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Recommendations/Opinions on a replacement for a Laars Mighty Therm for domestic hot water

Customer has a Laars Mighty Therm PW325 (with a 119gall tank). Heat exchanger is leaking badly. He has multiple locations with a similar setup. He has a bad taste for Laars products and doesn't want to go with another Laars. My suppliers are offering a couple of different alternatives. RBI 300, bradford-white (which looks like it's just a rebadged Laars) or an AO Smith burkay 300.

Does anyone have experiences good or bad with any of these for commercial use?



  • Snowmelt
    Snowmelt Member Posts: 1,334
    Yea I do go with a navien. Or the Ao smith burly. If you go tankles you really have to know what your doing for sizing, what gpm is the building using? You might want to go with the takagi tm-50
  • Abracadabra
    Abracadabra Member Posts: 1,948
    edited February 2015
    @Snowmelt it's not tankless, there's also a 119g storage tank which is staying. Unless I'm missing something, Navien doesn't make anything in the 300Mbtu range. I only see 199.
    Sizing requires recovery of 321 GPH

    It doesn't look the the Takagi (although it's 380Mbtu) won't give me the flow rate I need. Looks like it's only 14.5GPM.

    This is a 19 unit apartment building, 1bath, dishwasher, 1.5 occupants per unit, 2 coin-op washers. 2.5GPM on showers.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Several years ago, customer wanted to get away from tank type heaters. Water is kind of hard and volume water heaters are supposed to be able to deal with scaling better. Storage tank can last 20+ years since there's no flame being applied directly to it and scaling/sediment doesn't become an issue.
  • Snowmelt
    Snowmelt Member Posts: 1,334
    If your looking for 320 g.p.h. Divide that by 60 that's between 5 and 6. If you have two naviens doing 3 gallons a minute and a storage tank you will be able to keep up, he'll I'd put a third for redundancy. That way one is down for service you would be still ahead of the game..
  • Abracadabra
    Abracadabra Member Posts: 1,948
    I've never tried teaming tankless heaters like the navien or takagi. Won't I need some kind of multi-heater controller?
  • hot_rod
    hot_rod Member Posts: 16,347
    Might need to look into water quality, if the copper tubes are failing.

    Really copper tube is still a viable option for batch DHW. Copper is an excellent conducter and transfers heat energy quickly and efficiently. I suspect much less $$ compared to mod con options.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Snowmelt
    Snowmelt Member Posts: 1,334
    Navian just a cumunication cable up to I think 20 units.
    Takagi give you a cumunication cable, but you can only do up to 4 units. If you have to add more then 4 units to the application then your looking at a real big water demand and have a manufacture send a rep out so you get the right equipment.

    I like both the navien 240 or the takagi tm-50
  • Rich_49
    Rich_49 Member Posts: 2,692
    Does this job and / or the others require ASME vessels ? You have much better options than what has been mentioned so far .
    You didn't get what you didn't pay for and it will never be what you thought it would .
    Langans Plumbing & Heating LLC
    Serving most of New Jersey, Eastern Pa .
    Consultation, Design & Installation anywhere
    Rich McGrath 732-581-3833
  • wogpa67
    wogpa67 Member Posts: 238
    We did a whole complex here in Pa before the VWH's came out with 1 199 Peerless Pinnacle's(Munchies) and 2 120 gallon indirects . Constant Recirc line 24 units. Laundry rooms, dishwashers.

    Gang 2 HTP vwh's with that storage tank and you'll be good to go.
  • Abracadabra
    Abracadabra Member Posts: 1,948
    Ended up showing the customer some of the improvements in the mighty therm2. induced draft, filter on the intake to reduce heat exchanger clogging up. He agreed to go with the mighty therm2. We'll see how it goes. thanks for everyone's comments.
  • Don_197
    Don_197 Member Posts: 184
    I'm not a big fan of fin tube tabletop boilers for domestic HOWEVER they are by far the most economical first cost choice. I like Lochinvars packaged systems in this case. Were i to go with mod/com I am a BIG fan of the Lochinvar Armor (it's a Knight with larger tappings on the inlet and outlet.....different software in the control) and the Armor is now available in a Fire-Tube config. In my mind the jury is still out on tankless (I am waiting and watching though) but I have a customer with a large assisted living facility that has a whole wall full of Noritz tankless units that he absolutely swears by. When a customer insists that I give them a tankless option.......I bid the Noritz.......only because he swears by them and their tech support.