We replaced our boiler (circa 1954) in the winter of 2018/2019. In our area (Detroit) there are only a few hvac contractors who specialize in boilers. Given that forced air is far more common than radiant heat these days, there just aren’t many folks who do them, or at least do them well. We bid it out to three folks - two who primarily work with boilers and one who doesn’t. It became clear quickly that the third guy was out of his element. Out of the other two - one was very pro traditional boiler and one was very pro condensing. Their bids came within a few hundred bucks from each other - and when you’re taking about a $14k job, a few hundred bucks is nothing. We ended up going traditional. The company was able to get the boiler quicker, and it was winter in Michigan. Also- as you alluded to in your post - boilers are simple machines. It’s a bit tank of water sitting over a gas burner that heats the water until it either reaches designed temperature, or flashes to steam, depending on which type of system you have. The condensing boiler, while more efficient, seemed to complicate a simple solution. I just wanted a boiler that would do it’s job when the thermostats crank up in October. So - in short - Talk to a few local heating professionals. Home Depot is not the arena you want to be in for this. I hope this helps.

I have the same requirement as you. I'm looking for a heating system that will just heat when I tell it to heat.

I have scheduled two heating professionals to come next weekend, but I wanted to do my research before speaking to them.

May I ask if your boiler company gave you an option between several different traditional boilers? If they did, how did you pick which boiler to purchase?

They did not give us choices. There aren’t a ton of folks out there making boilers. The condensing folks would have given us a Veissmann. The folks we went with used a Utica. I believe Utica also makes boilers for many other brands - with badge engineering. We have a 4500 sf 100 year old house - so we needed a large btu/h boiler. That also helped dictate which boiler we needed.

I'd stay away from hardware store "affiliations". You're paying extra for the commission the contractors pay to them. Good contractors can stay busy without the referrals.

Go with one who has hydronic heat experience. Choose the contractor and let them choose the equipment they stand behind, not the other way around.

My local Home Depot, Rona, and Lowe's doesn't sell non-condensing boilers. Will it be difficult to find parts to fix a non-condensing boiler within the next 30 years?

First I tend to agree with Elmer in respect to affiliations between box stores and contractors. As far as parts it would depend on the part and the company who built it. If the part is exclusive and unique to just your boiler a well established sound manufacturer will usually have parts available for many decades into the future. With newer companies entering the U.S. markets without a track record, and the rarity of the boiler offered availability of parts may be questionable so you may want to avoid these companies. It's not uncommon to find proprietary parts for 80 year old boilers but again depends on the companies dedication to maintaining a parts department for older units.

If it's a universal part common to most boilers such as circulation pumps finding parts will not be a problem. With most common parts a substitution can usually be found without concern.

"I turn the heat on for only 4 months of the year. Does this damage the boiler in any way as the system sits idle for most of the year?"

It's always a nail biter firing up an idle boiler. It's hard to say what could cause a problem after sitting idle for several months, but doing the proper annual maintenance is the best way to minimize startup failures and extend it's life span. Your new boiler should be equipped with a strainer to remove sediment, rust and pipe scale (critical for an old house with cast radiators and steel pipes) and magnetite, an iron oxide used in the production of steel. These items all become suspended in the boiler water (it's called boiler ink) and a strainer captures this crud when water flows through it. When sitting idle for long periods flow stops and the crud becomes sediment and settles in and on components inside the boiler which may effect operation on start up.. (Think of it as a liquid in your frig you must shake before using.) One fault which comes to mind is a seized circulation pump because of it's low startup torque, and usually is corrected with a few bangs from a wrench to break the sentiment loose, or sometimes not. I would recommend firing up the unit every month or so to circulate the water which will give it a good strain, shake and stir. But follow the manual for sure.

"What should I be looking for in between different non-condensing boiler? Are there certain features I should be looking for? Should I be looking for an stainless steel heat exchanger?"

Stainless steel by all means but type matters. There are three main types, austenitic,

martensitic and Duplex stainless steels. in each type are grades and all have different properties to thermal expansion, creep strength, corrosion and scaling. With the type of stainless used there is usually a trade off of one property to the others but I'm sorry and can't give the exact type or grade which is best so you may want to find out.

Aluminum is a poor choice and suggest running not walking to the door. It's reactive to both Acid and base and will corrode, and It's not easy to maintain a neutral PH in a boiler.

I'm partial to cast Iron and it will withstand the test of time, but it has small draw backs and usually built in sections with slip joints in between, and I've seen even the best new boilers start leaking in a matter of years, but stainless is usually welded and less likely to leak. Now if you have cast iron radiators the sections are slip joints, and your old boiler may have slip joint cast sections but in the long run this process is reliable. Slip joint failures on new cast boilers are more brand and model specific production issues than anything else .

With boilers the most important item is the quality of the heat exchanger, everything else can be replaced, and you should focus on this if you want longevity. Second up is the burner assembly and like the exchanger should be rugged and of high quality materials.

Everything else can be replaced, some manufactures may use cheaper parts but I like to see quality names on the parts.

"Non-condensing boiler is less complex (minimal computer technology, less parts) so therefore would be cheaper to maintain and have a longer life-span"

Not necessarily. It's hard to go old school these days, and new required safety controls both condensing and non-condensing units will use nearly the same amount of technology and controls even with the no bell and whistle models. Going to a 80% AFUE boiler may also unintentionally becoming a condensing boiler in your flue. If the flue gases cool enough before leaving the flue they will condense and a forced draft will be needed. It depends on the flue height, size and flue gas temperatures, and I've seen this needed on even 80% forced air furnaces required when installed in old homes with high flues. If the unit you're quoted requires a draft fan (I suggest you ask the about this) to increase pressure above at the base, or forced draft fan above to decrease pressure below it will have the same controls as a condensing boiler to prove a draft and control the fan.

The only difference now between the two is a second heat exchanger (which should also be stainless), a condensate pump (which manually works and rarely fails) and a bunch of 2" PVC pipe.

It's sad a new boiler is said to last only 15 to 20 years. I know of and work on a cast iron boiler with cast burners about 90 years old. Old school controls, with countless new common parts over the years but works flawlessly. I clean the burners every year and they look brand new, but the coolest thing about this 50%-60% efficient relic is my father salvaged this boiler in the mid 50's which was built in the 30's for $25 and turned it into high efficiency condensing boiler. This was about 30 years before High efficiency condensing was even considered in the united states. He lived boilers, was a chief engineer at the Hamm's brewing company in St. Paul with 4 massive high pressure steam boilers to produce heat and generated power for the entire plant. To him this little home boiler was child's play.

There is nothing complicated about condensing, add a second heat exchanger to extract additional heat , a blower to get the gases out and drain the water. Many European countries have laws which state you can only install condensing boilers and I think it will be law in the United states as some point.

I hope I helped.

I'm sure if your fuel supplier, whether oil or gas, knew you had such an old and low efficiency boiler still in use, they'd be rooting for you to keep it going for as long as possible