[Gvt1911]

Having new home built and want to go with a propane on demand tankless hot water heater. Been checking around and of course, all are great.   Looking into the Japan units mostly. Anyone have one in their home? If so what can go wrong with them?
Thanks 

[Wayner]

Assuming your living in a rural area, I can understand the want for an LP version. I'll also assume that each one needs to be vented, have a starter and LP line brought to each one. An electric version may be a better cost (installation wise), but don't know your electrical rates in your area.

They will eventually corrode and that kind of usual stuff, plus the starter will eventually screw up as well. I think these kinds of units are cost effective, when used with a sink or small water consuming device. I think that the shower and wash machine would be better served with a hot water tank.

Just my initial thoughts.

Wayner

[woodsyi]

I have used it in Europe and Africa.  European ones worked fine.  African ones didn't but I think they used "alternative" fuel.

[roscoeiii]

Had them when I lived in Japan, and they were great. Will definitely go that when I own and can make those sorts of decisions. So wasteful for all that energy to go towards keeping a tank of water hot 24/7. Takes very little time to heat water, and no more running out of hot water.

The technology is ubiquitous in Japan, and so I'd feel comfortable with any Japanese model due to the technology's maturity.

[datman]

I used a Bosch natural gas demand water heater for 20 years in my business.  Except for having to eplace the burner unit at about 10 years, the heater workd flawlessly and saved a lot of money. Highly recommended.  Natural gas or propane should make no difference.

As for electric demand water heaters, I think using one for a whole hose is iffy.  I was looking at using one for a small coffee store at a car dealership and found even a medium sized one takes a LOT of electricity (12 kw or 50 amps at 220 volts).  I think a whole house electric would use a prohibitve amount of electricity,

[Wayner]

Well this isn't Europe or Japan, and when you have problems and Johnny plumber comes a callin' when you have problems, this could turn into an interesting (I'll have to order parts) scenario. That is when you find out how much the system actually costs.

Wayner

[Wayner]

I used a Bosch natural gas demand water heater for 20 years in my business.  Except for having to eplace the burner unit at about 10 years, the heater workd flawlessly and saved a lot of money. Highly recommended.  Natural gas or propane should make no difference.

As for electric demand water heaters, I think using one for a whole hose is iffy.  I was looking at using one for a small coffee store at a car dealership and found even a medium sized one takes a LOT of electricity (12 kw or 50 amps at 220 volts).  I think a whole house electric would use a prohibitve amount of electricity,

I would never buy an electric tank heater. Gas is the way to go on this one.

W 

[Dan Driscoll]

The cost of natural gas keeps going down due to a massive increase in proven reserves and major improvements in recovery techniques. Plus, the efficiency and insulation of storage water heaters keeps improving. Then add in the fact that the cost of a tankless system and installation are vastly higher; houses generally require 2 or more tankless heaters, as well as being more expensive to repair.

When I add it all up, I'm no longer sure that tankless is the better route. Keep in mind that tankless systems became popular some years back, when we believed natural gas supplies were running out and becoming much more expensive to extract. That was the driving force for tankless water heaters, but that's no longer the situation in the US or Canada.

[Gvt1911]

I am moving to southwest Virginia and wanted to go propane due to the blackouts...Electric is out of the question, propane is my answer...I don't mind the cost of 1-2 units in series now and being a mechanic, I can do my own repairs. The Jap models seem to be the best. Just wanted to know what goes wrong. I read stories about cleaning filters (no problem) and having a large enough gas feed. Should not be a problem either. Would like to do whole house. Also going to install propane back up generator. Last year after a storm the area was without power for weeks !

[Bizarroterl]

We've had a Bosch unit for about 10 years now.  I installed it myself.  It is a simple install if you are able to do copper plumbing.

The problems I've seen are:
1. It doesn't have the flow capacity of a tank heater.  We can't run 2 devices at the same time, IE no shower and dishwasher.  Not a problem for us as we take showers in the AM and run dishwasher at night.  Laundry is typically on the weekend during the day.
2. The minimum flow can be an issue.  If you have the output temp. cranked up, run a low flow faucet, and try to adjust the temp to warm at the faucet you can get the flow so low the heater will kick off.  I keep the output temp down to minimize this.
3.  It takes a little longer to get hot water.  When you turn the hot water on the heater has to heat up the exchanger before it heats the water.  This translates to a 3-4 second longer wait that with a tank heater.

Advantages:
1. Unlimited hot water.
2. less expensive to run.  I don't pay to heat water when I'm not using it.
3. Takes up less space.
4. Unlimited hot water.  You never run out.  With company we've had 6 showers taken in a row.  Try that with a tank heater.

Next year we're doing a remodel and the Bosch will be gone.  I plan on replacing it with a Navien unit (condensing, 98% efficiency) and a solar preheat tank.  This will turn the tankless into more of a booster, overcome the disadvantages listed above, and reduce our gas costs even more.

[Rich Carlson]

We got a Rinnai that runs on natural gas, and we're very happy with it.  Plenty of hot water for two devices - no problem showering while the dishwasher runs, for example.  It does save a lot of money.  Can't comment on long-term reliability, since we've only had it about a year and a half.

[JLM]

On demand can be a problem with excessive calicum build up if you have hard water.

I assume you're thinking about a whole house unit.  Not many electrics available at that capacity.

The upfront cost is high, but the power vent, high efficiency tank models cost nearly as much with extra complication and the inefficiency of the holding tank.  Up here in the great white north we kinda like having a heat source in the basement, so the tank ain't so bad.

I've never liked natural gas/propane tank heaters as the vent acts like a chimmey and as such naturally waste heat.  Folks add insulating jackets on the outside of solid insulation thinking it helps, but the outside of the tank is only warm while the vent just above the heater is too hot to touch.   

We looked at a Canadian product that would also heat the super insulated house via a hot water coil into the unit that looked like a furnace but only had filter, fan, heating coil, and cooling coil.  But due to high plywood cost (Katrina) and clay soils we didn't go with the super insulation package.   

[bacobits1]

Checked into Tankless Hot Water Heater a few months ago.
$6K complete install needless to say ridiculous!! $900 -$1200 for the heater and the rest install cost. And I have a gas line. Oh, I refused it and then they came back with a price of $4K, they cut some guarantee and something else. Who is shitting who here?

Consumer reports>>
http://www.consumerreports.org/cro/appliances/heating-cooling-and-air/water-heaters/tankless-water-heaters/overview/tankless-water-heaters-ov.htm

D