The previous owners never left a manual or anything and I can't find this info on the website or anywhere. I'd rather not call out a tech if I don't have to.
Dany Y is right on the pressure. Most systems are set up with an automatic filling devive that reduces your water line pressure to 12 LBS. You may have a manual valve in place but be careful not to overfill. Hot water boilers have a relief valve that pops off at 30 LBS.
Several people have answered 12-15 psi. this is partly correct but there is a thing called expansion that takes place when water is heated.So 12-15 psi is correct when the boiler is cold but as it heats that pressure is going to go up.There is an expansion tank to absorb this expanding water but the pressure will still rise some.Someone else stated that there is a relief valve that opens at 30 psi. and this is correct.Therefore the pressure on the boiler will depend on the temperature, but when it is at it's highest temperature the pressure should not go over 25 psi.This will give a little cushion before the relief valve opens.
Look at the identification tag that should be on the boiler. Get the name of the company, where they are located and the model number of the boiler. Call them, or see if they are on line, and get the information from them. The gas company should know as well, and can provide the information as well, or tell you where to get it. They shouldn't need to send out a tech if all you need is some information. is in their best interest as well as yours to supply information about things that use the fuel that they supply to you.
The water pressure on the gauge should be @ 12-15 psi.
Yup, assuming that the boiler is in the basement, 12-15 is good. If you have a two story home, you may want to boost it to 15-18.
