Current tank is gas, 50-gallon 38K btu dated 9/2011 (same as house build), original owners and original tank with house. Fortunately, it's not leaking but needs replacement due to age. We had the hot supply burst inside wall and due to the age of tank and the water damage repairs needed we are replacing the tank while we are at it. But would like to go tankless.

Questions...

Current location is in its own closet in hall upper level (2nd story) with a vented door. Tank vent is directly thru to roof.

Preferred brand? I am looking at Rheem.

Venting? I know this is different than a tank. Can you replace the metal venting and run the tankless pvc venting in the same space?

Size? We have 4 baths, dishwasher and clothes washer.

Is a recirc necessary or just a nice convivence to have? My understanding is this would put instant hot at all taps?

Would like to be able to fill a large tub, have dishwasher going and a clothes washer all at the same time. And/or a couple of showers being taken at same time. Is this reasonable with a tankless system and or possible? With our current tank it has never been possible. You have to take a choice and wait awhile to start another, if you want hot water.

Anything I am missing or should be asking my plumber?

Side note...

Whole house auto water shut off valves. Same questions, brand, size, location and any other info.

Plumber advised we have NIMBCO PEX throughout the house. There was a class action lawsuit for this pipe. It randomly burst due to its manufacturing process, not from poor installs. I am researching this, but it looks like the lawsuit claim time ended October 2025. But there might still be some claim availability. With this in mind since we are doing the tank or tankless, thinking of installing a whole house automatic water shut off valve. Thought is that we have a better chance of another pipe randomly bursting than not with this brand pipe ran throughout the house. Replacing all the piping is out of the question.

Thanks

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Would like to be able to fill a large tub, have dishwasher going and a clothes washer all at the same time. And/or a couple of showers being taken at same time. Is this reasonable with a tankless system and or possible? With our current tank it has never been possible. You have to take a choice and wait awhile to start another, if you want hot water.

^^^^^^^^^^^^
Beyond my pay grade. Are you running a large Bed and Breakfast? You must have great water pressure!

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Whole house auto water shut off valves. Same questions, brand, size, location and any other info.

^^^^^^^^^
Get a T bar shut off so you can it off at the meter. Just make sure the shut off valve is durable mine broke soon after install. Good luck!

quote:

Would like to be able to fill a large tub, have dishwasher going and a clothes washer all at the same time. And/or a couple of showers being taken at same time. Is this reasonable with a tankless system and or possible? With our current tank it has never been possible. You have to take a choice and wait awhile to start another, if you want hot water.

From my experience, yes you could as long as the unit is properly sized. I have a Rinnai and it's been flawless.

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Would like to be able to fill a large tub, have dishwasher going and a clothes washer all at the same time. And/or a couple of showers being taken at same time.

Is there sufficient water pressure going into the house for ALL of this at one time? Might have to jump around in the shower to get wet.

We have a Moen automatic shutoff valve. It keeps track of water pressure, water flow, checks for really small leaks. Before I knew we had one, I went to top off the pool and it shut the water off about 30 minutes later. Now that I have the app, that can be manually overused.

We did the same several years ago, after 3 50 gallon tankless replacements and have been happy.

You should check the rise in temp from the city/well water, the colder the starting water the longer it can take that and the desire for convenience will determine if you want a recirculation unit.

We did not install a recirculation unit, as the temp rise in Florida isn't that great so while it can take a little time to get hot into the farthest bath, it's not a problem. I just start the shower and then do a couple of things like brush teeth, take a leak, grab towel, shake wiener at the wife a few more times then the best part, unlimited hot water..

There is one thing I have found is the delay to start heated water delivery can play havoc with washing machines set to cycle on hot water, you can get an error code meaning it doesn't detect hot water soon enough. We just wash in cold water anyway, todays detergents don't need hot.

Bought the largest Rinnai Unit at the time the RU98EP condensing 9.8 gpm unit in 2015 and it's been running ever since without issue. It comes with a remote thermostat so you can turn it on and off or change the temp, ours is set to 130 and it can go to 140 but that can be dangerous especially if you have little kids.

While our gas tank was inside, I chose to move it outside and eliminate the exhaust through the roof as we were having a new roof installed then as well.

Rinnai has Smart-Circ, it learns your hot water patterns and can schedule it to start early and pre heat the water, so if you shower daily at 6 am, it will know that and kick on early. When we have to upgrade/replace that will be the go to...

Lots of information and choices on Bezosworld.com

https://www.amazon.com/stores/...ast_dp_brandLogo_sto


On the pipe issue, down here it's a poly pipe that has that rep, with it mostly the connections, many insurance companies won't
write your homeowners unless you replace it, mortgage companies won't finance the home unless it's done.

But yes, tankless is the way to go, you can fill that 50 gallon tub easily with hot water.

1) Our previous home was plumbed with hot water recirc. It works and it is excellent! If you have walls open already to run new plumbing it is well worth the cost imho, if your need is any distance from the heater. Our shower is right above the heater in this home so we get hot water quickly enough, but the kitchen is far enough away that it takes quite a while. The valve that can be retrofitted to one sink to create the recirc will work, but you will have warm to hot water in your cold water line as a result. So getting cold water now becomes a delay. Bottom line, worth it to plumb in with new lines, but probably not worth it to add the retrofit valve at your kitchen sink.

2) Our previous home had a Water Cop shutoff system. It works very well, with a couple of comments. First, the detectors can be hardwired or wireless. The wireless will have a battery in it, so don't forget to change those! I think it is a CR123, or something similar that is easy enough to buy. Second, be extra double triple sure that the detectors are at the low spot where any leak will reach them! We had a water filter housing fail, and the detectors were at slightly high points in the bathrooms and didn't detect the water. Ugh. It was a subtle angle in the floor but enough that the water didn't get to them. And, the builder didn't put a detector in the laundry room where the leak occurred. So, be sure you have detectors everywhere a leak might happen!

Finally, a wet mop will trigger the device. We had housekeepers trigger it twice and they didn't know what had happened, just that all the water was off in the house. Something to be aware of.

Just to point out what may not be obvious, you do not have to install tankless in the same location as your current water heater.

We replaced two tank heaters that were in the attic, thankfully before they leaked, with two outside wall mounted Rinnai gas fired tankless units, one on each end of the house.

Biggest install expense was running the gas lines from one end of house to other. Mine plug into an outside electrical outlet for the ignition source. This also allows you to plug into a standby generator if you do not have whole house.

I THOUGHT it would provide almost instant access by having one on each end of the house, BUT apparently my piping tied into wasn't plumbed to cooperate.

I will never have a tank water heater again.

I had a Rinnai. Leaked in heat exchanger. Apparently a thing for those that have copper exchangers. Now I have a Navien. Which, I sorta wish u had the option of that so, so long ago because the exhaust was so much easier. The Rinnai (at the time) was doing intake and exhaust on the same double walled pipe.

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First, the detectors can be hardwired or wireless.

Nice! I had no idea sensors that work with the shutoff valve were an option. Off to the Moen website to see if they have them for my valve. I found water sensor by the dishwasher and water heater, but assumed they were tied into the alarm system.

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Originally posted by BigWhup:
Just to point out what may not be obvious, you do not have to install tankless in the same location as your current water heater.

We replaced two tank heaters that were in the attic, thankfully before they leaked, with two outside wall mounted Rinnai gas fired tankless units, one on each end of the house.

Biggest install expense was running the gas lines from one end of house to other. Mine plug into an outside electrical outlet for the ignition source. This also allows you to plug into a standby generator if you do not have whole house.

I THOUGHT it would provide almost instant access by having one on each end of the house, BUT apparently my piping tied into wasn't plumbed to cooperate.

I will never have a tank water heater again.

I quote myself, since that's what I want to...

quote:

Originally posted by HRK:

While our gas tank was inside, I chose to move it outside and eliminate the exhaust through the roof as we were having a new roof installed then as well.

Yes I quote myself, We did the same - moved from inside the garage to just out the back side, gas was already there, access to main
plumbing for the whole house hot water plumbing.

I put a Rinnai in my last house in 2016 and it was troublefree through 2025 when we moved. Air exchange was two 3" PVC pipes that I ran about 20 feet across the basement ceiling and out the wall. I made sure to recirc vinegar through it every couple years to keep scale at bay.

quote:

Originally posted by HRK:

Rinnai has Smart-Circ, it learns your hot water patterns and can schedule it to start early and pre heat the water, so if you shower daily at 6 am, it will know that and kick on early. When we have to upgrade/replace that will be the go to...

Our system was a separate electric pump with several options, including learning use patterns. There were issues with it which might affect someone's decision matrix whether to spend extra money to get that smart feature. I believe it was a Grundfos brand pump.

It didn't have a clock, only a 24 hr timer that started when electrical power is applied. It learns your usage pattern over about 5 days. When first selecting the function you will not have instant hot water until it learns. If you go on vacation, it learns you don't use any hot water and then you won't have instant hot water for the first 5 days after you return. If there's even a momentary power outage, it resets and then the next 5 days you don't have instant hot water. If you don't have a strict daily routine, the times you shower or run an appliance outside of what it expects, you don't have instant hot water. When you have house guests, they'll be outside of the learned pattern for their showers and extra laundry runs.

I ended up leaving the pump ON. It has a thermostat that only runs the pump when the return water has cooled. The cost for electricity was negligible.

I wouldn't choose to pay extra to get the feature that learns our usage pattern. We just don't have a specific routine.