Tankless waterheaters

[iGas]

Anyone loaded and has tried out a solar heat panel tank and tankless heater combo?

Not sure if you can use it for potable water. Think it's used for radiant heating mostly.

I'm not loaded but back in my apprentice days I installed many houses with solar/tankless and/or geothermal heat pump in exclusive islands and solar is for bragging right, because the average recovery cost of solar heating is north of 37 years not including maintenance in relatively mild North West Coast climate.

Geothermal heating alone recovery cost on the North West Coast on average is some where around 22-37 years.

Air to air heat pump is roughly 7+ years for cost recovery in North West Coast.

In extreme environment such as Central/Norther Canada for industrial/commercial condition, geothermal cost recovery can be as little as 3 years.

 

[Squisher]

squisher, was you ever a member of OT, like 5+ years ago???

I'm not sure what you mean. I've been here since almost the beginning. I read the main site for months before Anand posted he was going for his driving test. I probably spent more time in Hot Deals than anything the first year in the forums.

 

[sjwaste]

My father is (was, retired) a general contractor with a book of mostly high end clientele. When we bought our last house, I told him the water heater was made in the 80s and that I wanted to replace it, maybe with a tankless. The extent of our conversation was this.

"A tankless? I've had clients ask about them, but not a single one has gone through with the install. Not when a decent 50 gallon gas unit is under $500 and won't run cold when two people turn the hot water on at the same time while the dishwasher is running."

He had a point. Families were rarely happy with these things because you had to spend a ton of money to get one that didn't run luke warm under some pretty typical usage scenarios for a family with kids.

His other question was, "What are you really going to do with those extra 2 feet of space in the basement?"

Yep, nothing.

 

[iGas]

I have one, no problems here. One big plus is you can shower all day long.

So as a 75 Gal. with 125,000 BTU gas hot water heater.

The 125,000 BTU is 135 GPH recovery time @ 50C / 90F.

If you drop down to 45 F rise it would be 270 GPH instead (or 4.5 Gal/minute recovery time), and not only that it have 135 Gal @ 120~140F storage as well.

It would take around 3+ hours of continuous usage at 9 Gal/min before you start to get lukewarm water.

 

[HeXen]

Get this!

http://www.hotwater.com/water-heaters/residential/hybrid/next-hybrid-gas/

oooh, i wants.
mine is 10yrs and will need replacing soon. i wonder if i can find that locally.

 

[the DRIZZLE]

IMO they don't really pay for the average family home. There are some usage patterns where they make sense though.

 

[fstime]

I have no direct experience, but an HVAC specialist has told me for a big house with a lot of bathrooms like yours, the unit may struggle to deliver ample water pressure if multiple people are say showering at once or there is a strong demand for hot water such as for washing machines, etc.

Also, if your house has long piping, some units may cause a delay to you actually receiving hot water.

Do you have oil or gas heating?

They make very nice indirect water heater tanks that are efficient and make sure you rarely run out.

 

[CPA]

Just replaced my 50 gallon gas water heater with another on Tuesday. Seriously thought about a tankless, but I would have had to reroute some pipe, but up some mountable boards and rework the venting for the size I would need to handle our household. Plus, it would have cost about 50% more. My gas bill is less than $40/month during non-winter months, so not sure it would have saved me that much money.

I will say it probably would have been a lot easier to get up in my attic than the 150lb replacement conventional unit I got.

 

[Jumpem]

Just replaced my 50 gallon gas water heater with another on Tuesday. Seriously thought about a tankless, but I would have had to reroute some pipe, but up some mountable boards and rework the venting for the size I would need to handle our household. Plus, it would have cost about 50% more. My gas bill is less than $40/month during non-winter months, so not sure it would have saved me that much money.

I will say it probably would have been a lot easier to get up in my attic than the 150lb replacement conventional unit I got.

Water heater in attic?

 

[Dubb]

What do you mean by heat pump storage water heaters?

If you mean geothermal heat pump with water source, then there is a possibility.

1-2 water storage tanks for heating with heat exchangers in the tanks to boost the domestic/potable water tank.

Another method is having 3 way valves or 4 way valve to switch load between tanks.

I have heard of air to water heat pump, but those aren't as efficient as air to air, water to water, and water to air.

Geothermal can help a lot too (though it's usually impractically pricey), but I was referring to the new crop of air to water heat pump water heaters. I think they first hit the market about two years ago. They're not quite as efficient as other types of heat pumps, but it's still less energy to move heat than it is to generate it. Numbers, off the top of my head, are around half of an equivalent electric tank type heater.

The one restriction is that since they draw heat from the surrounding air, you can't cram them in a tiny closet like you can with normal tank types (no good for apartments/condos), and you can't stick them anywhere that gets colder than 40-50F (though I don't know why you'd do that with a tank type anyway). When clients have wanted them I try to put them in the same room as sources of waste heat when possible. Mostly they wind up in basements or utility rooms next to the air handler / furnace, which works fine.

I'm still waiting for someone to come out with a combination water heater/refrigerator, where it pulls heat out of your food and puts it into your water.

 

[the DRIZZLE]

Geothermal can help a lot too (though it's usually impractically pricey), but I was referring to the new crop of air to water heat pump water heaters. I think they first hit the market about two years ago. They're not quite as efficient as other types of heat pumps, but it's still less energy to move heat than it is to generate it. Numbers, off the top of my head, are around half of an equivalent electric tank type heater.

The one restriction is that since they draw heat from the surrounding air, you can't cram them in a tiny closet like you can with normal tank types (no good for apartments/condos), and you can't stick them anywhere that gets colder than 40-50F (though I don't know why you'd do that with a tank type anyway). When clients have wanted them I try to put them in the same room as sources of waste heat when possible. Mostly they wind up in basements or utility rooms next to the air handler / furnace, which works fine.

I'm still waiting for someone to come out with a combination water heater/refrigerator, where it pulls heat out of your food and puts it into your water.

If you are using one of those inside in the winter then you're paying for it in your heating bills. You could use the waste heat from the central air system to be really efficient but that would be a lot of extra plumbing.

 

[Dubb]

If you are using one of those inside in the winter then you're paying for it in your heating bills. You could use the waste heat from the central air system to be really efficient but that would be a lot of extra plumbing.

I initially dismissed them over the same concern. About a year ago I put the question to one of the local energy modeling gurus, and his response was that they're efficient enough and houses have enough internal load (cooking, occupants, electronics) that it still outperforms a conventional electric heater over the course of a year by quite a bit, though the more heating degree days your area has can ding your overall efficiency.

He also mentioned that putting them in an unconditioned or partially conditioned basement (where the ground moderates temperature and a few degrees cooler is likely to go unnoticed or is even desirable) pretty much wipes out that concern.

I should email him and ask for numbers, and see if we can figure out what the difference in cost recovery time is for a temperate area (~3500 HDD) vs a far northern area (~10000 HDD).

 

[Red Squirrel]

Water heater in attic?

lol no kidding. I can't imagine trying to drag equipment up there. Some people even install their furnace or AC up there. Way more work for nothing.

That's what basements are for.

 

[Duder1no]

I've had one for around 8 years now and love it. Saves on money, frees up room, and unlimited hot water. It works flawlessly and I can say without any doubt I will never go back regular water heater ever again.

I've had one for 6 months and this is my experience too, unlike tanked waterheaters since it's only used when you need hot water you save a LOT of gas

 

[iGas]

Consumer Reports and Ask The Builder have articles that said tankless water heater doesn't save you money.

Tankless water heaters
They're efficient but not necessarily economical -- Consumer Reports

Heating water accounts for up to 30 percent of the average home's energy budget. Some makers of gas-fired tankless water heaters claim their products can cut your energy costs up to half over regular storage heaters. So is it time to switch?

Probably not. Gas tankless water heaters, which use high-powered burners to quickly heat water as it runs through a heat exchanger, were 22 percent more energy efficient on average than the gas-fired storage-tank models in our tests. That translates into a savings of around $70 to $80 per year, based on 2008 national energy costs. But because they cost much more than storage water heaters, it can take up to 22 years to break even—longer than the 20-year life of many models. Moreover, our online poll of 1,200 readers revealed wide variations in installation costs, energy savings, and satisfaction...

Tankless Water Heaters -- Ask The Builder

Summary:
Tankless water heaters may not be as energy saving as you think. A tankless water heater has a large gas appetite. These heaters are sometimes called on demand water heaters. What's more, some people who buy a tankless water heater end up using more hot water and fuel since the heater never runs out of hot water. This tends to erase all of the projected energy savings...

 

[the DRIZZLE]

I initially dismissed them over the same concern. About a year ago I put the question to one of the local energy modeling gurus, and his response was that they're efficient enough and houses have enough internal load (cooking, occupants, electronics) that it still outperforms a conventional electric heater over the course of a year by quite a bit, though the more heating degree days your area has can ding your overall efficiency.

He also mentioned that putting them in an unconditioned or partially conditioned basement (where the ground moderates temperature and a few degrees cooler is likely to go unnoticed or is even desirable) pretty much wipes out that concern.

I should email him and ask for numbers, and see if we can figure out what the difference in cost recovery time is for a temperate area (~3500 HDD) vs a far northern area (~10000 HDD).

Yeah, it certainly depends on the application and I can see it coming out ahead assuming you don't live at the north pole.

 

[Mark R]

Going to replace my waterheater, currently a 75gallon tank unit. I am considering a

http://www.rheem.com/product.aspx?id=5AE02BB6-A8A9-49DE-8F3A-08DA596EB980

for a family of 6, 6 bedroom, 5 1/2 bath home. Anyone own a tankless waterheater and have good or bad things to say about the newer models?

The main problem with them is that they have to be insanely powerful to get a good flow-rate in Winter. To support 2 high-pressure showers simultaneously, you'll be looking at around 200,000 BTU/hr to ensure that you suddenly don't lose hot water flow if, for example, your washer starts filling with hot water.

The other problem is that the flow-rate regulates the temperature (until the water reaches maximum allowable temp). This means if you are having a shower, and someone else goes to take one simultaeously, you end up with wild fluctuations in temperature, between ice cold and scalding (unless you have thermostatic controls on the showers - in which case the flow rates will fluctuate wildly).

There are other issues with installing such extreme power natural gas appliances - specifically, they may require upgrade of the nat gas piping in the house, due to the huge gas flow rates required.

My personal preference remains a suitably sized hot water tank (if you have 5 1/2 bath, then I'd suggest about 100 gallons as an appropriate size) with generous insulation. For extra convenience in a large house, install a secondary hot water circulation pump and insulate the piping thoughout the house. A secondary circulation pump, is a small pump which is installed at the end of a long hot-water piping run, and which pumps the water through a return pipe back into the hot water tank. This ensures that the hot water pipes in the house are filled with full-temperature water, meaning hot water is instantly available at the faucets. Note that it is essential that all the pipework is heavily insulated, otherwise the energy losses from this system will be stratospheric.

The problems that people have with tanked heaters (running out of hot water, and long recharge times) are due to incorrectly specified tanks. The vast majority that I've seen installed are too small, or have excessively long reheat times. The other possible issue is that the tanks have not been maintained correctly and are full of limescale deposits. A lot of people don't realise, but in hard water areas a water softener is not a luxury. It is essential for the correct operation of any water heating equipment - tankless heaters are particularly sensitive to limescale buildup. (In some areas, notably in Europe, it is actually a code requirement that water heaters operate only on soft [or softened] water).

 

[Kaieye]

I don't like the pulsation of temperature of the water coming out of the faucet in a home that uses a tankless water heater. Give me a tanked water heater anytime.

 

[MagnusTheBrewer]

Tankless heaters require a change in lifestyle as well as a change in technology. If you or, your family, can't handle a flow restrictor on the shower and hand sinks then, tankless is not for you. The temp swings/variations ONLY happen when folks have got the valve wide open as in many pull on or single lever valves.

 

[CPA]

Water heater in attic?

Two of them. Live in Houston, we don't have basements.

 

[CPA]

lol no kidding. I can't imagine trying to drag equipment up there. Some people even install their furnace or AC up there. Way more work for nothing.

That's what basements are for.

That's where both of my AC units are, as well. Again, where I live they don't do basements.

 

[TastesLikeChicken]

I installed one in my last house that provided hot water for the kitchen and washing machine. It was mounted in the garage, directly on the other side of the wall from my kitchen sink, so the best thing was that in 5 seconds there was hot water. Before it was installed I had to wait a minute or two for hot water in the kitchen so you have to take water use into consideration as well.

If I ever build my own place from scratch I will install small, dedicated tankless units in each bathroom and a larger one that serves the kitchen and washer. It may cost more initially but having nearly instant, unlimited hot water is great.

 

[gophins72]

Who washes their clothes with hot water anymore?

I'll wash my sheets and undies (not together) in hot water, but that's about it.

 

[JTsyo]

Was thinking about getting one when your old one burst. But it would have taken a few extra days for permits and installation. Will probably switch for the next heater.

 

[Scarpozzi]

I hear tankless sytems just take 30+ seconds to heat the element up and get the lines primed for hot water. Some folks will have a small loop installed in the line that recirculates hot water and pumps to speed the hot water down from the heater to the faucets.

It may cost a few hundred more up front, but you may want to consider those kinds of upgrades to your system to make it less noticible.