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So many combi-boilers...

Hello all... I am in the process of determining the right size combi-boiler for my needs. That seemed to be the hardest thing to do, but maybe it isn't. Once the right size selected, there's a slew of choices from different companies, some are within the US while others are from different countries.
Once you decide on the right size, how do you select the company that made the boiler? Is it based on repair record, reviews, reputation, warranty period, installer, etc?
I understand that the installer is the one, who will do warranty and any other repairs, selecting the right installer is probably more important than the manufacturer.
With that said, what is the general consensus for the "best" brand of combi-boilers? I am aware, that this might be a "loaded question", apologize in advance in that case. I tried to search reviews on the web, but each sites rate different manufacturers, cannot really compare the results.
So far, I've seen three contractors and all three of them recommended IBC boilers. There's no doubt that IBC makes fine boilers, but all three of them recommending IBC seems strange. These boilers are either really good, or there might be some financial interest for the contractor. I would not mind their financial interest, if the IBC boilers are really that good.
TIA
Once you decide on the right size, how do you select the company that made the boiler? Is it based on repair record, reviews, reputation, warranty period, installer, etc?
I understand that the installer is the one, who will do warranty and any other repairs, selecting the right installer is probably more important than the manufacturer.
With that said, what is the general consensus for the "best" brand of combi-boilers? I am aware, that this might be a "loaded question", apologize in advance in that case. I tried to search reviews on the web, but each sites rate different manufacturers, cannot really compare the results.
So far, I've seen three contractors and all three of them recommended IBC boilers. There's no doubt that IBC makes fine boilers, but all three of them recommending IBC seems strange. These boilers are either really good, or there might be some financial interest for the contractor. I would not mind their financial interest, if the IBC boilers are really that good.
TIA
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Comments
You could base the decision on what is popular and reliable in your area. Supplier, installer, rep and factory support are a good indicator.
Although brand recognition in any one area can change overnight if a rep or wholesaler decide to "go another route"
Those decisions are often based on $$ incentives, rebates offered, relationships, etc. Not always based on the best piece of equipment. The term "bean counter" comes to mind:)
I doubt you will find any brand that hasn't experienced some failures, learning curve. Keeping in mind many mod cons share the same brand of HX, gas valves, inducer, controls, etc.
They are a lot like bicycles these days, a name on the frame or enclosure, parts shared and sourced around the globe.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
OTH, this implies that there would be quite a few installed in your area. This usually means some faith in them and more importantly that many repair techs and replacement parts would be readily available in the future.
You see more and more of this consolidation in the boiler industry. Maybe some day a couple, few companies own all the boilers in the world. The smart ones are, should be looking into fossil free offerings😬
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
I am a Dodge guy, when it comes to pickup trucks...
Kidding aside...
As stated in the OP, I have nothing against the IBC combies, other than it's max output is 2-3 times more than I need. Oversizing the boiler is bad, no?
The DC20-125 is about 2-3 more on the high end, what I'd need for heat. I'd prefer 80,000 btu/hr for my heating needs, but IBC does not have a combi-boiler at that rating, at least not in their US website.
https://usa.ibcboiler.com/consumer/products/dc-series/dc-20-125/
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Wherever I've looked, most people warn against oversized boiler and frequent cycles. Will the modulation prevent frequent cycles?
Wouldn't the NCB-210E, 100K btu/hr and 4 GPM DHW, be better suited for my needs? I did do a heat loss calculation and @The Steam Whisperer estimated the boiler size based on last winter's natural gas utilization. Even the 100K btu/hr boiler seems oversized.
Again, I am still learning and respect your opinion, I am just trying to understand the different areas that go in to sizing a boiler.
TIA
That is the drawback to a combi.
I still think you are in the general ball park.
Ideally a stand alone boiler w/ a small indirect tank would be best as you can now size the boiler to the heat load... you Do NOT add the indirect to the heat load of the boiler.
Be careful w/ the flow ratings the Mfg give you ... what is the temp rise and the output? They can play games w/ the numbers.
PS... look at the inside of the Navien and look at the inside on the IBC. Which has less to go wrong?
Depending on the brand and model many mod cons allow you to not only limit heat output, but also features like SH limiting, anti cycling, ramp delay & outdoor reset. If you take the time to learn how those functions work you can really fine tune a boiler.
There is a huge amount of adjustability on boilers these days compared to the on/off fixed speed boiler.
With ramp delay the boiler starts at the lowest firing rate, you can program in how long it stays at low fire, say 20 minutes, then it steps to the next firing rate, all the way to full output. So on a mild day the boiler may only ramp up one or two steps, that can really help eliminate short cycling.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Thanks for the screenshots and your advise. I have not started to study the IBC manual yet, but the installer ensured me, that all of the functions in your boiler are available in the DC20-125. Except maybe the turn down ratio, that is 5:1 with the DC series.
The DC series has two-in-one aluminum HX:
Based on the image, it seems that the aluminum engulfed in flames and transfers the heat to the copper pipes. Isn't heating/cooling the aluminum will make it brittle in a relatively short time? Even if it is not, there might be some reduction in the aluminum's heat transfer property. While the HX comes with 10 years warranty, it will probably not last much longer beyond that.
The website compared the efficiency of both the SS and AL HX, makes me wonder:
Not mention that the DC series installation manual is rather strick when it comes to water quality on page 1-23:
"Other water chemistry allowable limits are as follows:
•Acidity pH is to be between 6.5 and 8.5
•Chloride is to be less than 125 mg/l
•Iron is to be less than 0.3 mg/l•Cu less than 0.1 g/l•
Conductivity is to be less than 400μS/cm (at 25°C)
•Hardness is to be 7 Grains or less"
How do I know, if the installer follows these requirements?
So, is the AL HX last as long as the SS HX? I am not looking for warranty information
My experience with early Al boilers was not great, but they used the aluminum as the waterway and fireside They had both water and fireside issues.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Between the IBC-Intergas version and the Triangle tube version I have +/-75 out there.
You have 3 contractors who have had good experience too.
Why the distrust?
I don't disagree, but...
How come the water specs didn't apply for the Phase III boiler? To my recollection, there has been no special treatment for the heat system, just plain old, hard tap water. It has been only drained once to replace the LWCO sensor. It is still chugging along after 20 years...
Yes, it does seem that the Al is only on the fireside. Is this a couple of years old technology, or has been around 10-20 years? That makes a difference...
I don't know if I'd trust Al HX for 10 years, much less for 20. Not to mention, that will I be able to get parts for it under ten years?
Much of Europe has water quality spec, which is checked by inspectors. VDI 2035 for example.
trainer for Caleffi NA
The magic is in hydronics, and hydronics is in me
Ive always been a Rinnai on demand fan, hoping these are as good. The pricing seemed ok as well. They dont modulate all that much.
anyone try one yet?
https://www.rinnai.us/catalog/boiler/i-series/i-series
Montpelier Vt
The SS type HX looks more tempting, than the Al/Cu type. And there's the 1/5/12 years of warranty (parts & labor/parts/HX); certainly, the DHW flow rate @ 70°F rise of 5.1 GPM does not hurt either.
What's the general consensus about Rinnai boilers?
Might as well I am at it, how about the Energy Kinetics combi-boilers?
Absolute Mechanical Co. Inc.
www.AbsoluteMechanicalCoInc.com
Time will tell how well Viessman serves us, but I am optimistic.
Thanks everyone for your help...
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