On demand water heater

[Graphite Dave]

I have a high capacity LP Gas tankless water heater for my house. I do not have the RV version, so my remarks are based only on the home system.

Tankless water heaters are not designed to save water; indeed, they waste considerable water waiting for the "instant" heater to heat the water to sufficient temperature and provide it through the household pipes to the faucet.

In our two story house the instant water heater is on the bottom floor on North side and the kitchen sink is on the second floor on the South and opposite side of the house. ie about as far apart as possible in the house. We used to waste a lot of water waiting for the hot water to get up to temperature. Installed a D'Mand recirculation pump to eliminate the wasting of water. A small pump is installed under the sink. You press a button to start pump when you want hot water. The water in the "hot" water pipe between the instant hot water heater and the faucet is pumped into the cold water pipe under the sink. A temperature sensor stops pump when hot water arrives at the faucet. When pump stops you now have hot water at the fixture without wasting water. We also have a wireless pushbutton near our shower downstairs. Press that button and a signal starts the pump under the sink. Again you wait a bit and hot water is available before turning on the faucet.

http://www.gothotwater.com/

D'Mand system had better reviews than the similar chilipepper system.

In an RV with limited water supply when dry camping, wasting water is more critical. In the Sprinter I modified a 5 gallon beer keg so I could heat water electrically. All the water in the tank was at the correct temperature so no water was wasted.

https://sprinter-source.com/forums/showpost.php?p=191820&postcount=16

The idea works well if you have a inverter powered by the vehicle 12 volt system to provide the 120 volt power to heat the water while driving. Took about 45 minutes driving to get 5 gallons of water up to 90 degrees. A submersible pump then delivers water to shower.

Will copy the system in the Transit build with a few improvements. Change to a 1000 watt vehicle inverter from the Sprinter 600 watt and change the heating element from 450 watts to 675 watts to reduce water heating time down to 1/2 hour. Also gas engine can be idled so do not have to drive to heat water. Instead of a beer keg I will use the wasted space under the portapotti for the shower water tank. The tank will be the support for the toilet.

 

[avanti]

Our Espar on-demand system has standard home-style adjustable tempering valve, sort of like this one

Seems to work fine.

 

[Don Horner]

Don,
On topic (sort of). You should look into the http://www.chilipepperapp.com/ system for your home on demand water system. I do not have on demand, but do have a solar system and don't like to waste the water while waiting for hot water to arrive. I have used this system for years and it really works!

Bob

Thanks! That could solve the wasted water problem, and possibly supply faster hot water -- but our house was owner-built in the late 70's by someone with almost no knowledge of construction, and has had additions and remodels, and I have a suspicion that the plumbing is in no logical sequence. It's probably impossible to get hot water any faster with one pump, through 3 bathrooms, 4 showers, 6 bathroom sinks, the kitchen and laundry room, all moved around and none installed by the same folks.

It's all on a well and septic tank, so I don't have to worry about water and sewer bills. Actually, I don't even worry about wasted water, as my theory is that it comes from the ground via the well and is returned to the ground via the septic system, so none is ever "wasted". But, my darling wife, SWMBO, hates the idea of letting the water run for even a few seconds (she also turns off the paddle fan in my office every time I leave the room, even for 69 seconds ).

But, to make her happy, I'll run some tests to see if getting hot water to one location speeds up the others, and figure out where to put the pump, if it's going to work. She's perfectly willing to spend $200 to save $5 in electricity to run the well pump....

{EDIT} Chilipepper has some competitive comparisons with other systems, including the D'mand, and comes out well, if they do say so themselves... But, I'll check it out, also, they seem to have the same idea.

{MORE EDIT} Woops -- the Metland D'Mand system is more than twice the cost of the Chilipepper!

 

[Graphite Dave]

I am also on a well with septic. The main advantage is the hot water gets to the faucet faster because the pump moves water through the pipe faster. The disadvantage is you have to press a button to start pump.
Maybe you can time each hot water location to see how long it takes to get hot water to determine which faucet is furthest from the source. Each morning do a different faucet before any hot water is used. We have had the D'mand system for about 8 years. Hardware is well made. Believe it was more expensive than the Chilipepper.

 

[icarus]

Excess water into a septic drain field is not altogether a goo idea either.

I have used demand water heaters for 30+ years and would never go back to a tank type. I currently run a Rinnai combi boiler that does both hydronic heat as well as DHW. Will produce hot water in seconds, and as long as there is gas in the line...forever, al at 95.6% efficiency.

The unit is centrally located in a closet (direct PVC venting) so it takes 5-10 seconds to the kitchen, less than 5 to the baths. No circ pump, no muss, no fuss!
Icarus

 

[Don Horner]

...The unit is centrally located in a closet (direct PVC venting) so it takes 5-10 seconds to the kitchen, less than 5 to the baths. No circ pump, no muss, no fuss!
Icarus

That was the neat thing about our installation. A previous owner had installed solar hot water panels and a giant storage tank in a little lean-to on the back of the house. The next owner saw the tank was rusting and found the solar panels were no longer functioning, so installed a small (30 gallon) conventional water heater in the lean-to.

When we bought the place, we removed the water heater and lean-to and installed the Rinnai tankless heater on the outside wall where the plumbing already existed. No venting necessary! Of course, living in Florida, we don't have to worry about excessive cold weather. The only drawback is that it's 30 to 50 feet to the kitchen and baths (the laundry is practically next to it, but the irony is we only launder in cold water .)

It's been in place about 5 years.

 

[icarus]

^In FL, solar hot water is very easy to do, and a proper installation will pay for itself in short order. Sublimented with a Rinnai is a great idea.

A even better idea is hot water capture heat pump (gathering waste heat from the A/C) is a fantastic way to get hot water. It dramatically increases the efficiency of the A/C while at the same time giving you "free" hot water.

Icarus

 

[Bone Head]

For what it's worth, I can speak to both the D'mand system and the Chilli-pepper as I have both and they each have their pluses and minuses. The D'mand by Metlund is a bit slower to pump, but is MUCH quieter than the Chilli-pepper while the Chilli-pepper gets the job done quickly but loudly enough to wake the dead.
I have had the Metlund system for about 12 years with no problems and have had the Chilli-pepper for about 6 years with one warranty replacement of the pump.
As to having to push a button, one can install proximity switches which will turn the pump on when one enters the room. That for me is too wasteful as the pumps would be going on and off frequently.

Bob

 

[Don Horner]

For what it's worth, I can speak to both the D'mand system and the Chilli-pepper as I have both and they each have their pluses and minuses. The D'mand by Metlund is a bit slower to pump, but is MUCH quieter than the Chilli-pepper while the Chilli-pepper gets the job done quickly but loudly enough to wake the dead.
I have had the Metlund system for about 12 years with no problems and have had the Chilli-pepper for about 6 years with one warranty replacement of the pump.
As to having to push a button, one can install proximity switches which will turn the pump on when one enters the room. That for me is too wasteful as the pumps would be going on and off frequently.

Bob

I assume one can still get hot water by running the water and waiting for the natural flow? I'm picturing guests at a party who might not quite understand the process of pushing the button and waiting until they hear the pump stop.

I also saw mention of additional wired buttons, such as doorbell buttons. I assume if one has easy access to wiring (as we do; our house is over a 4' crawl space), one could run buttons from each bathroom and kitchen to the pump and save the cost of the wireless remote system.

But, whether wireless or hardwired remote, how does one in a more distant location in the house know the pump has stopped running and hot water is at hand? I assume the noisier Chilipepper might be of help in this situation...

 

[230321a]

Has this solar hot water heater been used as a stand alone system on a Sprinter?

http://www.heliatos.com/
http://www.shop.heliatos.com/Complete-2-Panel-SW-Solar-Water-Heater-Kit-0770002.htm

 

[Graphite Dave]

I assume one can still get hot water by running the water and waiting for the natural flow? I'm picturing guests at a party who might not quite understand the process of pushing the button and waiting until they hear the pump stop.

I also saw mention of additional wired buttons, such as doorbell buttons. I assume if one has easy access to wiring (as we do; our house is over a 4' crawl space), one could run buttons from each bathroom and kitchen to the pump and save the cost of the wireless remote system.

You can run water and wait without turning on the pump. The D'mand comes with one door bell type pushbutton and one wireless remote. Installed pushbutton at kitchen sink behind sink front doors and installed the remote down stairs next to shower. Shower is located between the instant water heater and the kitchen sink so if sink has hot water then the shower also does. My pump is installed at the kitchen sink which is the farthest fixture from the water heater. If hot water is at sink then it also is at every other faucet in the house.

 

[Graphite Dave]

Has this solar hot water heater been used as a stand alone system on a Sprinter?

http://www.heliatos.com/
http://www.shop.heliatos.com/Complete-2-Panel-SW-Solar-Water-Heater-Kit-0770002.htm

Would work fine if the sunshine is available. Other problem could be freezing.

I will use the Heliatos centrifugal pump for my fresh water pump in the new conversion. The space required for the pump is about 1/4 what is required for a traditional RV pump and it is silent. Does require a switch to start/stop and the need to bypass a small amount of water back to the fresh water tank to prevent overheating the pump if I forget to turn it off. Pump will be located at back of slider door step so pump is below the fresh water tank outlet. I can also drain the tank through the pump.

 

[aljimenez]

But, whether wireless or hardwired remote, how does one in a more distant location in the house know the pump has stopped running and hot water is at hand? I assume the noisier Chilipepper might be of help in this situation...

You don't have to wait until the pump stops to open any hot water faucets, the water will not be hot yet, but it will be getting hotter. We have had a Chillipepper installed for over 12 years; we are on our second one and the latest ones are quieter... Al

 

[SiennaGuy]

I used to write instruction manuals for a living. Some things should never need instructions, like how to turn a regular doorknob. Taking a hot shower is another thing that should never need instructions. If performing a simple task needs an instructional video, then the equipment is poorly designed.

 

[avanti]

I used to write instruction manuals for a living. Some things should never need instructions, like how to turn a regular doorknob. Taking a hot shower is another thing that should never need instructions. If performing a simple task needs an instructional video, then the equipment is poorly designed.

Well, don't confuse "familiar" with "good design". Ever use a traditional toilet in India? Many tourist areas have "how to" posters on the wall for the benefit of tourists:

 

[bookman]

I used to write instruction manuals for a living. Some things should never need instructions, like how to turn a regular doorknob. Taking a hot shower is another thing that should never need instructions. If performing a simple task needs an instructional video, then the equipment is poorly designed.

I did that also, and I wholeheartedly agree. Hmmm. let's see... "Hot Water Showers for Dummies" might be in the offing.

 

[Bone Head]

I assume one can still get hot water by running the water and waiting for the natural flow? I'm picturing guests at a party who might not quite understand the process of pushing the button and waiting until they hear the pump stop.

I also saw mention of additional wired buttons, such as doorbell buttons. I assume if one has easy access to wiring (as we do; our house is over a 4' crawl space), one could run buttons from each bathroom and kitchen to the pump and save the cost of the wireless remote system.

But, whether wireless or hardwired remote, how does one in a more distant location in the house know the pump has stopped running and hot water is at hand? I assume the noisier Chilipepper might be of help in this situation...

Don, You can attach as many buttons (like doorbell button) as you wish. Normal "water down the drain" function is unaffected.
The pump would normally be located at the point farthest from the water heater or perhaps at the point of most common use. The reason we have two units is that the original D'mand system was located in our master bath which is most distant from the water heater and then we decided to add another under the kitchen sink because that is the point of greatest use in terms of the number of times per day wanting hot water.
The way these pumps work is that on demand, they turn on and pump water from the hot side of the faucet and return it to the cold side. When the hot water arrives at the pump, a thermostat turns the pump off. There is also a "time out" feature so that the pump doesn't continue to run if for some reason the water from the water heater was not hot.
Hope this helps. Sorry to all for getting "off topic"

Bob

 

[alichty]

I used to write instruction manuals for a living. Some things should never need instructions, like how to turn a regular doorknob. Taking a hot shower is another thing that should never need instructions. If performing a simple task needs an instructional video, then the equipment is poorly designed.

Sadly most of us consider this a given so when someone hands you a pile of manuals for your new toy the idea of reading a manual on how to take a hot shower isn't high on the priority list. Even after dealing with wildly inconsistent temperatures for several months it never occurred to me that there was another way to adjust the water temp besides grab the knobs and adjust the temperature. If you really want to make a product that differs so wildly from consumer operational expectations you probably need some kind of sign to hang on the faucets to get the customer's attention right from the start. My own frustrations with the system were reaching a point where I was getting ready to start shopping to swap it out when I stumbled into the video. I am not even vaguely surprised that LTV got a lot of bad feedback.

I will keep mine now that I understand how to live with it but I am almost surprised that Girard has made it this far in the market with a product like this.

 

[israndy]

Has this solar hot water heater been used as a stand alone system on a Sprinter?

http://www.heliatos.com/
http://www.shop.heliatos.com/Complete-2-Panel-SW-Solar-Water-Heater-Kit-0770002.htm

I really wanted to do that in my Gulf Stream MB Cruiser. The water heater was demand, so if the fresh tank was below 70° the hot water would be tepid. I thought about putting a small solar panel and a small solar water heater and run the fresh tank thru the solar water heater with the solar panels help powering a pump. Then when the sun went down the water in the van would be warmer than if it had sat indoors all day and keep the van warmer at night. There would have to be a thermostat on it to keep the sun from being too good and making all the drinking water hot.

I ended up getting the Serenity with a conventional water heater that I can heat in a few minutes, or in just a couple of minutes if I combine propane and 110 volts. Makes getting in the shower a no brainer, flip on the heat and get undressed and you should have hot water.

-Randy