Replace a Munchkin boiler before it fails, or keep it going?

Joscience

My elderly parents have a Munchkin Boiler that provides heating via radiant baseboards and also domestic hot water via an indirect exchange tank. The Munchkin was installed more than 15 years ago, and other than some occasional repairs, has worked well. It hasn't been especially well maintained, but they haven't seen any significant issues with efficiency.

They are considering having it replaced as they are concerned it has reached its end of life. Both plumbers we had quote want to replace essentially all of the boiler plumbing (valves, pumps, and even heat exchange tank). One quoted a Lochinvar khb-199n and the other quoted a Navien NHB 150H.

I am trying to help them make a decision and have some questions:

Is it reasonable to do such a large retrofit as precaution? Is it reckless to keep everything the same until the Munchkin totally fails?

Does it make sense to replace all of the support plumbing if replacing the boiler?

Any particular question to ask the plumber to verify quality/competency?

Any additional work to require (ie a combustion analysis)?

hot_rod

how many square feet are they heating ? 199k is a large boiler

One certainty the boiler will fail at some point. Parts are getting harder to find for older models cons

EBEBRATT-Ed

Go with Lochinvar not Navien. Find the best contractor you can and check references etc. pictures of jobs completed. Combustion test is always required.

The Munchkin's seem to hold up pretty well but as HR said parts are getting scarce.

Alan (California Radiant) Forbes

Does it make sense to replace all of the support plumbing if replacing the boiler?

I agree with @EBEBRATT-Ed and add - to answer your question - that the piping and indirect may need to be changed. Can you show us some pictures?

Joscience

@hot_rod : the house is 3600 square feet in Flagstaff, AZ. Its older construction with single pane windows, lots of shade from trees, and flagstone exterior. Supposedly the 150,000BTU Munchkin replaced a 400,000BTU beast that was originally installed in the house when it was built.

@Alan (California Radiant) Forbes Unfortunately I don't have any pictures and I am hundreds of miles away. Two plumbers bid, one wanted to replace the indirect (and quoted the Navien). The plumber who quoted the Lochinvar didn't think it needed to be replaced. The Lochinvar guy came in about 75% the cost of the Navien guy, which even including the indirect replacement, seems too high.

hot_rod

assume a number of 37 btu \ sq.ft, as the high side if what a radiant floor could transfer

3600x 27=97,200 btu/ hr

Ideally a heat load would give you a better number to size to

So if my guesstimate is even close ? A 125- 150k boiler should cover it

While mod cons have a wide turndown, size it as close as possible for a long healthy life

pedmec

I have a munchkin 199 and it is 20 years young. Not many issues and i wouldn't change it unless i had too. I believe that too many techs out there are intimidated by condensing boilers and are quick to recommend a replacement over a repair. I believe its one of the reasons that they have a bad rap as far as longevity. if you PM as many as i have you realize they are very simple machines and that the hard part is the engineering before its on the market.

parts availability should be the determining factor

kcopp

I would run the Munchkin a year or two longer. Certainly over a navien.

Parts are not that terrible to find . But i am on the east coast where HTP is located.

GW

the Navien option is a combination heat and hot water? I have a slight disdain for combis. They break more often. They are “less work” to install; i think some guys install them to save a little time. An opinion of epic proportion: real boiler guys don’t install combis.

Replace is? think of a 15 year old car. If it breaks down, do you have the energy to have a major repair done? Some people do. Some people toss it to the wind and buy a new car. There is no right or wrong answer. Older folks- maybe they don’t want the drama if it fails during a cold spell.

Arizona- what’s a cold spell over there? I guess “cold” is a relative term I suppose. Boiler seems big.

Navien: I’m a little irritated- a relative of an in-law switched from propane to natural gas (I know, normally the other way around). I offered to do the job. I had to spend an unbelievable amount of energy getting the correct part number for the orifice. When I finally got the part, the box said “high altitude” on it (I am a couple hundred feet above sea level) I had to spend even more energy trying to determine whether I had the correct part or not. I got conflicting information between the rep and Navien themselves. Never got an answer. That’s my two cents on Navien. The boiler runs safely but slightly out of spec on the o2 (small fraction of a point).

Alan (California Radiant) Forbes

I service about 200 Munchkins in the Bay Area and have noticed that those that heat low temperature systems (radiant) have been starting to fail for the last few years. Mine died after 17 years. If not serviced regularly, the condensate will eventually eat through the stainless steel heat exchanger. So, your system (high temperature) may last another few years as it probably doesn’t run in condensing mode all that often.
You said it was installed “more than 15 years ago”. If you give us a serial number, we can figure out how old it is.
Most, if not all parts are readily available at jupiterheating.com.

Joscience

@GW Flagstaff, situated at 7000' of elevation, gets all four seasons, including lots of snow. It will get down to the teens or single digits a couple times each winter, but rarely stays below freezing for more than a couple days at a time. The Navien proposed by one plumber is just a boiler, we would still have an indirect exchanger hot water tank.

@Alan (California Radiant) Forbes

I was able to talk a cousin in to going over and taking some pictures and to get the serial number (F16L11556). The system has seen more than a few plumbers come and go, as well as some DIY work here and there. I don't think it has received much in the way of regular maintenance. Realistically, at this point, we feel the Navien is eliminated, and the real option is nursing along the Munchkin or putting in a new Lochinvar. As others have mentioned, Jupiter seems to still have most of the parts to keep it going, but I am a little worried about taking the gamble with my parents.

hot_rod

https://forum.heatinghelp.com/discussion/comment/1856652#Comment_1856652

it’s an odds game at this point.

I suspect boiler prices will continue to go up as they are mainly imported parts even if they are assembled here.

What are todays tariff numbers for China and the EU? 10, 30, 50%. The tariff game will also lead to shortages at some point, limiting options and driving prices even higher.

GW

@Joscience ok yes- I merely assumed the Navien guy was pushing a combination unit. That’s often the case in my area. I didn’t slow down and read- the Navien guy is the 150k BTU option

Now I’m starting to second guess the Lochnivar guy- 200k btu for a 3600 sq foot home, it’s a big boiler.

If you have energy, get one or two more quotes. Any Viessmann installers in your area? See what that guy says

keeping the “accessories” is a case by case thing. We routinely keep all the zone control apparatus and general piping, if it’s semi modern. The expansion tank always gets replaced. The exhaust piping too (our state now prohibits PVC)

You have a munchkin- is it the sitting model? If it is, some general re-piping might be needed to make things look tidy.

Alan (California Radiant) Forbes

Serial number F is the month (June), L is the year (2005).
The piping looks messy; no primary-secondary as far as I can tell.

GW

ah a floor sitting Munchkin. Yes, all that needs to be re-piped, it’s a bit of a mess.

EBEBRATT-Ed

The boiler may be fine but the original installer created a big mess. Looks like crap.

Joscience

I appreciate all the input from this very helpful forum. I am going to lobby for the Lochinvar and to do a pretty significant replacement of the old plumbing.

pecmsg

https://forum.heatinghelp.com/discussion/comment/1856694#Comment_1856694

My back and knees hurt just looking at that! 😒

mattmia2

I didn't think it was so bad until I looked more closely. Is that water heater connectors snaked all over the floor?