3 Things They Don't Tell You About Tankless Water Heaters (On Demand Water Heaters) (2023)


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Join us as we discuss our decision to remove an electric tankless on demand water heater and upgrade the hot water in our debt free dream home project to a full on demand tankless natural gas boiler that provides bottomless hot water faster and cheaper than electric.


Foreign welcome to maybe the smallest.

But the second most important room in the house, the first being the bathroom, of course, so we've been working a ton on the mechanical room in our debt-free dream home.

And so we want to start into a video series kind of talking through a lot of the stuff happening in here like a lot of mechanical rooms.

There are many different phases of things that have sort of come all together over the years and kind of come together in this one room to make all the systems in the house work, good we're, not done because there's still other things that need to be added.

So this playlist, and these videos will grow over time.

So today, we're going to jump into hot water.

This is something that we started back when we were living in the RV.

And we really really wanted to get into the house.

We had originally thought we were going to move the RV inside.

And they become really obvious that the goal was just to get in the stinking house.

What are your parents doing over there? They're turd polishing.

So we we actually decided we had like a 30 second heart to heart that we're, not wintering in that structure.

We refuse to fix the rip in it it's gonna start raining so pretty much the push is on to get the RV in there and we'll do what we have to do Jesse mentioned an outhouse and showering elsewhere.

And so we kind of made some sort of temporary decisions that helped us kind of bridge from where we were then to where we are now.

So let me take you through some of the decisions that we made, then and we'll kind of talk about how those things have, um progressed in the mechanical room here.

Some of you who've been watching for a long time will remember we actually had a tankless electric water heater installed here.

And it was basically just coming from the cisterns up to the water heater and then fed the single bathroom in the kitchenette area that we had we did that because it was quick affordable, and it didn't require any kind of ventilation or anything like that.

So it was something that we could basically just bolt to the wall, put some electricity to it.

And we had hot water at the time we had a lot of room in the electrical panel, because we really didn't have anything else going on.

And so that that particular tankless water, heater took up three, Bays, 240, volt bays in the electrical panel again that tankless water heater was more of a short-term interim solution.

We didn't know how short short term was or how long short term was.

But it was a non-issue at the time, and it worked just fine, um, it met our needs.

And it gave us bottomless showers, which were great and allowed us to do laundry and do dishes and I think the cost for to set everything up was probably 300 and some chains, 300 and some change because we had to buy some heavy duty, cable I.

Think it was number eight wire something like that.

And then oh I forgot the breakers.

Actually, the breakers were brutal forgot about that.

Those were probably close to a hundred and fifty dollars a piece because they're a GFI breaker, which we needed to pass our electrical inspection because we're living in the house, and we needed to to be able to disconnect those.

So those Breakers probably worth 450 bucks.

But the good news is we were actually able to return those.

And so we got the money back.

And so I.

Guess, in the end there was Net Zero on the breakers.

One of the goals in the home design is to minimize internal combustion, minimize air change make up air, and um, also to minimize the heat load on the house.

And so those three things are achieved through a tankless water, heater system since there's, no tank, there's, no parasitic heat load in the house.

And so even though it was electric the on-demand water heater did not produce any, um, any parasitic heat.

It didn't add anything to the house, which is important, because we don't have any air conditioning.

And we don't want any we don't want to have to like heat up water and then cool down the air and do all this ridiculous energy stuff that a lot of homes do.

And so the tankless water heater allowed us to have zero parasitic heat load, uh.

The second thing is there's, no combustion and so there's, no makeup air.

And so we didn't have, uh, this kind of drawing of cold air or hot air into the house, uh, making it hard to acclimatize the house.

There were some downsides to the on-demand electric as I mentioned earlier, the sheer amount of electricity that was required to make this unit work.

It was a 36 kilowatt unit.

It had three heating elements.

We did not plan for that.

When we planned the electrical service to this property, when we talked to the electrician, originally, we said, 200 amp service or 400 amp service.

And he just assured us that 200 amps was way more than we would ever need ever and what's.

Interesting is right away.

We immediately had a problem because the on-demand water heater was 120 amps 240 capable, which sucked up a tremendous.

This amount of the capacity of our electric service.

So if we were to turn on the clothes, dryer the cooking range, which are both electric, and then the water heater.

Guess what we're actually going to exceed our electric service.

So we'll talk more about those things in another video, some of the drawbacks of these electric tankless, water heaters.

But the point is we wanted to stick with the same tenants, though with our ultimate long-term solution, having a tankless system to minimize parasitic heat, no internal combustion.

So this unit is our new domestic hot, water unit, it's, actually a combination boiler.

So it serves two functions.


Talk about the heat function later.

The point of today's video is about the domestic hot water side.

We will talk more about the natural gas installation and a lot more of the stuff in future videos.

But this is the direction we went because we actually have natural gas available, although at the time when we were originally planning this, we were going the direction of propane.

This unit actually has the ability to do both.

It can be either fuel source.

And that was important to us, because while we love the idea of natural gas, there's, always that reality that either becomes cost prohibitive or there's, some other issue down the road.

So this is a combination boiler, and it kept true to the no internal combustion concept, because it actually draws the combustion air from outside.

So this white pipe actually is the intake, which goes clear out the outside of the building.

And the gray pipe is the exhaust.

And so while the combustion actually does happen here inside the room, the air that is combusted comes from outside.

And it is returned to outside.

This unit does actually have a small water tank built into it I think it's around two gallons or three gallons so it's, not a lot.

But it does have some parasitic heat load.

The cool thing thing is through the computer system, we're actually able to disable that function.

So it's, literally just an on-demand tankless water heater, even though there's a small reserve tank, but to kind of minimize the short cycling like if you're just to wash your hands, or you know, rinse a dish really quick to keep the unit from short cycling.

A bunch.

We left that feature turned on.

But during the summer time, when we're kind of in that cooling mode, and we don't want all this parasitic heat load on the house, which by the way is Insidious, it's, it's, two or three degrees here, one or two degrees over there, a little here a little there and guess what now your house is uncomfortable and hot and now you're, paying more money to use energy to cool.

The house down see if I can show you the label here on the side.

So like I said, this is a dual feel capable boiler.

One of the reasons we went with this particular model of boiler is its capacity.

And this is important when you look at the total picture.

So a lot of you people out there doing HVAC are going to know that this boiler is way overkill for what we're trying to do on the domestic hot water side.

So if you needed just a tankless natural gas water, heater for just hot water, this would be absolutely Bonkers and you'll kind of see as you watch this playlist and get to know the system as a whole that this boiler is a Workhorse.

So it's, 199, 000, BTU, capable, there's a little fine print and an asterisk in the manual that actually says that from the factory it's actually only 140 000 BTUs, which works just fine because my imagination based on calculations is that we're probably only using around 40 percent of the capacity right now, which is not really a good design.

But over time as the house grows.

And a lot of the other applications grow the usage will increase and so it's actually capable of raising the water temperature at about.

Maybe around eight gallons a minute is the rough capacity, depending on the groundwater temperature, I think we're keeping our domestic water at around 115 degrees at the spigot.

And our ground water temperature is probably like around 45 degrees or so so there's times where it's going to be probably less than seven gallons a minute, maybe closer to five one of the other big changes in the domestic hot water is essentially that this tank is kept at room temperature.

Since this tank is not outside in some sort of well house or something.

And and basically the water heater is having to bring the temperature of that water up we're starting at around 68 degrees, maybe a little bit warmer because it's in the mechanical room.

So really our temperature rise is fairly small.

When you think about, you know, the total cycle.

So unless you took a shower that's, you know, or took, you know, use all this water up and it's refilling with groundwater, the water heater really isn't working all that hard I'll touch on this in this video, just because I know, there's people who are going to have questions, uh, but I think we'll probably do a video of its own later.

So why is the exhaust gray and the intake white? So the intake here is just schedule, 40 PVC, it's, drain, waste and vent dwv.

And this is obviously vent.

The problem is the building code has shifted so that we are not able to use the schedule 80 that we were using previously for the exhaust side.

The manual does require schedule, 80 within I think six inches of the exhaust and there's some parameters there.

But the building code is going this direction.

This is a completely new type of pipe.

It is called system, 636 it's, its own pipe, own fittings own glue and own primer.

It is expensive when we did this work.

This was about a hundred dollars for a 10 foot stick.

And each fitting was around 50 bucks.

We had actually built the entire exhaust, and it was all approved.

And when this information came to my attention, and so we made the executive decision at that time to bring the system up to Modern code.

And so we actually gutted the whole entire exhaust side and rebuilt it using the 636 system to put into perspective, the cost savings on the hot water side alone for this unit is astronomical just using the domestic hot water portion of this boiler.

We are barely over with a family of people taking numerous showers a day doing numerous loads of laundry a day hand, washing dishes, we're, not being conservative with water.

We're barely over the minimum bill for the natural gas on this particular unit, which tells you that we're we're, probably under 10 to 12 dollars a month, which is Bonkers to be fair.

We have very cheap power where we are.

And the electric unit was probably closer to 30 or 40 dollars a month.

And again, that was that was probably being more conservative with water.

So for us in our situation with our Energy prices, where we are the cost savings is probably between 20 and 30 dollars a month just going from the electric to a natural gas system.

So should I share this tank.

Let's, go ahead and talk about it.

Now, I think we're going to talk about it more in a future video.

So if another video comes out and we touch on the subject in more detail, give it some some thought, and it kind of has to do with what's behind me, but I don't want to get too much into the whole mechanical room.

Because this video is going to get to be really long this tanked water.

Heater is actually in line with the domestic hot water side of the combination boiler and it's electric.

Obviously, the reason or thinking behind that is twofold one in our area.

It is very common for people to get extremely excited, especially in the springtime and start digging things up.

And it is very common for the utilities to get dug up.

And it creates an outage at least for several days if not for longer than that, depending on the severity of the situation, which means we could be without natural gas that quick.

And so suddenly all that wonderful design and Engineering is junk because you have no hot water.

So we put in a tanked water heater just so we have a redundancy and it's electric there's, actually a third part to this and I'll just touch on it.

Now we'll talk about it more later when we talk about the heating panel and stuff, but ultimately, we want to have a sidearm heat exchanger on this tank.

So that in the future, when we develop the entire heating system, we'll have a wood boiler outside that wood, boiler will passively heat this tank as a reserve to 180 degrees.

And this will actually completely nullify.

The need for the combination boiler during the heating season when we're actually using the wood boiler to heat the house.

So this is a triple redundancy in the winter time, it'll be heated with wood passively to 180 degrees, we'll use a mixing valve bring it down so that we can heat the shower and everything like around 150 degrees, which will make this tank of water.

Go very very far.

When we get started getting wind storms and stuff like that start talking about power, outages and things, um, we actually fire this up by flipping the breaker and just bring it up to heat costs about four dollars to do that way.

If the power goes out, we can use our gravity fed water system.

And we actually have hot water.

We have to be conservative, but we have some.

And then if the power were to come back on, then everything would work the way we expect it to normally.

And so then this system just overrides the combination boiler, because the water is already up to temperature.

And so the boiler doesn't heat anything there's going to be a lot more bells and whistles to this system in the future.

One of the things that we want to build into the house is a hot water loop with a circulation pump, because of how far it is to the different Outlets.

We don't want people to have to wait to bring in hot water.

And so we've got a system that we're going to be implementing with a controller that will allow this to basically heat a loop of hot water that circulates very slowly with a very low wattage pump.

So that when you go to wash your hands anywhere in the house, you know, whatever it is take a shower.

The hot water is there? Absolutely right now.

Let's, take a look at the outside of this.

So you can kind of see the intake and exhaust on the outside right now.

All right.

And here is intake and exhaust on the outside the building.

Obviously, we've got them just sealed up for the moment.

We'll have to do a lot more detail with that when we get to the house wrap, but here's your exhaust side, and eventually we'll be probably doing a little bit more fitting with this because we're going to potentially have a deck back here in the future, and so we'll need to Elbow it out and meet code and get that exhaust away from people in the house.

And then the intake side is just a pvct and it's got a ventilation guard.

There, keep bugs and birds and things from getting inside there, all right.

So the system is actually on right now.

And what it's doing is it's just warming that small reserve tank there just to keep it I.

Think it keeps it like around 120, something like that, maybe 125 I don't think that's the correct temperature.

But you can hear how quiet the unit is almost as quiet as the electric unit, there's, a small fan there.

And of course, as the unit starts to work harder, it does make a little bit more noise, but we keep the mechanical room closed.

And so the noise is no, no negative effect on quality of life in the house for those who are curious when we bought this unit was pre-pandemic and I think we paid probably around fourteen hundred dollars for it we're going to do a lot more content on this subject, it's, something that there's a lot of detail around for those who want to discuss it more in detail.

We chose this particular boiler, because it was recommended by somebody we trust I think in the hindsight, um we'll, probably talk more about this later, but we probably wouldn't have bought this unit again.

And so we'll just share that more in another video kind of talking about why we bought it what its features are.

And then what we would have bought instead.

So that pretty much wraps it up for the combination boiler.

And the transition from the electric tankless to this Beast it's, amazing bottomless showers, bottomless dishes, bottomless, laundry, just as much water as you have, no there's is never going to be a time where people run out of water.

The only thing is I haven't quite figured out when the littles get big enough to take too long of showers, how we're going to do that, not sure if we're going to set a timer or how we're going to keep that under control because the bad side of this is it's, literally bottomless.


3 Things They Don't Tell You About Tankless Water Heaters (On Demand Water Heaters)? ›

The biggest downside of tankless water heaters is their higher initial cost. A good quality tankless heater will run you more than a traditional storage-tank model, although the savings in energy costs over time can make up for this difference.

What is bad about tankless water heaters? ›

The biggest downside of tankless water heaters is their higher initial cost. A good quality tankless heater will run you more than a traditional storage-tank model, although the savings in energy costs over time can make up for this difference.

Can tankless water heaters keep up with demand? ›

Although tankless water heaters technically cannot run out of hot water since they are designed to always heat up more water on demand, they can be overwhelmed with demand when there are multiple taps or appliances on at once.

Is hot water on demand worth it? ›

Advantages and Disadvantages

For homes that use 41 gallons or less of hot water daily, demand water heaters can be 24%–34% more energy efficient than conventional storage tank water heaters. They can be 8%–14% more energy efficient for homes that use a lot of hot water -- around 86 gallons per day.

Is it worth switching to a tankless water heater? ›

For many people, the long-term benefits of tankless heaters more than compensate for their initial expense. A tankless heater can be up to 34% more efficient than a traditional water heater. This increase in efficiency can amount to annual savings of over $100, depending on the type and size of the heater.

What is the life expectancy of a tankless hot water heater? ›

On average, a tankless water heater can last up to 20 years with proper yearly maintenance. With a copper tankless heat exchanger, your tankless water heater has a warranty of 12-to-15 years.

What is the maintenance on a tankless water heater? ›

Generally, your tankless water heater should be serviced at least once every year. If you have hard water, then you might need to service it twice yearly. During each servicing, a technician will carry out several tasks including cleaning the filter and flushing out the system.

How much longer does it take to get hot water from a tankless water heater? ›

Instant Hot Water

Tankless units take about 15 seconds to bring water up to temperature, but you still have to wait for that hot water to arrive at your shower head or faucet, just as you do with a tank-type heater.

What is good and bad about tankless water heaters? ›

A tankless water heater costs more upfront—both for the unit and installation—than a traditional storage tank water heater. While the expense may deter you at first, keep in mind that a tankless water heater—with its longer lifespan and energy savings—will pay for itself in just a few years.

What are the pros and cons of a tankless water heater? ›

Pros and cons of on-demand hot water
Pros of tankless water heatersCons of tankless water heaters
High efficiencyLimited flow rate
Long-term savingsHigh upfront cost
Environmentally friendlyCan require prior setup work
Jan 21, 2020

What is the best temperature for hot water on demand? ›

You'll want to shoot for 100-115 degrees Fahrenheit for your water to be heated.

Do tankless water heaters increase electric bill? ›

That said, the Department of Energy estimates that a gas-powered tankless water heater would lower energy costs by around $100 a year, and an electric tankless water heater reduces costs by $44 a year. Overall, tankless heaters are substantially more costly than their tank-based counterparts.

How much does a tankless water heater affect home value? ›

Tankless water heaters are considered a desirable feature by homebuyers, which can increase a home's value. Homebuyers are attracted to the energy efficiency and low maintenance of tankless water heaters, making them a valuable investment for homeowners looking to increase their home's resale value.

How much value does a tankless water heater add to your home? ›

If you are looking to increase the value of your home, adding a tankless water heater to your features is a great place to start. According to a study conducted by Zillow, homes with tankless water heaters sold for 4% more than their expected value. On average, these homes also sold 43 days faster than expected.

Are tankless water heaters high maintenance? ›

The good news is that tankless water heaters don't require much maintenance, either. A tankless system should be serviced as a part of the regular preventive maintenance that heating and cooling systems receive. Electric or gas components should be inspected.

How much money a month does a tankless water heater save? ›

The U.S. Department of Energy estimates gas-fired tankless heaters save an average of $108 in energy costs per year over their traditional tank counterparts, while electric tankless heaters save $44 per year.

How long does it take for a tankless water heater to pay itself off? ›

How long does it take for a On Demand or tankless water heater to pay for itself? The pay off time on a tankless water heater varies based on usage, utility rates and cost of installation. It can take from 7 to 10 years to pay for its self.

How often do you change the filter in a tankless water heater? ›

To keep your tankless water heater in prime condition, it is advised to clean out the filter once every six months. This routine maintenance is easy to do and only takes a few minutes.

How big of a tankless water heater for a family of 4? ›

36 kW 6.2 GPM Residential Electric Tankless Water Heater, Ideal for 4 Bedroom Home, Up to 8 Simultaneous Applications.

Why does my tankless hot water heater go cold? ›

A broken flow sensor can cause your tankless water heater to run hot and cold. The flow sensor measures the water entering your system and sends that information to your unit's control board. If there's a burst of cold coming into the system, then the controller adjusts the flame.

How do you fix a cold water sandwich on a tankless water heater? ›

You have two options for fixing a cold water sandwich: installing a recirculating system or putting in a small tank water heater. In fact, some manufacturers today already include this buffer tank.

What are two disadvantages of a tankless water heater? ›

Pros and cons of on-demand hot water
Pros of tankless water heatersCons of tankless water heaters
High efficiencyLimited flow rate
Long-term savingsHigh upfront cost
Environmentally friendlyCan require prior setup work
Jan 21, 2020

What is the life expectancy of a tankless water heater? ›

On average, a tankless water heater can last up to 20 years with proper yearly maintenance. With a copper tankless heat exchanger, your tankless water heater has a warranty of 12-to-15 years.

What is the lifespan of a tankless water heater? ›

Some people hesitate to decide on a tankless water heater because they can be a slightly higher cost; however, you get significantly more life out of one. A standard water heater tank lasts about 8-12 years. A tankless water heater can last as long as 25 years!

Is a tankless water heater better than a tank water heater? ›

According to Energy.gov, “For homes that use 41 gallons or less of hot water daily, demand (or tankless) water heaters can be 24% to 34% more energy efficient than conventional storage tank water heaters.” Tankless water heaters (if gas-fired) will save homeowners over $100 annually the longer they remain in service.

Do I need to clean my tankless water heater? ›

Over time, a tankless water heater may accumulate mineral build up which can erode the walls inside your tank's heating chamber. To properly maintain and clean your tankless water heater, it's important to flush those mineral deposits at least once a year.

What is the average yearly cost of a tankless water heater? ›

Electric tankless water heaters cost between $75 and $300 per year to operate whereas gas tankless water heaters cost between $175 to $500 according to our review of the most popular models. If you plan to use a tankless water heater for your whole home, then consider a heat pump water heater.

Why does it take so long for hot water with a tankless water heater? ›

The longer the distance between your water heater and the tap, the longer it takes for the hot water to reach the tap. This delay is due to the time it takes for the hot water to travel through the pipes.

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