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Discussion Starter · #1 ·
Hi,

I need to get a larger water heater and I'm trying to weigh my options. We frequently run out of hot water in the morning..

I currently have a 40 gallon water heater with a 38,000 BTU input natural Gas burner. I got it for 175 dollars barley used. It is about 3 years old now and doesn't really have any issues except too small.

Here are some options:

Get a commercial 40 gallon unit with a larger burner 80,000btu.
Pros: Same footprint
Cons: Cost?

Replace it with a 50 gallon gas unit.
Pros: only 10 more gallons, will that make a difference?
Cons: What do I do with the old one?


Put two 40 gallon gas units in series
Pros: would likley solve all my demand issues
Cons: takes up too much space


Put a larger electric tankless unit in series with the gas water heater as pre-heater
Pros: could take up little space, would be able to turn it on and off manually to save energy
Cons: Need to wire in 220v and increase electrical service panel size...

Put a small electric point of use unit before gas water heater as a pre-heater and turn on when I take a shower and off when not..
Pros: could power with 110 and use existing panel
Cons: Is this code? Would a 1500W unit take enough of the edge off to make a difference in demand when taking a shower? Most Point of use only have half inch connections, would this create too much pressure drop?

Where is the best place to get water heaters?
 

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Turn up the temperature (but not too much to prevent danger of scalding). Measure the temperature at the hot water faucet near the heater after giving plenty of time "for the water to get hot".

You can safely set the water heater so you get 120 degree water out. The hotter the water the more cold and less hot water each person will mix in to take a shower with.

Add a passive tankless preheater to the cold water supply entering the heater. This consists of some finned forced hot water baseboard pipes taken out of the baseboard unit and run zigzag across the basement wall or ceiling but not touching. The warmer the water going into the heater, the less time the heater will take to get the water up to the target temperature.

A second water heater should be connected in parallel with shutoff valves on both inlet and outlet. Shortly after installing the second, check (feel) the outlet pipes after each high usage period to see if one goes cold before the other. Close the inlet valve partially on the heater that "stays hot longer" to try to balance things so water is drawn evenly from each heater.

One advantage of two smaller heaters is that if one springs a leak you can cut it out (hence shutoffs on both inlet and outlet) and still have hot water while you shop around for a replacement. But few people will want to spend the money for a second heater if they did not already have the first one in place.
 

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Plumb or Die!
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120 degrees is too cold. I have a 50 gallon gas unit and set it to 135/140 degrees. Hot enough to kill bacteria, and never run out of hot water.
 

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Discussion Starter · #4 ·
I'm all ready at 145 degrees..

I'm intrigued by the passive pre-heater concept. Do you have any picture or links of this, or are these custom fabbed at the site typically?

Is there any code requirements around two water heaters? I have a friend that just bought a new house and it looks like they put them in series..

Seems like the pros of a series connection is that you can have the first water heater set to a lower temperature than the second and then you'd loose less heat from the storage dissipation of the first one.. Running them in parallel would give you more total hot water, but like you said, the load sharing is going to vary.. Are there problems with water heaters taking in already hot water?

heat pump water heaters are still too expensive, but what about power vent? I'd like to find a power vent water heater that can take a PVC flue. Can you get one of those for less than 600 bucks?
 

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Energy Saver
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Tank or Tankless?

There's a lot of things to consider and your goals might be to just never run out of hot water. In that case, you'd probably want to install a tankless water heater. It won't take up any floor space and a should be able to crank out all the hot water you could ever need.

If you have teenagers, never underestimate the amount of money you save from your hot water running out. Some kids like to camp out in there all day as long as there's hot water coming out.

Whatever you do, stay away from using electricity to heat your hot water. It's 3 -4 times more expensive than natural gas.
 

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I'm intrigued by the passive pre-heater concept. Do you have any picture or links of this, or are these custom fabbed at the site typically?s?
Custom fab' at the site. You don't want to hang it on a low ceiling because hitting it with your forehead leaves deep thin cuts like diving at the beach and hitting coral.
 
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