Tankless Water Heaters

[OldJeff]

Anyone have one of the tankless water heaters ? Please share your experience good or bad

Have been hearing good and bad, we are considering making the switch, but we need to be sure.

Will probably be a $2,000 investment with installation, so I am trying to find all the information I can.

Not looking for more energy efficiency, more interested in the non stop hot water.

[LJR]

I've installed exactly three of those to date. All were electric units. One was to provide hot water to a garden hose - owner wanted full flow of hot water from a 3/4" garden hose - other two were each for hand wash sinks.

The garden hose heaters took a 60 amp 240 volt service. The sink heaters would each work on a 15 amp 120 volt circuit (we just used the circuits that were already in the bathroom).

My impressions: mount them as close as possible to where they'll be used, they do work, probably even save energy, newer ones keep getting smaller and more efficient, you can run them out of hot wahter. Still haven't seen one I'd spend the money and time to put in my own house. But at today's natural gas prices I prabably really should go back and think that one through again.

[leehljp]

We have them in our Japan house and most houses use tankless, even 40 year old ones. They are much more effecient and cut our electric and water bill considerably - when we moved from a house with a water tank.

Prices are generally much higher in Japan for utilities but the US utilities are catching up quickly.

[jAngiel]

We have one in the addition that we built. I like the idea of never running out of hot water. The only thing I do not like with mine is that in order for the heater to cut on there needs to be a specific amount of flow through the unit. I'm not sure what the flow rate is but it's easy to drop below the rate and have it cut out. BTW it's a natural gas unit, I don't know if the electric ones are different.

The jist of the problem is that the valves that I installed for our baths/showers were the single knob mixing valve type. The flow is usually constant, so if the water is too hot coming out you rotate the knob towards the cold side which in effect reduces the amount of hot water AND increases the amount of cold water. When the amount of hot water gets too low the heater cuts off and you get a mixture of cold water and cold water. Makes for some screaming kids in the winter time.

Bosch's solution was to adjust the temp of the hot water from the unit to be comfortable without having to add any cold water. I don't like that solution at all, it makes it really hard to wash clothes in hot water when the water is only warm.

The best solution is to have separate valves for all locations instead of those fancy scald guard singe knob units. That way you can set the hot water so that it comes in hot and then adjust with the cold water without having to reduce the hot water. I know this works because this is what I can do in the sinks in the bathroom.

I just need to find find the money and the time to replace the shower and bath valves. The workaround that we have been using is to run the sink hot water while they are in the bath or shower so that the flow is high enough to not cut out. Works but wastes water. I suppose I could always capture it and use it for plants and stuff when it cools down but thats just too much of a hassle.

We like it since we have 5 kids and never run out of hot water but they are a little quirky. With the right valves it would be a little more consistent.

[Tom Slick]

I checked into them a couple of years ago. the biggest issues with them are parts availability and repair knowledge. they just aren't very common yet. you may need to have your gas line replumbed with a larger line and the exhaust duct will have to be redone. another issue is if your water supply is really cold the uint may not be able to heat it fast enough and you'll end up with only warm water.
I bought a "tank" waterheater instead. the plumber's advice was "when your new tank water heater goes out then tankless heaters will be common and parts and repair will not be an issue." Being a maintenance guy, that comment made a ton of sense.
Look into a Rennai tankless water heater. they were highly recommended and seem to be the best from my reserch. a couple of plumbers said bosch units don't perform as advertised and they have replaced a few of them due to lack of hot water output.

[stewchi]

When I lived in Europe our apartment used tank-less and they were more common there, it seems when they build things they only to plump things for cold water, maybe cause many of the buildings are old and everything is built from concrete or stone, but the washing machine, and dishwasher had built-in heating units so they only had a cold water line hookup, each of the sinks and shower/tub had it own small tank-less unit. It worked well for that scenario, but here in the states I don’t see it as necessary, as many pointed out the price is much higher, technology has not been here as long and parts are harder to find. I also don’t buy the energy savings pitch, I can walkup to my hot water heater a touch the outside and its cool to the touch, I think the insulations in modern tanks is good enough that it is very cheap to keep the water in the tank warm. Plus you have the option of installing a circulation pump to keep the water at the tap hot so you don’t have to run the hot for 5 minutes wasting for warm water to come up from the basement. (Granted this is also solved by adding a tank-less at each tap)

What I don’t like about whole house tank-less units is the surge in electricity or gas needed to power them. You often need to upgrade you electrical service or gas line to power it. The tank units have a big tank that acts like a buffer and spreads the heating out over time. The tank-less needs enough heat to bring 58* water to 130* while it is flowing through the unit, that equals a lot of power.

The house we just bought (but don’t move into for 18 more days (it killing me))
…has two 50 gallon tanks, 1 electric and 1 gas, they are in SERIES with each other (first time I have seen that). When we did the house inspection, the inspector wanted to test the gas water heater to read carbon monoxide, see color of the flame etc. We shut the breaker off to the electric (first in line) and ran the hot water on full for nearly 20 minutes before the heater fired up. I don’t think we will be running out of hot water, plus if the electricity goes out we still have hot water if the gas goes out we still have hot water.

For me a tank-less is only an option when I already have a cold water line and it is too expensive to run a hot water line to the location.

[91FE]

quote:Originally posted by stewchi

Plus you have the option of installing a circulation pump to keep the water at the tap hot so you don’t have to run the hot for 5 minutes wasting for warm water to come up from the basement.

Sorry for the Hijack, but can you tell me more about this? What does it entail? I'm sick of waiting for my HW to get from the basement to the second floor.

[mschrank]

I installed a Takagi T-KD20 natural gas tankless heater about 4 months ago. We are very happy with it.

I can't vouch for the energy savings until I can compare gas bills next summer, but our primary motivation for installing it was endless hot water and space savings (Now I just need to figure out what to do with that extra 16 square feet of floor space in my utilty room!.

I saved a bundle on installation by doing much of it myself. I bored a 4" inch hole through a concrete wall for the exhaust vent, hung the unit on the wall, and removed the old tank POS. Then I called in a plumber to make the connections. This way, the warranty (longer than most tank heaters offer, btw) is still valid, but I saved approximately $600 (plumbers estimate) versus having the unit still sitting in the box when the plumber got there.

This is a relatively powerful unit, and we find that it actually perfoms better than the old tank unit. For example, when I'm in the shower and the wife flushes the toilet, I feel only a slight lowering of pressure but no real temp change. And this is with the single knob anti-scald mixing valve that James (jAngiel) has problems with...works fine in my situation.

It easily supplies hot water to two taps at once...unless one of them is the washing machine. But I could never take a comfortable shower with the washer running with the tank unit, either. Performance hasn't been quite so good now that the incoming winter water temp is around 43 degrees, but is just dandy when the incoming is 50 during the non-frigid months. The unit will always supply water at the pre-set temp, but it can only provide so much flow. So when more demand is placed on it, less hot h20 goes to each source. Again, if I'm in the shower and somebody turns on the hot-water faucet, I mostly only feel a decrease in pressure and a small decrease in temp.

Sorry for the long reply, but I'm very "pro-tankless." You will find many that will discourage you because it is different. But if you do your homework, I think you'll be happy.
1. Realistically calculate your hot water demand.
2. Research as many units as you can.
3. Find a willing plumber.
4. Make sure your gas supply line is adequate (My unit can suck 190,000 btu...if you have several other gas appliances you may need to increase your input pipe size.
5. Do as much of the install as you can. Most warranties are only valid if installed by a "professional," but they don't need to know that the pro just came in to sweat two connections!

[mschrank]

quote:Originally posted by 91FE

quote:Originally posted by stewchi

Plus you have the option of installing a circulation pump to keep the water at the tap hot so you don’t have to run the hot for 5 minutes wasting for warm water to come up from the basement.

Sorry for the Hijack, but can you tell me more about this? What does it entail? I'm sick of waiting for my HW to get from the basement to the second floor.

Forgot to mention about this...it does take a bit longer for the hot water to get to the tap, so I may look into one of these ciruclation pumps. http://www.cetsolar.com/chilipepper.htm

Also may consider a UPS (uninteruptible power supply) as we have frequent short power outages...wouldn't be pleasant just before final rinse [:0]

[stewchi]

There are two typed that I have scene the cheaper ones use the cold water line and hot water line as a loop, to circulate hot water from the tank to the tap, Advantage is they are easy to install, disadvantage is you get hot water in you cold water line.
The real ones use a third line pipe to complete a loop from you tap to you hot water heater. The one I was thinking about connects to the drain in the hot water heater. It works like this, you connect the pump to you drain on the water heater (or nearby and plumbed into the drain doesn’t matter were the motor) then from the motor to a Tee installed as close to the tab as possible, the TEE connect the original hot water pipe from the water heater, the hot water pipe to the tap and the new pipe to the drain on the water heater were the motor is. The motor has a thermostat on it and will start circulating when the temperature drops below a preset level. The hot water flows out of the water heater from the main line and circulates back into the water heater from the drain line.
I am not sure how that would work with a tank-less unit. There would not be anything to recalculate back into.
I imagine you could use a small tank water heater in line with a thankless system. So that the tank-less only turns on when you are doing more than just washing your hands worth of hot water. Plus you could use the recirculation pump to keep the line warm.

When I lived in AZ I had the opposite problem, most of the plumbing went through the attic and some of it was exposed to direct sunlight, in the summer you had almost instant hot water but had to wait a while for enough water to come out of the ground before it was cool enough to feel good. I rented the house for a few years, and when I went to sell it I found the master bathroom sink that hot water tap was not working. I asked my former tenant about it, he said he it broke at the end of May but never got around to saying anything since he never used the hot water in the sink the water was usually warm, (no AC in that bathroom either).

[RickT]

I saw Ed Del Grande install a recirculation pump last week on "Ed the Plumber." Here's the info about it.
http://www.diynetwork.com/diy/hi_plu...347744,00.html

I've also considered a tankless water heater, but I've heard different opinions about them. Of course the guys who sell them say they are great.
Rick

[JimD]

My comment concerns the anti-scalding comment by James.

The anti-scalding valves I have messed with have simple stops to control how far in the hot direction you can turn the knob. I had to adjust the Delta shower controls in a couple of our baths in our new house. All I had to do is to remove the control knob and rotate the stop. You may want to try this before thinking you have to replace the valves.

Jim

[stewchi]

I saw a this old house episode were they explained how the ant-scald valve works, it has a bar with a series of holes, and the hot and cold intakes do an X so that when the pressure on both sides is even you get full flow through the valve for both hot and cold,. When the pressure drops on one side the pressure difference forces the slide bar to move in one direction (or the other depending on whether hot or cold was the pressure drop) when the slide bar moves is starts to cut off the flow to the higher pressure side. When that flow naturally reduces itself to a balance between the 2. The idea is that if you flush the toilet and the cold water pressure drops the valve will compensate by throttling the hot water side so that the water temperature does not change very much. When you adjust the temperature on the knob it changes that weighting on the equilibrium for the slide bar.

[jAngiel]

quote:Originally posted by JimD

My comment concerns the anti-scalding comment by James.

The anti-scalding valves I have messed with have simple stops to control how far in the hot direction you can turn the knob. I had to adjust the Delta shower controls in a couple of our baths in our new house. All I had to do is to remove the control knob and rotate the stop. You may want to try this before thinking you have to replace the valves.

Jim

I will have to check that out. It'll be rather large pain to replace the valves. Thanks.

[rfisher7381]

quote:Originally posted by 91FE

quote:Originally posted by stewchi

Plus you have the option of installing a circulation pump to keep the water at the tap hot so you don’t have to run the hot for 5 minutes wasting for warm water to come up from the basement.

Sorry for the Hijack, but can you tell me more about this? What does it entail? I'm sick of waiting for my HW to get from the basement to the second floor.

I installed a Bosch 125HX unit about 2 years ago. We have a family of 5 and it has worked out very well. In regards to having to wait a long time for hot water. At the time installed the Bosch unit I also replaced the hot water plumbing using a technique called "home run plumbing". Each faucet, shower, etc. has its own separate line (3/8" diameter) running all the way back to the Bosch unit. I read about this when I was planning my project and it made a lot of sense to me. The time it takes for hot water to reach the faucet or shower is dramatically shorter than it was before. The reason is that most homes are plumbed with 3/4" copper main line and then 1/2" copper branches. When you calculate the amount of water in the line which needs to be displaced it is quite large. With the "home run" concept you are only displacing the water in the 3/8" line which is significantly less volume. I was worried if 3/8" would be to small but I can't see any difference than before execpt we get hot water a lot faster. May be worth thinking about.