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!
Power-Pipe, It DOES have to feed the cold water side
It DOES have to feed the cold water side of the HW heater AND the cold side of the shower to get the full efficiency out of it. (If it feeds just the hot water heater a 50% unit will only be delivering ~40%, which is still way better efficiency than just feeding the cold side of the shower with it.) With an open crawlspace I'd think the lateral runs of cold to/from the heat exchanger to the tank or to the cold input to the house would be pretty easy to implement, and the cold run to the shower would be pretty close to the drain pipe.
If the cold water input to the house is closer to the shower drain than the hot water heater, just putting the heat exchanger in series with the cold feed to the entire house accomplishes the same thing. (That's how my house is plumbed, with a 4 x 48 DWHX a bit north of 50% efficiency.) Under that configuration the other cold taps would be running other than cold-cold water when someone is taking a shower, but at Portland's relatively cool incoming water temps a ~50% heat exchanger would raise the incoming cold water to the mid to high 70s F in summer when the incoming water temp is highest, and about 70F in winter. When it's 75F indoors cold water stagnating in the distribution plumbing is also in the 70s, which doesn't bother most people. In warm-water areas like Florida it might take it up to an unappealing tepid temp for some people, but not in OR (or MA, where I live.) When another cold water draw is in progress, the output temp of the DWHX drops a bit too- it's something I've measured, but it's never been something anyone in my family has noticed or complained about.
Not having super-cold water out of the tap while someone is in the shower is a fairly small inconvenience to pay for the ability to take showers at half the energy use (or showers twice as long for the same energy use.) But if it's easier to plumb it to serve ONLY the hot water heater and the cold feed to the shower (or just the bathroom with the shower) it won't affect the temp of the cold water in the kitchen.