tankless water heater

[travelover]

.......
As for a pan under the tank I am not sure that it is a standard practice or a requirement to have a pan connected to a drain if the unit is located in the basement at least it was not the case in the three houses I owned before this one.

Not a requirement, but a darned good idea, because all water heaters eventually leak. A pan is only a few bucks.

 

[NW-Bound]

It is just a 1/2" copper pipe that runs from the farthest end of the hot water line back to a T connection on the drain valve on the bottom of the water heater. Natural convection circulates the water.

That might not work in all houses, particularly mine where the pipes zigzag every which way. I knew how they were run, because I had the whole house replumbed.

 

[ronocnikral]

Tell me more about this return circuit--I've never heard of them before. My bathroom is at the far end of the house from the water heater and I would like not to run lots of water down the drain every time I want hot water there.

it's best to put them in with the rest of the plumbing and is relatively cheap to do at that time. mine is certainly dreamy. open faucet, instant hot water. it does require a small electric pump, but it doesn't pull much electricity.

 

[audreyh1]

We have a Tagaki tankless water heater. We love it. The main reason we chose it was because it freed up a closet in our new house, and because the water tank in our old house ended up leaking and causing a mess.

 

[ERD50]

The leak was not from the pipes but rather from the bottom of the tank that got corroded.

As for a pan under the tank I am not sure that it is a standard practice or a requirement to have a pan connected to a drain if the unit is located in the basement at least it was not the case in the three houses I owned before this one.

Are tankless units less likely to leak? I dunno.

I think some people are talking about a recirculator pump with tankless units. Note that that requires a small tank heater - else you would be recirculating cold water, as the tankless only delivers on demand.

-ERD50

 

[JoeWras]

I don't think 1 minute is unusual, but it is still annoying. I have been considering putting in small electrical on-demand hot water heaters under the kitchen and bathroom sinks to have instant hot water. As I'm thinking of it the electrical unit would heat the water until the hot water arrives from the main system. Has anyone out there tried something like this?

I have a friend who did exactly that. Exactly. He really wanted to save water and was willing to pay a bit more for that extra shot of electricity for the beginning stream to not be wasted.

He was disappointed, however, because the point of use heater had a water hammer problem.

We think it was the brand of heater and installation. Plumber tried to fix it a few times and failed. I would say just be aware of his problem, but don't think it is the norm. At w*rk all our auxiliary wash sinks have these and they work fine without a hammer problem. The only thing anyone complains about is that you have to have decent flow for them to turn on -- which is true of the whole house tankless too.

 

[pb4uski]

Thanks. I will probably try insulating the hot water pipes to the extent they are accessible first and see if that helps at all.

If that isn't sufficient, I may try one of these in the kitchen since it is already set up for electrical with the nearby dishwasher. Also, we use the kitchen hot water more often than the bathroom sinks

 

[ERD50]

Thanks. I will probably try insulating the hot water pipes to the extent they are accessible first and see if that helps at all.

If that isn't sufficient, I may try one of these in the kitchen since it is already set up for electrical with the nearby dishwasher. Also, we use the kitchen hot water more often than the bathroom sinks

Hard to understand how a 2.5 Gallon unit can cost $169, while a 40 Gallon unit costs $208. The volume and forces from water pressure are so much higher on a larger tank - that's a lot more material (6.77x the weight - one measure of cost for something as basic as this).

-ERD50

 

[Texas Proud]

I looked at tankless when I was getting ready to replace my old 40 gallon natural gas heater. I just couldn't see the payback or benefit. I picked up a new heater off Craigslist for $125 (guy bought the wrong one and couldn't return it). My gas bill with hot water, stove, clothes dryer and BBQ runs about a buck a day, even with a return circuit that always keeps hot water at the farthest tap.

The tankless would just about have to run for free to give a reasonable payback.

Just read this and am curious...

Did the return line come with the house or did you install it later

Do you have mulitple lines on the return? IOW, my house has 3 full baths and a half bath along with the kitchen and a wet bar... basically all corners of the house... from the banging of the pipes when my dishwasher was having problems, they are not centrally located.... so I have at least 5 separate runs.... I would hate to think that I would need 5 returns...

 

[travelover]

Just read this and am curious...

Did the return line come with the house or did you install it later

Do you have mulitple lines on the return? IOW, my house has 3 full baths and a half bath along with the kitchen and a wet bar... basically all corners of the house... from the banging of the pipes when my dishwasher was having problems, they are not centrally located.... so I have at least 5 separate runs.... I would hate to think that I would need 5 returns...

My water heater is at one end of the basement. The main hot water line pretty much runs from one end of the house to the other, thus one return line. It was installed when I bought it.

Your main hot water line is probably centrally located with branches to the faucets. If so, a return line from the farthest faucet area should do the trick. You may have a little cold water in the branch lines.

Newer Pex installations use a manifold and multiple home run lines.

 

[samclem]

We have a little electric pump that is installed inline from our gas hot water heater. We get almost instant hot water even at our faucets farthest from the hot water heater. In our old home it was nothing to wait 30 seconds or more for hot water. Now we have it in just a few seconds.

That's a convenience a lot of folks will appreciate. People installing them need to be aware that they are creating a 24/7 loop of hot water, which will lose energy. Insulating the supply and return line can help, but it will always be losing heat. The heat loss for a 50' supply line and a 50' return line can easily be much more than the heat lost from a large water heater (in effect doubling the "storage" heat loss of the home's hot water system). And, that doesn't count the energy used by the recirc pump (not much).

 

[JoeWras]

That's a convenience a lot of folks will appreciate. People installing them need to be aware that they are creating a 24/7 loop of hot water, which will lose energy. Insulating the supply and return line can help, but it will always be losing heat. The heat loss for a 50' supply line and a 50' return line can easily be much more than the heat lost from a large water heater (in effect doubling the "storage" heat loss of the home's hot water system). And, that doesn't count the energy used by the recirc pump (not much).

A friend at w*rk says it costs him about $20 a month in gas. That's quite a bit. So he echos what you say.

 

[jimnjana]

A friend at w*rk says it costs him about $20 a month in gas. That's quite a bit. So he echos what you say.

Hmmm... ours does not cost us anywhere near this. We have a 50 gallon hot water heater and a nat gas stove/oven . Our bill was 33.69 last month for nat gas usage. BTW the hot water heater temp is set high, I've been sneaking it down a little bit each month until DW says its not hot enough.

 

[JoeWras]

Hmmm... ours does not cost us anywhere near this. We have a 50 gallon hot water heater and a nat gas stove/oven . Our bill was 33.69 last month for nat gas usage. BTW the hot water heater temp is set high, I've been sneaking it down a little bit each month until DW says its not hot enough.

The guy lives in a huge house. I would guess it has a very long home run.

 

[travelover]

The guy lives in a huge house. I would guess it has a very long home run.

If in a cold climate, half the year the lost heat is used to warm the house.

If in a hot climate, not so good.

 

[JoeWras]

If in a cold climate, half the year the lost heat is used to warm the house.

If in a hot climate, not so good.

Yes, it is a hot climate so it is bad. There's got to be some electrical load on both the circulating pump, and the air conditioning.

 

[travelover]

Yes, it is a hot climate so it is bad. There's got to be some electrical load on both the circulating pump, and the air conditioning.

One option is to use a timer on the pump to minimize loss during down time.

 

[jimnjana]

If in a cold climate, half the year the lost heat is used to warm the house.

If in a hot climate, not so good.

Doubt this contributes to our overall AC load. Our pipes run under/through our concrete slab.

 

[samclem]

Doubt this contributes to our overall AC load. Our pipes run under/through our concrete slab.

The heat taken from the hot pipes and into your slab doesn't disappear. It's making your floor warmer and increasing your AC load somewhat. Figure about 2/3 of the "lost" heat is warming the floors and increasing your AC load (the rest is warming the soil under your slab somewhat, being slowly conducted away through that soil). It takes about .3 watts of air conditioning (at typical efficiencies) to remove one watt of heat gain from other sources (your gas hot water heater via this hot pipe). Given the typical difference in cost (per watt) of electricity vs NG, it's likely that, in a climate where cooling is required, a circulating hot water system in the slab is costing about as much in electricity (for AC use) as for NG to heat the water. And then there's the electricity used to run the pump (oh--which also generates heat. Not a factor if it's outside the conditioned envelope).

 

[painterbill]

You may be able to install a pump that is operated with a proximity/IR switch that senses when someone enters the bathroom and turns on the pump only when someone is in the room. I believe you could use the existing cold water line as a a return line for the pump or if able run a separate line (small pex line?) back to the water heater.

 

[NW-Bound]

Thinking about this some more, I realized that I have been spoiled. People in colder climates need to do the above things to get hot or even warm water. Where I am, the water comes out of the faucet at temperature in the 70F. I do not need hotter water to ensure that my hands and face are clean!

I am going to get out of the bad habit of wasting half-gallon of water to wait for hot water.

 

[jimnjana]

The heat taken from the hot pipes and into your slab doesn't disappear. It's making your floor warmer and increasing your AC load somewhat. Figure about 2/3 of the "lost" heat is warming the floors and increasing your AC load (the rest is warming the soil under your slab somewhat, being slowly conducted away through that soil). It takes about .3 watts of air conditioning (at typical efficiencies) to remove one watt of heat gain from other sources (your gas hot water heater via this hot pipe). Given the typical difference in cost (per watt) of electricity vs NG, it's likely that, in a climate where cooling is required, a circulating hot water system in the slab is costing about as much in electricity (for AC use) as for NG to heat the water. And then there's the electricity used to run the pump (oh--which also generates heat. Not a factor if it's outside the conditioned envelope).

Okay. I'll admit it, I'm paying a little bit for the convenience of having hot water, virtually on demand. But it is well worth the extra few pennies a month we spend for it. This small cost saves us about 2 minutes per day of waiting for hot water or over 10 hours or so over the course of a year. Also saves us conservatively about 2 gallons of water per day or over 700 gallons per year, water that otherwise would have went down the drain, further increasing my sewage costs based on water usage. Most importantly DW loves it, a happy wife means a happy life.

 

[samclem]

You may be able to install a pump that is operated with a proximity/IR switch that senses when someone enters the bathroom and turns on the pump only when someone is in the room.

How about this idea: Plumb the toilet water supply from the hot water pipe under the sink? Assuming most hot water use in the bathroom is after the toilet flushes, the cool water that is in the hot water pipe would be used to fill the toilet tank and the warm water would arrive at the sink just in time to wash up. No water wasted down the sink drain while you wait for it to get hot, it fills the toilet tank instead.

The two problems:
1) The flow rate through the normal toilet tank valve is less than a sink faucet, so it might take more time for the hot water to arrive (hey, flush and then finish reading that magazine article).
2) A second toilet flush shortly after the first would waste good, hot water.

In some commercial/industrial applications, the heated water going down the drain is used to warm incoming water on the way to the water heater, reducing energy use. In theory, you could accomplish this in your home by winding a copper pipe that feeds the water heater around the large drain pipe from the shower (or dishwasher, etc). It would be impractical for most residences, probably having a payback period of decades.

 

[meekie]

My old house had a really long delay, so we got one of these pumps.

http://www.gothotwater.com/hot-water-pump

Just press a button, wait two minutes, then instant hot water for the shower. Our unit was installed under the kitchen sink, which was the furthest from the heater. IT did return slightly warm water into the cold line, but I didn't need cold water all that often.

 

[pb4uski]

My old house had a really long delay, so we got one of these pumps.

Recirculating Hot Water Pump - Gothotwater.com

Just press a button, wait two minutes, then instant hot water for the shower. Our unit was installed under the kitchen sink, which was the furthest from the heater. IT did return slightly warm water into the cold line, but I didn't need cold water all that often.

It seems to me that the only real advantage is avoiding wasting the cool water in the hot water line but it doesn't reduce the amount fo time that you need to wait for the hot water to get to the faucet.

In other words, if the concern is time, whether I push a button and wait two minutes for the hot water to get to the faucet or open the hot water spigot and wait the two minutes it doesn't make much of a difference.