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ke4pym
Premium Member
join:2004-07-24
Charlotte, NC

ke4pym

Premium Member

Got a Rinnai installed today!

Had a RC98HPi Condensing Tankless Water Heater installed today. It will heat up to 9.8gpm (depending on inlet temp). 96% efficient. The thing is amazing. Had it installed my the local gas company. This was the first 9.8 they'd installed. They mostly install the ~7gpm units. But, my middle name is overkill so I went with the 9.8

They re-worked the plumbing and cleaned up/upgraded the meter as necessary (meter didn't need an upgrade, but the outside regulator did) and got it done in about 5 hours.

Very pleased with it. Took a shower this evening and it was a constant temprature. Something I rarely got from the old tank.

I decided on a tankless a long time ago. I wanted the space my old 40 gal tank was using. I got about 80% of it back after all was said and done.

Now, I just need to get a cap for the old chimney, patch the hole in the celing from it and go on taking nice long hot showers! My middle name is about to become "prune"!

Acc708
join:2008-06-28

Acc708

Member

If I can ask. what does something like that cost? Installation included... I ask because I am near the end of my 30 gal hwh and am considering the switch.

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey to ke4pym

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to ke4pym
said by ke4pym:

It will heat up to 9.8gpm (depending on inlet temp).

You didn't mention cost savings; is that a factor? What does the flow curve look like, at your seasonal low inlet temperature? Can you do preventive maintenance yourself, or will your gas company handle it?

I like the idea of tankless for the same reasons you do, but I have recirc lines which would require a small storage tank.

I am always warned about the flow being sub-par given the winter inlet temps here, where can run into the 30s in the deep of winter and sometimes don't go above the 40s until mid-May.

On a macro level, I also wonder about the effect on gas distribution if everyone has a tankless and is in the shower at 6:30 AM while the furnace is running full tilt. Maybe in 20 years they'll be offering incentives to put in storage tanks.

macsierra8
Baby Newfoundland
Premium Member
join:2003-11-30
Minden, NV

macsierra8 to ke4pym

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to ke4pym
I went with the R94LSi Rinnai, 9.4 gpm NG and also run a Rinnai hydronic air handler for the forced air heat. I've been in the shower with the forced air on and it handles both at 125 degrees.

The RC98HPi Condensing is LP gas and runs a bit hotter.

»www.amazon.com/gp/produc ··· KIKX0DER

»www.amazon.com/Rinnai-RC ··· 5&sr=1-2

Just Rachel
occasional optimist
Premium Member
join:2003-07-10

Just Rachel to ke4pym

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to ke4pym
We've thought about going tankless for many years. Problem is, we are on alternative power and nobody can answer for us if this would run well off of an inverter. Our inverter messes with digital (clocks won't keep proper time) and I worry that you couldn't keep the settings proper.

Congrats to you! Hope you save a bundle of money.

cowboyro
Premium Member
join:2000-10-11
CT

cowboyro

Premium Member

said by Just Rachel:

We've thought about going tankless for many years. Problem is, we are on alternative power and nobody can answer for us if this would run well off of an inverter.

Likely not. It would require way, way too much power (10kW+). Plus it would only run when there is enough energy generated (sun? wind?)

TJ_in_IL
join:2006-06-10
Winthrop Harbor, IL

TJ_in_IL to ArgMeMatey

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to ArgMeMatey
said by ArgMeMatey:

I am always warned about the flow being sub-par given the winter inlet temps here, where can run into the 30s in the deep of winter and sometimes don't go above the 40s until mid-May.

I am just South of you on the border and the Lake, and I have no issues with my tankless I installed last winter. The unit puts out as much as I need.... doing laundry, running dishwasher, and taking a shower at the same time. I went with a Paloma 199KBtu unit, NG.
ke4pym
Premium Member
join:2004-07-24
Charlotte, NC

ke4pym

Premium Member

@ACC708 - There will be several factors to your final cost. Mine was around $2600 installed before tax rebates (30% from feds, $250 from State, $200 from gas co.). They used the existing water plumbing and had to do minimal replumbing for gas (meter is on the outside wall from where the heater is) so labor wasn't that much.

@ArgMeMatey - I didn't really do this for cost savings. I doubt I will recoup my costs during the life (or before I move out) of the unit. I'll have to keep you updated on the flows. During the summer inlet temps are around 78-80 degrees. But I've seen them as low as 38 during the winter. I suspect that this bad boy will have plenty of juice to take care of a couple of showers.

As far as gas distribution - I don't think that'll be a problem. I suspect there's plenty of over build in the system to deal with this.

@Macsierra - My heater is NG.

@Just Rachel - Rinnai recommends a UPS to keep it running during power outages. That's probably one you'll have to try for yourself.

@Cowboyro - That's if she had an electric on-demand heater. The gas units use 88 watts max and 2 in idle.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

Let's see tax rebates from feds 30 percent, state $250 and gas co $200. Now that's a lot of money that others are having to pay thus making the energy savings a voodoo calculation. There is nothing ever free.

My position is if these energy saving and "green" alternatives are in fact viable they should stand on their own with those using them not depending on others to make it affordable for them.

I'm considering installing one because of a long run from present tank to kitchen but will pay the entire cost myself as it will benefit me and my family.
ke4pym
Premium Member
join:2004-07-24
Charlotte, NC

1 recommendation

ke4pym

Premium Member

said by Jack_in_VA:

Let's see tax rebates from feds 30 percent, state $250 and gas co $200. Now that's a lot of money that others are having to pay thus making the energy savings a voodoo calculation. There is nothing ever free.

My position is if these energy saving and "green" alternatives are in fact viable they should stand on their own with those using them not depending on others to make it affordable for them.

I'm considering installing one because of a long run from present tank to kitchen but will pay the entire cost myself as it will benefit me and my family.

FWIW, I would still have done this regardless of the rebates. Those are just icing on my forever hot cake.

macsierra8
Baby Newfoundland
Premium Member
join:2003-11-30
Minden, NV

macsierra8 to ke4pym

Premium Member

to ke4pym
said by ke4pym:

@Macsierra - My heater is NG.

My Rinnai list shows the NG RC98HPi at 8.1 GPM and the LP model at 9.8 GPM. I was looking at one for the neighbor and we have NG here also and I noticed that's quite a spread.

marigolds
Gainfully employed, finally
MVM
join:2002-05-13
Saint Louis, MO

marigolds to ke4pym

MVM

to ke4pym
said by ke4pym:

@Just Rachel - Rinnai recommends a UPS to keep it running during power outages. That's probably one you'll have to try for yourself.

This is an excellent idea. I will have to consider doing this for our tankless. The performance on tankless heaters is so nice, I have to wonder how return you get on house value from one of those.
marigolds

marigolds

MVM

While I am thinking about it... any suggestions for a UPS to back up the tankless? My tankless heater plugs into a 20A outlet coming straight off the panel. I think the model is a Noritz NR798-SV (NG)
»www.noritz.com/homeowner ··· _heater/
(Edit: I think I had the wrong model before... I will check when I get home.)

Killa200
Premium Member
join:2005-12-02
TN

Killa200

Premium Member

how long are you looking for it to last without power? How much of that time will it be running?
Gimmered
Premium Member
join:2005-02-26
Mccook, NE

Gimmered to Jack_in_VA

Premium Member

to Jack_in_VA
said by Jack_in_VA:

Let's see tax rebates from feds 30 percent, state $250 and gas co $200. Now that's a lot of money that others are having to pay thus making the energy savings a voodoo calculation. There is nothing ever free.

My position is if these energy saving and "green" alternatives are in fact viable they should stand on their own with those using them not depending on others to make it affordable for them.

I'm considering installing one because of a long run from present tank to kitchen but will pay the entire cost myself as it will benefit me and my family.

Unless I'm mistaken the tax credit is for the unit only not the install.

If you are looking at a tankless for savings you might be disappointed. Payback will be a long time coming if ever. But there are also different reasons for going tankless other then savings.

I've had a tankless for about a year now and for the most part I like it but there are also a few downsides to them too.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

I'm considering one because I have a long run from my HW tank to the kitchen and it takes forever for the hot water to get there. It would be to alleviate that problem rather than energy savings. It's just the two of us and we don't use all that much hot water.

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey

Member

said by Jack_in_VA:

I'm considering one because I have a long run from my HW tank to the kitchen and it takes forever for the hot water to get there. It would be to alleviate that problem rather than energy savings. It's just the two of us and we don't use all that much hot water.

So you're going to put a tankless in the kitchen? Have you looked at the Grundfos retrofit systems? Or putting in a recirc loop?
Gimmered
Premium Member
join:2005-02-26
Mccook, NE

Gimmered to Jack_in_VA

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to Jack_in_VA
said by Jack_in_VA:

I'm considering one because I have a long run from my HW tank to the kitchen and it takes forever for the hot water to get there. It would be to alleviate that problem rather than energy savings. It's just the two of us and we don't use all that much hot water.

If that is the case you would need to install it very close to the kitchen or the problem would be much worse. With your tank type you can turn your hot water off and the water in the pipes will still be hot for a time. With a tankless the water in the pipes will still be hot followed by cold water and then hot again.

In my house my bathroom is farther away and also has 3/4" lines to a manifold. If I forget to start the shower before I turn off the sink I need to wait for the cold water sandwich to pass though the pipes. I lose close to 2 gallons every time.

I'll likely add another water heater close to the bathroom within the next year.
scooper
join:2000-07-11
Kansas City, KS
·Google Fiber

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Jack - you could do what I've done - I installed an EEmax EX95T electric tankless right under the kitchen sink for use with the kitchen sink and dishwasher. I choose the T model because it has the thermostat (so I can feed it with my tank water heater hot water) or I can feed it with just cold coming out of my well.

Now - the disadvantage of this - it takes a 50AMP 240V circuit for that puppy. It's nice having hot water in 5-10 seconds instead of the 2 minutes it takes from my tank to the kitchen, and I don't have the losses of running the recirc.
TheMG
Premium Member
join:2007-09-04
Canada
MikroTik RB450G
Cisco DPC3008
Cisco SPA112

TheMG to ArgMeMatey

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to ArgMeMatey
said by ArgMeMatey:

I like the idea of tankless for the same reasons you do, but I have recirc lines which would require a small storage tank.

Afaik tankless heaters, especially of the condensing high-efficiency variety, are NOT recirc friendly.

They have a maximum inlet temperature rating, which means the tankless heater CAN NOT be part of a recirculating loop and can not be used to heat the water in a storage tank.

Also, the colder the inlet temperature the more efficient they are, it all has to do with the laws of thermodynamics. Efficiency would go down the drain if the water at the inlet is already somewhat hot.

ArgMeMatey
join:2001-08-09
Milwaukee, WI

ArgMeMatey

Member

said by TheMG:

said by ArgMeMatey:

I like the idea of tankless for the same reasons you do, but I have recirc lines which would require a small storage tank.

Afaik tankless heaters, especially of the condensing high-efficiency variety, are NOT recirc friendly.

Sorry, I meant a small tank-type heater, not a storage tank without heat like you'd use for an indirect.

I seem to recall from other conversations that there is one tankless manufacturer that has a special input for recirc, while others diagram something using a tank-type heater that does not feed the input.

Either way, it's a lot more complicated than what I have now: One burner, one pilot, one millivolt stat, two check valves. Power failure? Nice hot shower in the dark.

Regarding recirc in the abstract, think of supply and convection recirc lines as long, tubular storage tanks with a capacity of a few gallons. They are well-insulated except the last few feet of recirc at the bottom of the loop.
medbuyer
join:2003-11-20
Memphis, TN

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can you post pictures of your installed unit?
ke4pym
Premium Member
join:2004-07-24
Charlotte, NC

ke4pym to Gimmered

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to Gimmered
@Gimmered - The tax credit is for the unit *AND* the install.

@TheMG - I can't speak about all tankless heaters, but the instruction book for my heater explicitly shows you how to install it in a recirc system.

I will be happy to post pictures of the install later.

UPS sizing - they don't use a lot of power to begin with. The bigger the UPS, the longer it'll run. Just depends on how much coin you want to spend.
itguy05
join:2005-06-17
Carlisle, PA

itguy05 to Just Rachel

Member

to Just Rachel
said by Just Rachel:

Congrats to you! Hope you save a bundle of money.

Unless you are running a real old hot water heater you probably won't. Especially when you factor in the cost of the heater. When we replaced ours last year I thought about tankless.

Average NG bill is $30 in summer, $150 in winter. Assume 6 mo of each.... $1,080 per year.

From Home Depot:
50 Gallon NG HWH was just under $500
Tankless was around $1000.

So $500 more and that doesn't take into account the gas upgrades we would probably need. I would have to save a boatload of natural gas for any type of payback for the extra $500+. Even saving $10/mo the payback will be around 5 years at the best.

It's even worse if you pay more.

marigolds
Gainfully employed, finally
MVM
join:2002-05-13
Saint Louis, MO

marigolds

MVM

said by itguy05:

So $500 more and that doesn't take into account the gas upgrades we would probably need.

The gas company here paid for all the gas upgrades for installing the tankless. I really do not understand why, but they did.

MsTerra
Mouthy Broad
Premium Member
join:2002-08-20
Nerdvana

MsTerra to marigolds

Premium Member

to marigolds
said by marigolds:

While I am thinking about it... any suggestions for a UPS to back up the tankless? My tankless heater plugs into a 20A outlet coming straight off the panel. I think the model is a Noritz NR798-SV (NG)
»www.noritz.com/homeowner ··· _heater/
(Edit: I think I had the wrong model before... I will check when I get home.)

No ideas on this yet? I would be interested in hearing others' thoughts on this as well. We had a tankless wh/furnace combo unit installed last March, and we've been very happy with it, but I am a little concerned about what would happen if we lost power. There had been talk prior to the install of adding a battery backup, but the electrician who worked with our plumber said we couldn't get one that would provide sufficient power.

Zupper
Premium Member
join:2002-12-28
Novelty, OH

Zupper

Premium Member

said by MsTerra:

said by marigolds:

While I am thinking about it... any suggestions for a UPS to back up the tankless? My tankless heater plugs into a 20A outlet coming straight off the panel. I think the model is a Noritz NR798-SV (NG)
»www.noritz.com/homeowner ··· _heater/
(Edit: I think I had the wrong model before... I will check when I get home.)

No ideas on this yet? I would be interested in hearing others' thoughts on this as well. We had a tankless wh/furnace combo unit installed last March, and we've been very happy with it, but I am a little concerned about what would happen if we lost power. There had been talk prior to the install of adding a battery backup, but the electrician who worked with our plumber said we couldn't get one that would provide sufficient power.

You need to look at the spec sheet for your WH, and see what its electrical power consumption is. Then compare that to specs of a UPS. Those Rinnai units appear to use 49-83W when running, and 104-184W for some anti frost mode.

Looking at this run time chart for APC higher end RS line:
»www.apc.com/products/run ··· amily=23
Even if you went with the biggest unit, you're only really talking about a few hours of run time. (assuming 200W peak, 100W average). What's your expectation?

marigolds
Gainfully employed, finally
MVM
join:2002-05-13
Saint Louis, MO

marigolds

MVM

Well, see, I don't get if that is the power consumption all the time, while running, or during standby?

If it is consuming 108W all the time, then it looks like at best I am going to get 3 hours out of it and it is probably not that worthwhile.

If it is only consuming 108W while running, it runs less than 30 minutes a day (we would not be washing clothes or using the dishwasher if the power is out anyway), in which case we could get a couple of days out of some of these.
(Although, I suppose if we had a power outage, we could just turn it on for showers and off otherwise.)
Automate
join:2001-06-26
Atlanta, GA

Automate to Zupper

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to Zupper
said by Zupper:

Those Rinnai units appear to use 49-83W when running, and 104-184W for some anti frost mode.

The freeze prevention mode would only apply if you had the water heater mounted outside and the internal heater kicked in to prevent the pipes from freezing. Tankless hot water heaters generally pull 3 to 12 watts when in standby mode.

Jack_in_VA
Premium Member
join:2007-11-26
North, VA

Jack_in_VA

Premium Member

quote:
Tankless hot water heaters generally pull 3 to 12 watts when in standby mode.
Would not that 3 to 12 watts be considered a "Vampire Load" that everyone is urged to take steps to eliminate?