Navien Combi vs Lochinvar with indirect -- updated opinions?

ebow

First, I'll say that I've read older discussions with much interest, but it wouldn't surprise me if I missed something relevant, so feel free to point me at other threads. Discussions like Different take on tankless vs buffered, NG Combi Boiler versus indirect tank and boiler setup, and Condensing combo boiler are at least two years old, so one of my main questions is if there are any updated opinions on the Navien combi boilers now that they've been on the market for a longer time, with (I suspect) revisions and improvements?

I'm looking to replace my 50 year old Weil-McLeain boiler (nat gas, hot water). I'm in the suburban Boston area, in a ~1300 sq ft duplex with 3 zones: 1 wall-mounted radiator in the finished half of the basement, ~25 feet of baseboard in the first floor (open plan), and ~27 feet of baseboard in the second floor (3 bedrooms, at least one of which currently has poor insulation). First and second floor currently circulate as a single zone, but are piped separately. We have 1.5 baths, 2 adults, and 2 young kids. Hoping to be out of this "starter" house within 10 years, but who knows at this point.

Current boiler labeling says it's 75k BTU input, 60k output. We have a "regular" 40 gallon hot water heater.

When I put my numbers into U.S. Boiler Company's heat loss calculator I get around 30,000-35,000 for "Total Heat Loss for 60° F Temp. Diff" depending on how I interpret and fudge the numbers.

I've received a variety proposals from 4 installers; two interest me at this time. First is the Lochinvar WHN-085 boiler + indirect water heater and the other is a Navien NCB-210 combi unit (with tankless DHW). I know we shouldn't talk prices here, but I hope it's OK to say that the estimate for the Lochinvar + indirect is about 50% more than for the Navien combi. I could easily work the Navien's installed price into my budget; going with the Lochinvar makes things notably tighter.

(First installed proposed Lochinvar KHN-106 (I think he meant KBN-106?) as an alternative to save some money, but we'd only save about 10% if we skipped the indirect water heater (after account for lining the chimney) or 4% if we included the indirect.)

(Other proposals were for Burnham Alpine ALP080, Williamson GWC, and Viessmann CU3A (all boiler only), and Viessmann 222-F combination unit, but everything except the Burnham Alpine were more expensive when factoring everything in.)

So is the Lochinvar + indirect worth paying 50% extra over the Navien combi? Worth it for us if we move in 5-7 years? Worth it for a boost in home appraisal price? A neighbor, in exactly the same type of house, got the Navien put in last fall and is happy with it for the 1 year he's had it so far. My wife did a bit of research on indirect vs tankless, and besides the apparent extra cleaning maintenance, she found this Amazon.com review, both of which have soured her to the idea.

Side question: According to the WHN-085 spec sheet, that model puts out from 16,150 - 80,750 BTU. Is that the right size for my house, considering the heat loss estimate and length of radiators described above? The Navien NCB-210 lists "100,000 (180,000 for DHW) to 18,000 BTUh", which also feels a bit large. No?

SWEI

WHN-055 would be my choice there.

Navien has replaced their boiler line three times in something like five years? I can't sell or support anything that moves that fast.

ebow

SWEI said:

WHN-055 would be my choice there.

Even with the indirect DHW added? Just checking.

SWEI said:

Navien has replaced their boiler line three times in something like five years? I can't sell or support anything that moves that fast.

Huh. That's not terribly reassuring. Of course the installer who proposed it says he's done a whole lot in the last few years and really likes them...

Thanks for reading and weighing in!

SWEI

ebow said:

SWEI said:

WHN-055 would be my choice there.

Even with the indirect DHW added?

Yes. Oversizing a heating boiler is a spectacularly bad idea.

If you actually need more DHW, you can upsize the indirect. Don't forget that a standard gas water heater only puts out 30-32k (and a fair bit of that goes up the flue.)

ebow

SWEI said:

If you actually need more DHW, you can upsize the indirect. Don't forget that a standard gas water heater only puts out 30-32k (and a fair bit of that goes up the flue.)

I assume you mean upsize the storage capacity of the indirect? I didn't actually get a size number in the proposal, so I'm not sure what's included. Based on the price he gave me compared against retailer websites, I'd guess it's a 40 gallon.

If I understand your suggestion correctly, you're saying that the WHN-055 should give me up to 52,250 BTUs/hr, minus 35,000 BTU for the house (assuming my heat loss calc is right) leaving around 17,250 BTU for DHW. And while that might not be as much as the ~30k in a conventional water heater, I can make up for it by storing more heated water?

RobG

The modcon boilers have a feature called "Domestic Hot Water Priority". When heating the indirect it will stop the space heating until the domestics call is satisfied. I have never had a complaint about the space heating being diverted for that brief period.

SWEI

How many people in the house? Any multi-head showers or big soaker tubs?

Believe it or not, you might even consider a 30-gallon indirect. I have replaced 50-gallon tank heaters with 30-gallon indirects and had happy customers. If you do have large continuous loads, I would consider a tankless plus boiler instead of an indirect. Around here you also snag two gas company rebates going that route.

ebow

My household is two adults, two young kids. We have a single shower, plus a dishwasher and washing machine that we have no problem putting on delay timers to space the load out if needed. Actually, we run the washing machine on cold 90% of the time. Sounds like 30 or 40 gallons should be plenty.

SWEI

With kids, I'd get the 40 gallon. Cost difference probably under $200.

ebow

Based on the attention the Lochinvar option is getting, I'm guessing people think that's the better way to go that the Navien combi? To the tune of 50% better?

SWEI

Easily.

njtommy

I like my Navien Combi Boiler NCB-240. I installed it last year this time and have yet to have a problem. I can tell you first hand you are going to need a buffer tank for the Navien combi right off the bat. NO if and or butts about it. I will guarantee you that is not included in your price and your installer won't think you need one cause its a mod con boiler. Like stated up at the top 18,000 btus min firing rate for heating/ dhw. Your going to short cycle like crazy if your heat load is only 30-40,000btus on a design day.

RobG

The biggest challenge is finding the right contractor to do the installation. Where are you located?

njtommy

Honestly Your going to like the inderect over the tankless. You won't have hot water flow problems for you washer or dishwasher or the wait for dhw.

ebow

njtommy said:

I like my Navien Combi Boiler NCB-240. I installed it last year this time and have yet to have a problem. I can tell you first hand you are going to need a buffer tank for the Navien combi right off the bat. NO if and or butts about it. I will guarantee you that is not included in your price and your installer won't think you need one cause its a mod con boiler. Like stated up at the top 18,000 btus min firing rate for heating/ dhw. Your going to short cycle like crazy if your heat load is only 30-40,000btus on a design day.

I've attached a photo of the Navien installed in my neighbor's house. I suspect the gray tank is an expansion tank and not the buffer tank you refer to.

Would such a buffer tank prevent / reduce the short-cycling?

ebow

RobG said:

The biggest challenge is finding the right contractor to do the installation. Where are you located?

I knew my initial post was too long. I'm northwest of Boston, Mass. I got the Lochinvar proposals from a local installer with excellent reviews on Yelp, for whatever that's worth (not sure if it's alright to name names here).

ebow

ebow said:

I knew my initial post was too long. I'm northwest of Boston, Mass. I got the Lochinvar proposals from a local installer with excellent reviews on Yelp, for whatever that's worth (not sure if it's alright to name names here).

Here's a photo that installer sent me showing a similar install to what he's proposing for me.

hot_rod

That photo shows a classic install.

A nice blend of components, ECM circ, well planned and installed.

You will be better served with the indirect, as will the next occupant.

njtommy

@ebow
Yes a buffer tank prevents short cycling a boiler. Once sized for your system they will give you a minimum run time of 10-15 mins depending size and btus of your zones.

ebow

Thanks for all the replies and helping me understand this better!

On a related topic, anyone have the "actuarial tables" (i.e. chance of irreparable failure) for a boiler in its 50th year?

BobC

It could fail tomorrow or last another 20 years. If it did last another 20 years you will probably pay enough in excess fuel consumption to pay for it's replacement.

Start planning it's replacement TODAY so when it goes all decisions will have already been made. You don't want to be thrashing about if it rolls over in mid winter.

Bob

ebow

BobC said:

It could fail tomorrow or last another 20 years. If it did last another 20 years you will probably pay enough in excess fuel consumption to pay for it's replacement.

Start planning it's replacement TODAY so when it goes all decisions will have already been made. You don't want to be thrashing about if it rolls over in mid winter.

Bob

Funny you should mention 20 years. Based on my most recent 20 months of gas bills, we spend approximately $102 per month on home heating from Nov through April. (Avg 12 months' total gas bill was $829, and it looks like we bottom out at ~$16/month during the summer; avg for all gas usage is $69/month). I figure that if the new boiler were able to cut my total gas usage in half (I've been told elsewhere that that's not realistic) it would take 22-33 years to pay back the investment just from fuel savings, depending on which proposal I go with and how the price of gas changes.

One hiccup in the timing consideration: if I choose to go ahead this fall, and can get the contractor in with the time limit, I can get a $3500 Mass Saves rebate for the boiler, $400 off the indirect, plus 0% financing over 7 years. My hesitation has been over the fact that the monthly repayments would squeeze my budget noticeably. (The contrasting perspective is that paying for it all out of pocket if it fails during the winter would be an even bigger squeeze). When I learned about the lower cost Navien a few days ago, I wondered if that would be the route to go.

SWEI

ebow said:

Here's a photo that installer sent me showing a similar install to what he's proposing for me.

That is very nice work.

BobC

A boiler should last 20 years, make sure whatever you choose is likely to make that mark. It's going to cost more than you want but how many cars do you think you will need in those same 20 years and what will they cost?

Don't let the rebate decide your boiler selection, find the best installer you can and listen to him.

I don't think gas will stay this low forever, sooner or later people will figure out the terrible costs of fracking. When that time comes the cost of oil and gas will go up. Do whatever it takes to tighten up the house to reduce consumption, that is the best bang for the buck.

Bob

lchmb

you get what you pay for...pay now or pay later..but pay you will...btw, odds are your old boiler will fail on the coldest day of the year, a holiday weekend...good luck...

ebow

The larger rebate and financing are for any gas boiler over 90% AFUE. I haven't seen a quote for a non-condensing / less than 90% boiler that's low enough to offset the loss of that rebate.

@lchmb -- yeah, I figure some kind of Murphy's Law / worst possible time thing would be my luck.

ebow

Oh, if the installer insists that I need the WHN-085 (80k BTU) and won't do well with the WHN-055 (50k BTU), any suggestions? Drop him? Challenge him / make him prove the need?

SWEI

assuming it's the guy with the photo above, ask him why.

Gordy

My guess is the installer is playing it safe in knowing there was no heating issues with the existing 60k output boiler. If he did his own heat loss calculation......which he should, and it matches yours then the whn55 is as good as it gets. Still a bit oversized.

His view will be that you will still save money with the whn85 even though it's output is more than your existing boilers due to the fact it can modulate.

No one ever complains about the ability to heat, but will always complain for the lack of it. This creates an installer insentive to upsize for their piece of mind while sacrificing the customers wallet. The math never lies when done correctly have faith.

I can never understand using a blow tourch to heat ( NBC 240) then having to add a buffer tank to make it some what efficient. It's output for heating is all most twice your existing boilers. Does that make sense?

The install pic of the whn quote is very nice work.

njtommy

With the Whn-085 your going to be in the same range of short cycling. 16,500 btus for whn-085 and 18,000 btus for the Navien.

Neither boiler have any mass.

Also with the Whn-085 I'm sure the contractor doesn't want to under size for DHW either. The Whn-055 will take a bit more to heat the hot water.

Smaller is better for you. Try and tighten up the house more. Insulation can go along way.

Gordy

That's why you up size indirect, and or increase storage temp of indirect many ways to skin the cat.

njtommy

@Gordy
Totally agree

njtommy

@Hatterasguy
Like my dad always says cheap is best and only rich people can afford to do it twice.

ebow

BobC said:

...
Don't let the rebate decide your boiler selection, find the best installer you can and listen to him.

...

Been thinking about this some more. Does this mean I shouldn't have started off the conversations with contractors with "I want a high efficiency boiler b/c I'll get a rebate"? Think any many have spec'd out a small (appropriately sized) non-condensing model, which could fit my needs better and save me some dollars?

To be honest, the simplicity of traditional boilers appeals to me, and with the fuel savings payback time likely exceeding the lifetime of the boiler, considering our relatively modest current fuel use, condensing, high-efficiency doesn't seem like an obvious choice.

ebow

--deleted--

ebow

CI = cast iron = "traditional" non-condensing, right? Checking b/c I thought condensing models could be cast iron too, but perhaps not.

Didn't know you could hook up an indirect DHW tank to a non-condensing boiler. Good to know!

njtommy

That maybe your ticket is a cast iron boiler and a inderect tank. You have stated its your starter home. Some times it's just not worth the extra cost.
What are your fuel bills like in the winter?

ebow

Last winter we used 67-123 therms per month, for bills of $100-$166. Our gas usage bottoms out at 7-10 therms over the summer (dryer and hot water), so I'd guestimate our total fuel cost for heating the house last winter was something like $640.

njtommy

There is literally no real cost savings for you to do a mod con boiler or combi boiler.

Gordy

One thing about ROI you must subtract the ci cost from the mod/con cost, and then figure ROI from that point. Your buying a new boiler either way so is the "additional" cost of the mod/con going to be an exceptable time line to get your money back. The cost of fuel is always an uncertainty.

Rich_49

Lots of opinions and good advice here . You could easily have a system that goes lower , is from a locally owned company , will do everything everybody stated prior and will be cost competitive . Support would be awesome and your resale value would be top notch while still giving you the benefit of a quality system .

HTP UFT80 boiler , SuperStor30 indirect , Taco controls and circs . Nothing in that list is not owned and supported more than 75 miles from your location , all state of the art , all eligible for rebates even through the perverse MassSaves program . Emerson Swan reps everything and they are even in Randolph .

http://www.htproducts.com/UFT-Boiler.html

http://www.htproducts.com/superstor-ultra-waterheater.html

Low end on this boiler is 8,000 and the 30 gallon SSU will give you ample hot water , store at 140* and mix down . Contact HTP or Emerson Swan so they can help you find a contractor . You will not be disappointed . You may even be in real good shape with an SSU20 . STAY AWAY FROM THE NAVIEN ,