject: Re: [WISPA] Small auto start generator > > > > > >> The tripplite APS is what we use for this. Small generators are a pain. > >> > >> On Sun, Aug 02, 2009 at 02:57:23PM -0430, [email protected] wrote: > >>> You might want something like an inverter (Xantrex for example) which > >>> includes a DC to AC inverter, battery charger, and automatic transfer > >>> switch. Add the batteries and you're done. > >>> > >>> Greg > >>> > >>> On Aug 2, 2009, at 2:38 PM, Jerry Richardson wrote: > >>> > >>>> Thank you, > >>>> That is very good advice. After some research, I'm leaning toward a > >>>> UPS. > >>>> > >>>> A pair of good AGM batteries and charge controller will cost less > >>>> and be far less maintainence. Then I'd just run the CMM off the > >>>> batteries @ 24VDC. > >>>> > >>>> Thanks again > >>>> Jerry > >>>> > >>>> > >>>> -----Original Message----- > >>>> From: [email protected] [mailto:[email protected]] > >>>> On Behalf Of Gary Garrett > >>>> Sent: Sunday, August 02, 2009 11:59 AM > >>>> To: WISPA General List > >>>> Subject: Re: [WISPA] Small auto start generator > >>>> > >>>> Small generators do not auto start very reliably. > >>>> When cold or dampness causes hard starting the starter can overheat > >>>> and > >>>> burn out. Generally you need an electric choke to start gas engines, > >>>> propane can "flood" and need to rest before trying again, diesel can > >>>> be > >>>> REAL hard to start when cold. Auto starters can not adapt to changing > >>>> conditions. > >>>> Our best generator is a Propane Ford inline 6 cyl. 25 KW 3 phase. > >>>> (1955 > >>>> Model) > >>>> The monitor cranks for 1 min then rests and tries 3 times. > >>>> Everything is > >>>> adjustable. It knows to stop cranking when it sees AC voltage from the > >>>> Gen. so the motor over runs the starter for just a few seconds. Only a > >>>> huge starter motor can take this abuse and last unattended. > >>>> > >>>> You may be money ahead to find out why the existing generator is not > >>>> starting and get it fixed. > >>>> > >>>> Jerry Richardson wrote: > >>>>> We rent on a tower that is suspposed to have gen-set backup but it > >>>>> does not start reliably. > >>>>> > >>>>> Any recommendations on a small auto-start generator? We only need > >>>>> to power a CMMmicro - ~100watts. > >>>>> > >>>>> Thanks > >>>>> > >>>>> > >>>>> > >>>>> __________________________________ > >>>>> Jerry Richardson > >>>>> airCloud Communications > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> -------------------------------------------------------------------------------- > >>>>> WISPA Wants You! 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