Navien Combi vs Lochinvar with indirect -- updated opinions?

ebow

I found a proposal for a CI boiler among several that one of the contractors sent me. It's a Buderus boiler (unspecified model, 85% AFUE), Grundfos circulators, Taco zone controls, etc. Parts & labor for the main work comes out to 33% less than the Lochinvar proposal (from a different installer, also this doesn't include any kind of water heater). Then he suggested adding on Tekmar weather responsive controls for another ~15% on top of the main price. I didn't realize that the outdoor controls would work with / be beneficial for a CI boiler. From comments in this discussion or other threads I have the impression I could skip those without much disadvantage.

I get the impression that a big part of the reason I'm seeing high-ish costs for these installs, even for a CI chimney vent model, is adapting my house to the new boiler layouts. Seems like most new CI models have pipes coming out the left side, but my old thing has them out the right side. I've attached a picture of my current setup.

@Rich , thanks for the suggestions. I've seen you recommend HTP models in other threads, too. How would you (or others) suggest I think of that HTP UFT + indirect vs. the Lochivar Knight WHN-055 + indirect. Install cost, reliability / cost of repairs, maintenance need, durability, parts availability...

Gordy

Which brings to point what is your ability to use lower water temps? 52' of baseboard, and a Rad in the basement.

Type of baseboard, and Rad helpful.

ebow

Hatterasguy said:

What's the plan from this fellow regarding hot water? Does he then need to add an indirect to his price?

This proposal would leave the existing standalone DHW heater/tank in place.

Hatterasguy said:

Depends on the capability of the CI boiler to handle lower return water temps. Many of them can tolerate down to 110°F so there is some benefits in outdoor reset controls.

If you're not too lazy to go down to the boiler every couple of months, you can reset the boiler's supply water temperature yourself. Of course, I will get pummeled for this suggestion because, obviously, it is nowhere near as precise as a proper outdoor reset control. However, if the cost of the manual reset by the HO is compared to the cost of the precision control from Tekmar, I do believe that the HO might come out ahead in the manual approach.

Additionally, the capability of the outdoor reset is also dependent on the amount of radiation in the building. If the radiation is sufficient to heat the building at 150°F on the design day, you only have about 20°F of adjustment in the control before you reach 110°F on the return water temperature (the low limit for the boiler). 20°F isn't worth bothering with, IMHO.

Of course, the converse is also true. If the building requires 180°F SWT on the design day, there is a decent range (50°F) to work with for the outdoor reset.

This is where I need to learn more in order to really follow you. I'm fine with doing occasional manual system setting changes--I've been setting up recurring reminders in Google Calendar, which also show up as notifications on my phone, for that kind of thing.

Gordy said:

Which brings to point what is your ability to use lower water temps? 52' of baseboard, and a Rad in the basement.

Type of baseboard, and Rad helpful.

The baseboards are, umm... along the base of the wall? There's a central pipe that I would have thought was copper but looks more like stainless steel (but it's very hard to see) with ~2x2 inch fins spaced about 3/16" apart. Enclosure is about 6 inches tall, protruding 2 inches from the wall. Actual total baseboard length is 36.5 ft 1st floor + 31.5 ft 2nd floor = 68 ft with at least as much heat piping running on each floor between radiators (previous numbers were estimates).

The basement radiator is a wall-mounted Buderus thing that the previous homeowner had installed. Wish I'd looked for a model # when we had it off the wall for renovations. Photo attached.

njtommy

any update?

ebow

Sorry, got caught up in life. We've put the replacement on hold for now, so we can take the time to be sure we get the right system (and probably eek another season out of our current one).

The plumbing & heating guy who's worked on it a few times in the past came over to get the CO levels down (from levels measured during an energy assessment in the summer) and said we shouldn't be in a huge rush to replace it. He also echoed the comments I've read here about the mod-con boilers being overkill, and said something about liking a side-venting W-M model (it was a lousy cell phone connection, so I didn't fully catch that part) with an indirect DHW tank.

Oh, and the sensor he used for measuring CO level also seemed to produce an efficiency rating... of 78%. I was surprised to see a number that high.

ProblemSolver

The Lochinvar plus boiler pic... The air vent and expansion tank is on the primary loop, not the secondary loop. The Indirect loop - the pump is on the supply, not the return. The domestic doesn't show a mix valve. His backflow preventor is on a vertical pipe, not a horizontal pipe. He is zoning with zone valves with an ECM pump which I would never do. I always zone with pumps because in most cases they are less expensive than zone valves to replace, and getting the pump sized right for that zone you directly control the gallons per minute for the type of heating element and head loss which gives a better response time and shortens the boilers operating time. Plus, if one of the pumps fail, you still have heat in the other zones; but if the ECM pump fails, the wholes system is down.

ProblemSolver

All the boiler does is heats the water as the water passes through. Everything beyond the boiler is very important; it will determine how long each operating cycle runs and how many cycles in a given 24 hour period. So, we have the efficiency of the boiler and we have the efficiency of the piping, components, and heating elements beyond the boiler. The second efficiency must be considered because if its' efficiency is improved, so will your comfort level be improved. The two go together; you can't improve one without improving the other. And it goes the other way as-well; you diminish the efficiency of the piping, components, and heating elements, you diminish your comfort.

I guess what I am saying hear is; your not just buying a boiler, your also buying how everything is laid out beyond the boiler!

Rich_49

Problem Solver '
Zoning with an ECM circ is fine . The fact that you do not do it is a preference . In fact , ECM circs were made for this type of application where zones open and close and the flow and head vary from one minute to the next .
Where would you utilize an ECM circ ?

SWEI

That system efficiency includes the electricity required to run all those pumps.

What pump do you use for zones that only need 2-3 GPM flow?

joca

hi,
Been doing my research on mod/con units and their piping arrangements. the information on this site has been incredibly helpful and a bit overwhelming, but i guess that's what all my research is for.
Question on the navien combi install photo:
is this a primary/secondary piping arrangement? if so, is the primary pump built in to the unit? how does this create a "pumping away " system? what about the "closely spaced tee's"?
Please understand i am an amatuer trying to understand these piping arrangements,so my questions could be way off, but its a start! thanks

Rich_49

Joca

Start a new thread with your questions . It will be easier that way for all involved .

joca

Ok , thanks . I'll try it tonite.

ProblemSolver

Rich said:

Problem Solver '
Zoning with an ECM circ is fine . The fact that you do not do it is a preference . In fact , ECM circs were made for this type of application where zones open and close and the flow and head vary from one minute to the next .
Where would you utilize an ECM circ ?

The ECM circ is the better choice! But the HO has full power over that choice - of course. I offer both of them to the HO, but never offer zone valves. In addition, I was specifically talking about the Lochinvar pic.

ProblemSolver

Besides, most of my work is in large homes.

njtommy

Not sure where the money savings is when you run multi pumps and the have to by circuit setters at $$$ each to balance the flow.

Or your the guy that just puts B and G HV pumps in every job and over pump.

ProblemSolver

njtommy said:

Not sure where the money savings is when you run multi pumps and the have to by circuit setters at $$$ each to balance the flow.



Or your the guy that just puts B and G HV pumps in every job and over pump.

So sure of yourself; are you?

ProblemSolver

Installing the most efficient equipment is all the HO understands. It's a challenge to also sell the most efficient system (what gets attached to the equipment). So the best I can do is pipe it right with what the HO is willing to pay for.

Your remarks were unnecessary, njtommy.

ProblemSolver

I never said I would save them money on the cost of the job; I don't do that. Using circ's saves on the operating time of the boiler when there are multiple zones, compared to zone valves and one pump (ECM's don''t come-into play here, customers choice.) And yes, I use the pump curve graphs.
shoot, I can't remember the last time I explained myself this much!

Rich_49

Maybe you've never discussed such things with this many people who know how these systems really operate in the real world . Is there nothing you can learn from this point in your career ?
You mentioned that you normally work in large homes . The average size home we do here in NJ as a new work job is > 8,000 sf . We fine tune the loops , manifolds the best we can to get head numbers as close as possible so more than one can be serviced by a single circ . Do you not use actuators on manifolds that have multiple zones ?

ProblemSolver

You guessed it. I have never had to fine-tune loops, manifolds to get head numbers as close as possible. A large home here in Detroit / Oakland County area would be about 3,000 to 4,000 sf.
I guess the difference in our conversations is the size of the whole system.
But bear in mind, there are neighborhoods that have >8,000 sf. homes; but I grew up in this trade with the +/- 3,000 sf. homes.

Thanks for putting that out there "Rich"

ProblemSolver

I was going to actually mention that njtommy must be working in extremely large homes where the HO wants the best of the best, then make it better.

njtommy

@ ProblemSolver I will apologize for making that comment. I'm sorry, but not totally directed at you, but a lot of systems are over pumped.
I work on very large systems in commercial to small residential applications.

ProblemSolver

I totally understand njtommy; 30% of my boiler work comes from customer complaints about a new install/replacement not working, by other contractors who got paid in full. I typically have to re-pipe the whole boiler room from scratch because the boiler was piped as though it was a hot water tank. The last 15 years I worked for a friend who did all the sizing & purchasing, and I put it all together. Last season (after my friend retired) I taught myself how to size circ’s; it was the only info I was missing.

ahgu

ebow,

What system did you end up installing?
I am thinking about lochinvar NKC-150 noble. No space to buffer tank. Live near Boston. I have no space for the water tank.

What system do you guys recommend? hot water + baseboard heating. combi unit.

HG

Zman

The Lochinvar is probably the right choice assuming your DHW needs are not huge.
How big is the home? How many feet of baseboard? How is it zoned?
Do you have a heatloss calc?

ahgu

A house converted to 2 condo unit. each unit has 2 floors. Total 2000 Sqft for each unit.
Don't know the length of the baseboard. Just go with 2000 sqft. 2.5 Bedroom, kitchen, living room.

Some plumber said I need an indirect fired tank. But I got no space for tank. Not sure the impact without tank. It will turn on/off very often when I turn on/off faucets. But that is the basic principles for those units and should work right.

Also, what is the rough cost for material and installation?
The unit itself is $3000, it needs many parts, and labor for installation?

HG

Zman said:

The Lochinvar is probably the right choice assuming your DHW needs are not huge.
How big is the home? How many feet of baseboard? How is it zoned?
Do you have a heatloss calc?

ebow

ahgu said:

ebow,

What system did you end up installing?
[...]

HG

We rolled the dice and are still rocking our original W-M museum piece of a boiler + 7 year old standalone water heater.

I just re-read this whole thread and while it's full of great advice, I dread having to re-familiarize myself with it sooner or later. I think the most practical takeaways were finding an installer/servicer I can trust, looking for systems and parts that can be replaced readily, and not letting them oversize or overspec the system.

ahgu

What plumber did you plan to use? I need to find one. Do you have one you recommend?

What BTU did he recommend for your house? Is it 1000 sqft?

ebow said:

ahgu said:

ebow,

What system did you end up installing?
[...]

HG

We rolled the dice and are still rocking our original W-M museum piece of a boiler + 7 year old standalone water heater.

I just re-read this whole thread and while it's full of great advice, I dread having to re-familiarize myself with it sooner or later. I think the most practical takeaways were finding an installer/servicer I can trust, looking for systems and parts that can be replaced readily, and not letting them oversize or overspec the system.

Zman

There is no talking price on this site.
Given your restraints, the Lochinvar would be a good choice. I assume you are doing one per unit? You don't want neighbors sharing hot water, especially if the sizing is close.

ahgu

Yes, one per unit. Do I need a buffer tank?

Zman

If you had room for a buffer tank, I would say go with a smaller boiler and an indirect. It looks like the Lochinvar will turn down to approx 13,000 btu/hr output. I think it probably the best product for your application.

ahgu

Anyone can recommend a installer?

ebow

To close my loop in this conversation...

We got initial estimates from the following companies which I did some sort of screening for, but we didn't get as far as vetting, checking references, etc. :

• Doughty & Sons Inc
  
• Total Comfort Mechanical
  
• Central Cooling & Heating
  

And our neighbor who got a new system installed (mentioned in an early post) went with:

• Gonzales Heating and Plumbing in Wilmington.
  

These aren't recommendations, but perhaps starting points?