Tankless WH

I am upgrading my water service piping in my home to PEX and had a local plumber over today for an esitimate and I mentioned to him that I would be also upgrading to an on demand tankless water heater…he just looked at me and grinned. “I’ve put in 17 of them things and taken out 15” he says.
He said the problem stems from sediments. With a tank you get sediments at the bottom of the tank…no big deal, but without a tank the sediments deposit and clog the coil.

I have not as of yet gotten to inspect on of these tankless heaters, but I am looking at ways of reducing my home energy bills and have seriously considered them, but now I am rethinking that.

Anyone got any insight into these tankless systems pro or con?


Ask him how many of the 15 had soft water.

Soft water does not produce hard sediments.

I’ve not heard of that problem. People I know have had them for 5 years or more and love them.

If your area has excessive minerals, etc., I wonder if a filter of sorts would be cost effective?

I have one in the new house that I live in now and have had no problems My gas bill is a lot lower than at my other house. Cut it in half! So far I love it!

I have 5 - one at home and four at rental properties.

No problems so far (4 years).

They are usually not energy savers though:


I use them in rental rehabs as in my urban market every sq/ft of habitable rental space is gold.

For those not familiar with tankless units I finally got around to pulling together all of my various posts WRT my experience with these water heaters:


I have inspected a number of them and no one has ever mentioned a sediment issue and in fact they all loved the tankless units. There are probably half a dozen easy solutions to sediment, depending on it’s source. If for instance it is coming in from the street service, filter it to remove sediments. Google will most likely have a zillion hits to look for solutions.


I personally know of six that are in use. All in friends homes who live in my neighborhood. All have well water, none have a water softener, most have a gross filter on the incoming water, none have any further filtering and none have had any problems with the tankless units(with the exception below). I think the youngest is two years old, and most are over four years old.

One friend’s unit has to be reset frequently, it has always been that way. I’m almost certain they didn’t configure it correctly, and have suggested that it could be fixed to not have that problem, but they seem to think it’s not a problem, and who am I to think things should work as designed???

As for costs of operations, all of them have told me that they have reduced their gas bills, but only two of them replaced a tank water heater with the tankless in the same home (others were installed when they built a home or added on or…), and since most of them heat the house partially or fully with gas, not sure how they could back up that claim.

I do know of one who is off grid, heats by passive solar and wood stove, gas on demand w/h and stove which are run off propane. He has a 150 gallon tank, and he fills it once a year. I think he told me he only needed 80 gallons last year. So it can’t be too bad efficiency wise.

I will say that a couple of my neighbors had issues with sizing the units properly. Everyone out here has a well, and many of them are poor producers, so most of us have cisterns (500-1500 gallons), usually a black poly tank sitting outside somewhere. In the summer the water can get fairly warm, in the winter it can approach 35-40. So, if you wanted your hot water to be delivered at 105 say, then you would need over 60+ degree rise in temp at whatever rate you need for your family. However, the other eight months or so, you may only need 40 degree rise in temp.

This is only a problem for us country folk, city water dwellers, generally do not have a concern about this as their pipes are (or better be) buried deep enough for them to have very minimal variances in temperature delivery from winter to summer.

There are a number of solutions to this problem that my neighbors have come up with. They range from moving the pressure tank into a heated space to building a solar hot water heating panel, and of course one simply bought the larger unit, and traded a little in efficiency for the guarantee of HOT water!

Hope that helps.

– bz

It would be inexpensive to place a sediment filter to the incoming water line. Even municipal water will contain some sediments.

This is one I did last month. Thought the data tag may be of some help with parameters. Of particular interest is the rate of recovery (193 gals/hr).

I was going tankless. I told my plumber money wasn’t an issue, since I had it upfront, and the tax break was a plus. He said, wait and research it. I am not interested in tankless anymore.

  1. Many residential gas systems aren’t sized to the water heater for a high demand source. So I need to upgrade my gas lines.

  2. Living in the north, unless I go to a 3+ appliance rating heater, I would have problems operating just 2 in the winter.

  3. The concept of opening the hot water handle in a tub, actually decreases the temp, was too confusing.

  4. Even with the tax break, the increased cost of installation, increased cost of equipment, it wouldn’t break even for a LONG TIME. It seemed beyond my life expectancy. :wink:

I re-evaluated my needs, and I really just need a larger, efficient tank heater. Biggest motivation was my 38 gallon tank didn’t stand up to my wife taking an “hour shower.” For a 4 bed, 2.5 bath house, it’s undersized.



I have a tankless unit in my home.

Installed in May 2005-- never had a problem, oh yea… July and August gas bill was $12.00 tax and everything else aded in.

Never got below $50.00 before


If I ever installed one my bill would go up just because I would spend all day enjoying the endless supply.
For myself the issue is not saving energy as much as not having to wait for the tank to reheat.

Shower together save even more.
Try it, works for us .

… Cookie

How many people in family and…how much time did you spend at the cottage or away on vacation…virtually impossible for a family to have $72 DHW bill per year these days with normal use.

Another thing people do not think about in the north is they need a lot of air and need to be inside so they do not freeze.
Well in the summer they are pulling cool air out of the home and in the winter out goes warm air .
This is an added cost many never even consider.
I feel in the south great in the north Never .
… Cookie

Hey Roy, I think you were asking before about timers for electric water heaters. Presumably because of the smart metering program underway in Ontario. I guess that means when the mood strikes you can just hop in to the shower with your spouse :wink: you have to wait until the rates go down. :sad:

I installed an ELECTRIC unit on our new house…5 months have gone by and we LOVE it. The plumber who did the underground shook his head in disbelief and said our bill would sky rocket. Compared to our other eletric bills (old house had electric w/h and stove and new house has ondemand electric water heater and stove) our bills are literally the same. Yes, I realize there are other factors involved but the moral of this story is we are very pleased with our ELECTRIC on demand unit.

P.S. the electric units can be installed about anywhere and are almost half the cost of the gas units…and are claimed to be more efficient (whatever).


Regarding post 15


The bills were for July and August.

Furnace was not running, obviously. Only gas consumption was for Hot water and the BBQ.

The gas bills are considerably higher in the colder months :frowning:

A lot of the units here are direct vent:


I have four of them installed in rental rahabs, mostly because wall mounted across from the furnace they recover floor space that allows an additional 1/2 bath or larger closets.