Ademco Vista 20P or Vista 50P system?

For your needs the Vista-20P is more than sufficient. The 50 is overkill and won't really give you anything you can't get with the 20P.

=3D=3D=3D=3D=3D=3D> =3D=3D=3D=3D=3D=3D>
Vista 20 p would be way to go 50 does not have some of the features the 20 does like x10 interface.

You may wish to include a power supply. Each keypad draws 150ma in alarm. The Vista 20P only has 600ma for aux power.

As others have stated, the 20P is what you are looking for.
If your house is big enough for 3 sirens (watch out for power problems there as well) it would seem to be too big for only 4 smoke detectors.
Are you putting them inside all the bedrooms?

Thanks to everyone for the rapid response. Wow!
We have a 4500 sq. ft home + a 500 sq ft garage along with a 1500 sq ft out building. We have two existing smoke/fire detectors circuits in the home now, for a total of 20 detectors (at least one per room and two hallways have two each). All of the detectors are hard-wired with battery backup. We would like to simple add "monitored" detectors in a few of the primary areas; we may need to increase to 6.
We would like to install a siren on each end of the home (external) and one near the soffit (hidden) of the out building. I imagine there are limitations on the length of the wire to feed the external sirens. We have 4 extra cat5e wires that are running from the house to the outbuilding at this time (approximately 100 feet of wire in length from central point we would like to install the alarm base).We do not have a lot of immediate neighbors, so the extra sirens may assist in getting noticed. :-)

The external sirens are not of much use (IMHO). Unless you live in a unique neighborhood - when was the last time you called the police because you heard a car alarm going off?
Your response will come from your monitoring station. I would stick with internal siren(s) in the house. The cat5 to the outbuilding negates any need of wireless. It could be used to run a relay board (4204) or a combo zone expander/relay board (4229) and then you could do hardwired zones (less expense, less maintenance, can take temperature extremes better) in the outbuilding and use the relays to switch a power supply driving a siren.
The same data bus that controls the expander also can connect to a keypad out there. With 12 zones in the outbuilding I would recommend one 4229(8 zones w/ 4 relays) and a 4219 (just 8 more zones)
The 20P is a two partition panel (well - three if you count the 'common lobby') so you could have the house and the outbuilding on separate partitions that operate independently from each other. An external siren in the outbuilding would be useful in the even of a break in while you were home.
By enabling and learning the "Go To" feature to switch back and forth between partitions from any keypad I think you will be very happy with the resulting system.
The programming is not that difficult and if you get stuck you shouldn't have too much trouble getting help here in the form of step by step instructions and if you ask right, there may even be a person or two who might help you with with remote programming (though that is never a given).
To get the most bang for the buck in regards to X10 (in terms of ease of use) I would also suggest at least one graphic keypad.
Good Luck!

. =3D=3D=3D=3D=3D=3D=3D> =3D=3D=3D=3D=3D=3D=3D> The Vista-50P uses the same interface that the Vista-20P has
The 15P and 20P were derived from the 50P

the home now, for a total of 20 detectors (at least one per room and two hallways have two each). All of the detectors are hard-wired with battery backup. We would like to simple add "monitored" detectors in a few of the primary areas; we may need to increase to 6.
That's a fairly common request. Most existing homes already have adequate sensors to wake the family and get them out. Adding a few monitored detectors will give some additional protection while the family is out during the day. Just be sure you install the detectors properly and use the correct wire. Since your smoke alarm system is already in place, you can go over what you have in light of the following guidelines to make sure it's complete. Then add whatever you need to accomplish the stated goal and to make certain the system covers all necessary elements. Here are a few excerpts from fire alarm manuals.
-------------
"Do install smoke detectors as follows: -- At least one smoke detector should be installed directly outside each sleeping area. If there is more than one floor, additional smoke detectors should be installed on each level, including the basement. The living-area and basement smoke detectors should be installed near the stairway of the next upper level.
-- For increased protection, additional detectors should be installed in areas other than those required, such as the dining room, bedrooms, utility room, furnace room, and hallways. Heat detectors, rather than smoke detectors, are recommended in kitchens, attics, and garages due to conditions that may result in false alarms and improper operation. Large areas and areas with partitions, ceiling beams, doorways, and open joists will require additional detectors.
-- Refer to NFPA Standard No. 74 (National Fire Protection Association, Batterymarch Park, Quincy, MA 02269) for additional information, including proper mounting of detectors.
Do NOT Install Detectors in the Following Areas:
-- In or near areas where particles of combustion are normally present such as kitchens; in garages (vehicle exhaust); near furnaces, hot water heaters, or gas space heaters.
-- In very cold or very hot areas.
-- In wet or excessively humid areas, or next to bathrooms with showers.
-- In dusty, dirty, or insect-infested areas.
-- Near fresh air inlets or returns or excessively drafty areas. Air conditioners, heaters, fans, and fresh air intakes and returns can drive smoke away from the detector.
-------------
There are length limitations which vary with the guage of the cable being used. Larger cables (smalle gauge number) can go farther.
from central point we would like to install the alarm base). We do not have a lot of immediate neighbors, so the extra sirens may assist in getting noticed. :-)
CAT5 cable is not adequate for most sirens. The 24-gauge conductors can't handle the current for anything larger than a piezo type sounder. For a 100-foot run to a typical siren (for example, an ELK-SS30 which draws just over 1 Amp at 12 VDC), you'll need at a minimum 18-gauge cable. If you can't run new cable and if you have not yet chosen a system, consider using a system with the capability of remotely powered sirens.
I've done this on a number of occasions using Napco's P9600 system. What we did was install a keypad in the remote building using doubled-up CAT5 cable (each pair was used as one wire). A relay expansion module and local power supply at the out building provided power for detectors, a siren and strobe. This allowed us to protect each of several buildings independantly (some structured armed while others were disarmed) yet keep everything on one system. Personnel in the main building can arm and disarm any or all areas simultaneously. We gave some staff codes that could control everything while others could only control the area for which they were responsible. In a home environment this would be used similarly for the maid or babysitter. Similarly, the lawn care person could have access to the garden shed but can not enter the house.
Napco handles this kind of thing well though there are other manufacturers that can also do it if you have the right modules.

That's a valid point, Joe. The primary reason for an external siren is to try to scare the perpetrator off. Perhaps no one will make a call but he doesn't know that. It's hard to guess what will work as each thief is different, but I still like the alarm to make a racket. YMMV.

No problem with that but the guy is describing a power hungry system to begin with.
Any externals would be, if I were installing this system, on a separate power supply.
For the record, I'm all for racket...

Joe and Robert, the two of you are both making some very good points here. You have provided even more food for thought on the matter. Now the tough part, how to tie the requirements together and devise a solid solution that provides the immediate needs, while leaving a little room for any future changes (room addition, additional out building). I am all for being energy efficient too. :-) I just got home from church and now have a few minutes to research a little more. I am still confused on the expansion modules, relay/non-relay, and how to separate the out building (believe that was a partition if I read above correctly). I might also add, all door and windows currently had a cat5 wire running to them already. When we build the house, we installed a wire for that purpose. If the wire is not large enough I suppose we could twist a pair of wires together to increase capacity. We did not wire for add-on motion or smoke detectors. There are plenty of ways to add additional wires so I am not worried about the add-on items from a wiring perspective. Initially I think wiring doors, windows, and smoke alarms will give us the most bang for the buck. Well, I think.. :-)

Great feedback on the smoke detectors! Thanks!
I like the idea of separating the outbuilding on another partition (if that is the correct term) and installing a keypad just inside the outbuilding door. That is an awesome idea! From a technical perspective, I can grasp the general idea of separating the area; however, from an alarm perspective, I am not sure how to spec/order the right expansion module that will provide that level of coverage and remotely power a siren too. I suppose a little more research and we will be good to go. Bob, I see you also sell alarm systems. I may contact you via telephone to discuss further, if you do not mind.
=3D=3D=3D=3D=3D=3D> =3D=3D=3D=3D=3D=3D>

That's true. In general though, I believe it's a good idea to have at least one loud, outdoor siren. YMMV.
Same here.
Tennis, anyone? :^)

No problem. I'm usually around during the day though I don't stay in the office. When you call, ask the girls in the office for my cell phone number.

It's not as complicated as it might seem. Once I know how many sensors there will be in each area I can make suggestions regarding hardware and how to configure it.
Each manufacturer has various types of modules with several inputs, outputs or both. First you decide how much "stuff" will be in the system, long term. From that you can select an appropriate system. The fine tuning is just putting a few pieces together.
Some companies use the term partitions. Others say "areas". Either way it's the same idea. After you wire up the system to the panel you assign keypads, zones (sensor loops) and output devices to each partition. For example, if there are three doors, one motion and rwo smokes in a guest house, we would program all of those items to "Area 2". By default, the rest is already in "Area 1" which would be the main house.
Specific outputs (such as sirens and strobes) can be assigned to activate when specific zones (sensor loops) are tripped or when any sensor in the system trips. You make a few decisions about what the system should do and I can walk you through programming it. It'll be a learning experience, but not all that hard.
CAT5 is not the ideal cable for door and window sensors mainly because the overall cable is larger than the stuff we normally use. The individual conductors are a tad smaller than usual (24 rather than 22 gauge) but that's not a problem with cable runs of a 100 feet or so. Magnetic door sensors don't draw any current. For motion detectors you can double up on the power leads as you mentioned and it'll be OK.
That'll be fine, except for smoke detectors. For those you'll want to run the proper wire.
I'll send you a simple schematic that illustrates how to wire for the smokes.
That's a good enough start. You can add more things later as time allows and as needs progress.

Nah - it's just handy for law enforcement if the loud noise in the dead of the night startles the bad guy into having a bit of DNA running down his leg as he makes his get away...

Ick! What a graphic imagination. :p