Cast Iron to Mod Con Boiler-Regrets??

Cyclist77

So anyone who has made the change from a CI to a mod con boiler have you had any regrets?

clammy

KISS plain and simple ,long haul long life span any fool can fix just about cast iron .Mod con the best you will do is 10 to 15 years w yearly cleaning ,combustion anz and a tech or company who will be honest and be there a extreme good luck on that one .lol .

Be smart get your chimney lined and stick to a properly sized cast iron boiler .The more fancier you go the more every different contractor will tell you some else . If zoning use a multi either circ or zone valve to neat things up no one likes having to re check a bird nest of wiring on a simple no heat call only adds to the nonsense and increases the bill .

The only place a mod con makes any sense is on a system that is suited for it mid to low temp system meaning radiant or panel rads trying to do low temp w baseboard it's hog wash and would only be done in the usa that way again hog wash the rest of the planet uses panel rads plain and simple

Cast iron can operate for ion usually without much being done if you try that w a mod con it wont be service call it will be replacement ,

proceed carefully . peace and good luck clammy

GW

That's where we are at it seems. Yes, some wall hangers will fuss. We do Viessmann and Bosch, they are solid. Some we install and never hear a peep ever again. They will last indefinitely. I have a 12-year-old Viessmann at my home, I replaced the igniter once

Kaos

No regrets. Everything was better after the swap. Fuel use went down and pipe banging stopped because there was no more cycling.

I think you'll find that a lot of modcon issues come from incorrect sizing, install or setup. Lot of times all 3. It is pretty easy to set one of these up to cycle itself to death. A well sized and configured modcon should fire in mid Nov and not shut down till Mach.

PC7060

no regrets; modcon is perfect match for gravity system converted to low temp. As @clammy said earlier make sure you have sufficient radiators if you decide to go this route.

hot_rod

I see 15 years or more from a properly installed and maintained mod cons. The top brands anyways.
If you are at all handy a yearly or every 2-3 years you could do a complete service. A clean burning mod con may not need a yearly service

The modulation is a big advantage for zoned systems the cast boiler is sized for maybe a handful of design or below days. It is oversized 85% of the heating season, assuming you find one the exact btu/hr that you need

Even on a system requiring 180 swt, much of the year it can run on lower temperature.

The heating system should be designed for 120 swt on design day! That would not be a good temperature for a cast boiler

As mod con running 120f would have a flue gas temperature around 130f the cast boiler 400f plus

EdTheHeaterMan

I remember the first time I needed to replace a boiler that I installed when I was younger.  It was a Columbian Emerald and I took good care of it until I went out of business.  Several Years later I went back into business and when many of my old customers heard that I was back in business, they came back to me.   Mrs. Flounders has  a basement you can't get to without moving a piece of furniture and opening up a basement door hatch in the floor.   As a result there were several years that the maintenance was not done properly while others were doing the service.   Eventually she needed a new boiler and I installed a wall hung ModCon since the natural gas line went past har home on the way to a new development down the street from her home.  I felt Old seeing something that I installed years ago needing to be replaced.  I was still in my late 40s at the time.

I like the ModCon with the cast iron radiators. I also installed ModCon with baseboard radiators and that also saved the homeowner in Avalon, NJ $$$ compared to the CI boiler that I removed. Of course the CI boiler on the floor got flooded on occasion and the ModCon was hung on the wall so high that I needed a step stool to work on it. but it never got flooded while I was working on it.

tim smith

Here is my take, if properly service a condensing boiler can see 15-20 years. Not much more, sometimes less. What we see when servicing condensing boilers is the build up of the granules ie coffee grounds is what will kill a heat exchanger. In firetube style condensers even when cleaning out the combustion chamber and burners, the granules start stacking up in the very narrow tube passages. They won’t flush out, cleaners available don’t break them down. Even though not in maintenance procedure we have resorted to a flat Silvos brazing rod which fits in tube to try and dislodge as best as possible. You cannot get all the way down through tube due to dimpling pattern on tube. Eventually the tubes will become too restricted to allow flu gasses to pass through or condensate saturation of granules left in tube or condensate pan will corrode the stainless. All above is just an opinion of real world 100s, maybe 1000s of boilers serviced. Water tube condensers are more readily cleaned but I feel have more contact area with granules and condensate between the tubes creates issues with corrosion.

All above said, I still think condensing boilers do a great job but their cost of ownership vs a new cast iron that may last 30-40 yrs may come in question. A cast iron boiler will have less annual maintenance & repair cost.
The simple modulating & reset controls on condensing boilers make for great comfort control & efficiency where as to get similar control on a cast iron boiler takes a fair amount of additional components to get close.
In summary, I can’t tell you which way to go. I would personally do condensing but I can do my own maintenance & repairs at a fraction of cost.
Find a reliable local company who has been around the block a few times and ask them what they support and install. Make sure suppliers carry parts in your area.
Good luck

hot_rod

So many variable related to the specific installation and location. I ran a Laars Mascot combi for 6 years before opening it for the first time. I'm not proud of that, just never got to it. So I ran it 10 more years, replace it as we were trying to sell the home.

Not a single deposit or any "coffee grounds". Never did a repair to it in 16 years. It was a Baxi 330 rebadged as Laars before they built their own. Thanks Joanie!

I installed a Munchkin, heat and DHW via indirect, at a farm store in Missouri with a gravel parking lot, years ago. Vent and intake was 15' up out a side wall. It needed a cleaning every 6 months. The owner ended up learning how to do it himself. It would have hands-full of "coffee grounds" in it every time.

Dating back to the late 1980's I have owned a MZ combi, Laars Mascot Combi, HTP Munchkin, HTP Contender, a HTP Solar Phoenix, Lochinvar Cadet, 2 Lochinvar Knights, and a Nobel Combi. All of these were LP, except my current Knight is NG.

Many more at customers homes and businesses.

On my boilers I never replaced anything more than flame and spark rods. No modules, gas valves, inducer fans, circuitboards, nothing.

The expected life cycle will probably be dictated by parts availability. I think that will be the case for the electronics, gas valves, ventb dampers, electronic aqua stats on cast boilers also. We see a fair share of failed cast iron sections on this list in under 20 years or service.

Electronics seem to be the weak link on most anything these days, boilers, appliances, cars and trucks. My 2022 Ram has been in twice for electronic updates in less than 3 years!

For boilers a power conditioner can be a good investment if you live in an area with dirty power, brown outs especially.

In Missouri we got power from a small Co Op they furnished whole house power conditioners for a small monthly fee, and warrantied any failed electronics. Although that program didn't last long :(

tim smith

Hot rod, on the Lochinvars we have seen very little to speak of electronic part replacements needed. Triangles tended to need a few more electronic parts as did Munchies + cleaning yearly. All the boilers that use the vertical firetube heat exchangers and spiral water tube heat exchangers have had fair amount of grounds in them, not everyone but most. All ours are natural gas. Just our experience.

RascalOrnery

As a question piggy backing off the original post, what type of modern boilers require the most versus the least amount of regular maintenance?

I'm a little befuddled at the boiler lifetimes, many of us over at coalpail.com have steel boilers from the last century, lots from the FIFTIES and sixties. Mine is a 57 and the insidewas in great visible shape when I put a new coil in. Anyone have any thoughts on this?

My suspicion is a fire that is always lit and the resulting dry surfaces and flues are helping things out. Plus steel is more resilient to shock over cast iron? But obviously lacks with thermal storage.

Certainly a lot to think about!

Long Beach Ed

The few we've installed, on the customers' instance have been regretted.

Nothing beats the dependability and long term efficiency of the most basic system available. All our work is commercial, and tenants can't be left without heat for days awaiting parts.

We specify systems that can be repaired by a handyman with a screwdriver and paper clip. To the best of our knowledge, every single system we've specified over 45 years is still operating. I don't know of any that couldn't be repaired with parts on the truck in less than an hour.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1839557#Comment_1839557

The gas valve manufacturers like Dungs tell me it is all about getting the combustion dialed in, and keeping them breathing clean air.

I've heard tree pollen in the NW can be an issue at times of the year. Insects also tend to get ingested and turned into some type of deposit.

Recycling exhaust air must add to the problem.

Was it the early Polaris that came with a huge air filter inside a large PVC tube?

tim smith

I think Polaris did have filter. What I’ve been told are the grounds are iron leaching out of stainless from condensate running down the surfaces then fired into crystals from heat. Not for sure but some theories.

Grallert

All the Viessmann modcons I've installed are running like tops. some on fin tube convectors and some on panels. The oldest is passing 20 now with no issues. All on propane and with minimal service. Lucky? maybe. No complaints.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1839588#Comment_1839588

I would think someone has had those particles sent to a lab for analysis. But why do some load up, others run for years without a single formation?

tim smith

not sure if it’s gas composition or system temp. I do know majority we worked on had proper flue & combustion air separation so gas recirc not the case.