New custom home build, need feedback

[Danny Soroudi]

Been lurking on this site for a while learning about the world of plumbing as I prepare for our new home construction, and now that we're getting close, I'm ready with my questions, I think.

I will be building a new 6,200sf, 3 story house in the Los Angeles area. It will be a totally custom home, with relatively high end finishes and construction quality (or so I hope).

There will be 1 kitchen, 2 laundry rooms (1st and 3rd floors) and 5 full baths + 2 half baths, spread throughout all 3 floors of the house. As we went through the design process of the house, my design team decided, without really much thought or input from me, that tankless was the way to go, and so my plumbing engineer designed the house with space for 2 tankless units in the bottom floor, and 1 re-circulation pump.

My plumbing engineer is recommending two Takagi T-H3-DV-N tankless heaters, and one Taco 006-IQB4 Bronze Smart Plus recirculation pump.

On the other hand, my general contractor is recommending 2 Rinnai RUR98iN units, and he is fine to use the Taco recirc pump or the solution provided by Rinnai (he hasn't specified a model from Rinnai for the recirc to me yet).

Questions:

1) For a house of the size I'm describing, are two tankless heaters + 1 recirc pump sufficient? Both my plumbing engineer and my general contractor (and his plumbing sub) say yes, but of course I would like some unbiased / real world feedback too.

2) Which is the "better" system Takagi or Rinnai (or should I even consider something else)? Assume cost, while important, is not the deciding factor, but capacity and reliability (and service if there's ever an issue) are the more critical elements to for my decision making at this stage.

3) For the re-circulation system, is there something else other than the Taco Smart Plus for me to consider?

4) My plumbing engineer says he has sized all the piping correctly for hot/cold lines, etc, and the plumbing contractor has confirmed he agrees with all sizing. From what I can tell, its all "L" copper, starts at 1.5" main hot water line coming out of the tankless heaters, which branches at appropriate places to 3/4", then drops to 1/2" as it hits wash sinks. As the hot water line returns it eventually drops down to 1.25" then down to 1" before it hits the recirc pump back in the basement area. Is there anything else specific I should be looking for in the plans and specifications?

5) Anything else for me to consider?

Thanks in advance!

 

[Stuff]

For a high end house tankless is appropriate as it will cost the most money. Then when your guests complain about the hot water issues you can show them your high end system.

Traditional tank systems are the way to go. You can buy high end efficient systems that are much more reliable than tankless. The tankless have their role in the world but only for specific applications.

What is a "plumbing engineer?" I don't recall that being one of the university options.

 

[Sponsor]

 

[Danny Soroudi]

Pretty much the answer I was hoping NOT to hear.

The 1st level of my house, where the water heaters will be located is the basement/underground level. There is no room or way to get a full size tank heater in there (or replace down the line), so short of a major redesign of my house, which isnt an option, I'm basically stuck with the tankless solution.

Would something like the Rinnai RH-180 Hybrid system be something for me to look at? That I believe I might be able to fit in the area I have available.

Considering where I am, I need to just make the best of the options I can reasonably have available to me.

I guess plumbing engineer is a fancy word for the guy my architect hired who drew all of the plumbing diagrams and plans for the city to review/approve and my contractor to bid on.

 

[Terry]

I've seen a few dual tankless units on high end homes in my travels as a plumber. I would wait to see what Dana says, as he knows a lot about these systems. I also like the heat reclaim pipes he mentions that are now code in Canada to preheat the incoming cold with heated waste water from showering. In California the tankless works better than the cold climate of Seattle.
I had considered installing two tankless units in my home to see how it worked. I installed on, and the other is still in the box.
You do need the recirc for tankless if there is any kind of distance. I do like that I'm not limited to time in the shower. I like water, what can I say?

 

[Master Plumber Mark]

Architects hire "Plumbing Engineers" to make the cost of the house be higher so they get paid
more at the end of the line..... Its what they all do......


you have to ask yourself if this "plumbing engineer" will be around in a few years when the
units begin to break down and give you troubles....?? Will you be able to find a guy to work on
these jewels if they break down on a long holiday weekend ...like this 4th of july weekend ??
Probably NOT.

If you just installed 2 common 75 gallon
Rheem gas heaters with 12 year warranties you would probably be just
fine with hot water and maybe not even need the recirc pump...
The odds are you will not be using all 5 bathrooms and most likely
they will be idle most of the time......

simply ask them what the cost difference between the two options would be.....
it cant hurt to ask.......

good luck....

 

[Stuff]

If the architect didn't plan to give you access to or room in the basement I predict many more problems for you.

I don't mean to be harsh, but to point out that your architect, builder, etc. are letting you down. It is their job to anticipate and avoid issues so that you can enjoy your new home.

That Rinnai shows a first hour rating of 180 gallons which is impressive. Maybe someone who has experience with one can chip in.

 

[Master Plumber Mark]

If the architect didn't plan to give you access to or room in the basement I predict many more problems for you.

I don't mean to be harsh, but to point out that your architect, builder, etc. are letting you down. It is their job to anticipate and avoid issues so that you can enjoy your new home.

That Rinnai shows a first hour rating of 180 gallons which is impressive. Maybe someone who has experience with one can chip in.

Thats a very good question.. Here you got a 5 bathroom house being built and I wonder how much space the Architect made for the mechanical room in your new home??
You are designing this home from the ground up ,,, It would be nice to have lots of ROOM around the plumbing fixtures and furnace in the mechanical area.. Its always wise and better to have plenty of space instead of cramming one of these things into an un-godly tight spot...

Designing your mechanical room as though it was as tight as being on the space shuttle is never a wise thing to do. Sometime down the road , if you are not happy with the performance of one of the tankless units..
you will be stuck with them because nothing else will fit back into the spot... Tankless were made for being
in small homes with no room to spare like over in Japan or Europe.....
and many of these gurus do not plan for the possibility of having to change out these things way down the road...

I am sorry , but I admit that I do not like these things...all you have to do is read other horror stories on this site about them and you can see why ...

many of the experts know the math, and can talk a good story but when
it comes to in the field experience they are lost......

good luck.

 

[Danny Soroudi]

So my mechanical room is 8' x 4.5' .. not tiny, but I guess not huge. For what the design team is using for the space for (2 tankless units, and a recirc pump) its not cramped at all. I have a totally different closet for all the audio/visual/cabling stuff for home automation, and my HVAC condenser units are on the roof.

I'm going to explore whether adding a tank is doable without some major redesign, and also looking into the hybrid system as well.

Very much appreciate the feedback so far, although I wish I had come here about 6 months ago, at least I'm not in the middle of construction yet, so if I make changes, its still potentially possible

 

[Reach4]

Do you know the maximum hardness of the water you will be receiving? I would consider a water softener. It is nice to use, and it is more important for tankless water heaters. Some tankless water heaters voided the warranty if your hardness was over 7 or 12 grains. But they all have a descaling procedure that removes deposits with a mild acid. That is a chore for you or a service that you will hire out. Harder water means more frequent descaling, even without regard to warranty considerations.

http://www.takagi.com/media/31647/2000537890.pdf says

5. THIS WARRANTY WILL NOT COVER THE FOLLOWING:

• Introduction of hard water measuring more than 7 grains per gallon (120 ppm) for single family domestic applications or more than 4 grains per gallon (70 ppm) for all other types of applications into the product.​

 

[Danny Soroudi]

"The fluoride concentration in your water ranges from 0.6 to 1.2 mg/L. Your water's average hardness is approximately 290 mg/L or 17 grains/gallon."

Pretty hard I guess. But I suspected that already, and descaling is something I've already assumed would be required on a year basis. Now I will look into a water softener as well. Thank you.

 

[Master Plumber Mark]

"The fluoride concentration in your water ranges from 0.6 to 1.2 mg/L. Your water's average hardness is approximately 290 mg/L or 17 grains/gallon."

Pretty hard I guess. But I suspected that already, and descaling is something I've already assumed would be required on a year basis. Now I will look into a water softener as well. Thank you.

It just keeps getting better and better dont it??

some plumbers around here install Tankless without mentioning the de-scaling process that cost
usually around 300 bucks a year---which usually eats up the total yearly savings you get with a tankless .

Many plumbers around Indy also live on a commission basis and need hat
big Tankless sale of around $4000 to get a big bonus... so they never mention the added
cost of a water softener at the time of the sale....which I feel is very dishonest.... WE run into
this problem all the time and its far too late to save the unit.....and the warranty is VOID too..

. Our water is 22 parts hard in the city with plenty of lime

Basically any design person worth his salt should make enough room
available for water softeners and water heaters stood next to each other.....

just saying.....

 

[BadDad]

We are also in the planning stage and are having a 2600sqft house built. our architect has put in 3 tankless water heaters. one for the master suite on the opposite side of the house, and two in the garage area, one for the kitchen and the other for two bathrooms and washroom.

idk, but here in CA they really are fking us over with engineers for every damn thing.
from what i understand, but havent dealt with, we will be hearing from a plumbing engineer, electrical engineer, mechanical engineer, seismic engineer and the last one idk what he's called but it has to do with installing fire sprinklers in the house. new ca law.

i can only imagine what headaches the OP will have building in LA... sounds like he has a big budget to work with.

 

[SteveW]

Thats a very good question.. Here you got a 5 bathroom house being built and I wonder how much space the Architect made for the mechanical room in your new home??
......

good luck.

Mark --
Slight correction - he's actually going to have a 7 bathroom house...

 

[Master Plumber Mark]

We are also in the planning stage and are having a 2600sqft house built. our architect has put in 3 tankless water heaters. one for the master suite on the opposite side of the house, and two in the garage area, one for the kitchen and the other for two bathrooms and washroom.

idk, but here in CA they really are fking us over with engineers for every damn thing.
from what i understand, but havent dealt with, we will be hearing from a plumbing engineer, electrical engineer, mechanical engineer, seismic engineer and the last one idk what he's called but it has to do with installing fire sprinklers in the house. new ca law.

i can only imagine what headaches the OP will have building in LA... sounds like he has a big budget to work with.

No offence meant here but a a 2600 square foot home is not a huge house and that is about average...
putting 3 tankless heaters in a home that size is basically overkill..... Just having to have those tankless heaters de-limed every year will probably set you back 800.

We install a trouble free and basically maintaince free 75 gallon power vent
in 3500 to 5000 square foot homes 4-6 bathrooms no problems to speak of.....

Remember that I am only a mid-west hick plumber so my view on
tankless is probably quite different than people living in the fast lane of L>A think

 

[BadDad]

No offence meant here but a a 2600 square foot home is not a huge house and that is about average...
putting 3 tankless heaters in a home that size is basically overkill..... Just having to have those tankless heaters de-limed every year will probably set you back 800.

We install a trouble free and basically maintaince free 75 gallon power vent
in 3500 to 5000 square foot homes 4-6 bathrooms no problems to speak of.....

Remember that I am only a mid-west hick plumber so my view on
tankless is probably quite different than people living in the fast lane of L>A think

i dont ever recall saying the house will be huge. it will cost a shit-load to build. but you're right its actually average size and thats what i want.

what i was saying is that my architect also put in multiple tankless heaters in the plan. the logic was to have hot water by the point of use.
i'm still not 100% sold on tankless either... actually in our temporary home now we have a 50 gallon electric water heater and our power bill is really low... so i may stick with an electric tank, just because we are on a propane tank and dont want to use propane for anything other than the stove.. and eventually the hvac, but being in bakersfield ca, we really dont have much cold.

 

[Danny Soroudi]

So, to respond to the above replies (which I really appreciate the feedback so far, its been eye opening and quite helpful!)

First, to my "plumbing engineers" credit, he did specify I will need a water softener in the plans, I had just missed it. He did not spec out a specific brand/model and says he can give me a few suggestions. Also, my engineer is working on a flat fee, he gets no commission or incentive to spec out one model or another; he is not the plumbing subcontractor who will do any of the work.

BadDad is correct... California (and Los Angeles in particular) is basically insane in the amount of plans they require, and # of consultants, engineers needed. I didnt need a seismic engineer, but I need architect, LANDSCAPE architect (seriously, they required a licensed landscape architect), structural, civil, mechanical, electrical, plumbing, shoring engineers, and I'm probably missing a few others.

Back to my situation, after reviewing options in some detail, going away from tankless this point is not an option I will pursue. It will cause too many redesign challenges, delays, etc., and I'm about to break ground on my house in 5 days. I will have to live with this for a long time, but it is what it is and now I just need to make the best decisions available to me.

So now that the tank vs tankless is settle for my house, the main question remaining is whether Takagi or Rinnai or some other brand of tankless offers the best solution for me. The engineer still says Takagi, contractor still says Rinnai. Both agree on the recirc pump

Would definitely love to hear some thoughts on the two options (or other tankless options I should consider)

 

[BadDad]

ah, yes. forgot about the landscape engineer... never even heard of one before. we're fortunate enough to have picked up a 5 acre parcel in one of the most desirable parts of town.. but i cant even imagine wtf they will try and have me landscape....

but i am also interested in seeing what is suggested for the better tankless.

just food for thought, i saw this a while back on kickstarter and found it intriguing.

https://www.kickstarter.com/projects/550514292/model-3-tankless-electric-water-heater-and-mobilehttps://www.kickstarter.com/projects/550514292/model-3-tankless-electric-water-heater-and-mobile

 

[Jadnashua]

A tankless system can work, and you may be happy with it as long as you know the limitations and abide by all of the requirements to get it installed properly. That being said, my limited experience with them has not bee great, and I do not like the limitations. Make sure you pick a tankless system that allows recirculation...not all do. They tend to cost lots more than a tank system when you consider initial cost, installation, and at least annual maintenance. Plus, (probably doesn't apply to you), when the ground water coming in is cold, you either need more of them, bigger units, or live with limited hot water volume. With a good recirculation system, insulating the pipes, a tank-type system gets hot water wherever you need it. Think about hotels, large commercial buildings...they all have recirculation, and you don't typically have to wait for hot water...

Given the small size of the room, and the prodigious need for combustion air, you will need a unit that gets its fresh air from outside (a closed combustion system). You're probably talking about 199K BTU units...they need LOTS of fresh air to burn properly.

 

[Danny Soroudi]

So the model of tankless proposed is the Takagi T-H3-DV-N ... 2 of them. And yes, they are 199k BTU units, and confirmed they work with recirc pumps

 

[Dana]

"...my design team decided, without really much thought or input from me, that tankless was the way to go...."

Huh?

Getting down to basics, why tankless? what do you expect to get out of a tankless as opposed to a condensing tank (or tanks) or some other system?

The #1 reason most people opt for tankless is to save space, which doesn't really make sense for a 6200' weekend getaway shack.

The #2 reason is to never run out of hot water, but if there are ever 5 full bathrooms in active bathing use at the same time, "Houston, we have a problem...", even at SoCal incoming water temps. They'll be all sharing dribbles of hot water.

The #3 reason is efficiency, but with recirculation pumps you're throwing much of that away.

If any of the showers/baths need a high flow rate (any luxury ensuite showers with side-sprays? Any big soaker tubs?) the risk of not having sufficient burner capacity is high.

The lipstick-on-mirror math reads...

* At wintertime incoming water temps of 50F and a showerhead temp of 105F (not super hot, not tepid either) it's a temperature rise of 55F.

* With five 2.5 gpm shower heads running you're running 12.5 gpm, which is ~6250 lbs per hour.

* That adds up to a BTU rate of 55F x 6250 lbs= 343,750 BTU hr

* To deliver that with a 95% efficiency burner requires a minimum of 343,750/0.95= 361,842 BTU/hr of burner input.

* So a pair of 199K condensing tankless could (theoretically) take 398,000 BTU/hr, with only 36,000 BTU/hr of input BTU margin to cover all other loads.

That ain't much! A gusher-flow showerhead or a couple of deluxe sidesprays or the kitchen staff giving a pan a hot rinse would break the BTU budget.

Buffering the burners with 50-75 gallons of storage gives you a HUGE total flow potential, and you can even fill a decent sized soaker tub without dying of boredom while waiting, as long as the tank is sized for the tub.

Doing it with tanks means you can drop the burner size, and you won't have to upgrade the gas service or internal gas supply plumbing. Pretty-good all stainless condensing tanks have comparable burner efficiency, low standby loss, and should last at least as long as any tankless. HTP's Versa series can be had in multiple sizes with 130K burners, leaving you a bit more meter/regulator capacity for other systems in the house (and have solar & space heating options as well, and you might be able to pull this off with just one, but two for sure (probably overkill.) If that's more complexity than you need or want their Phoenix Light Duty (light duty, only relative to bigger burner commercial water heaters) has a modulating 25- 76,000 BTU/hr burner, and fewer bells & whistles, which means even less gas service capacity is being chewed up by water heaters. A 76K condensing burner is enough to run a single full flow shower 24/365 in your neighborhood with margin to spare, even without the thermal buffering of the tank(s). As long as the tank is big enough to fill the biggest tub on the loop without needing to rely on the burner, it's fine. The recovery rate of the Phoenix Light Duty at full-fire is twice as fast as typical non-condensing standalone tanks, and with a 130K Versa it's 4x as fast. The only time you'd run into issue is if multiple showers are in use while someone else is filling a the big tub.

Terry mentioned drainwater heat recovery heat exchangers, which might make a lot of sense in a 3 story 5 bath house with showers on the 2nd & 3rd floors. A 4" x 48" or taller heat exchanger delivers about half the heat going down the drain back into the incoming water stream when at a steady flow of 2.5gpm. From a water heating rate capacity is like adding ~25-30K of burner to the system (whether tankless or tank). For showering applications (but not tub fills) that expands the "apparent capacity" of a tank water heater, or "apparent efficiency" of a tankless. Since it's a "burner" that uses no fuel, it's a net energy saver. For a 3 person 1-2 bath household the "payback" would be pretty long at SoCal type incoming water temps, but for a 5 bath house of mostly-showering people it's pretty quick. It does absolutely nothing for tub filling capacity or efficiency, since the heat exchange only occurs if the drain and potable flows are happening simultaneously.

The tallest & fattest one that fits is the "right" one, since the installation labor is about the same independent of size, and the marginal increase in heat recovering efficiency makes it "pay back" quicker, even thought the hardware cost is higher.