Navien 150

Docfletcher

This spring/summer I plan on replacing my boiler. The Navien NHB 150 has a turndown of 15 to 1 so I believe it may fit the bill to handle my several micro zones with 12 ft baseboard radiator sections. I've seen the video with Navien reps talking about this product at a trade show and when they said it would handle micro zones it peaked my interest. Of course I would need to go to a stand alone hot water heater but I don't see it as a problem. So I'm asking you pros to chime in with your thoughts on my going this route . One thought which concerns me is would it ever even get into condensing mode. 1600 sq ft raised ranch home in Ct. Thanks for your help.

Docfletcher

Ah then I can keep my current indirect (HTP). Thank you for telling me of the Lochinvar. The Navien peaked my interest because of the 7700 btuh. These new tech boilers are a mystery to me. I like the idea of the micro zones not causing short cycles. So I'm trying to explore my options.

Docfletcher

The spec sheet on the link you sent says it uses 12 amps. Is that correct, I mean will it be expensive to run?

Docfletcher

Thank you for the information.

Docfletcher

The current boiler is piped primary/secondary. I see you say the Knight can be piped direct and I would like to know if there would be an advantage to doing so? Also can you please give me a rough estimate of what the Knight list price is?

Docfletcher

I've called FIA and I'm waiting on the rep to call me so we can discuss the product. Do you know if they make the KHN-085 in a wall hung version? Thanks Don

Docfletcher

My boiler is out in the garage, the town requires 14 or 16" off the floor placement. My current WM sits on a metal stand. Since the Knight sits 41" off the floor I'm not sure how it would pan out install wise and service wise. If I can get the rep to come out we could go over all that and more. There is a feature I think I like very much, the multi temp loop control. I wish it did more than 3 loops though.

Docfletcher

Just got off phone with factory rep. I asked him specifically .about that. He said the outdoor reset is needed so that zones not on the the 3 zone loop would operate at optimum temp. That's the way I understood it so take it with grain of salt. He also said I should keep primary/secondary and that the smallest boiler would work OK even with the indirect. Up to a 40gal indirect. Coming to look next week. I'm excited at the prospect.

Leon82

There are 3 odr curves and set points for the three sh terminals.
The hottest one gets priority

Leon82

I should say it uses the hottest temperature when multiple Zone call

Leon82

There is also a parameter for mixing valve timer but I have not looked into that further

Docfletcher

Literature says the multi loop will do 3 zones at 3 different temps while other larger zones will will run as hot as system determines required. Again, it's my understanding so take it with a grain of salt. I think that's where the outdoor reset comes into play.

Leon82

I have a whn from May of 2015. They may have made a software update but as far as terminals on the low voltage board there are three zones. Each one has its own ODR and set point. and set.. the manual states that boilers under 400,000 BTU are required to have an odr

Docfletcher

Yep, rep says ODR comes standard.

njtommy

I own a navien combi in my own house it's a nice unit, but after installing 2 lochinvar boilers this week I can tell you I really like the controls package on them.You can really dial in your water temps and ramp delays to get the most efficiency out of your system.

Leon82

I think you will need a mixing valve setup to run different temps simultaneously. I am using 2 set points but not to run different types of emitters. There is an icon on the display which shows which setpoint temp is priority.

The boiler only has one output as far as I know.

Docfletcher

they do mention control of up to 3 24v mixing valves.

http://www.lochinvar.com/products/Default.aspx?type=ProductLine&lineID=186#

Leon82

Yes just making sure you knew it would be an option item.

Docfletcher

Hatterasguy, I will do the 085 if the installers the rep is calling don't cause the deal to die do to high cost. The rep on the phone said the price I had in mind was doable. So I now am waiting to see.

Ironman

The WHN wall hung only has a 5 to 1 turndown. The new KHN floor model has a fire tube HX and is 10 to 1.

The multi loop control installs external to the boiler and will maintain up to 3 separate reset curves from the boiler on 3 separate floating mixing valves. The control is not cheap and neither are the mixing valves. It will constantly maintain the separate reset curves even if a higher temp loop is calling.

I must ask: 12' of BB on a zone? I'd combine some of those zones.

Paul48

I agree......There are better options, than having a zone that small.

Docfletcher

I plan on combining the two 12' zones upstairs. The downstairs bath will be tied into the family room zone yielding 28' of baseboard. The upstairs bath however is a vexing problem with it's 6' of Runtal 2 tier when it goes in. The only bright note there is it will rarely be used.

njtommy

You could consider a buffer tank and keep your micro zones. It's an added cost, but at least you don't have to give up flexibility. It would also allow you to add other small zone in the future like radiant floor in the bath rooms.

Docfletcher

Njtommy, Thank you. Do you mean a buffer tank with the Knight boiler? My plan "B" is/was a Burnham ESC3 with an Erogomax or as Hatterasguy suggested a Turbomax. I don't think I could afford the Knight with the added cost of the buffer tank

njtommy

I believe the turbomax and erogomax can be used as a buffer tank? I could be wrong tho.
If so the knight and erogomax/ turbomax would be a good combination.

Docfletcher

Reverse pipe either one

njtommy

It's pretty much free hot water in the winter months.

CMadatMe

If you use a Ergomax/Turbomax aren't you just creating a new heat source instead of parking btu/hr being made by the boiler? Caleffi makes a nice buffer tank.

njtommy

I think the biggest thing is @Chris your not buying a buffer tank and a indirect tank. So your saving money on the cost of installation.

Docfletcher

The thing that attracted me at first to the Ergomax is they say "The only unit that can heat domestic water, buffer boilers,. heat your house (baseboard, radiators & radiant). and do it all at the same time. " Current flyer says they have improved it with 2 extra connections to boiler. And I like it's low cost. However I have been told turbomax is better but it's almost 2ice the cost.