I have a rozen base board heating pipe. I don't know where it's frozen. Most of the pipes run along the outside wall but are difficult to reach because of how they are hidden. Is there an easy fix?

NO. If the system was shut off or not calling for heat for a long time and it froze someone will be in the hurting when it thaws and floods so I would shut down the boiler if possible and also kill the water supply to prevent more damage.

We found the burst pipe. Isn't there new pipes that are similar to hoses that we can replace the burst pipe with?

I guess there is since anything can be replaced today but being a old guy I just replace copper with copper etc. If you want to use the new style plastic heat pipe like PEX you are going to have to solder or mechanically attach the adapter anyway.

I agree with hvac1000. Replace the copper with copper when dealing with hot water heat piping. Also, it may be time to add antifreeze to your boiler system. This will prevent any future freezing problems. Make sure to get the correct antifreeze for your boiler(we are not talking regular car antifreeze here). It cost a bit, but will save you any future headaches of this type.

How do you add antifreeze?

You have to pressurize the antifreeze or install it into the system under pressure. Usually years ago we would blow the system and all zones down with compressed air then attach an electric pump (pony pump we called it) and fill the system to its normal capacity. Once the system is up and running we would top it off if necessary. If your system has any leaks then it will take an on demand setup which I will not go into since it is reserved to a more professional audience (Very complicated). A recovery bucket setup might be required by code if your area has laws against sewering or discharging antifreeze.

I actually would advise you to have the antifreeze done by a professional to start with since then there is a guarantee involved.

If the system was set up correctly(to today's standards) there will be boiler drains on the supply and return piping directly off the boiler. You use a pump and pump the antifreeze into the system through the boiler drain on the supply side through a garden hose. At the same time you will let the water out through the boiler drain on the return side(hooked to a garden hose that is run to a drain, or outside.) I suggest having a boiler tech, or plumber come in to do this. They will have the correct equiptment to do it properly, and the knowhow to add boiler drains if nonexisten on your current system.

I would like to thank everyone that responded to my questions. You've been very helpful

Thank you for responding. Please let us know how everything turns out. Good luck, take care. Lee.

Ditto here. Here is a pic of a fun boiler system.

Thanks for the pic hvac. Id love to tackle a job like that. Looks very professional.