On demand gas heaters

[shup]

Hi everyone.

Was just wondering what you folks think about on demand gas water heaters.

We will be buying a new older home and will probably have to do some remodeling and one of the things that have come up is this type of heater.

The house will be 1 story with a full basement or a 2 story with a basement.
We are looking for 2.5 baths and will probably have 2 sinks in the kitchen as well as one in the laundry room.

I was wondering how many heaters would be best and also for what we want is it worth doing it and is a good way for hot water for the house.

It will be install professionally but would like some ideal for when it comes down. We live in Washington state if that makes a difference.

Any advise would be appreciated.
shup

[Pipestone Kid]

shup: Do a search on this forum for tankless water heaters. You will find that most plumbers do not recommend them. I personally cannot say one way or the other, but I do have lots of respect for most of these guys. They know their business and will give you a straight answer. It seems like the tankless is expensive to maintain.

[westcoastplumber]

Hi everyone.

Was just wondering what you folks think about on demand gas water heaters.

We will be buying a new older home and will probably have to do some remodeling and one of the things that have come up is this type of heater.

The house will be 1 story with a full basement or a 2 story with a basement.
We are looking for 2.5 baths and will probably have 2 sinks in the kitchen as well as one in the laundry room.

I was wondering how many heaters would be best and also for what we want is it worth doing it and is a good way for hot water for the house.

It will be install professionally but would like some ideal for when it comes down. We live in Washington state if that makes a difference.

Any advise would be appreciated.
shup


If your doing a large remodel, where you can pipe everything in and do the install the correct way, then go with a Rinnai, get a certified installer.

you will be fine. Tankless is expensive to retro fit, but if your doing a large demo, you can absorb some of the expense.

Tankless is not for everyone, but there is energy savings and endless hot water.

the savings are more then meet the eye, just call Rinnai support and they can break down the cost savings.

[bjdavis]

I have an on demand gas water heater & I love it. It only heats water when I need it instead of keeping it hot all day for no reason. I replaced my electric water heater with it and my electric bill dropped $125.00 a month. My gas bill only went up $15.00 a month. I have a 3 bedroom 2 bath house.

[VASandy]

OK....so this whole tankless water heater thing. I love the idea. From the perspective of user-friendly, and even "green" building, tankless is the way to go. Maintain comfort levels, but at a lower cost.

So...tankless retrofit seems problematic. Is this just because of the way tankless heaters are designed to be used with a manifold system? Or is there some other "gotcha" with tankless I've missed somewhere? I get how retrofitting a manifold system into existing is a total ...well...PITA at the very least. Just trying to think of how to retro a tankless into my home causes me to have nightmares...and I don't do plumbing! Is there something beyond the manifold installation that I'm missing?

[JCsPlumbing]

I have an on demand gas water heater & I love it. It only heats water when I need it instead of keeping it hot all day for no reason. I replaced my electric water heater with it and my electric bill dropped $125.00 a month. My gas bill only went up $15.00 a month. I have a 3 bedroom 2 bath house.

This persons electric bill did not drop $125.00 a month!:eek:

[PLUMBER RICK]

without repeating my post a dozen times. please do a search on tankless.

i can tell you from personal knowledge, the savings will never add up.

you're also limited to 4-8 gallons per minute depending on the size and the incoming water temperature.

very few get installed properly and don't even think of a recirc system.

please do some research on old post and then ask again.

rick.

added note, my monthly gas bill is only 15.00 a month with a 40 gallon gas heater. my dryer and stove are gas too.

even if my bill droped to 5. a month, there would never be a payback for me.

[shup]

Thanks guys for the info.

Plumber Rick, thanks I will do the search.

shup

[Masterplumb]

without repeating my post a dozen times. please do a search on tankless.

i can tell you from personal knowledge, the savings will never add up.

you're also limited to 4-8 gallons per minute depending on the size and the incoming water temperature.

very few get installed properly and don't even think of a recirc system.

please do some research on old post and then ask again.

rick.

added note, my monthly gas bill is only 15.00 a month with a 40 gallon gas heater. my dryer and stove are gas too.

even if my bill droped to 5. a month, there would never be a payback for me.


That 4-8 gpm is the key for me. I will install them for my customers, but I try and talk them out of it. Around these parts, I try to have them put in indirect heaters.

[NHMaster3015]

Ain't it amazing how when the price of energy goes up the same gadgets get trotted out all over again. Tankless heaters are nothing new. They've been around for at least 40 year, maybe longer (I'm not in a google mood so you'll have to chect that for yourselves) but I do remember Paloma Pak and Aquastar and two or three others. I will admit the Rinnai is a much better, more refined product but the technology is nothing new. The key here is the gallons per minute. Look closely at your plumbing code. It says you must provide hot water to every fixture (that uses hot water) when they are all open at once. A quick look at the sfu (supply fixture unit) tells you right off that a 4gpm draw will not satisfy the code. Then those of you in the north east have been installing boilers with tankless coils capable of a paltry 2 1/2 to 3 gpm for years.

[UA22PLumberdude]

personally I'd go with an AO Smith Vertex....tankless just have way too many issues.

[saysflushable]

Wait until they spring leaks like all water heaters will. People think there power vents are great until they get the bill for the new one! When the price of a new heater is lost in the cost of a big remodel or new home it's no big deal, but when it needs to be replaced , then people start wishing they had a standard vent W/H. If they become popular enough I'll be one of the only guys around to learn how to work on them. When they need to be replaced they will be a lot lighter then a tank water heater. If they have the money for one now then in 10 years I will show no mercy on price to replace or fix one. all the money they imagined they saved on efficiency will adequately compensate me for my time. I've had to work on 2 they were a pain in the neck. From now on it's going to be $150.00 an hour to watch me fumble around getting the thing to work!

VERY EFFICIANT AND YOU GET ALL THE HOT WATER YOU WANT.

It don't work that way folks!

[westcoastplumber]

Rinnai is top of the line when it comes to tankless.

On their web site they have a savings chart and all the information you need to make an informed decision.

The unit saves money in a couple different ways, one way is not heating 40 gallons of water when no one needs it, another way, is only heating the water you need, on demand.

the unit may not work at 199,000 btu until the flow rate is needed.

Take some time to research Rinnai on their web site and once again make sure you hire a certified installer.

As far as the comment as springing leaks, the poster needs to do his research also.

the heat exchanger is warrantied far longer then a tank 10 years.

depends on you and your needs. yes, tankless are not for everyone, but they do have a use and they are an excellent product.

[NHMaster3015]

If you read throug the specs. here you will note that the best of these units is capable of 8.0 gpm. The combined supply fixture unit value of an average 2 bath house, with all hot water taps open at the same time, (yes, highly unlikely) is above the apacity of the unit and therefore non code compliant. Now I know full well that only an a-hole of an inspector would bag you on this, but he could. The usual residential unit installed only has a capacity of 4.8 gpm. If you sell these (and I do) it is vital to clearly explain to the customer that though the hot water supply can be endless, if there is too much demand on the heater it will not be. You can't take a shower, run the dishwasher and the laundry all at the same time.




will have an endless supply of hot water 24 hours a day. Unique to the Rinnai tankless water heaters is the ability to utilize up to three water outlets simultaneously with a constant temperature of hot water. The Rinnai Tankless Water Heater supplies hot water at the rate of up to 8.5 gallons per minute continuously with no time constraints!

ModelDimensionsMin/Max BTU'sFlow RateTemp RangeR85e Plus
http://www.rinnai.us/docs/filestore/r85eplus_0.jpg
Height 22.9"
Width 14"
Depth 9.8"15,000 - 199,000 0.6 to 6.5 GPM
(50 F rise)
0.6 to 8.5 GPM
(35 F rise)Factory preset to 120 F

MC-91
Controller 96-140F included





R85i Plus
http://www.rinnai.us/docs/filestore/r85iplus.jpg
Height 22.9"
Width 14"
Depth 9.6"
15,000 - 180,000 0.6 to 6.5 GPM
(50 F rise)
0.6 to 8.5 GPM
(35 F rise)Factory preset to 120 F

MC-91 Controller 98-140 F
included


R53i Plus
http://www.rinnai.us/docs/filestore/r85iplus_0.jpg


Height 22.9"
Width 14"
Depth 9.6"
15,000 - 180,000 0.6 to 5.3 GPM
(50 F rise)
0.6 to 5.3 GPM
(35 F rise)Factory preset to 120 F

MC-91
Controller 98-140 F
included
R98i (http://www.rinnai.us/Products/water_heaters/3237FFU/FeaturesBenefits.aspx)

http://www.rinnai.us/docs/filestore/r98ismall.jpg
Height 23.6"
Width 18.5"
Depth 9.3"19,000-237,0000.6 to 8.0 GPM (50 F rise) 0.9 to 9.8 GPM (35 F rise)
Factory preset to 120 F

MC-91
Controller 98-140 F
included
R98e
http://www.rinnai.us/docs/filestore/r98esm.jpg


Height 23.6"
Width 18.5"
Depth 9.3"19,000-237,0000.6 to 8.0 GPM (50 F rise) 0.9 to 9.8 GPM (35 F rise)
Factory preset to 120 F

MC-91 Controller 98-140 F
included


R85i (http://www.rinnai.us/Products/water_heaters/2532FFU/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2532ffu_0.jpg
Height 23 5/8"
Width 13 25/32"
Depth 8 13/16"15,000 - 180,000 0.6 to 6.5 GPM
(50 F rise)
0.6 to 8.5 GPM
(35 F rise)Factory preset to 120 F

MC-91
Controller 98-140 F
included


R85e (http://www.rinnai.us/Products/water_heaters/2532W/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2532w.jpg

Height 23-5/8"
Width 13-3/4"
Depth 8-7/8"15,000-199,000 0.5 to 6.5 GPM
(50 F rise)
0.7 to 8.5 GPM
(35 F rise)
Factory preset to 120 F

MC-91 Controller 96-140F included

R53i (http://www.rinnai.us/Products/water_heaters/2520FFU/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2532ffu_0.jpg
Height 23-5/8"
Width 13-25/32"
Depth 8-13/16"15,000 - 180,0000.7 to 5.3 GPM
(50 F rise)
0.7 to 5.3 GPM
(35 F rise)Factory preset to 120 F

MC-91
Controller 96-140F included

R53e (http://www.rinnai.us/Products/water_heaters/2020W/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2020w_0.jpg

Height 20-7/8"
Width 13-3/4"
Depth 7-3/8"19,000- 150,000 0.7 to 4.9 GPM
(50 F rise)
0.7 to 5.3 GPM
(35 F rise)

Factory preset to 120 F

MC-91
Controller 96-140F included
R42e (http://www.rinnai.us/Products/water_heaters/1616W/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/1616w_0.jpgHeight 20-7/8"
Width 13-3/4"
Depth 7-3/8"17,700- 120,0000.7 to 3.9 GPM
(50 F rise)
0.7 to 4.2 GPM
(35 F rise)Factory preset to 120 F

MC-91
Controller 96-140F included


C85i (http://www.rinnai.us/Products/water_heaters/2532FFU-C/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2532ffu-c_0.jpg

Height 23 5/8"
Width 13 25/32"
Depth 8 13/16"15,000 - 180,0000.5 to 6.5 GPM
(50 F rise)
0.7 to 8.5 GPM
(35 F rise)Factory preset to 140 F

MC-91
Controller 96-180 F
included

C85e (http://www.rinnai.us/Products/water_heaters/2532W-C/features_benefits.aspx)

http://www.rinnai.us/docs/filestore/c85e502.jpg

Height 23-5/8"
Width 13-3/4"
Depth 8-7/8"15,000-199,000








0.6 to 6.5 GPM
(50 F rise)
0.6 to 8.5 GPM
(35 F rise)
Factory preset to 140 F

MC-91 Controller 96-185 F
included

C53i (http://www.rinnai.us/Products/water_heaters/2520FFU-C/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/c53i.jpgHeight 23 5/8"
Width 13 25/32"
Depth 8 13/16"15,000 - 180,0000.7 to 5.3 GPM
(50 F rise)
0.7 to 5.3 GPM
(35 F rise)
Factory preset to 140 F

MC-91 Controller 120-180 F
included
C42e (http://www.rinnai.us/Products/water_heaters/2020W-C/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/2020w-c_0.jpgHeight 20-7/8"
Width 13-3/4"
Depth 7-3/8"19,000- 150,0000.6 to 4.8 GPM
(50 F rise)
0.6 to 5.3 GPM
(35 F rise)Factory preset to 140 F

MC-91
Controller 120-185 F
included
C42 (http://www.rinnai.us/Products/water_heaters/1616W-C/features_benefits.aspx)
http://www.rinnai.us/docs/filestore/1616w-c_0.jpgHeight 20-7/8"
Width 13-3/4"
Depth 7-3/8"17,700- 120,0000.6 to 3.8 GPM
(50 F rise)
0.6 to 4.2 GPM
(35 F rise)Factory preset to 140 F

MC-91
Controller 120-185 F
included

[westcoastplumber]

don't forget to factor in the temp rise.

I think 8.5 is for 70 or 80 degree incomming water, we have like 50 or 60 here, so it cuts down on the flow.

[NHMaster3015]

Woops, one more thing. Note the delta t (temp rise) it's rated at 50 degrees, which for the southern half of the country is ok. For those of us north of the Mason Dixon line, most of the fall and winter months, 50 degrees is only going to give us 100 degree water. The gpm drops drastically at higher delta t flow rates

[shup]

Wow, Thanks again guys.

When you say ask the experts you really are asking people in the know.

I didn't mean to start this over again but really appreciate your thoughts.

Again when you want to know ask the people in the know.

[DuckButter]

Coincidentally, I got a call two weeks ago regarding a Bosch Aquastar tankless.
I'd installed this unit two years ago despite hearing they were the worst on the market.
The customer had already purchased this wonderful piece of machinery based on what the "plumbing guy" at Lowes told him...I tried to get him to exchange it but, if I recall, he was told the sale was final.

I spent 2 hours looking at this unit trying to figure out why it wouldn't kick on until the flow rate was at least 1.5 gpm, flushed it with vinegar for 1-1/2 hours, took out the flow device and it was clear...checked the blower, shut off the units supply & checked all hot fixtures for backfeed, then shut off ALL hot feeds in the house to eliminate the possibility of cross connection and it still wouldn't work right.
Finally I got their customer service/tech support on the phone, after waiting 20 minutes on hold on my customers dime.
They told me it was the flame sensor, that I need to let them mail a new one and replace it.

Five days later, I replace the electrode...nothing, no improvement...once again I call & wait 20 minutes.
This time the guy I reach admits the last fella was taking a shot in the dark and that wasn't whats wrong.
I tell him I think it's the flow detection, thats what I told the first guy...he explicitly denies this and says it's the houses plumbing.
I thought that was odd, since he hadn't yet asked what I'd done to check for cross connection.

I explain to him that I'd already checked that by shutting down all hot feeds in the house...he continues to insist that my customer will need to have some plumbing redone.
He then insists there must be a cross connection in the actual piping, after 2 years it seems odd that a cold water line would suddenly resolder itself to a hot line...all by itself.
I then ask him, "So, lets say it turns out you're wrong and I wind up repiping his water lines...who pays the bill for that?".
He then takes a more aggressive tone, "Look, there's nothing wrong with this unit, I don't know what the problem is...the warranty doesn't cover bad piping in the home."
I asked him if he could just send out a new flow device, he flat out refused, telling me they have never once had a problem with that device...ever.
Niiiiiccce!
After running fine for almost two years, it's bad piping in the house.
So, now my customer is out the money paying me to talk to "some guy" who reads responses from a manual...and it would seem is trained to do all he can to avoid owning responsibility of the warranty.
The finale, my customer is going to wait for the unit to die, we'll be replacing it with anything but Bosch...period.

I'm open to you guys experience with these units if anyone thinks of something I may have missed, but I can honestly say I will strongly advise all customers to avoid ALL Bosch products after seeing how they treat their warranty.

[Pete M]

Coincidentally, I got a call two weeks ago regarding a Bosch Aquastar tankless.
I'd installed this unit two years ago despite hearing they were the worst on the market.
The customer had already purchased this wonderful piece of machinery based on what the "plumbing guy" at Lowes told him...I tried to get him to exchange it but, if I recall, he was told the sale was final.

I spent 2 hours looking at this unit trying to figure out why it wouldn't kick on until the flow rate was at least 1.5 gpm, flushed it with vinegar for 1-1/2 hours, took out the flow device and it was clear...checked the blower, shut off the units supply & checked all hot fixtures for backfeed, then shut off ALL hot feeds in the house to eliminate the possibility of cross connection and it still wouldn't work right.
Finally I got their customer service/tech support on the phone, after waiting 20 minutes on hold on my customers dime.
They told me it was the flame sensor, that I need to let them mail a new one and replace it.

Five days later, I replace the electrode...nothing, no improvement...once again I call & wait 20 minutes.
This time the guy I reach admits the last fella was taking a shot in the dark and that wasn't whats wrong.
I tell him I think it's the flow detection, thats what I told the first guy...he explicitly denies this and says it's the houses plumbing.
I thought that was odd, since he hadn't yet asked what I'd done to check for cross connection.

I explain to him that I'd already checked that by shutting down all hot feeds in the house...he continues to insist that my customer will need to have some plumbing redone.
He then insists there must be a cross connection in the actual piping, after 2 years it seems odd that a cold water line would suddenly resolder itself to a hot line...all by itself.
I then ask him, "So, lets say it turns out you're wrong and I wind up repiping his water lines...who pays the bill for that?".
He then takes a more aggressive tone, "Look, there's nothing wrong with this unit, I don't know what the problem is...the warranty doesn't cover bad piping in the home."
I asked him if he could just send out a new flow device, he flat out refused, telling me they have never once had a problem with that device...ever.
Niiiiiccce!
After running fine for almost two years, it's bad piping in the house.
So, now my customer is out the money paying me to talk to "some guy" who reads responses from a manual...and it would seem is trained to do all he can to avoid owning responsibility of the warranty.
The finale, my customer is going to wait for the unit to die, we'll be replacing it with anything but Bosch...period.

I'm open to you guys experience with these units if anyone thinks of something I may have missed, but I can honestly say I will strongly advise all customers to avoid ALL Bosch products after seeing how they treat their warranty.


Maybe this will be helpful. http://www.aquastarwaterheater.com/HelpfulResources/TechnicalSupport/BoschModels/125BOTechSupport/Troubleshoot/tabid/602/Default.aspx

[MPMGinAL]

Just a thought for those of you like myself that like to look at the long term result. The government offers incentives to HO's to go tankless, along with advertised savings. This is appealing to most. What would happen if everyone in a particular nieghborhood went tankless. Demand would typically come at the same time at everyone's house. Do you think the city gas mains could support the extra 150K BTU at once. What if there was one tankless per bathroom? That could equate to alot of gas for a 2" main.

[DuckButter]

Maybe this will be helpful. http://www.aquastarwaterheater.com/HelpfulResources/TechnicalSupport/BoschModels/125BOTechSupport/Troubleshoot/tabid/602/Default.aspx
Pete...lol...I really appreciate the help, but I'm sick of looking at that site.
It's a model 250 SX...I actually copied part of the troubleshooting guide & parts list to bring there.
Bottom line, there's something wrong with the unit that their tech guys either are trying to avoid admitting to, or simply don't know how to deal with it.
I may humor them with one more call to entertain a third "theory" on whats wrong with it if I get some time, but as it stands the homeowner recalls me mentioning it wasn't a very good unit....he may just await it's demise and replace it with a better name.

[DuckButter]

Just a thought for those of you like myself that like to look at the long term result. The government offers incentives to HO's to go tankless, along with advertised savings. This is appealing to most. What would happen if everyone in a particular nieghborhood went tankless. Demand would typically come at the same time at everyone's house. Do you think the city gas mains could support the extra 150K BTU at once. What if there was one tankless per bathroom? That could equate to alot of gas for a 2" main.
"Was" offering a tax credit through 12/07...gone now.
Local gas co still offers a $300 rebate on indirects & tankless with ratings better than 82%, $1000 on boilers better than 90%...but rumor is that may not be too long either.

[haycad]

what do you guys think of this
Paloma Industries is one of the largest and oldest gas appliance manufactures in the world. The Paloma PTG-42PVN Natural Gas "On Demand" Tankless Water Heater is designed to supply continuous hot water for your family for up to 20 years or more. The 118,000 BTU burner provides hot water at 4.2 gallons per minute allowing one to two major applications such as one shower and sink to be used at the same time. The "On Demand" feature heats water only when needed, saving up to 30% on fuel costs compared to a standard gas water heater or up to 70% when compared to a standard electric water heater. The .81 energy factor exceeds the requirements for most utility rebate programs. This compact power vented appliance allows for installation flexibility, saves valuable floor space and can be vented horizontally or vertically with no costly add-ons. The built-in digital control thermostat provides precise temperature control.

Continuous hot water - 4.2 gallons per minute
Indoor models supplied with a 120 volt power cord
RTG20003 stainless steel vent kit for horizontal venting (sold separately)
10 Year limited warranty on heat exchanger, 3 Year limited warranty on parts
Height 22.25 In.; Width 13.75 In.; Depth 5.125 In.
Eco Options approved product
Heats water only when needed
Electronic ignition - no standing pilot
Handles one to two applications at the same time
.81 EF exceeds requirements for most utility rebate programs.
Digital thermostat allows precise temperature control and diagnostics
Compact space saving design
Power vent blower allows flexible venting
Low NOx emissions meet SCAQMD rule 1146 requirements
MFG Brand Name : Paloma
MFG Model # : PTG2-42PVN
MFG Part # : 531830

[NHMaster3015]

I think if you're in the shower and the dishwasher or washing machine is running you're not going to be a happy camper. Read your code books fella's. You need to provide continuous hot water to all the fixtures at the same time.

[Big Dog]

i really like my Rinnai, but I live in the south where the water temp doesn't have to be heated a lot. In fact, during the summer months, you don't even have to turn the hot water on to take a shower. The water lines are shallow enough in our whole area, that the water is plenty warm just on cool.