Tankless Unit Recommendations?

Users who are viewing this thread

fastsvo

New Member
Messages
4
Reaction score
0
Points
1
Location
CA
Hi,

We are looking to replace a standard 75gal water heater with a tankless unit. The original unit has an external recirculating pump and 1/2” gas line and shares the vent with the furnace (which has a 3/4” gas line next to it).

So far the brand names discussed have been Noritz (EZTR75) and Navien (NPE-240A2). Both specked at around 11.2GPM and 199k BTU. What are the good/bad points of both brands? Any others I should consider?

Looking at the pictures attached, which brand name/model would you recommend here? Should I stick with the old recirculating pump or go with a tank that has one built-in?

The house was built in 1988. We are looking to have the replacement tankless heater stay indoors and use as much of the existing hook ups as possible. Most notably the venting. Can it be directly attached to the existing vent or does a flexible hose have to be pushed all the way through to the roof? Any problems with the vent being shared with the furnace?

With regards to gas line the plan is to tap into the 3/4” line dedicated to the furnace. Could this possibly interrupt the gas flow on both the furnace and the tankless unit when they are being utilized? Is it common practice to splice both the 1/2” and 3/4” gas line to ensure no loss of volume to either the tankless unit or furnace?

Thanks in advance!

C2687A94-906D-4321-8431-E3F6EB3CD11C.jpeg
 

Attachments

  • 806FC387-B70B-4C4E-A0C6-6B0EA6C3C109.jpeg
    806FC387-B70B-4C4E-A0C6-6B0EA6C3C109.jpeg
    75.7 KB · Views: 26
  • 4020743E-10A0-450D-B77E-BBFA911F3B56.jpeg
    4020743E-10A0-450D-B77E-BBFA911F3B56.jpeg
    60.8 KB · Views: 28
  • BE37C6F8-4AD1-4178-B5C9-CEE4CB2093ED.jpeg
    BE37C6F8-4AD1-4178-B5C9-CEE4CB2093ED.jpeg
    90.1 KB · Views: 25
Last edited:

breplum

Member
Messages
731
Reaction score
256
Points
63
Location
San Francisco Bay Area
You will need a new vent. The old B type vent is not able to be used. The vent for any high efficiency tankless will be PVC and there is a need to have a place to drain the acidic condensate. A condensate pump can be used but the pressure relief line needs gravity drainage.
I am a Navien trained and experienced fanboy.
But Noritz is excellent if you have good number of service people in your area.
Navien is the only mfr still, with a mini tank built in (along with a recirc pump). That mini tank is a fantastic feature.
FYI Tankless are slightly noisy and not recommended near bedrooms...
Not likely you can use that existing 3/4" gas line. A new homerun will be needed unless the meter is less than 10 ft. away.
 

jadnashua

Retired Defense Industry Engineer xxx
Messages
32,663
Reaction score
1,146
Points
113
Location
New England
Depending on the volume of the space where you want to install the tankless unit, you may need to run the air intake outside as well, and for maximum efficiency, that's highly recommended. Remember that all of the exhaust air is made up of conditioned air inside of the house...that air needs to get replaced, and it's better to avoid that entirely and get it from outside in the first place. When I looked at the possibility of doing one, the space did not have enough volume to meet the minimum recommended. That makeup air gets into the house from any gaps in the sealing, pulling in outside air along with potentially pollen, air pollution, and humidity that you really don't want in the home. If you have fiberglass insulation, a tell-tale indication of a leak is that it is darkened like a furnace filter. Note, there's a maximum length the exhaust and intake can be, it needs to be sloped down back to the unit so it can capture condensation from the exhaust, and the condensation, as mentioned, is acidic, and should be run through a neutralizer before being dumped into your sewer or otherwise, you might be just eating away the pipes and fittings there.

SOme new tank WH are now also condensing, and require similar condensate handling, but their air volume requirements are much smaller so don't need the higher capacity gas line.

Depending on where you live in CA, if your ground water gets quite cold in the winter, you may not like the tankless. THere's a limit on how much temperature rise it can produce while generating a useful volume so you need to know that, along with your maximum expected hot water use. If you will have multiple people showering at the same time, or running a dishwasher or washing machine, it may not be able to produce enough instantaneous hot water. It might work out fine for you, but you should know before you make the (significant) investment to install it. Also note, some places in CA are now limiting NG appliances, so make sure you can even install one!

If you've done any tightening up of the home, and considering your furnace is in there, too, you need to take its combustion air volume into consideration as well.

A typical tankless system may have 3-4x the heat capacity of your furnace...it needs a LOT of air to burn properly, and it can cause all sorts of problems if it doesn't have it.
 

fastsvo

New Member
Messages
4
Reaction score
0
Points
1
Location
CA
Thanks for all the replies.

I am starting to think it might be easier to just replace it with another hot water tank. Bradford White?
 

Jeff H Young

In the Trades
Messages
4,788
Reaction score
1,048
Points
113
Location
92346
Thanks for all the replies.

I am starting to think it might be easier to just replace it with another hot water tank. Bradford White?
I'm thinking of looking into electric heat pump water heater. I heard I can get 3500 from the government to install, and burning gas o9n the way out here in Ca.
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,374
Reaction score
288
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
Thanks for all the replies.

I am starting to think it might be easier to just replace it with another hot water tank. Bradford White?


You wise to just replace it with another heater...... so much cheaper and none of the future headaches that
can happen..... If you dont have a water softener just throw in another tank and you are good for another 10+ years
 

jadnashua

Retired Defense Industry Engineer xxx
Messages
32,663
Reaction score
1,146
Points
113
Location
New England
While you can get away with little to no regular maintenance on a tank type WH (doing it can help, though!), if you don't with a tankless, you may lose your warranty coverage and the performance will constantly be going downhill. If you can't do this yourself, you will need to pay for this. How often, depends on how hard your water is, figure annually unless the water is very soft. Also, if you go that way, make sure the install is setup with the required valves so you can do the deliming procedure. What's done is basically, isolate the tankless system with those valves, then on another port (part of the install if done with the proper prep), you run a mild acid into the heater, and a pump circulates it for some time. Eventually, it dissolves any mineral deposits, you drain the acid out, flush it with clean water, and put the valves back to normal service operation. It can take a couple of hours, so if you're paying a plumber, that could easily get over $200 annually. Materials wise, it pretty cheap once you have all of the bits, the hoses, fittings, pump, acid (that's a one-time use, but fairly cheap).

IMHO, unless you can do this yourself, that more than offsets any fuel savings you might have unless you use huge amounts of hot water, and then, you'd need to do this more frequently.
 

Master Plumber Mark

Sensitivity trainer and plumber of mens souls
Messages
5,374
Reaction score
288
Points
83
Location
indianapolis indiana - land of the free, home of
Website
www.weilhammerplumbing.com
While you can get away with little to no regular maintenance on a tank type WH (doing it can help, though!), if you don't with a tankless, you may lose your warranty coverage and the performance will constantly be going downhill. If you can't do this yourself, you will need to pay for this. How often, depends on how hard your water is, figure annually unless the water is very soft. Also, if you go that way, make sure the install is setup with the required valves so you can do the deliming procedure. What's done is basically, isolate the tankless system with those valves, then on another port (part of the install if done with the proper prep), you run a mild acid into the heater, and a pump circulates it for some time. Eventually, it dissolves any mineral deposits, you drain the acid out, flush it with clean water, and put the valves back to normal service operation. It can take a couple of hours, so if you're paying a plumber, that could easily get over $200 annually. Materials wise, it pretty cheap once you have all of the bits, the hoses, fittings, pump, acid (that's a one-time use, but fairly cheap).

IMHO, unless you can do this yourself, that more than offsets any fuel savings you might have unless you use huge amounts of hot water, and then, you'd need to do this more frequently.


You just said it all about a tankless..... we run into homes all the time here where some house flipper throws one in without
knowing they need a water softener in our area with rock hard water..... then the units clog up with lime in less than a year
and the person who bought the home is stuck holding the bag.. and the house is so tight it is nearly impossible to install
a water softener or go back to a tank type heater

People just think that they are gonna save tons of money until they are told about the maintaince needed to have one...
.
 

fastsvo

New Member
Messages
4
Reaction score
0
Points
1
Location
CA
I understand the venting needs to be 3ft away from a window (coming off the side of the home), but how about venting towards the front entry (which is covered and about 15ft away from the front door). Are the gases strong enough for it to be a real issue as people walk up to the front door?
 

jadnashua

Retired Defense Industry Engineer xxx
Messages
32,663
Reaction score
1,146
Points
113
Location
New England
You have to follow the manufacturer's recommendations and any local code requirements, period. While the warm outlet gasses tend to rise, it depends on the ambient temperature and the winds where they end up going.
 

fastsvo

New Member
Messages
4
Reaction score
0
Points
1
Location
CA
The warm air rising might be an issue if the outlet is underneath a covered walkway. Right now it has about 40' of 3" PVC piping running across the garage to the outside. I want to reduce that to 20' and perhaps might have to step it down to 2.5" piping and have it vent out from the starting point of the home's formal walkup/entry.

For the PVC connections, how are you guys preventing the condensation from dripping out?
 

John Gayewski

In the Trades
Messages
1,887
Reaction score
477
Points
83
Location
Iowa
The recommendations I've read prefer the tankless units to exhaust up and out the roof. The condensate drips back to the unit or outside. There's no preventing it.
 

John Gayewski

In the Trades
Messages
1,887
Reaction score
477
Points
83
Location
Iowa
The warm air rising might be an issue if the outlet is underneath a covered walkway. Right now it has about 40' of 3" PVC piping running across the garage to the outside. I want to reduce that to 20' and perhaps might have to step it down to 2.5" piping and have it vent out from the starting point of the home's formal walkup/entry.

For the PVC connections, how are you guys preventing the condensation from dripping out?
Let me know if you find some 2.5" PVC
 
Last edited by a moderator:
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks