Tankless hot water heater

NotaSuv

Pros, cons, your experience's Gas or electric Thanks in advance

audioluvr

I have the Rheem on demand propane with no recirculation pump and my GF has the Navien on demand natural gas. They are not quiet so if you have someone who decides to take a shower at 1am you will know it. Kind of a low rumble. My LP usage dropped like 30% or more which is awesome. They need flushed out once a year (which all water heaters should for long life but rarely are) which you can do yourself (google it). We both converted to tank systems to on demand which requires more planning but for the lover of DIY projects not so bad.

Rheem is quieter and has almost no noticeable change in temperature if you are taking a shower and someone else decides to use hot water for something. Takes a little longer to get hot water unless you install a recirculation pump. Very trouble free.

Navien is noisier. has internal pump which is a good thing but throughout the night it will turn on and fire up to keep a little hot water ready to go. Good thing is it's programmable with your smart phone so it all can be turned on and off according to your schedule. Bad thing is if your WIFI is down you loose everything and have to start over again.

drselect

Would recommend having one installed if you never want to run out of hot water.... but only if it is gas/propane.... Would recommend to have it installed next to a floor drain because they do need to be flushed on some frequency. Also would say have a water softener installed in front of it if you don't have one now. Will reduce the frequency of needing maintenance. We did see a reduction in our gas bills after it was installed but not enough to pay for the difference in price of a tank replacement. Moved from the place were we had it installed and will install one in new place once the current tank one dies....

The one we had was installed was a Rheem. I think they had several models with different BTUs. I am pretty sure we went with a mid range model. At the time the more BTU the quicker the water came up to temp...

Willow

We have a gas one, it's amazing with 2 kids and a wife, we never run out of water. Ours is a rental. Most of them are.

Emlyn

Also need to be aware of installation costs if the gas supply needs to be beefed up but that would also be true of adding a new gas fireplace. Electric isn't so much of an issue.

I don't have a tankless heater because it would be placed in my utility room on the other side of my house from the main bathroom. As it is it already takes a couple minutes for the hot water to reach that room.

I am very used to them though having spent a lot of time in Europe where they use them to provide the water for radiators as well as hot water on demand.

invalid

How long do tankless water heaters last? I work around plumbers quite often on new houses and they all say do not get a tankless water heater.

Tony M

Looking into fixing my water heater the past 2 weeks, I saw some tank-less on demand reviews at 2 or 3 of 5 for some of them. I thought about getting one UNTIL I saw the low reviews. I've even forgotten how many had reviewed each model.

BUT...I didn't read ANY of them so that's that. I WILL read up on them and why the dislike from some. Are they real reviews? that still needs to be determined.

Emlyn

I don't know anyone in the US market who has one long term but I know the central wall mount types that provide heat and hot water work for 20 years or more in Europe. My family members over there have a "boiler" mechanic come around once a year to do some maintenance, adjust something or other, and replace parts when needed. They're really pretty simple things. There are also separate electric shower units that don't last nearly as long.

mhardy6647

my beef about (old!!!) tankless water heaters is that -- if any scale builds up in the coil -- the heat exchange suffers and, after going through a coil-full of water, the stream goes tepid. Descaling the coil "fixed" the problem. Now -- mind you -- this was a very old tankless system (whole house, not point of use) that was in the house in MA when we bought it. I hated it, and we went to a system with a tank fairly shortly after we moved there.

I am sure the modern systems are better... but, I would underscore two comments that are peppered throughout the earlier posts in this thread.

1) maintain the tankless heater (coil) as instructed by the mfgr.
2) feed it softened water if you have hard water.

Jstas

So nobody tries to tell me I'm talkin' out my aft regions, I have a Rheem RTEX-18 electric tankless water heater.

I posted about it previously here: https://forum.polkaudio.com/discussion/comment/2619211#Comment_2619211

Here's the Rheem page for it:
https://www.rheem.com/group/rheem-tankless-electric-water-heaters-professional-classic-series-rtex-18

With that out of the way, there's some considerations here. But first, the reason I went with electric was because of cost. It was about $3200 in total with all the new electric and all the parts and equipment I had to get plus plumbers. But, to run a gas heater, it would have been over $8K because I would have needed inspections and I would have needed to punch a hole in the wall for the venting and I would have had to run a gas line all the way upstairs in a 100 year old house. So electric was the better idea because most of the facilities were already there.

BUT

If I were to do tankless for the whole house, I would go gas.

The other problem I have is that I'm on well water and if you look at the data sheet on the tankless water heater, their ratings are based on a nominal baseline of water temperature and pressures. Pressures are pretty standard everywhere and usually dictated by code. That baseline temp is about 45-55 degrees for your water feed which is, again, common for most municipal water supplies. That was a problem for me. All a single bathroom with a shower should need is 2.5-3.0 GPM capable water heater. But, since my well water comes out at about 35-38 degrees in the winter, I needed to consider the efficiency of a 2.5-3.0 GPM unit in that it would struggle to reach 120 degrees on the bath water alone. So instead of a single element, 240v service at about 30 amps for the smaller unit, I needed a 2 element unit at 240v with two 50 amp breakers to handle the 43 amp load on each element. That's big power for a single appliance. But it was necessary and maybe we change in it the future, I dunno yet. I barely had $3500 to pay for it when I needed it, no way did I have the $8K++++ to run gas.

That said, I'm not regretting it at all. The unit works as well if not better than a similarly sized gas unit. The only drawback is that LED lights with dimmable ballasts or on dimmer switches will flicker when it's running because the element heating is controlled by an SCR. So because of it's rapid switching when it's heating the elements, it causes voltage drops and surges that LEDs can be susceptible to if they have the variable dimmer ballasts. Otherwise, works like a champ.

Now I also have a boiler system for hot water for the rest of the house and heat with radiators everywhere. But, I have been told that I could do a tankless water heater for the heating as well as the hot water for the rest of the house. I don't know how well that would work out so I'd have to crunch some real world numbers on it but it is a possibility.

The other option is that I pull the hot water off the heater boiler and set it on it's own tankless system for the rest of the house. That way if the boiler conks out, I still have hot water. That really sucked when the boiler broke and I had no hot water except in the master bathroom.

If I do separate the hot water from the heater, that hot water heater will likely be gas and tankless. The size of the heater I would need for the rest of the house if I went electric would max out my service load all by itself. So it's not feasible for a whole house.

However, one thing that is possible if you have the time, money and inclination is small electric hot water heaters everywhere. Depends on how many bathrooms you have, though. I have a laundry room, a dishwasher, two kitchens (one is the bar), 3.5 baths and a utility sink. I would probably be spending $6K on the hot water heaters alone. But if all you have is a laundry room, kitchen and the 1.5-2.5 baths that are common, you could do 4-5 small, 1.5-2.5 GPM electric water heaters on 120v circuits and put them at the point of use. That distributes your load around the house and instead of one big hot water heater coming on for any faucet being turned on, only a small one at the location comes on. You reduce feed time from heater to fixture so your run time is minimal and you're not wasting water waiting for a cold hot water line to drain and send the hot water up. Additionally, if you have a small number of heaters, you could be using less electricity overall than if you had a single huge heater.

If you have a pile of hot water fixtures, though, a centralized tank system might be a better bet. If you're more "normal" in your needs, a tankless gas unit for the whole house would be workable just make sure you size it so if you have two showers, both plus 1 sink can be run at the same time. That would be about 6 GPM. That's a fairly sizable tankless heater and it's going to be 4 figures in cost for the unit alone plus install.

You really just gotta look at what's available in your abode in regards to gas and electric and look at the costs of operation for your needs and figure out your load planning. Then find a unit or combinations of units that will get you where you want. Maybe many small units is best, maybe one big unit is best. Maybe it's all electric, maybe it's all gas, maybe it's a mixture of both? Iunno but it's not hard to figure out and some planning and research now will save you a boatload of time and money when you go to change things.

As far as brands, all the major names have them in gas and electric now. Go with the brand you know/trust. Do some research too because some companies are reselling lesser known brands with their brand name on them. Others are building their own units.

Hope that helps.

NotaSuv

Thanks all..................................................... lots of good info

audioluvr

You have to take reviews with a grain of salt. Some are of good use, others are stupid people putting themselves in stupid situations WAY over their head and blaming the world on their stupidity. You decide.

quickr1

I have to agree with the last post.
Knock on wood but I’ve had one that I installed 10 years ago. It’s a gas unit. Roughly once every year or so we get a condition where we won’t get hot water. I have to disassemble the internals and finely sand the igniter and blow out the passage ways. Takes. ABout an hour start to finish. I have the flushing connections but have only done it once or twice. I really can’t speak on savings on the gas bill it’s been so long. I’m pretty sure I will get another after this one dies. Hopefully not for a while longer though.

Willow

They are installed in most new build around here part of the energy efficient program.

charley96

I give all the credit to John Kerry.

motorstereo

My neighbor had a tankless system installed in his totally remodeled home. He told me how wonderful they are at the installation and how they're best thing going now for hot water. 2 years later the tankless system is gone and has been replaced with propane heated 40 gal tank. He said he got tired of running out of hot water constantly with his family of 4. After talking with him about it chances are pretty good that I won't be swapping out my tank for a tankless system.

CH46E

Our new Home Owner's insurance (last year) company told us we had to replace out hot water heater. I looked at thankless but did not like the idea of a electrical nuclear process taking place everytime i ask for hot water. It would be on the other side of the wall as my sons headboard.

We went with a Rheem water heater. So far so good.

audioluvr

CH46E wrote: »

Our new Home Owner's insurance (last year) company told us we had to replace out hot water heater. I looked at thankless but did not like the idea of a electrical nuclear process taking place everytime i ask for hot water. It would be on the other side of the wall as my sons headboard.

We went with a Rheem water heater. So far so good.

Not to let the air out the OP's search but Rheem does make a hybrid water heater (like a heat pump) that's kinda expensive but is crazy efficient for a tanked water heater. @CH46E, ya that's why I didn't go with an electric on demand. Mixing water and 1.44 jigawatts to heat it just didn't seem safe.

motorstereo wrote: »

My neighbor had a tankless system installed in his totally remodeled home. He told me how wonderful they are at the installation and how they're best thing going now for hot water. 2 years later the tankless system is gone and has been replaced with propane heated 40 gal tank. He said he got tired of running out of hot water constantly with his family of 4. After talking with him about it chances are pretty good that I won't be swapping out my tank for a tankless system.

Some families just use an insane amount of hot water. Also there are other ways to plumb them which makes things better such as point of use thermal sensor valves used with a recirculation pump that keep the water hot in the hot water lines throughout the house (which minimizes wasted water also) and they can be doubled up too for twice the capacity. Many new large homes today have multiple water heaters anyway.

Milito

The new home we just bought and closed on today has a tankless water heater. I'll see how I like it as I've been following this discussion. The home is very energy efficient and has foam insulation.

We move into it next Wednesday.

mhardy6647

audioluvr wrote: »

CH46E wrote: »

Our new Home Owner's insurance (last year) company told us we had to replace out hot water heater. I looked at thankless but did not like the idea of a electrical nuclear process taking place everytime i ask for hot water. It would be on the other side of the wall as my sons headboard.

We went with a Rheem water heater. So far so good.

Not to let the air out the OP's search but Rheem does make a hybrid water heater (like a heat pump) that's kinda expensive but is crazy efficient for a tanked water heater. @CH46E, ya that's why I didn't go with an electric on demand. Mixing water and 1.44 jigawatts to heat it just didn't seem safe.

motorstereo wrote: »

My neighbor had a tankless system installed in his totally remodeled home. He told me how wonderful they are at the installation and how they're best thing going now for hot water. 2 years later the tankless system is gone and has been replaced with propane heated 40 gal tank. He said he got tired of running out of hot water constantly with his family of 4. After talking with him about it chances are pretty good that I won't be swapping out my tank for a tankless system.

Some families just use an insane amount of hot water. Also there are other ways to plumb them which makes things better such as point of use thermal sensor valves used with a recirculation pump that keep the water hot in the hot water lines throughout the house (which minimizes wasted water also) and they can be doubled up too for twice the capacity. Many new large homes today have multiple water heaters anyway.

Not to digress (me?!?), but there are heat-pump clothes driers now, too. Pretty cool idea (no pun intended).

CH46E

I wanted to go with a hybrid water heater. But could not swing that extra up front cost at that moment. Home owners insurance only gave us like 2 weeks to change it out.

Since our @NotaSuv Florida garages are so dang hot 9 months of the year, I liked the idea of the hybrid water heater taking some of that ambient heat and transferring it to the water. Figure it might cool the garage a hair.

NotaSuv

Garage is a sauna especially after parking the car in and closing the door

audioluvr

When you guys get sick of that heat your welcome to trade me places for a week(end). It's currently 48F here.

Milito

Well my tankless water heater seems to only go to 120 degrees. I don't have the manual yet to see if there is a way to set it higher. The controls on the front of the unit don't allow it to go any higher. Probably some govt reg or something.

Jstas

The 120 degree thing is likely a safety measure put on your system for liability purposes. Anything over 120 degrees runs a high risk of scalding someone. Many units have warnings that will let you still go past 120 degrees but they will pause or blink the temp at 120 before letting you continue. Others have fail-safes in place that you can by-pass but you have to do something deliberate to get around it so if you or someone in the house ends up getting hurt, you can't sue the manufacturer because you did something to circumvent a safety feature meant to prevent injury and subsequently assumed responsibility for it.

It's really not a problem unless you have young kids who might turn on a faucet with just hot water and not temper it with cold water and end up being scalded.

mrbiron

I can tell you this, I* have probably installed close to 2,000 Navien over my last 4-5 projects. There is an initial failure rate (guesstimate) of around 2-3%. Need replacement boards upon startup is the common problem. After they are setup by a professional and are serviced regularly, they are pretty bulletproof. They have all been gas fired appliances.

*I’m a GC, not a plumber, so I do not personally install them.

I have a gas Navien in my house. They are finicky with pitch of pipe, air filter cleaning, water filter changing and even air pressure coming through the concentric vents. I had an issue with ours that needed a switch and/or solenoid that needed to be swapped. It was covered under warranty by the installer. Pain in the **** for that week waiting for the part.

A plumber will be by in the coming weeks to show me how to service the appliance. Other than that, it just runs.

YMMV

I hate typing in a phone. 🥺

Milito

Jstas wrote: »

The 120 degree thing is likely a safety measure put on your system for liability purposes. Anything over 120 degrees runs a high risk of scalding someone. Many units have warnings that will let you still go past 120 degrees but they will pause or blink the temp at 120 before letting you continue. Others have fail-safes in place that you can by-pass but you have to do something deliberate to get around it so if you or someone in the house ends up getting hurt, you can't sue the manufacturer because you did something to circumvent a safety feature meant to prevent injury and subsequently assumed responsibility for it.

It's really not a problem unless you have young kids who might turn on a faucet with just hot water and not temper it with cold water and end up being scalded.

Jstas wrote: »

The 120 degree thing is likely a safety measure put on your system for liability purposes. Anything over 120 degrees runs a high risk of scalding someone. Many units have warnings that will let you still go past 120 degrees but they will pause or blink the temp at 120 before letting you continue. Others have fail-safes in place that you can by-pass but you have to do something deliberate to get around it so if you or someone in the house ends up getting hurt, you can't sue the manufacturer because you did something to circumvent a safety feature meant to prevent injury and subsequently assumed responsibility for it.

It's really not a problem unless you have young kids who might turn on a faucet with just hot water and not temper it with cold water and end up being scalded.

I figured it was a safety feature, I just want to turn it up to 130 or 135. We only have young kids around when our grandchildren visit.

Jstas

Your best bet is the manual.

If you know your brand, model and model number, most manufacturers have digital copies of their documentation available online. A search on Google or other search engine should bring it up.

Milito

We are still unpacking boxes from the move. The last few weeks have been getting our house ready to sell. We put it on the market today with two offers already way over ($25,000 & $30,000) the listed price. The real estate market is crazy right now. We are going to stop taking offers Monday. It will be interesting to see how many we get.

One of our new neighbors in the area we moved to has a million dollar home (way more house than ours) who put their house on the market today too. They already have two offers. That is why we bought a new house as purchasing a used one is a bidding war right now.

audioluvr

You must love moving.

Milito

Yes I do, that's why it's my first move in 26 years.