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Installed a tankless water heater this week...


fyrmnk
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Well, finally bit the bullet and installed a tankless water heater. My old tank unit was 15 years old so time for an upgrade. I definitely see why it costs so much to have one installed with all the labor to convert (took me about 8 hours or so).

I installed a Rheem 74PVN, a brand new '06 model. Can see some definite things to watch for on inspections since these are becoming more prevalent, particularly with the tax credit.

Saw the previous check list done several years ago that Mike was putting together, but thought I'd reiterate some things to watch for (keep in mind this is my unit only, and based on manufacturer for it, but applies to some others as well):

-Much, much higher BTU rating (199,000 for this one) compared to the 40,000 rating of the one I replaced

-Requires 3/4" gas line instead of 1/2" that is standard here for tank type

-Stainless steel venting, can't be galvanized (EXPENSIVE stuff!)

-Can be sloped up or down in horizontal install. If installed sloped up or vertical, must have condensate drain/collector (I did slope down for mine due to no issues with condensate draining outside)

-Must have check valve on supply plumbing connection

-Must have TPR extension pipe installed and connected to proper TPR valve/extension tube (same as other water heaters)

-Drain valve installed near the hot water connection

-Incoming water shut off near the unit

-Has air filter screen on combustion air intake that must be kept clean (mine takes combustion air from inside)

-Must have ADEQUATE combustion air for it and everything else with the very high BTU rating, something to watch for if it does not take it from outside (mine has a higher BTU rating than my furnace)

-Mine is an automatic ignition type, kicks on just by operating a faucet, no standing pilot

-Mine has a remote thermostat that can be adjusted. Factory set at the standard 120F, though can be programmed to go up to 140F (I did this to mine because we preferred 125F)

-Proper clearances to combustibles and outside clearance requirements for snow level of 12" (same as others I believe)

-Vent termination has proper barrier on exterior

-Proper wall thimble to maintain clearance between vent pipe and walls it penetrates

-Properly sealed wall thimble and vent/thimble area

-Estimated life expectancy of 20+ years according to manufacturer, and 12 year exchanger warranty

-Copper heat exchanger/water supply connections so dielectric unions not required for connecting copper lines

-Some low flow or partially blocked faucets may not have enough flow to trip the sensor to activate the unit, though none of ours have any issues with it

-Can have three remote point of use thermostats installed for individual settings depending on use. I only have the main thermostat though. I plan to install it in the upper level hall at some point for ease of adjusting the temp for individual use

Only downside I can see so far is that it requires 120V to operate the burner ignition and vent blower fan, so no hot water when the power is out. Also takes a while longer to receive hot water when a faucet is on since it has to sense the initial flow to ignite and does not have a tank full of water waiting there.

If any odd ball things come up I'll post them. I do like the remote thermostat

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There's a lot of good information there, Kevin. Thanks for taking time to explain the nuances of tankless heaters. I've only encountered one or two in my area, but I'm sure I'll see more in the future. When I do, I'm certain I'll be searching TIJ's archives for this post.

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It'd be interesting to keep track of your gas bills to see if the unit will really save any money.

Yeah, I might try to track it some. Not really gonna save much if any since now there will probably be more hot water used since it won't run out.

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  • 2 months later...

Well, for my first three months of use, have reduced gas usage by 25-40% over last year, even with longer showers being taken (only gas appliance being used).

So far we are VERY happy with the water heater, not one problem (knock on wood).

Grant it, a new tank unit would have performed better than our old one too, but doubt it would do this much better.

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Good info about tankless units. I've seen maybe 4 or 5 in the field and all were either Rinnai or Rheem. Each had PVC vents. Please keep us posted on your opinions of this unit as you use it more.

My gas tank unit is 10 years old, so I know I am within the 8~12 year window now. I've heard good and bad things about tankless ones, so I don't know if I'd go the tankless route when it comes time to replace my unit. 2.5 bathrooms but just me and my wife.. no kids. For our use, a tankless unit may really save us some $$$. I've heard that install costs can run $2,000+ (including install of larger gas line) and that payback may not happen for 10 years or more.

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Good info about tankless units. I've seen maybe 4 or 5 in the field and all were either Rinnai or Rheem. Each had PVC vents. Please keep us posted on your opinions of this unit as you use it more.

My gas tank unit is 10 years old, so I know I am within the 8~12 year window now. I've heard good and bad things about tankless ones, so I don't know if I'd go the tankless route when it comes time to replace my unit. 2.5 bathrooms but just me and my wife.. no kids. For our use, a tankless unit may really save us some $$$. I've heard that install costs can run $2,000+ (including install of larger gas line) and that payback may not happen for 10 years or more.

If i hadn't done it myself I definitely wouldn't have shelled out the extra dough for the install I doubt. By buying a new prior year model, I saved about $500 or so on the purchase of the unit, and ended up being able to do it all for just a few hundred more than what the tank unit would have cost. I also researched the units quite a bit before purchasing.

If anything new comes up, I'll post it. So far so good! [:-thumbu]

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Here, in North Georgia we have our share of freezing weather. Maybe every five years we have single digit temps and I have seen 0F few times. In January 1985 I had -8F in Lawrenceville. With that background, in the last few years I have seen several of these tankless units, in new construction, mounted on the outside. This obviates TPR vent and exhaust gas issues, but I am ignorant of any freeze protection devices that would save you under noted conditions. The ones I have seen have been on upscale >$250K homes. //bb

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Here, in North Georgia we have our share of freezing weather. Maybe every five years we have single digit temps and I have seen 0F few times. In January 1985 I had -8F in Lawrenceville. With that background, in the last few years I have seen several of these tankless units, in new construction, mounted on the outside. This obviates TPR vent and exhaust gas issues, but I am ignorant of any freeze protection devices that would save you under noted conditions. The ones I have seen have been on upscale >$250K homes. //bb

Yeah, the model I put in does also have and outside mounted option rated for freezing temps. I didn't even want to risk that at all, but they seem to do pretty well from what I've read.

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  • 3 months later...

Well just an update, but so far still very happy with the tankless water heater I installed. Has been performing great and the savings are definitely noticeable.

I was also really impressed with the warranty. I've never dealt with Rheem, but the circuit board started acting up a few weeks ago and it wouldn't communicate with the remote thermostat, so I had to disconnect it to bypass it. Called Rheem, gave them the error code, serial number, model number, etc. and they overnighted a new circuit board to my door, and contacted a contractor who called me the same day to set up an install. Took all of about 5 minutes on the phone. They also would have let me install the new part without affecting the warranty (since they were paying for it, I had it done).

So far so good.

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