Boiler repair versus replacement

[argentstache]

We are having some problems with our boiler and are trying to determine whether to repair or replace.  it looks like the repair and cleaning is around $2800; however, the repairmen said that the CO2 levels coming out are really high (this is going outside the house, not inside) and that since the boiler is over 20 years old, we should consider replacement.  We haven't received the estimate for replacement, but we are sure it will be more than $7K. Would love some advice.  The repairman kept emphasizing that the boiler is over 20 years old, but that doesn't seem so old to me.  However, i confess that we have not performed the requisite maintenance on it.  So, the follow up question is, if properly maintained, how long should a boiler last? Thanks for any advice.

[ctuser1]

What type of boiler? Gas? Oil? From your description it seems to be Gas - because Oil boilers will *not* last 20 years without proper maintenance.

Cast Iron Oil boilers, with maintenance however, can last a very long time - easily 40+ years. We were house hunting in 2016. Lots of old houses where I live. 40Y old oil boilers were dime-a-dozen. I've even seen a 60+y old one. It is a different matter that the older boilers are often very inefficient and hence may be better to replace them.

I'm also in the process of converting from Oil to Gas right now. Gas boilers usually come with with stainless steel heat exchanger or fire tubes - I have not heard of or seen them to be so old. Not sure of the reason. Any pro I talk to say "15+ years" when they talk about gas boilers longevity, compared to "25+ years" for oil boilers.

At 20 years, I'd probably replace it.

If gas, you have likely used up it's life. New gas boilers can be very efficient (95% AFUE and higher) and replacement should not be all *that* much more expensive than repair if no new piping is required.

If oil, and you have not maintained it well, then you have likely damaged it quite a bit. Do you want to spend more money on it to have to replace it anyway sometime soon? I'm also a little anal about safety. Not-well-maintained oil boilers will have all kinds of deposits (soot etc) built up everywhere. Even after you do all kinds of repair to make it function - I'd be worried about CO risk. CO can kill silently and very quickly without any warning!!

Note: I am not a HVAC technician and have no expertise on this. I just happen to have researched it a bit during house hunting, and now when replacing oil with gas.

[argentstache]

Thanks so much.  It must be gas, and it is good to hear that it is worth replacing.  Also embarrassed that I wrote CO2 rather than CO. This is all very helpful. Unless the replacement cost is way out of whack, we will likely go that route.  Thanks again.

[ctuser1]

Thanks so much.  It must be gas, and it is good to hear that it is worth replacing.  Also embarrassed that I wrote CO2 rather than CO. This is all very helpful. Unless the replacement cost is way out of whack, we will likely go that route.  Thanks again.

I live in CT (i.e. one of the highest cost locations in the US with a much higher cost of labor compared to other regions. Our skilled labor cost is often 2X that of low cost regions like TX).

Replacement cost for a Gas boiler is ~$5k for us, assuming the most typical setup, when no piping is required.

For reference, I am looking to spend ~$10k or so on a completely new Gas install in the next few months. This costs more because of new piping/plumbing etc.

[The_Pretender]

We have a 40 + year old gas boiler.  We just had the same dilemma.  We had repairs ~2K and we decided to get quotes on getting new.  I believe the cheapest boiler w/ not much better efficiency was about 7K and and it went all the way up to 13K which was very high efficiency which also provided hot water for the house (replacing a 12 yr old hot water heater).  We really wanted to do the $13K boiler which would be 2 birds and one stone.  We could not justify the major expense as we are not certain how much longer we would be in the home.  A question you may want to answer:  How long do you anticipate being in this home?

We instead, did the repairs.  In our region, boilers are rare, so parts and skilled labor is equally as rare.  So,our issue was to get a qualified tech who you trust and for them to get access to parts.  We went through 3 or 4 different service techs and are happy with the one we have now.   

You said your boiler is 20 years old.  I'd say go with your gut.  We repaired as our boiler was made of cast iron and the iron was in great shape and the repairs would mean it could last another 10-20 years no problem. If you anticipate this repair could band-aide your boiler for 5-10 years. 

One more thing... If we went with the $13K combined boiler/hot water heater... we would have to pay an extra $100 annually to have a flush service from them to make sure the system was in check.  If you get a combined unit, something to research and ask.

[frugaliknowit]

You need to look at the fuel savings of a new boiler and how long the payback period is versus doing the repair taking into account how long you plan to own the home.  Age, by itself should not be the determining factor.

My parents house (which was sold recently) had an oil furnace that was 60+ years old (with a newer "gun") and "purred like a kitten" with 83% efficiency.

[moneypitfeeder]

If you see white smoke streaming out of your chimney when the boiler is running, it is time to replace it. While your at it, you might want to take a look at "greening" your system (if it is an old steam boiler), to save you some cash in the long run; i.e. newer piping techniques and insulation. New boilers are much smaller and have very specific piping that needs to be done to dry out the steam and not waste fuel trying to push heavy wet steam up the piping. Hot water might not be as fussy (I have an old 2-pipe steam system). If you have steam, take a look at heatinghelp.com it has a ton of info on how to get the most efficiency out of a system, and can give advice on both DIY or finding the best pipefitter. They also offer help with hot water, but I don't have any personal knowledge of that forum. When we bought our home, it had a new boiler, but it was piped way wrong, so I had to replace all the near-boiler piping, but it's been running great ever since.