Is Rinnai Worth the Premium?

Discussion in 'Tankless Water Heater Forum' started by Amish Electrician, Feb 25, 2013.

  1. Amish Electrician

    Amish Electrician New Member

    Messages:
    17
    Location:
    Arkansas
    Just to remind folks, I am doing a complete-gut remodel of my 1957 house. I plan to complete the framing changes this Spring, and be ready to call in the plumber around Memorial Day. Those with supreme memories will recall that my little house will have a few unique twists to the plumbing.

    I have decided to go with a tank-less water heater and small-diameter PEX (from a manifold) for the hot water. Simply put, most of my appliances will need very little water flow, and the smaller PEX will mean quicker hot water with less waste. The one big exception will be the walk-in tub, which will want LOTS of hot water when I (occasionally) use it.

    Fancier tank-less units will adjust the burner to match the flow, from "cigarette lighter' to 'blowtorch,' as needed. Thus, they can handle low-flow and big flow situations with ease. No need to keep a 100-gallons of hot water sitting around, or spending for a commercial-duty / quick recovery unit.
    That's why I think I'll go tank-less.

    Now ... the $2000 question: Is Rinnai worth the premium price? Or, should I just let the plumber drop in whatever he wants? I mean, while we all want to save money ... I notice that Yugo is gone and BMW is still around. Hmmm.

    So, what do you guys think? While Rinnai has the Ad budget, I'd like to hear about the other makers as well.
  2. Scott D. Plumber

    Scott D. Plumber In the Trades

    Messages:
    67
    I think they are. Rinnai and Noritz are the top of the food chain. Either of these are gerat choices. However Rinnai has a better dealer network in place including Autthorized Service Providers than Noritz, at least in most of the country from what I can tell. Also Rinnai now had a 5 year labor warranty! THey both are high-end products that do a very good job. As always I recomend buying and having it installed by a trained dealer in your area and by getting it through their dealer network if anything goes wrong, you won't be chasing some phantom .com trying to get help. The Tankless 101 Articles has a lot more info on it.
  3. Dana

    Dana In the trades

    Messages:
    2,849
    Location:
    01609
    Find out who has more local distributors & installers in your area. Some vendors have reasonable tech-line support for DIY debug & repair (eg. Takagi), but others have broader local certified-technician support (Rinnai), but it varies by location- don't know about Arkansas. If you stick with Rinnai, Noritz, or Takagi you won't get stranded with zero support.

    FWIW: Rinnai is THE worlds largest manufacturer of gas-fired appliances, by both annual sales and installed base. In terms of accurate temperature control at very low flow Noritz can't be beat. Takagi is usually (but not always) cheaper, and with pretty reliable rugged units (and won't void the warranty if you use it as a space-heating boiler the way Rinnai & Noritz will, except for a very few models.)

    Low flow appliances with bursty fill cycles have issues with almost all gas-fired tankless water heaters due to ignition delays and minimum flow requirements for ignition. A condensing tank type hot water heater has comparable real-world efficiency, but none of the incompatible-personality problems when married to highest efficiency dishwashers & clothes washers that sip hot water in multiple 1-quart draws for filling. The main reason to go with a tankless in my book would be if you have VERY large tubs to fill, at which point it's more space & cost efficient than an 80-100 gallon tank.

    For efficiency and "endless showers" a 50 gallon condensing tank with a 75-100KBTU/hour burner would serve most peoples' needs better than a gas-fired tankless. (Even with a soaking-tub, but not monster-spa.) If the house has a full basement (or is 2 story with the main shower upstairs), for showering rather than tub-bathing, a condensing tank HW heater plus a drainwater heat recovery heat exchanger (DWHR) yields even higher efficiency and capacity than a 180KTBU/hr tankless. You need at least 4' of vertical drain downstream of the shower to implement DWHR though- which is often not possible with slab-on grade, but usually is with full-basements or many crawlspace configurations.

    Full-gut rehabs are opportunity moments for getting the most cost-effective energy efficiency (==creature-comfort, not just utility cost savings) out of the building envelope. Hopefully you've been doing your homework on how to air-seal & insulate, and minimizing thermal bridging from framing & foundation elements(?).
  4. Amish Electrician

    Amish Electrician New Member

    Messages:
    17
    Location:
    Arkansas
    I want to thank you guys for your thoughtful replies.

    Homework? You bet - I'm doing lots of homework, on many topics. Working with an existing footprint, I'm pretty much re-making the entire house. It's like any recipe; all the parts have to be planned with the others in mind.

    There are a few area where I'll end up doing things twice - once, now, to meke it work for now ... then again later, to fit the final plan. In terms of this forum, that means the wall-mount toilet now, the open shower now, the walk-in tub later. Hence (and here you have me thinking, Dana), I just might go with a tiny 30-gal conventional water heater until I get that tub. If I do that, I can put off the gas line work for now; running electric for a 'normal' water heater as a stand-by is in the plans anyway.

    (I know a 30-gal tank will work, as I've used one for years without hardship).

    It seems everything costs a grand ... before you know it, you're into real money. I'm beginning the carpentry now, and expect to be ready for the plumber in June. I have a flooring guy coming to look things over at the end of March, as I have specific plans there, as well. Barrier-free shower, entire bath a 'shower pan,' floor drains, seamless epoxy terrazzo floor.
  5. Dana

    Dana In the trades

    Messages:
    2,849
    Location:
    01609
    There is a significant amount of info & recommendations on how to get best bang/buck out of insulation and how to avoid moisture traps etc on the buildingscience.com (BSC) website, but it can be tough to surf to what you actually need. There are pretty good how-to info on higher-R assemblies to be found on the greenbuildingadvisor.com website & forum too.

    For new construction and full-gut rehabs I find BSC's analysis here to be a useful starting point. Read at least the first chapter, but take note of Table 2 on page 10.

    Most of Arkansas is in US climate zone 3:

    http://www.greenbuildingadvisor.com/sites/default/files/images/H-T Zones with Cities ABC .jpg

    Bythe BSC analysis, according to their table, using typical methods at mid level material and labor costs, there is an economic rationale for:

    R20 walls

    R50 attics

    R10 basement walls (if full basement or conditioned crawlspace)

    R7.5 slab-edge (if slab on grade)

    U0.30 windows
    R5 in the center of basement or grade slabs

    Above that it becomes ever harder to make it on economic arguments alone (net present value construction vs lower future energy costs), but with some DIY labor and lower cost materials, maybe. In high construction cost/low energy cost markets the crossovers are lower than that, in high energy cost/low construction cost markets you can do quite a bit better.

    These are "whole assembly" values too, not center cavity. For example: A 2x6 studwall with R21 high density batts comes in at only R12-R14 after the thermal bridging of the framing is factored in. If you add 2" of rigid EPS to the exterior using 1x4 furring through-screwed to the studs with timber screws 24" o.c. (to limit thermal bridging of the fasteners) you'll be at about R20 with that 2x6 assembly. A typical 2x4 R13 wall comes in around R8.5-10 after thermal bridging, but adding 2" of rigid polyiso on the exterior brings that up to ~R20, etc.

    In my area it's possible to buy reclaimed roofing foam from commercial re-roofing, which takes 60-80% of the sting out of the material cost on a foam-over. Most of it can be had at 3-4 cents per square foot per R (R10 costs 30-40 cents per square foot, f.o.b. the recycler's yard) which is cheaper than high-density batt pricing in most markets. If you're interested in going this route, call some commercial roofers in your area and ask around- many will have stockpiled pretty-good used stock in a variety of thicknesses from demolitions and re-roofing projects. Last resort you can try insulationdepot.com, but I'm not sure how close their nearest yard is to you (they have several nation wide), but will ship in truckload quantities, for price. (Local is always better, if you can.)

    There is a lot of how-to tips on how to install it [URL="http://www.greenbuildingadvisor.com/blogs/dept/musings/how-install-rigid-foam-sheathing"]here[/URL], with plenty of links to blog pages going into greater detail on various aspects.

    Using open cell foam or spray cellulose in the wall cavities is inherently tighter than any batt solution, but if you caulk the sheathing to the framing with acoustic sealant type caulking (including the seams between doubled top plates and between the bottom plate and subfloor, etc) you can still get pretty tight. Tight is always right- a leaky house in Arkansas has a HUGE summertime latent cooling load at any R value, and if you make it tight the interior air stays drier and more comfortable at any temperature. Air sealing is the cheapest performance upgrade you'll ever buy- if you're doing it yourself, buy a powered caulking gun that takes the bigger cartridges, and a $50 foam gun that goes onto the screw-on 1-part foam cans- it'll save a lot of time, material, and your carpal tunnels/wrists will thank you later. :)

    Air sealing & insulating basements & crawlspaces is a special topic in itself- won't go into it unless asked, but I've spelled it out for people several times on the Remodeling forum on this site in recent years.

    Air sealing the upper floor ceiling plane is also critical for getting the stack-effect infiltration drives down too. If you love recessed lights, you're in for a lot of work there. If you are running ducts or air handlers in the attic it's better (but expensive) to insulate at the roof deck rather than the attic floor (there's some bang/buck issues there that can be optimized too.)

    Last year I was involved in an advisory way on full-gut rehab on a friend's 3 story w/full basement circa 1905 balloon framed 2x4 house. We added 4.5" of polyiso to the exterior walls, 6" above the roof deck, all as part if a deep energy retrofit (my buddy got some subsidy from the local utility as a demonstration project, and boy did WE get schooled! :) ) With lots of air sealing details and ridiculously tight low-U window the final air tightness came in at 464 cubic feet per minute at 50 pascals pressure (applied with a calibrated blower door.) That's about 1/10 the air tightness of a typical pretty-good house that size. Between all the measures taken the heating and cooling loads were low enough to do all heating & cooling with one mini-split heat pump per floor (!), which proved to be oversized at 1.5 tons each (I kept telling him to go with the 1-ton units at least on the lower 2 floors, but it looks like a 1-ton would handle the loads on the top floor too, but he was worried...) He did about 85-90% of the exterior foam with reclaimed goods from local recyclers, saving over ten grand in upfront cost(!).

    But the result is amazing- they didn't flip the mini-splits into heating mode until November, and back in the muggy ~90F August heat they were just idling along at low speed, with the interior temps maintained at a (too cool for my liking) dry 70F. You don't have to take it nearly as far as he did to reap most of that comfort level, but this place is by far the least drafty most-comfortable place to hang in winter than any house rehab I had any part in. It's truly the case that you need to check a weather report to know if youll need a parka instead of a light sweater for stepping outs (it gets below 0F here a few times most winters)- the interior wall & window temps don't give you much of clue, and the temperatures are rock-stable.

    If you insulate and air seal well enough your loads plummet, and the size/cost of mechanical systems for supporting those loads can fall too. On the rehab project I was initially thinking of using baseboard or panel radiators running off the hot water heater, but when we penciled out the heating loads and the cost of a water-heater based heating + air conditioning it seemed like a ridiculous expense for very little gain in wintertime comfort over what a ductless heat pump would provide, and in retrospect that was still the right decision. (The condensing Rinnai in the basement I'm less certain about, but hey, it works great! :) )
  6. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    Careful with undersizing long runs of PEX. Frictional and constricted fitting losses can result in low flow. For the fast or instant hot water experience, install a recirculation pump that is thermostat'd and timed. Personally, I like tankless a lot. I have had great experiences with my Noritz.
  7. Amish Electrician

    Amish Electrician New Member

    Messages:
    17
    Location:
    Arkansas
    That's a good point about long runs!

    Fortunately, in my case, I doubt it will be a concern. The house has a 25 x 35' footprint. The run from the water heater to the shower head will need about a 15-ft length of PEX; the longest run (kitchen sink) can be easily done with a 30-ft. length.
  8. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    30' is long enough to not use 1/2" tubing. And remember, 1/2" PEX has a smaller ID than 1/2" copper. Personally, I use 3/4" for individual small fixture runs all the way to the vertical in the wall, which is 1/2" for a couple feet. For the shower and tub I use 3/4" in the wall, connected to a 1" trunk pipe. But I am using copper so the layout is different - not the home-run manifold.

    With your manifold approach I would use 3/4" minimum for small fixtures, and 1" for the tub and shower. Use 1/2" copper from the shower valve to the tub spout as 1/2" pex provides too much restriction.

    If you undersize the tubing you'll notice it every time you use the water for the life of the house . . .
  9. Amish Electrician

    Amish Electrician New Member

    Messages:
    17
    Location:
    Arkansas
    I recognize the bias toward larger piping ... and, for the cold water I would agree. There's no harm going 'big' with a trunk system.

    For PEX, the advantage is in the manifold. This, and the greatly reduced fittings in a PEX method, makes it child's play to run a separate line to each appliance.

    I'm seeing shower heads that routinely claim flows of less than 4gpm, and most sink uses are comparable. About the only fixtures that might need a higher flow are the tub, the toilet, and the washing machine. With the tables showing 3/8" PEX being 'acceptable' beyond 200 ft, I don't think I'll see any problems, even once you account for the sweeping bends. Remember- the 'hot' line provides only part of the flow.

    The advantage to using small lines with a manifold system is that you get hot water at the faucet quickly. In the case of my longest run, a 3/8" line will have but a half gallon of cold water sitting in it - as compared to the multiple gallons that a large trunk can hold.

    This is what I call "revolutionary" about PEX. It's not just the material- it's the method. It changes EVERYTHING we 'know' about plumbing.

    There might be a little of the electrician in me speaking. I figure that if I want a larger line later, I can always 'fish' it in. Not having all those fittings has its' advantages.

    Trunk for the cold, Manifold for the hot. Just seems right to this noob.
  10. lifespeed

    lifespeed Member

    Messages:
    321
    Location:
    California
    LOL. I suggest you have a real plumber look at your proposed design carefully before sealing it behind sheetrock, etc. I personally would never run 1/2" pipe for more than a few feet (no more than 5'). Who in their right mind would use 3/8" tubing as permanent plumbing anwhere in a house? That is a water line for a refrigerator for a few feet, nothing more!

    While I understand the heat and volume on the hot water side, it appears to me you are wanting to err towards undersizing your hot water lines. Yes, of course they carry less than 100% of the shower flow. But if you undersize them, the pressure varies with flow rate (friction). Like I said, use a recirc pump for fast hot water. Undersize your lines and you'll be kicking yourself in the shower whenever somebody opens a tap or flushes the toilet.

    I can't believe you even mentioned 3/8 tubing . . . :confused:
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