So many combi-boilers...

Skyline

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

hot_rod

good questions! And answers:) Ford or Chevy?

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.

JUGHNE

Perhaps it is a good thing that 3 contractors are recommending the IBC. Yes the factory could be pushing them at discounts to installers.
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.

kcopp

I would second...( or 4th ) the IBC DC... only 4 moving parts. Easy to service. I have a couple dozen plus in the field.

hot_rod

Not that it matters, and it may change, IBC became part of Intergas maybe 6 years ago. Rheem absorbed Intergas, and I believe Rheem was recently acquired by Paloma a privately owned Japanese company.
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😬

Skyline

Thank you all for your reply, it's helping me a lot...

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.

hot_rod

The DC 20 modulates down to 20,000 on the heat side over 3 gpm domestic, what’s not to like about that, seem like it is ideal for what you describe?

https://usa.ibcboiler.com/consumer/products/dc-series/dc-20-125/

Skyline

hot_rod said:

The DC 20 modulates down to 20,000 on the heat side over 3 gpm domestic, what’s not to like about that, seem like it is ideal for what you describe?



https://usa.ibcboiler.com/consumer/products/dc-series/dc-20-125/

I am still learning, bare with me for a second...

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

kcopp

That may be true but typically the lower output on a combi the less hot water output also.
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?

hot_rod

as @kcopp suggested, some combis are crazy cluttered under the hood. Here is a look at the Nobel I have. I can get my hands around most all the components. A few screws and molex plugs and all the electronics can be removed and get to this stripped down condition.

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.

Timco

Another vote for what’s under the hood. Is it all name brand components or no name knock off parts? EBM blower? Honeywell gas valve? Taco or Grundfos pump? The HTP ELU is Italian design and very nice. The UFT / UFTC are Korean and all generic parts with little copper.

Skyline

@hot_rod

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:

Source

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

hot_rod

Looks like the water passages are copper, then the water spec refers to those. Personally I feel that water spec should apply to all heating boilers, copper, steel, iron, SS, Al.

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.

kcopp

I have head great experience w/ this design.
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?

Skyline

@hot_rod

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?

hot_rod

Boiler Manufacturers are getting weary of warranting failed boilers due to water or fluid issues. So just lately they have been adding more guidelines.
Much of Europe has water quality spec, which is checked by inspectors. VDI 2035 for example.

Tom_133

Rinnai is stepping up their boiler game with a new series.

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

jumper

Nobody asked but the only meaningful advantage that I perceive in combi is that boiler gets exercised regularly. And I'm not sure that it is an advantage.

TJK500

We can also look for a new IBC Combi in the coming months. They also have the new SFT Superflow out now. We have a couple out there now and so far not one issue.

kcopp

Yes. Similar HX as before. A bit higher hot water flow rate. DC fan. Boiler circulator modulated directly from the control board.

Skyline

Tom_133 said:

Rinnai is stepping up their boiler game with a new series.

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

The i120CN combi does look nice and one could pick it up @HD for reasonable cost. I'd probably could install it, but won't go there...

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?

gennady

Skyline said:

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?

Installer must do load calculations and sizing. Then he has to discuss options with you.

Skyline

With so many boilers around, it took me some time to select one. The finalist is the Viessman 222-F Model B2TB 125 with NG. It costs about 30% more than combi-boilers without the 26 gallons DHW reserve, but I like this boiler.

Time will tell how well Viessman serves us, but I am optimistic.

Thanks everyone for your help...

Alan (California Radiant) Forbes

Good choice. The two that we’ve installed have been flawless.