Plumber left me with no hot water!

[Duckbutter]

Through the roof

Probably gonna be the end result, assuming there's no clearance with the windows and there's no other side of the house to go to (finished basement?), unless the electrician/electric tank is less expensive.

Electric tankless is definitely a bad idea relative to those two.

 

[Jeff Handy]

What about an alternate location for the tankless?

Laundry room?

Or take over a broom closet, etc?

 

[Clag]

Most direct vented (both intake and exhaust piped to the outside) condensing appliances will allow as little as 12 inches from any door/window because there's no pressure displacement (Air mixed with that exhaust won't be sucked into an open window to displace outgoing exhaust)

The pitfall in your case is steam from the exhaust being visible outside a window or glass door on colder days.

Power-vented (vs direct vented) appliances only vent exhaust, the intake is inside the home which will suck air back in through a window, those vents usually require 3 or 4 feet from windows/doors.

As for electric tankless, don't do it, trust me, you'll probably need a sub-panel off your home's panel, and the lights will dim any time you use it, might as well go with an electric tank type, which will require a 40 amp circuit vs 100+ amps for a tankless. either option will require an electrician, but the 40 amp/tank option is less money.

I know it may seem trivial, but the way your old tankless was vented was a serious hazard, especially where it sounds like it was power-vented (intake in the same room as the tankless and furnace), I'd also make sure there's a CO detector in the mechanical room with the heater. If the tankless was running while the furnace was heating, CO was being sucked back in through the furnace's vent hood to displace the tankless blower's negative pressure.

The timing of your install was an "ouch" (Saturday, supply's closed), but I'll wager your plumber will call tomorrow with a pretty close explanation to what I just said.

As for a "standard efficiency" draft vent tankless, not sure they exist, but if they do they likely require a wait to be shipped, a very uncommon item. the alternative would be an ordinary tank type, but the entire PVC vent going all the way to the connection to your furnaces common vent would have to be replaced with galvanized pipe.

Your two best options, IMO, are electric tank, or direct vented tankless.

Thank you so much, you hit the nail right on the head. The plumber called on Monday and suggested that I return the tankless water heater and purchase a direct vent instead. I got a Raheem tankless. He was then able to vent it out the back wall, a couple of feet west of the deck and sliding glass doors.

 

[Clag]

What about an alternate location for the tankless?

Laundry room?

Or take over a broom closet, etc?

We definitely considered the laundry room, but because of the design of the house it would have required knocking down some of the wall to do it. As it is, the laundry room already has a wonky plumbing set-up that will require the plumbing to tear up the floor to correct, which I plan to have redone when I can afford it. I wish I had the money now to do it all, which would have made it easier to go ahead and install the water heater in the laundry at the same time.

 

[Clag]

Depends on local code that would [stupidly might I add] take precedence over manufacturers guidelines. The attached are excerpts from the current Rheem condensing tankless, 95% efficient. You have under normal circumstances a lot more options with a through wall installation than a separate through roof or wall termination dealing with hot gas. Something like this would solve her problem.

Sometimes people don’t want to spend the money for a high efficiency unit. Venting a conventional unit with SS flue pipe can get costly. I spent over $500 on SS vent parts for an $1100 tankless some years back.

The tankless that I purchased was high efficiency and plumber did come up with a way to install it, but the required parts were going to cost and additional $400 (heater cost $1200). So, he had me return that heater and get one with direct venting, which required him to reroute the pipes vent through a back wall with pvc.

 

[Clag]

He's right you can't use pvc on exhaust anymore. They do have a plastic that works though. It's a long story about why you can't and why everyone is afraid to put into the code and instructions that pvc doesn't work. Basically they messed up years ago, now they don't know how to fix it.

Your can walk to to a boiler or water heater that used pvc on the exhaust and tap it with channel locks and it cracks like an egg shell. It turns nasty yellow and crumbles.

Is what happens when you let companies police themselves. They say "oh yeah we've tested it, it works". Then it takes years before the results of a I'll thought it technique realizes itself.

Oh boy, now I’m concerned because the plumber ended up solving the problem, but he used pvc.

 

[Clag]

Nonsense! I had the same Schedule 40 PVC as a vent on my furnace (two of the actually) for 27 years. Ditto for the power vent water heaters; three of those in 27 years. Exposed to Michigan winters and summers. Was absolutely OK. 27 years old. NOT BRITTLE. If the manufacturer says OK, and local code adaption allows, it’s fine. Exhaust temp nowhere near 140 btw. Warm not hot, mostly water vapor.

Which manufacturer? The one whose appliance you’re installing!

The plumber did end up using pvc.

 

[Clag]

I sure am glad that I don't have to depend on incompetent plumbers to do my plumbing! How big an electric water heater could you get in your crawl space? You could put a 15 or 20 gallon electric in the crawl space and probably get along just fine, tankless water heaters aren't all their cracked up to be! Small tank type can even be run on a heavy extension cord until proper wiring can be installed. You could even put 2 small tank type in series if you can't get a bigger one into the crawl space.

The tallest I could have gotten was 45” I believe he said. But I would have needed a 30 gallon.

 

[Clag]

The problem is that you absolutely cannot vent a natural (draft, gravity) vent with a positive pressure direct vent or power vent.

Fault for this falls on whomever installed it that way to begin with.

When the blower kicks on from the tankless it will overwhelm the heater's draft vent and push CO back into your home.

What you found online is likely connecting two natural vent fixtures to a single common vent, that's fine as long as the common vent is sized correctly.

If the tankless is in a crawlspace, he can potentially run it to the outside of the house depending on mfg specs for max vent length.

Yeah, I’m slowly learning just how much of a mess a lot of stuff is in this house. It was built in 1983 and it’s in an unincorporated county, so that alone tells you that there has been no oversight. The person I bought it from did do a renovation in 2008, but left a lot of stuff like the way it was. For example, this is my laundry room set-up, which I didn’t think would be a big deal to correct later, but it turns out the floor and walls will have to be knocked out to pipe everything correctly. And, seriously, how much would it have cost them to run the pvc a little further so the sink wouldn’t be that close to the washer?

 

[Clag]

Problem fixed. Thank you all so much for your knowledge and suggestions. The plumber had me exchange the tankless heater with the “B” vent for one with direct venting. He did end up having to run new pipes (pvc) and found a place to vent through the wall. But after reading some of your posts about pvc, I hope it doesn’t end up being a problem in the long run.

 

[Jeff Handy]

Wow, so much of this whole story just does not add up.

But if the OP is happy, and no one dies from fire or carbon monoxide, I guess all is well.