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Tankless Water Heater - are they more efficient?

DWKX31

Well-known member
I have one it works great for showing but when you dishes it's cold you have to let run,it waste water. Low water pressure it shuts off and on.
 

KingDom

Active member
Has on-demand HW improved? Seems like it makes sense to “heat it when you need it!”
Would you let your truck run all day? Or turn it on when you want to use?🧐
 

RockDr896

Well-known member
Speaking from experience, no. The problem is the low water pressure shut off on them. If you want to see if this will affect you, try taking a shower and having someone wash dishes. If the shower water changes temperature, then the tankless system will most likely shut off. Leaving you in a cold shower, until it turns back on. This can also happen if you use too much cold vs hot water. The problem is caused, in my opinion, by the various fittings that people use for convenience, that doesn't make the system a true 3/4" water system. Like my run on sentence...LOL. I am considering replacing my 1/2" pipe runs to 3/4 " ....
 

Bozo

Well-known member
No. They are not more efficient. They just allow a longer shower. I turn on my tank style when I need it to shower and dishes, otherwise it is off.
 

RockDr896

Well-known member
Timely video by Changing Lanes:
Perfect timing on the video post! I wish he would have tried running the shower and the sink at the same time. I would bet money, the low flow on the tankless would be triggered and shut off.
 

Oregon_Camper

Forum Moderator
Staff member
Timely video by Changing Lanes:
Good thing I read all the replies, because I already had Chad's video copied and I was ready to post a link to it. He did a great job with explaining the two systems. I don't think I will ever want a tankless system, based on what I saw.
 

RockDr896

Well-known member
Good thing I read all the replies, because I already had Chad's video copied and I was ready to post a link to it. He did a great job with explaining the two systems. I don't think I will ever want a tankless system, based on what I saw.
Had one on my first ..... never again!! Your timing was great!
 

Jim Beletti

Owner Experience Liaison
Staff member
My observation only - not an endorsement... Like DC refers, tankless water heaters seems to be the direction much of the industry is going. While the RV variants seem to be a bit more nuanced in their use residential units, I believe they will continue to improve in usability.

That said - I've used a couple of brands over the years and will soon be using the Furrion brand in my Delta. We'll see how it goes :)
 

KingDom

Active member
My observation only - not an endorsement... Like DC refers, tankless water heaters seems to be the direction much of the industry is going. While the RV variants seem to be a bit more nuanced in their use residential units, I believe they will continue to improve in usability.

That said - I've used a couple of brands over the years and will soon be using the Furrion brand in my Delta. We'll see how it goes :)
Thanks Jim. I agree that technology keeps improving. We need to adapt when it makes sense for us.
 

RockDr896

Well-known member
Just a thought experiment, for any to chime in on. Possibly a discussion on it's own. You can decide Jim.......
The typical RV industries 1/2" plumbing approach, creates many of the volume and pressure issues experienced by most.

A house will usually run a 3/4" pipe and then branch off to 1/2" to hit sinks and such. So there is more volume for several sinks to draw from, without affecting each other.

Volume is then further compounded by the users choice in supply hose size, filer sizes used, and shut off valves. If a person uses a 3/4" hose and then places the typical hose splitter at the connection point, volume has already been reduced down to a 1/4" flow at whatever pressure. That reduction in volume, will never keep up with (2) two fixtures plumed with 1/2". So no shower, when the dishes are being done.

Since I am retired and have time on my hands, I am considering running 3/4" or maybe 1" before reducing to the existing 1/2" in the walls. I just need to spend the time figuring out, whether I make my own Nautalis control panel or see if they make a 3/4" or 1" version.

In conclusion, the problem is volume. Any thoughts are welcomed.
 

Bozo

Well-known member
Being a plumber and hvac/r guy, my experiences with tankless heaters is where I draw my conclusions from. Tankless heaters are more trouble than they are worth. Only advantages are that you can take a shower longer. No more efficient at all. What little savings they might claim is used up in another resource…water. Flow is key, too little, you have a problem, too much(for a given heater) and you have a problem with not enough hot water. Maintenance is higher, not necessarily hard but more. Must flush and descale at least yearly. Controls can also be problematic. I am not a fan.
 

KingDom

Active member
Being a plumber and hvac/r guy, my experiences with tankless heaters is where I draw my conclusions from. Tankless heaters are more trouble than they are worth. Only advantages are that you can take a shower longer. No more efficient at all. What little savings they might claim is used up in another resource…water. Flow is key, too little, you have a problem, too much(for a given heater) and you have a problem with not enough hot water. Maintenance is higher, not necessarily hard but more. Must flush and descale at least yearly. Controls can also be problematic. I am not a fan.
Bozo, Now that’s what I’m talking about. When you want advice about your teeth, get it from a dentist. When you want pro advice on a HW tank. Get it from an HVAC/R pro. Thanks
 

daemonic3

Active member
Just got a Delta after 6 years of Grand Design with traditional 6gal gas/electric water heaters. After reading this thread I was scared that the tankless heater would disappoint. Well, it DID disappoint 😔

I read the warning here about proper PSI so ahead of time I got a regulator with inline gauge, rather than my previous 30psi regulator. It came factory default set to 45psi but I tested the campsite and it seemed to max at providing 40psi.

First night shower testing, it took a surprising while to get hot with only the hot knob. Maybe because it was 50 degrees outside? The furrion was set to 115F. I didn't bump it to 124F until day2. As far as kitchen (rear in the 294RK, much further than shower) it took FOREVER to get any warmth out, enough to wash a greasy dish. Over the weekend I think we wasted MORE cold water into our kitchen holding tank than we used warm (never got fully hot in the kitchen) to wash dishes.

Only the final morning, was the shower so hot it burned and we needed to mix in cold! Not sure what changed from the day before when it was also set to 124F.

Will it be better in warmer weather? Or with more PSI? We shall see! But definitely disappointing how it wastes holding tanks waiting for the hot.
 

Bozo

Well-known member
Just got a Delta after 6 years of Grand Design with traditional 6gal gas/electric water heaters. After reading this thread I was scared that the tankless heater would disappoint. Well, it DID disappoint 😔

I read the warning here about proper PSI so ahead of time I got a regulator with inline gauge, rather than my previous 30psi regulator. It came factory default set to 45psi but I tested the campsite and it seemed to max at providing 40psi.

First night shower testing, it took a surprising while to get hot with only the hot knob. Maybe because it was 50 degrees outside? The furrion was set to 115F. I didn't bump it to 124F until day2. As far as kitchen (rear in the 294RK, much further than shower) it took FOREVER to get any warmth out, enough to wash a greasy dish. Over the weekend I think we wasted MORE cold water into our kitchen holding tank than we used warm (never got fully hot in the kitchen) to wash dishes.

Only the final morning, was the shower so hot it burned and we needed to mix in cold! Not sure what changed from the day before when it was also set to 124F.

Will it be better in warmer weather? Or with more PSI? We shall see! But definitely disappointing how it wastes holding tanks waiting for the hot.
What you described is exactly why tankless is not a good choice for rv applications. Also if flow diminishes enough, say when trying to modulate temp with cold, it could also shut off momentarily causing a cold shot to the shower. I have spent countless hours educating residential customers on this. In some respects, they are snake oil. They do have uses, just not good for rv, in my opinion.
 
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