Should we replace the cast iron boiler in our 1968 home?


Should we replace the cast iron boiler in our 1968 home?

Asked by Kathy L

Brick one-story house is 2600 sq ft with 45 year old gas-fired cast iron boiler with baseboard hot water heating and 3 zones. Separate AC and separate gas hot water heater (ready for replacement). HVAC (employee of local gas company) said not to get talked into replacing the boiler, but is this still good advice? We don't want to waste energy/pay too much for gas/electric use. But we don't want to replace anything that doesn't need replacing.

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Sean Lintow Sr's picture

Well Kathy that is a good question and quite honestly it is a pretty hard one to
simply answer.

While the person recommending you keep it may think that isthe best answer, it really does come down to you.

  • Are there ongoing repairissues / how many more years will it remain trouble free?
  • How long do youplan on living there?
  • Is it still operating as efficiently as possible?
  • How well do you stay up on the maintenance?
  • Why do you want / are considering a replacement? Do you want something more efficient, less maintenance issues, have comfort issues which you think maybe caused by it?

In short I would get a whole house energy audit done andget the system checked along with the ductwork. You might find that thereare some minor things you may wish to take care of first which would allowyou to get a smaller unit or maybe an all in one unitwhich can heat your water and take care of your space heating needs using yourbaseboards. Or maybe you'll decide to go with a hydronic based furnace and AC combo.

Anexperienced auditor in your area that knows these systems should be able tocrunch all those numbers for you and tell you which one would make the mostsense based on initial and yearly costs while also balancing that with yourneeds and wants. That is, if you want efficiency and lower yearly costs, theyshould tell you the upfront and give you the best options based on theefficiency and yearly costs instead of fixating on initial costs which manytend to do with paybacks, etc.

One other item to strongly consider is how are these existing unitsvented. If they are atmospherically or power vented, I would strongly leantowards replacement with a direct vent unit.

My last caveat is do notassume, nor allow the contractor to assume that a replacement unit should bethe same size. Not only are many units oversized, but by increasing theefficiency you actually reduce the size needed.

  • For example a 50k unit at60% efficiency produces 30k usable BTU's whereas an 80% efficient unit wouldbe producing 40k.
  • So if you only need 30k, a 40k unit would give you that andthen some extra.

For more information:

The Find A Pro directory on GreenHomeGuide listsapproximately2,500energy auditorsand ratersacross the U.S.Click hereto find one near you.

Read Sean's blog post "Energy Savings & Efficiency 101".