Need to replace my gas hot water heater,

i am debating whether to intall a tankless hot water heater rather than a tank one. What is the opinion here as to what is best?

Any suggestions on who to call to get bids?

We use Tom Lyne or his franchise, Benjamin Franklin Plumbing.

Recently replaced a 40 gallon (gas - attic above 2nd floor). Considered an on-demand system, but with only two people using it 99% of the time, it would take a loooong time to justify the expense.

I called Tuma and they replaced with new and hauled off old for $1.5k.

Good grief

Went ahead and used JB Gause plumbing for the 5th time and Tyler the tech did a great job. We have never had an issue with them.

How much ?

woodiewood said:

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Need to replace my gas hot water heater,

i am debating whether to intall a tankless hot water heater rather than a tank one. What is the opinion here as to what is best?

Any suggestions on who to call to get bids?

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I owned a half dozen homes over 20 years before I built my current home in 2016. All of those older homes had a traditional water heater where gas or electricity keeps the water hot in the tank, and you draw from it as needed.

We decided to go with tankless water heaters in our new home. In a semi-rural neighborhood with no natural gas, so we went with propane in our 4k sqft house. I suppose we could have gone with just one heater (a larger one), and conventional wisdom might have said two. We went with three because I wanted some redundancy for the four baths in case one went down, we could still get hot showers in the other two baths. The third heater supplies the kitchen, laundry, and half bath.

So happy with our choice and wouldn't do it any other way. I think they were $2.5k each, but it was financed into the construction and not a big deal. During winter it can take 45 seconds for hot water, but then it never runs out after that. Even if you've got a family member that takes ridiculously long showers, or someone just took one before you, it is no longer a concern. In the summer, it only takes about 15 seconds for hot water.

The redundancy option paid off. One of them temporarily went down last year. Took a few days for a technician to come out and repair, but we kept rolling with showers in the other two baths.

With the old style water heaters, there was always a limit and we had to time when people took showers, or did laundry, or whatever to minimize the risk of running out of hot water in the winter. And sometimes we failed at that and got a rude awakening halfway through a shower.

Ours is the Renai brand. Very reliable, running strong and approaching 9 years of service.

Edit: the $2.5k might have been total cost, including the cost to run propane lines to all the heaters, and other stuff. Actual cost of the unit might have been less than that.

I waffled for a year over going with tankless or not. There was so much contradictory recommendations by pros out there, that even I as a contractor was staying confused. The day before Thanksgiving mine went out. I ended up going back with a 50g conventional gas WH, cost me 950 installed.

Our house came with a tankless gas Rinai. It's been going strong for 5 years with no problems.

I looked into tankless when our last water heater died. The plumber said it's pretty expensive and time-consuming to retrofit so we just replaced the tank.

Here is the deal.

If we get another wild cold snap with hard freeze days, you will be on thin ice with an EXTERIOR tankless. The unit has some minor freeze protections, but it cannot withstand hard freezes for multiple days. The copper could burst when it thaws out or something electrical could be frozen and destroyed.

Keep in mind, all the good guys plumbers were $700 an hour IF they called back during the last freeze. The parts are near impossible to replace, and it would take a super skilled plumber to do so. There is copper tubing in there. There are computer components in there. The error codes are very generic and do not tell you much if something craters.

If you got some money in your wallet, go for an interior unit. If you feel brave, get an exterior unit.

legalbird said:

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Here is the deal.

If we get another wild cold snap with hard freeze days, you will be on thin ice with an EXTERIOR tankless. The unit has some minor freeze protections, but it cannot withstand hard freezes for multiple days. The copper could burst when it thaws out or something electrical could be frozen and destroyed.

Keep in mind, all the good guys plumbers were $700 an hour IF they called back during the last freeze. The parts are near impossible to replace, and it would take a super skilled plumber to do so. There is copper tubing in there. There are computer components in there. The error codes are very generic and do not tell you much if something craters.

If you got some money in your wallet, go for an interior unit. If you feel brave, get an exterior unit.

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Mine are all exterior. We let the hot and cold water drip from all faucets in the house during the big freeze and come through it just fine.

The problem I mostly saw were busted heat exchangers in most of the exterior tankless. In feb 2021 when rolling blackouts started and we were 3-5 degrees there was no constant 110 power source to keep the gas tankless running so they froze up. Saw a few busted copper lines going to them as well. A gas tank heater does not need 110 to heat water.

JP76 said:

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The problem I mostly saw were busted heat exchangers in most of the exterior tankless. In feb 2021 when rolling blackouts started and we were 3-5 degrees there was no constant 110 power source to keep the gas tankless running so they froze up. Saw a few busted copper lines going to them as well. A gas tank heater does not need 110 to heat water.

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I was fortunate not to lose power, but I can understand how that would have been an issue for those who did.

Why are they mounted externally in the first place? I didn't ask during construction, but it does seem odd.

I never lost power during the freeze. I woke up every hour on the last two days of the freeze. Not sure what happened, but my tankless was ruined on the last day of the freeze. The internal mechanisms have cold weather "protection" to a certain level.

There is zero insulation in the units, so cold weather passes right through.

I have learned alot. I still have a tankless, but it will never crater due a freeze.

Same. Our neighborhood backs up to a fire station, and we didn't lose power in Snowmageddon. I kept the hot and cold dripping, and the hot water heater was fine.

I installed a tankless back in 2007 after being told how bad they are. my opinion is that plumbers dont like them because they dont fail as often. for instance, lime build up does not happen because the water is always moving and other corrosive with a tank. freezing has not been a problem, let the water drip. have 4 kids to shower at night not a problem, one after another. leaving town for the weekend? you are not heating water while you are away.

The problem with tankless is if the power goes out while it's cold outside, the heat exchanger will freeze and crack.

I believe it was JB Gause that told me a big part of his winter revenue was replacing cracked tankless units.

Why are tankless heaters mounted externally instead of inside the house?

My mom's is in her attic.

MemphisAg1 said:

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Why are tankless heaters mounted externally instead of inside the house?

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Here's what I found:

Key reasons for mounting a tankless water heater outside:
Space saving:
Outdoor units free up valuable interior space, especially beneficial in smaller homes.
Simplified venting:
Outdoor units can vent directly to the atmosphere, eliminating the need for complex indoor venting systems.
Weather resistance:
Modern outdoor tankless water heaters are designed to withstand extreme temperatures, rain, and snow.
Ease of installation:
In some cases, installing an outdoor unit can be easier due to readily available exterior wall space and simplified plumbing connections.

My interior unit is mounted on a free-standing frame in the garage. Had to rig it since the tank popped on Christmas Eve, and I haven't made time to properly install it. I made a frame for it to attach to, and swapped the vent to the double wall. I had no issues with it being there when the temps were below freezing. You can open a hot water faucet to let water flow through the manifold so it won't freeze if there is no power. One of these days I'll mount it to the wall and get the angled vent so I can ditch the 2x4 frame.

Thanks. Those all make sense except for the weather resistance. Interior is going to perform better there.

We bought a home with the tankless system and was curious if I need to do any preventive maintenance with it like a flush ? We moved from an area with heavy calcium but don't think that's any issue here.

JP76 said:

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The problem I mostly saw were busted heat exchangers in most of the exterior tankless. In feb 2021 when rolling blackouts started and we were 3-5 degrees there was no constant 110 power source to keep the gas tankless running so they froze up. Saw a few busted copper lines going to them as well. A gas tank heater does not need 110 to heat water.

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The newer electronic ignition ones need power to fire up, no pilot lights anymore.

Maintenance is recommended.

There is a tiny little screen, see below, that should be rinsed out every year or so. You have to turn off the water to the tankless to do the rinse. Be careful, many of the genius builders allow the electrician to mount the AC plug directly below the water connections.

https://www.homedepot.com/p/DANCO-5-8-in-Hose-Washers-with-Screen-80070/203193499


If you do a true flush, you use vinegar, two short water hoses, a five gallon bucket, and a sump pump. If you want to see on Amazon, here is the name of the pump. You run the vinegar thru for about 10 minutes.

Superior Pump 91250 1800GPH Thermoplastic Submersible Utility Pump with 10-Foot Cord, 1/4 HP

Keep in mind you got to be aware of basic plumbing things because you don't want anything to leak after you finish.

legalbird said:

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Maintenance is recommended.

There is a tiny little screen, see below, that should be rinsed out every year or so. You have to turn off the water to the tankless to do the rinse. Be careful, many of the genius builders allow the electrician to mount the AC plug directly below the water connections.

https://www.homedepot.com/p/DANCO-5-8-in-Hose-Washers-with-Screen-80070/203193499


If you do a true flush, you use vinegar, two short water hoses, a five gallon bucket, and a sump pump. If you want to see on Amazon, here is the name of the pump. You run the vinegar thru for about 10 minutes.

Superior Pump 91250 1800GPH Thermoplastic Submersible Utility Pump with 10-Foot Cord, 1/4 HP

Keep in mind you got to be aware of basic plumbing things because you don't want anything to leak after you finish.

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Thanks. I looked up on YouTube Tube and found that exact video. Thanks.

And to add more discussion!! Choose between condensing and non-condensing.

Yes, I do recommend a tankless. In a garage is best with normal insulation.

For anything you have in the attic, have some protection. Maybe a good drip pan with an alarm in case water accumulated.

If you do have a new install, make sure the orientation/location of the water and gas shut off is accessible to you, the homeowner.

All the brands are the same at the end of the day.

If two showers are running, that is kind of the max. Schedule washing the clothes after everyone is showered up.