I have new a Laars Minitherm JV225NDISU2 natural gas forced hot water boiler with six zones of baseboard. When the previous owner added a kitchen and dining area in 2004 they added the sixth zone and also expanded the basement zone. The tubing that returns from the kitchen and basement baseboards is black rubber “½ ONIX” instead of the peach-colored plastic “PEX” and copper that connects the rest of the heating system.
My boiler guy says I should replace the ONIX tubing with proper PEX tubing. He says the rubber is deteriorating and will eventually gum up the pumps and may leak because it is not rated for the high temperature of the boiler. He drained some water from the boiler to show me its dark color. The water was fresh/clear in July. He says I should hire a plumber.
Do you think the tubing should be replaced? Will it leak or just gum up the pumps? Replacing the tubing is a huge job because there is no access under the kitchen - the crawl space is blocked by a beam - so the plumber would have to cut through the floor. Also, the basement tubing is behind walls. And a bedroom above the kitchen also uses ONIX. Replacing the ONIX is such a big job that it may be cheaper to replace pumps as needed.
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