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Considering Tankless water heater for multifamily renovation

I'm renovating a 100-year old 3 family in Brooklyn, NYC. Currently everyone runs off a 70 gallon gas water heater. 5 full baths, 3 kitchens. There's one hot water pipe that runs for everyone.

The new setup will have 6 baths, 3 washing machines, 3 dishwashers, and anywhere from 8-11 people across the 3 units.

Each unit will have 2baths, 1 washing machine, 1 dishwasher.

I'm considering installing a tankless water heater for each unit. And let the tenants pay for their hot water usage.

I have 3 separate gas meters in the basement.

NYC groundwater is about 57.6 degrees. A 45-50 degree rise should get me to a comfortable shower level. My guesstimation is a water heater with a flow rate of ~8GPM at a 45 rise will be adequate for each apartment. Is that in the ballpark?

Would setting up tankless heaters in the basement be best? I could exhaust into the existing steel lined flue that runs to the roof. Brand new, double lined steel, 7" or 8" oval from what recall. Currently my gas Steam boiler and hot water heater run into that flue.

Another concern is the run to the top floor is 25' from the basement. And 15' to the second floor. Should the water line be piped with 1/2" or 3/4" copper pipe from the tankless water heater to the main valve in each apartment? The bigger the pipe, the more water will be wasted waiting for the water heater to get the water hot.

Thanks for the help!



Comments

  • Brewbeer
    Brewbeer Member Posts: 616
    I'm wondering of your chimney flue is large enough to support 3 tankless heaters and the boiler all firing at the same time?
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread: http://forum.heatinghelp.com/discussion/154385
    System Photo: https://us.v-cdn.net/5021738/uploads/FileUpload/79/451e1f19a1e5b345e0951fbe1ff6ca.jpg
    branimal
  • SuperTech
    SuperTech Member Posts: 1,854
    If the tankless water heater is a condensing unit (I hope it is) then you will have to find another means of venting. You will also have to consider some means for condensate treatment and disposal.
    branimal
  • TAG
    TAG Member Posts: 735
    edited February 2019
    You are adding a lot of complexity with absolutely no payback. You already have common heat. How is the gas billed? -- what else is gas? Stove -- ?

    With only three gas meters -- one has to be tied to the heat bill. No common meter. You as owner and occupier -- fine ..until you sell?

    There is a reason buildings have common hot water -- it's overall cheaper and easier. KISS

    Get a tank unit large enough and most important quick recovery burner to take care of the water needs .... bill them 10 bucks a month if you need to do it that way. Pipe it properly for the task you are asking -- that's important. With NG -- the payback for tankless is very small.

    Typically when doing what you are thinking about -- the units are on each floor on a back wall ... in NYC the new self contained use electric.
    SuperTech
  • SuperTech
    SuperTech Member Posts: 1,854
    I agree with everything stated above. My first thought after reading the original post was why not just get a bigger tank style water heater?
    branimal
  • Snowmelt
    Snowmelt Member Posts: 1,383
    what are you heating the space with, if you have three gas meters I am gong to assume you have 3 boilers or furnaces. for the third & second floor I would use a return loop or have a 5 gallon electric on the 2nd and 3rd floor. I would used the Navien with the 2 inch venting they have to go out the side of the house. if you go with tanks I would go with a loop to the basement to each floor. if you have boilers I would run an indirect off the boiler with a return loop to keep the water hot. I would use a 3/4 minimum trunk line. if you use pex I would go to 1 inch minimum but that's just me. What you don't want to do is complete the job and not have enough volume of water to run all the appliances at the same time.

    if you use a common water for all three I wouldn't go less then 1 1/4 hot then branch down from there. Maybe 1 1/2 on the cold side.
    branimal
  • TAG
    TAG Member Posts: 735
    He does have a boiler ... and it sounds oversized from previous threads. So he could use a large indirect .. and that would be great in the winter.

    In the summer he would have to be careful with a big boiler heating up every time -- with 3 apartments it not impossible for water use all day long.

    Hot boiler in the basement -- first floor AC ??
  • branimal
    branimal Member Posts: 178
    I have a gas steam boiler. Burnham IN7. And one 70- gallon gas water heater from 2012.

    There are 3 separate gas meters.

    Each unit pays for their own gas powered stoves. The owners unit (one of the three) pays for the boiler and water heater.

    Doing some rough calculations and speaking with someone in the area who has a similair setup I believe the water heating cost will be in the range of $150/month.

    My thinking is if I could pass that cost onto each unit ($50/per), I could pay off the tankless water heaters fairly quickly. There are rebates offered in my area for tankless water heaters.

    Headline rent numbers without the gas cost seem more appealing for renters. Or at least that's my thinking. I'm a rookie landlord, so I really don't know.

    Right now the hot and cold water piping is setup with one main 3/4" riser which branches off on every floor.
  • TeachMeSteam
    TeachMeSteam Member Posts: 128
    edited March 2019
    With that said, if it's a question of going tankless or tank, it's almost always better to go with tank. Even in a personal home, you'll never get a return on your money with a tankless.
    branimal
  • bob eck
    bob eck Member Posts: 930
    One gas boiler and one large tank type water heater.
    Caleffi just came out with BTU meters where you might be able to bill each apartment by the amount of BTU they use. Call your local F W Webb in the Bronx 718-378-1010 they can get you in contact with the local Caleffi rep to go over their BTU meters to see if you use this type of set up.
    SuperTechbranimal
  • bob eck
    bob eck Member Posts: 930
    https://www.caleffi.com/usa/en-us/technical-magazine

    Please check out their Idronics Book 24 it’s all about BTU metering
    SuperTechbranimal
  • TAG
    TAG Member Posts: 735
    Forgot he was steam. Scratch the indirect

    No way three apartments in NYC are going to use $150 in gas per month just for water heating. Mine is nowhere near $50 for water.

    The top floor will not be happy with the on-demand unless you can get it on that level.

    Also -- one 3/4 trying to run everything on the second and third floors is going to be a problem. You need to get someone to do it correctly.

    NYC has so many restrictions on how venting of gas appliances can be done ..
  • TeachMeSteam
    TeachMeSteam Member Posts: 128
    edited March 2019
    TAG said:

    Forgot he was steam. Scratch the indirect

    No way three apartments in NYC are going to use $150 in gas per month just for water heating. Mine is nowhere near $50 for water.

    The top floor will not be happy with the on-demand unless you can get it on that level.

    Also -- one 3/4 trying to run everything on the second and third floors is going to be a problem. You need to get someone to do it correctly.

    NYC has so many restrictions on how venting of gas appliances can be done ..

    Tag,

    I don't know if you were referring to my post but I was referring to the water and sewer bill from water usage.
  • ComfEffic
    ComfEffic Member Posts: 3
    Great info on above posts!

    Heres's another thought:
    With electric utility costs/tenants paying elec and current rebates, have you considered electric tankless? If so, just add an electric tankless with cold water tapping into inlet for water capacity, size for worst case, and use mixing valves on showers. Still reccomend use Btu meters and keep existing tank heater.
    branimal
  • branimal
    branimal Member Posts: 178
    @TAG. Which water heater are you using? How many units does your building have and how many tenants and bathrooms? Maybe my water heater is super inefficient. My water heating bill right now is $65 with two people living in the building. 3rd floor is being renovated and me and my tenant occupy 2nd and 1st floors respectively. When the building becomes fully occupied (8-10 ppl) it will scale up - not linearly but definitely by some factor.

    The cold water supply and sewage bill is a separate bill. $30 a month or so. I only have one water meter.

    Seems like a lot of folks here don't believe tankless will work for my situation. I'm growing skeptical myself.

    An option is to install separate gas or electric tank hot water heaters for each unit in the basement. I might have the space to make this work. Let's say for argument sake each heater is $800x3 =$2400. If I can pass the $150 water heating bill onto the tenants (50/per). I will pay for all the heaters in 16 months. It's definitely a good investment for a landlord. Even if the tenant reduces his rent amount by say $25/month because he's paying to heat the hot water, I'll pay for the water heaters in 32 months. Everything after that is gravy. I see all the new buildings in my area with separate hot water and heating. It's the new model. People tend to behave in a civil manner when they need to pay for their consumption.

    @bob eck : I'll give the Caleffi rep a call. Thanks.

    @ComfEffic - I looked at electric tankless heaters, but they didn't seem to have adequate flow rate for all the fixtures/appliances I have in my units. Maybe I could install two per unit?? The other issue with electric tankless water heaters is their lifetime is shorter than gas powered ones.

    @TeachMeSteam NYC has a forgiveness program for leaky pipes. You need to prove there was a leak (history of water bills showing the upsurge) and you need a plumber to document and repair the leak. NYC DEP will refund you the leaked amount.
    TeachMeSteam
  • TAG
    TAG Member Posts: 735
    Teachmesteam: was referencing the OP's figures on estimate for water heating. The OP had not mentioned how many meters for water from NYC -- he has now. Only one.

    ComfEffic: I mentioned this above. There are so many rules and regulations in NYC -- going all electric is a common way to make each stand alone -- as long as you have the power.
  • TAG
    TAG Member Posts: 735
    Branimal: You're in the business of renting an apartment -- not selling hot water. My goal has always been to buy properties with upside value potential -- fix them properly so they function with as little interaction with me as possible ... all the while giving me a decent return.

    Most of my properties are small singles -- The one duplex shares heat and HW. I put in electric stoves -- electric dryers.

    How are you figuring that it costs you $65 to heat hot water for two small places?

    Typically -- decisions to isolate units is done for ease and cost on the landlord. Example: you make them all electric because it's the easiest and cheapest way to get it done -- the fact that the running costs are higher for the tenant is not your concern. Typically for a small space -- it's not much more anyway.

    Apartments rent on total cost -- most people ask all the details. $50 for hot water is an obvious overcharge.

    I have no idea if your current piping will do what you want to add on -- it sounds like it will need to be changed with only 3/4 Obviously, doing individual setups will require a complete replacement of the hot water supply.

    I use Bradford White
  • TeachMeSteam
    TeachMeSteam Member Posts: 128
    edited March 2019
    branimal said:



    @TeachMeSteam NYC has a forgiveness program for leaky pipes. You need to prove there was a leak (history of water bills showing the upsurge) and you need a plumber to document and repair the leak. NYC DEP will refund you the leaked amount.

    @branimal I learn something new every day. Unfortunately, I probably can't use the Forgiveness Program because most buildings still use a common water meter. So, even if a tenant does go haywire and just let things leak, the amount of waste doesn't represent a large enough increase. It may be an increase of 400% for him but not for the entire building, so it's not enough to qualify for the program. But, I still appreciate learning about the forgiveness program. Kudos.
  • TAG
    TAG Member Posts: 735
    Teachmesteam: Believe the OP lives in the middle unit. Not to prejudge the OP -- but looking at his other threads -- he is a little late with this decision. Get how these things happen -- at first it's just "fix it up". Before you know it .. half the house is gutted and it's a money pit.

    In a prefect world you have three of everything and nothing ever fails or needs maintenance.

    If completely gutted or all new space -- you look to see if there is a space on each floor for a water heater. Off times there is because most need ductwork for HVAC -- so there is a mechanical space.

    I have two "on demand" units at my beach house. Both are gas -- one does the master bathroom addition and the other does the outside shower. The one for the outdoor shower is in the garage next to the shower -- the one in the master is in a closet within the room. They work in single point situation -- I don't like them for whole houses .. or multiple bathrooms and kitchens.

    It's all a question of cost/ maintence/ return .... how it fits into the property.

    My properties in Philadelphia as they turn over are going to a management company -- they like to manage the city water sewer bills. The rent includes a mandatory $50 dollar fee -- they base the amount on past experience. They do this because the city has a bad accounting system and they don't want to get stuck with a big bill if a tenant does not pay. My old tenants get a e-mail from me and include the charge it in next months rent -- the water sewer is in my name. There is no other safe way to do it -- you have to go with what's best given the local situations.

    The gas and electric bills are easy to switch in and out and follow the tenant -- the water sewer falls to the owner of the house.






    TeachMeSteam
  • TeachMeSteam
    TeachMeSteam Member Posts: 128
    edited February 2019
    TAG said:

    Teachmesteam: Believe the OP lives in the middle unit. Not to prejudge the OP -- but looking at his other threads -- he is a little late with this decision. Get how these things happen -- at first it's just "fix it up". Before you know it .. half the house is gutted and it's a money pit.

    In a prefect world you have three of everything and nothing ever fails or needs maintenance.

    There is no other safe way to do it -- you have to go with what's best given the local situations.

    Sounds like you now what you're talking about. I agree with you that you have to go with what's best given the situation. Most of the time, it's very far from perfect.

    What kind of units do you rent? All residential apt buildings, single family homes, or something else?
  • neilc
    neilc Member Posts: 2,084
    TAG said:

    Forgot he was steam. Scratch the indirect ..

    Why couldn't one do indirect domestic from a steam boiler?
    just like a add on hot water loop?
    Yes?
    No?

    known to beat dead horses
  • TAG
    TAG Member Posts: 735
    Teachmesteam... after grad school in the later 80's I got transferred in and out of DC/NYC and Philadelphia .... I bought at a time what RE in those areas was so cheap .... people can't understand that no one wanted to live in CC Philly or most of DC. So ...I sort of understand what the OP is doing and going through in Brooklyn.

    My first place in DC was a carved up huge single family that I sold in 2006 -- now back to one family. The Philly places are RE -- the house is worthless. I'm not sure where the OP is --- but some areas people just want the ground .. the house get demolished
    BrewbeerSuperTech
  • ComfEffic
    ComfEffic Member Posts: 3
    @branimal Elec tankless have a flow rate spec of when heating element kicks in and rated flow rate per temp rise. Remember the water will be warmer cuz its preheated by existing tank. If tenants already paying separate elec bills this will definitely cover with system expansion.

    Why would their life be shorter compared to nat gas?
  • metrorental
    metrorental Member Posts: 30
    i think whatever money you might save on gas will be lost many times over with the cost of 3 tankless heaters plus installation plus yearly maintenance. i run a 6 unit building 1 bath 1DW with common laundry with a 75 gallon atmospheric 125k tank. i've never had a problem, even when power has gone out. good luck
  • TeachMeSteam
    TeachMeSteam Member Posts: 128
    TAG said:

    Teachmesteam... after grad school in the later 80's I got transferred in and out of DC/NYC and Philadelphia .... I bought at a time what RE in those areas was so cheap .... people can't understand that no one wanted to live in CC Philly or most of DC. So ...I sort of understand what the OP is doing and going through in Brooklyn.

    My first place in DC was a carved up huge single family that I sold in 2006 -- now back to one family. The Philly places are RE -- the house is worthless. I'm not sure where the OP is --- but some areas people just want the ground .. the house get demolished

    Sounds like you did great in your investments. I met a person who bought in Hoboken, NJ 30 years ago. Buildings were dirt cheap ($50-100k). A lot of poor immigrants and students. Now, his real estate is valued at $80 MM.

    The hard part is to predict where real estate is going to boom. I manage places in different spots and in some spots, 30 years hasn't changed the rent that much. Where did you see the best returns on your investments? What was the reason you think for the upturn?