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Thread: AO Smith Vertex, Bradford White High Performance, Or Eternal Tankless

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  1. #1
    DIY Member handyman923's Avatar
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    Default AO Smith Vertex, Bradford White High Performance, Or Eternal Tankless

    I am looking to replace a 10 year old Bradford White conventional 50 gallon water heater. We are a family of 4 with two small kids so we take a lot of baths. Also, we have a dual showerhead shower in our master that uses 4 gpm when we have both heads on. Needless to say, we often run out of hot water.

    I am considering the following systems:

    1) AO Smith Vertex (GDHE-50-NG) - This 100,000 btu heater has a 1st hour rating of 129 gallons and a recovery of 129 GPH. I like the fact that it is energy efficient, can deliver 3.2 gpm (at 60 deg rise) once the tank is empty, and recovers quickly due to the 100,000 btu's. However, I have read on these forums that a lot of pros don't like AO Smith and am also a little concerned that there are a lot of parts and electronics that could break down. The installation cost is probably a little more due to the venting, electrical, and condensate line.

    2) Bradford White High Performance (GX-1-55S6BN) - This 80,000 btu heater has a 1st hour rating of 200 gallons and a recovery of 86 GPH. My basic understanding of this unit is that it superheats the water (160 or 180 deg?) and then uses a mixing valve to bring the temperature back down. I like that it has a great 1st hour rating, it is a pretty simple design without electronics to break down, and I can use my old venting. The recovery at 2.2 gpm (at 60 deg rise) is not as good as the vertex, but then again you are starting with a ton of water. I am a little concerned that the mixing valve could fail and that you could be scalded with 160 deg water. Also, I read that the minimum input for the mixing valve is 0.25 gpm. Is it possible to trickle a faucet to wash your hands and not reach this 0.25 gpm?

    3) Eternal Tankless (GU195) - This 199,000 btu tankless can deliver 6.4 gpm at a 60 deg rise. I like that this tankless doesn't have the cold water sandwich problem, can give us endless hot water, and is efficient. However, I could see situations where we are starting a bath and taking a shower at the same time and exceed the 6.4 gpm. Then there is the cost of adding 40 ft of 1" gas line, and more parts to break down. I also read some very mixed reviews of this on Amazon.

    At this point, I am probably leaning towards #1 or #2, but I am not sure. What do you think? Are there any other models I should consider?

    Thanks so much for any advice!

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
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    If you have the vertical space where you can install one, with the showers, a waste heat recovery system would mitigate the need for a super large WH. There's a lot of discussions here, so use the search function. With a lot of tub baths, there's usually some time inbetween, so there, the recovery rate is less important, and the waste heat recovery system won't work. One way to make any WH appear larger is to run them hotter. Where I live, they require a tempering valve, regardless of what temp you run the WH. Mine's fairly old, and still seems to work. In a tub/shower, the modern valves all have a high limit adjustment you should use and check periodically. I prefer a thermostatically controlled valve in the shower/tub. There, it doesn't really mater what the incoming hot is, it adjusts itself to your preference.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3
    In the trades Dana's Avatar
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    What Jim said- a mid-sized drainwater heat recovery heat exchanger rated for >50% recovery at 2.5gpm, and the smaller/cheaper 76KBTU/hr Vertex and a 125-130F storage temp on the tank would allow you to take a 4gpm shower all night and day, no need for a bigger burner or a bigger tank. It's like adding another 50KBTU or more of burner to the system, but it's a "burner" that uses no fuel. (In OR there are even rebate subsidies for drainwater heat recovery heat exchangers, in steps by rated efficiency.)





    EFI is the US distributor for PowerPipe, and they will open an account & honor the published price via phone with a credit card, and they don't tack on handling charges to the shipping- they're a very reasonable outfit to deal with.

    Last edited by Terry; 02-09-2013 at 05:53 PM.

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    DIY Member handyman923's Avatar
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    I like the idea of a drain waste recovery system, but I read that it needs to be installed on a vertical drain pipe, is this correct? We just have a crawl space, so everything under is horizontal. I do have 2" shower waste lines coming down from the 2nd floor, but they are in 2x4 walls, so I don't think the heat exchanger would fit...

    Any other thoughts?

    Thanks!

  5. #5
    In the trades Dana's Avatar
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    Yes, the heat exchanger has to be vertical to work. But even a 2-footer (Power Pipe R4-24 ) delivers 30% return, and would put out as much hot water in shower mode as the Vertex 100.

    You might call Renewability (the makers of PowerPipe) and find out the exact outer dimensions of the 3" versions. The outer wrap is squared off and flat- if it's 90mm or less it'll just make it into a 2x4 cavity, but even if it's 100mm you can make it work with a bit of sculpting on the gypsum. Assuming you have at least 8' to work with, even with 2"x3" reducer couplings you should be able to fit a 3" x 72" in there, which runs ~59% return efficiency @ 2.5gpm.

    They also make 2" drain versions which would surely fit, but you may have to buy them at a Canadian Home Depot (or order one through a US Home Depot) direct from Renewability at a more retail-type price.

    A 2" x 72" is still returning over 50% @ 2.5gpm, and the 2" x 60" (available from EFI as well as Home Depot) still returns a respectable 46%.

    In general, fatter & longer == better return efficiency, due to the greater surface area interface, and putting the tallest & fattest that fits (allow some room for the couplings) is usually worth it, even at full-retail. A 2" x 72" at full retail is still only about the price difference between a Vertex 100 and the 76K burner model, but the smaller heater + PowerPipe's "apparent capacity" and efficiency is bigger/better than the Vertex 100 without a drainwater heat exchanger.

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    In the trades Dana's Avatar
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    BTW: The OR rebate may only apply if you're heating water with electricity, and they don't list any of the 2" drain models anyway.

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