Hopefully this information will help. I would ask for references and then CALL them. Be sure to ask how the reference heard of the contractor, could be his bother-in-law. Ask if he: is licensed insured bonded who does the electric work who does the hook-up to water supply is a permit required
Ask what brand of equipment they will use and ask what grade of equipment. For example Rain Bird has several levels of equipment, one is what you would buy at most home centers for consumers and the other line is for professionals. There is a difference between the two. Just because the consumer has a lifetime warranty is not enough to call them equal. Do you want to have to replace these a couple years down the road? Hope you can still find the receipt.
I used to install systems so let me tell you what is involved then you can ask questions based on this. One thing to keep in mind is you location. Do it freeze there? If so be sure to ask what you contractor will do to prevent the system from freeze damage. Best solution is to put automatic drains at each head with gravel under it. These drains are inexpensive and work by pressure. Water pressure causes the drain to close, no pressure then the head drains.
Water supply (city, well, pond/lake) – In designing a system you will need to know the flow (GPM) and pressure (PSI) of your source. Every head has a specification of how much pressure and flow is needed. This is one of the things that determines how many zones you need. If you have a complex system there are tables to aid in the flow/friction through the pipe and number of fittings can come into play as well. But this is not the case for most residential installations. Be sure the contractor does plan to install an backflow device most codes require this. In the event the pressure from the source drops there is the potential for the system to backflow into your water source. This means dirt, fertilizer, insecticide, fungicide………. Will get in to your water source.
Controllers – These are the devices that will control the valves. There are numerous controllers on the market today. Again there are consumer brands and commercial. You want a timer that will allow multiple programs. For example you want a timer that can have a program for the lawn, one for the shrubs, one for the flower beads . These programs are independent from one another. You will also need a rain indicator. This is a small device that is wired to the controller that is adjustable based on how much rain you receive. This device overrides the controller and shuts the system down when you have had an appropriate amount of rain.
Valves – My strong advise here is to go with stainless steel internal components. Good values will allow you to rebuild the value from the top without having to remove it form the ground. The value(s) should be in a value box. I generally put small gravel in the bottom of the box and along the side as well to keep dirt out and allow water to drain. It is a good idea to put the values close to the controller. This means having to pull more (a lot) pipe but you will not have wire running from the controller to every valve box location scattered throughout your lawn. I run a PVC pipe from the controller to the value box that contains the wiring. It get expensive trying to track down broken wires underground and most time is easier just to dig and replace. If you keep the valves close to the controller there is not as much wire.
Heads – These go for $5.00 to $100. You do get what you pay for. I tried the low end heads once and over five years replaced everyone. Glad this was in my yard and not a customers. The low end ones are made from plastic with a metal spring. The better ones are made from plastic but have some stainless or bronze, are gear driven and have a selection of nozzles available. Nozzles do matter, you have a zone that has a head that goes in a full circle and a head that does a quarter circle you need to put a smaller nozzle in the quarter circle or a larger nozzle in the full circle in order to get even coverage. Heads should not be connected directly to PVC pipe. Parts break easy this way, no give. Head should be connected to PVC using flexible PVC. Do not place heads close to driveways or streets (damage form edgers, snow plows, cars). Here is a common problem, proper spacing. You should have head to head coverage. The heads will have specs on spacing based on GMP & PSI. If the head has 15 foot spacing put the heads every 15 feet DO NOT let anyone talk you into spacing them 30 feet. The water pattern is design for overlap.
Sorry this is so long but believe me I could keep going. I do not want to knock anyone out there trying to make a living but this is a business that is easy to get into. I did this work for many years and I made a good amount of money just fixing systems that were poorly installed. It is rough telling someone that the system they paid $1,000 for last year need $600 worth of repair this year. And it could have been installed properly for $1,300.
I guess the big thing here is DO NOT shop for price only. You said you travel a lot. Don’t you want to know that your landscape is being watered properly and don’t want the surprise of a returned trip to find brown grass?