Tankless waterr heaters

irishred42

New User
Planning to add hot water to my shop. Need to know what people think about the tankless models? Do they
really provide unlimited hot water?Won't use hot H20 often,but maybe a load of shop towela now and then.
Any comments are appreciated.
 
For continous hot water and a seldom used location (less than daily) they can be just the thing. If you use water daily the savings are not there vs a tank type. If you plan to use lots of water here and there whereas it has to shut off and start back up there is a lag time in them to get hot water again as it lights the burner or starts the coils. The larger electric ones are hogs on electric like 100 plus amps while in use. The small 1500 watt units don't give much temp rise vs flow rate. You need to plan on cleaning it yearly cause the minerals will plug the small internal heat exchanger tubes. Have you checked into a mini tank unit?
 

I have three , two at our home on town gas, the other an LPG unit at the farm .
Our family finds them very convenient and we never run out of water .
Gas usage is high when in operation but then the operating time is miniscule compared to a gas fired hot water storage system . You save on gas costs overall.
I would use this analogy , A storage system is the same as keeping the full kettle boiling on the stove 24 hours a day just in case you feel like a cup of tea .
An instantaneous / tankless unit is the same as boiling the water for one cup when you want it .

I would stick to the simpler and in most cases cheaper to purchase models offered by well known makers like Bosch or Junkers . The overly complicated electricity supply dependant versions are not reliable . My advice is not to buy one that needs to be plugged in .
The only drawbacks I have found with them are slightly less water pressure and a pulse effect in the temperature . By this I mean that if you turn off the hot water for a moment , then turn it back on straight away there will be a cold 'pulse ' of unheated water that comes down the pipe momentarily while the unit starts to heat the water again . No great problem and easily avoided .
Water flow and temperature can be regulated at the unit and some have small water driven piezoelectric igniters to light the pilot for you .
 
I don't have one, but hear from folks that do have them that they are fantastic for several reasons. It's said that they save money off of the get go because they are not constantly trying to keep water temperature at a heated level when not in use because folks are at work, away on vacation, etc. I hear that once they get the temperature up to heated, that they can actually keep up with multiple demands such as dish washer and shower at the same time, from folks that actually have them. I hear that they are a little salty on initial installation (purchase) cost, but the savings more than outweigh that in the long term. I hear that about once per year, they have to be cleaned internally with a solution that may include vinegar and ???, but hear that isn't hard to do. Overall, from folks that I know that have them, they are fantastic. Both of my existing water heaters are still in good shape so I'm not looking to go out the costs of replacing them, BUT when then time comes, I'll certainly look into it. What can it hurt for your to research the possibility?

Good luck,

Mark
 
I tried an electric one a few years ago. It was a real adventure in the shower going from freezing to scalding and every where in between every time the pump ran or another faucet was used which varied the water pressure and volume going through that fiasco. They may be okay for other uses but a shower ain't one of them. Your mileage may vary greatly. It's back to the good old 40 gallon tank for me. TDF
 
Do not spend money for 120 volt unit. Organization I belong to tried to save money for install on a kitchen sink.
To get just warm water the flow must be very very slow.
 
Rinnai seems to be the go around here.

We got to one via solar (rotted out 2 tanks in 19 years - with a payback of about 20 years on the first). And the anode in the second had plenty of meat left - not sure about the first.

Then a temporary plug-in electric (which cost a fortune) and now the Rinnai, which costs less than half of the electric. Off peak electric might have been cheaper to run but the rewiring cost wasn't.

It is a mains power one, so no hot water when the power is off but we've handled that so far.

Re showers - we have the option of rainwater from tanks or well water. We try to run the hot system off rainwater when possible on an independent pipe system to eke out the supply. From experience we run 2 constant pressure pumps and that avoids the scalding/freezing shower problem. Grundfoss is the go to brand there - we found that Hydroscan pumps were an expensive hobby like solar hot water.
 
Also note that they come in different sizes.

So, like Goldilocks and the porridge you need one that is "just right" for your needs.

We went with what worked fine for similar useage.
 

Don't put a tankless in the house if there are "water buffalo" in your house. A tank heater will eventually run cold and put a limit to the length and gallonage of thier showers.
 
We have a 220V electric on demand one in the truck shop and it does OK for washing hands but the water has to be flowing fairly slow for it to put out very hot water. It might be a smaller capacity model compared to some others. In the old shop I have a 30 gallon propane water heater that I got for free out of a mobile home. It has been flawless for at least the past 15 years. I don't have it vented to the outside and the fumes aren't noticeable in the shop.
 
I've been using one for over 10 years and believe them to be awesome. I use propane BTW. Just replaced the first one, a Bosch with a Takagi. The Bosch made it's own electricity for the spark and was simpler but the Takagi works better and the electronic adjustable temperature is nice. It will heat up to 160 degrees and protects itself from freezing. Bosch quit making the model I had so after much shopping and review reading I went with the Takagi. I did have some intermittent electrical problems with the Bosch but was able to fix it myself. Both have very efficient heat exchangers and you can put your hand right in the exhaust without getting burned.

After I put the Bosch in I noticed that during the warm months (when we're not using the furnace for heat) the gauge on the propane tank barely moves. They really save on propane vs. a tank type. I was surprised by how much difference it made to only heat water at the moment you're using it.

The downside is that plumbing and venting requirements are different vs. a tank type if you are converting. The Bosch used a 5" natural vent. The Takagi is outside so no venting issue but I had to construct a chase to protect the supply pipes from freezing (again, the unit protects itself but I wasn't sure how far on each leg it would help. The other downside with my new one is if the power is down then no hot water. Hasn't happened yet but is a vulnerability. With the old Bosch I just needed water pressure and fuel.

I have no more delay getting hot water than when the old tank one was in the garage. One thing I like about the new one is I can quickly turn it up scalding hot for washing and then turn it way down for kid's bathing.
 
Not sure what make/kind we've got but we have one in our house with 7 people. MUCH better than the old tank heater. Usually take a bit longer for the water to heat up but it supllies water to all appliances at the same time without any problems.

So yeah, I would say they really provide unlimited hot water
 
We put one in the work building 3years ago, I will be putting a larger 1 in the house when the tank ones goes out. A word of advise, if you buy an electric unit, have a professional wire it.
 
They will flow only so many GPMs. Check the specs to be sure that what you are looking at is adequate for your needs.
 
(quoted from post at 18:32:19 02/08/16)
Don't put a tankless in the house if there are "water buffalo" in your house. A tank heater will eventually run cold and put a limit to the length and gallonage of thier showers.

I had a "water buffalo" in our house. So I fixed the water heater so it could nut run when the exhaust fan, in the bath room was running.
Wife and I tested it. We could get two quick showers, one each, on a tank of hot water.

Dusty
 
The 3 conditions that would make a tankless in the shop a good choice:

Space saving, mounts on the wall, no floor space needed.

If the shop is not occupied daily or the hot water is not needed often but when it is a continuous supply is required.

You have natural gas or propane, or a lot of spare amperage available in the electric panel.


I personally don't care for them. Installed one for a friend of my wife's. It is small nat gas model. It makes plenty of hot water, but it has to reach a minimum flow requirement for the fire to come on. In the summer when the water is just cool enough to want to add a little heat, it's impossible to do. Turn the hot down too low, the switch shuts the flame off, no hot water at all.
 
Replaced a tank water heater in the barn with one...plenty of hot water...the only caviat is that the unit must be kept from freezing.
 
do you have hard water ? if so it may corrode & block heat exchanger making it very ineffecient. i put one in. lasted one year.
 
If your tank is non-venter, I would be leary of MUSTARD GAS when spilling some compounds on the shop floor.

John,PA Just finished heat exchanger job and spilled anti-freeze on shop floor.
Propane flame turned from LIGHT BLUE SKY to DARK GREEN/yellow. Too toxic for me.
 
Put one (Rheem) in a 2nd house I bought which my daughter and friend lived in for about a year. Love it. Easy to install, saves space. Replaced an electric tank with a natural gas tankless (before & after pics) and have had no problems with it.




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