I was interested in finding out if other Eichler owners have questioned the wisdom of replacing their original boiler, and if so, the conclusion that they came to.
The reason I ask this is because we still have our original AO Smith boiler which many people would say has reached the end of its useful life. The cost to replace the bolier is around $5,000, however when your replace the 50-year old boiler you obviously aren't doing anything to address the 50 year old copper piping that everyone has told us WILL leak at some time in the future. While I know folks say that the 50 year old copper piping will last forever, I don't take that to mean that it will function indefinitely without requiring costly repairs. Knowing that the $5k investment isn't going to solve the old pipe/slab leak issue and that the total cost to replace just a few leaks over the years (i.e. remove new flooring, dig, fix leak, replace new flooring) could very quickly eclipse the $5k investment in the new boiler, i'm wondering if its a rationale decision to replace the boiler.
While we love radiant heat, my gut tells me that replacing the boiler might be throwing good money after bad. Wouldn't it make more sense to use this money to invest in alternatives which would appear to have a much lower total cost of ownership (as well as lower monthly PG&E bills) such as a ductless system which can provide heat and A/C, a base board heating system, etc? We could always run a separate/newer radiant heat system over specific sections of the house (i.e. bathroom floors) that wouldn't require a huge investment in tear out/replace.
There are two sets of piping in your slab; radiant heat, and domestic water. Here is the lowdown on future reliablity of these pipes.
1. Radiant heat pipes-
Most people who have steel pipes have had to abandon their floor heating due to leaks. If you have copper (which you do), most are in pretty good shape and according to Anderson heating, they should last the life of the house. There are issues of slab settling etc. but you should look at your radiant leak history and have a pressure test done by Anderson or any of the advertisers on this site. The copper pipes for radiant heat are completely enclosed in concrete which means their corrosion is so slow it's not worth worrying about.
2. Domestic water-
These copper pipes are lying just below the slab in the dirt. Because of the contact with the dirt, there is lots more corrosion going on. Lots of owners have had domestic water leaks and this is a real problem for owners. I have put cathodic protection on my pipes to stop further corrosion.