Solution for 4300 sq ft rancher 5 bedrooms, 4 baths, 4 adults, triplet boys

We going to move to a 1960's rancher in the Northern California Sierra Foothills that we are remodeling. The summers are blistering hot at 110F days and nighttime lows of 60F. Winters can get down to 25F at night with highs in the 60's. The U-shaped house is over 100 ft wide with the kitchen/great room in the center. At one end is our master suite with a laundry room. At the other end is the bedrooms for our triplets (2 years old now), another laundry room, and another master suite for our in-laws. We have 5 bedrooms, 4 full baths, 2 dishwashers, 2 laundry rooms, a regular sink in the kitchen and a commercial basin with jet sprayer in the pantry for big pots and pans.

So we usually have at least 4 adults and 3 kids in the house. The kids obviously take baths at this point. My MIL takes baths and her bath tub is 72 gallons. The kids' tub is 55 gallons. Our tub is a 139 gal monster. Our bathroom will have a shower with 3 shower heads. I prefer taking showers with at least one shower head hitting me from each direction. If my wife jumps in there with me, we'd have 3 shower heads going at the same time. When the kids get older they'll probably shower at the same time in the morning one right after another or simultaneously.

Combine this with the fact that we may have washing machines and dishwashers running at some point. We need a LOT of hot water! And we want it NOW with no cold water sandwich.

I was initially drawn to tankless until I started to look at their flow rates for our use in the winter. A 55 degree temp rise yields 7.7 GPM max on the top of the line Bosch or Noritz units. But during the winter it's 25F out there so I'm guessing the flow rate will be even lower. Thus we would need two units.

My contractor suggested we use a separate recirculating hot water line with a separate in-line electric hot water heater feeding a small tank for the recirc line to eliminate the cold water sandwich effect. Needless to say, this gets costly. And I've heard various things as to the reliability of the units.

I'm also not thrilled with the idea of having to clean the heat exchangers every so often.

He suggested as an alternative two conventional 50 gal hot water heaters. But that's what we have now with our current 5 bedroom 6 bath home. And while showering is ok, if we run the dishwashers and/or washer while showering, or if we have multiple people showering one after another, we definitely run out of hot water.

So from this forum I learned about the AO Smith Vertex 100. Apparently this thing has a rapid recovery and delivers a lot of hot water in the first hour. I'm thinking two of these things will give us more than enough hot water no matter the number of showers/baths/appliances we are running. And with a recirc line we'd have nearly instant hot water with only the water sitting in the terminal branch lines that are cool.

My contractor stated he'd use insulated PEX so that the heat drop-off is not as noticeable.

BTW, if we use a Vertex we'd probably have to build a small enclosure around the two tanks on one end of the house since we don't have room in the garage. That's being turned into a home theater at a future date so I don't want any tanks in there.

Any thoughts/comments? Is this complete overkill for our usage? It's a pricey solution but still way less than the two tankless and recirc system alternative.

How is the house heated? Using a furnace or a boiler or something else?

jadnashua said:

How is the house heated? Using a furnace or a boiler or something else?

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We have two central forced air HVAC units, one on each side of the house.

The reason I asked is in case you might have a boiler...

You have a significant maximum demand, and it's going to take some significant funds to get what you want. There are some good people here that may have some suggestions, but none of them will be cheap unless you are willing to compromise some.

Do you have NG available, or would you need an electric or propane solution? If NG, what size line?

jadnashua said:

The reason I asked is in case you might have a boiler...

You have a significant maximum demand, and it's going to take some significant funds to get what you want. There are some good people here that may have some suggestions, but none of them will be cheap unless you are willing to compromise some.

Do you have NG available, or would you need an electric or propane solution? If NG, what size line?

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I do have NG available. I'm not sure of the size line. I'm sure it's whatever is "standard" in this area. My guess is a 3/4" line.

TheLex said:

I do have NG available. I'm not sure of the size line. I'm sure it's whatever is "standard" in this area. My guess is a 3/4" line.

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NG should make your water heaters much cheaper to operate. The gas company can provide a bigger pipe to the house if needed, since the pipe to the meter can handle a lot more gas than a house would need. Its the regulator and meter that limit the BTUs/hour available to the house. While you are at it, maybe you will want to add a gas fireplace or stove that could work during a power outage. While you are at it, consider running pipe for a NG powered generator that you might want to get later. You might get one of your water heaters to not require AC power to work.

High capacity (fast recovery) WH may or may not require upgrading the service...just depends on what's currently being used verses what would be needed at peak demand. But, it is a consideration that needs to be taken into account.

We are changing out two wood burning fireplaces and converting them to gas units. The dryers in the two laundry rooms are gas. Plus the cooktop will change from electric to gas. So we are definitely going to be needing more gas. I just hope it doesn't cost a small fortune to make the required change.

As to the water heaters themselves, what the better solution for us -the two tankless units or the two Vertex units?

Thanks for all the replies!

Update:

My contractor likes the idea of the two Vertex 100's. He says to put one unit on each side of the house so that each unit supplies half of the house.

He also said that to save money I might be able to get by with the 75 gal Bradford White M-I-75S6BN 76,000 BTU High Input Atmospheric Vent Energy Saver. Two of those would be less than the cost of one Vertex 100. Either way he'd have to build a little shack on each end of the house for the units so that we don't have to mount them inside.

Your plumber has the right idea with the two 75 gal units. That's what I'd do.

Bradford White makes a 55 gallon "high performance" heater. It as a 200 gallon "first hour" rating, (the typical 75 gallon heater gives 155 gallon fhr). It combines a large but input burner, high temperature water, and a built in mixing valve to create large first hour capacity, and a 1.25 gpm recover rate. Two of these should be more than enough for you needs.

If this house has a full basement that can accommodate it, a drainwater heat exchanger on the gusher-shower could extend the "apparent capacity" of any hot water heating system by quite a bit, shorten the recovery times, and save you some fuel to boot. But it takes at least 4' of vertically oriented drain down stream of the shower to get a big enough unit in there to make it worthwhile. It won't do squat for tub-filling capacity, but assuming your three-shower heads add up to no more than 5-6 gpm it can turn a Vertex-100 into an "endless shower" experience- it never runs out from the shower draw as long as the incoming water temp is in the mid-40s or higher.

But it could also more than double the showering time of the standard Vertex, giving it more apparent capacity than the Vertex 100, and far greater capacity than a standard 75 gallon tank for heavy showering draws. But it also raises the apparent-efficiency of a standard 75 gallon tank to more than a condensing Vertex when the main draws are showers, not tub fills.

A 4" x 48" returns over half the heat going down the drain at a flow rate of 2.5gpm, and sill over 45% @ 5 gpm. Bigger is always better though (both fatter and taller), since you get more return when there is more surface area.



If your house is slab-on grade this option won't fly.

Dana, I love the idea of the drainwater heat exhanger but this is a single story ranch home that is over 100' wide and it has no basement to speak of. And because we're converting the area that houses the existing single water heater into living space. So there's nowhere to install the heat exchanger.

Dana said:

If this house has a full basement that can accommodate it, a drainwater heat exchanger on the gusher-shower could extend the "apparent capacity" of any hot water heating system by quite a bit, shorten the recovery times, and save you some fuel to boot. But it takes at least 4' of vertically oriented drain down stream of the shower to get a big enough unit in there to make it worthwhile. It won't do squat for tub-filling capacity, but assuming your three-shower heads add up to no more than 5-6 gpm it can turn a Vertex-100 into an "endless shower" experience- it never runs out from the shower draw as long as the incoming water temp is in the mid-40s or higher.

But it could also more than double the showering time of the standard Vertex, giving it more apparent capacity than the Vertex 100, and far greater capacity than a standard 75 gallon tank for heavy showering draws. But it also raises the apparent-efficiency of a standard 75 gallon tank to more than a condensing Vertex when the main draws are showers, not tub fills.

A 4" x 48" returns over half the heat going down the drain at a flow rate of 2.5gpm, and sill over 45% @ 5 gpm. Bigger is always better though (both fatter and taller), since you get more return when there is more surface area.

If your house is slab-on grade this option won't fly.

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dj2 said:

Your plumber has the right idea with the two 75 gal units. That's what I'd do.

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Yeah, and it's 1/4 the cost as well. My only concern is the recovery of these units at 80% efficiency is much lower.

hj said:

Bradford White makes a 55 gallon "high performance" heater. It as a 200 gallon "first hour" rating, (the typical 75 gallon heater gives 155 gallon fhr). It combines a large but input burner, high temperature water, and a built in mixing valve to create large first hour capacity, and a 1.25 gpm recover rate. Two of these should be more than enough for you needs.

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Thanks I'm going to look into this.

quote; So there's nowhere to install the heat exchanger.

They are overhyped anyway.

I found two Bradford White WH's that may work besides the expensive AO Smith Vertex 100:

#1 is a 75 gal plain ol' atmospheric vent model - 76k btu and it has a 82 GPH recovery at a 90 F rise: http://s3.pexsupply.com/product_files/M-I-75S6BN-Product.pdf

#2 is a 55 gal atmospheric vent high recovery model - 78k btu and it has a 86 GPH recovery at a 90 F rise: http://www.bradfordwhite.com/sites/default/files/product_literature/115-B.pdf

#2 is almost $1k cheaper for a pair than #1.

Since they have roughly the same recovery, it would seem that other than size differential, the cheaper #1 model has a larger reserve to deliver more hot water during that first hour anyway. Is this correct? Plus I have the bonus of saving some money.

BTW, these tank units are recovery rated at a 90 F rise, which is quite different than tankless units that are typically rated at a 50 F and 70 F rise. With the tankless units, as the rise increases the GPH flow rate drops dramatically. Am I correct to infer that with a tank water heater this is not the case and that the unit will deliver all its reserve water at whatever flow is demanded, no matter what the draw is up to the point it runs out of hot water in the tank?

Until you dilute the existing water in the tank, you can draw it off as fast as you want.

That is a big home. You might just consider doing this. Pipe the hot water pipe in a big loop. Somewhat like the veins in your own body. You would just need to do a good job of insulating the hot water lines. Put a recirculating pump on it and keep it constantly moving. A small pump will use very little electricity. That is how my home is plumbed and I wait almost no time for hot water.

Hairyhosebib said:

That is a big home. You might just consider doing this. Pipe the hot water pipe in a big loop. Somewhat like the veins in your own body. You would just need to do a good job of insulating the hot water lines. Put a recirculating pump on it and keep it constantly moving. A small pump will use very little electricity. That is how my home is plumbed and I wait almost no time for hot water.

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You're absolutely correct. Our contractor recommended a recirculation line with a pump. We'll be using insulated aquapex so decrease the water temp dropoff.

In fact he recommended we place one hot water tank on each side of the house (over 100 ft wide) and have separate tanks serving each side of the house.

My question to that is would it be better to have the two 75 gallon tanks serving the entire house on one big loop so that as we draw down one tank, the other one is in reserve so any draw in the house has a full 150 gallons in reserve as opposed to 75 gallons if only one water tank served that side of the house.