Is there a difference as far as the dangers of a WH using gas vs propane? Wife is leaning towards just putting the natural gas hot water heater in the garage vented through the roof. Right next to her freezer/frig. where the electric one was planned to go. She wants to have the option of the unit always working even in a blackout and does not want to wait for hot water like the tankless one would provide without adding more extras. As a side note, for $600 the electrician is going to provide me with an outside connection to power the house with my generator. Plumber being used by the builder seems to want to tack on lots of extras using the outside WH unit. Happy wife, happy life!
A tankless water heater generally needs a larger gas supply than a traditional standing burner. It uses a LOT more heat to heat the water on demand. Also, I don't think a $300.00 Tankless is a good idea. That's FAR too cheap. I good quality one is probably $1500-2500 minimum. Of course it depends on your exterior temperatures and the number of appliances you run. I have a 40,000 BTU Rinai tankless, that can run both showers in my home as well as the dishwasher and the Laundry, with no lack of hot water. My kids are spoiled.
Rinai seems to be the Cadillac of tankless (and gas space heaters) - Not sure what makes them so much better? I'm looking at going that route in our house eventually and yes, the gas requirements are up there which may sway my decision. W/everything I want to do I'm looking @ 2" pipe (800 CFH) off the meter per gas code. I haven't done the calculations for a std. tank WH but if it drops me down to 1-½" it may sway me. I'll need to pull a permit regardless so... I do see deals on brand new tankless WH's on Craigslist and have seen Rinai's. Ppl but them and the project doesn't pan out.
I don't remember what the branch line to the WH itself was (prob. ¾") but of course coming off the meter you have to be able to supply everything simultaneously per code and that was what it all added up to.
Yes, a 3/4 inch main is fine. The 1/2" copper might be insufficient depending on the distance from the meter to the tankless unit. I know it would have been for me, as that's what I started with and the inspector called it out... At least the wall was still open.
You can't make a blanket statement about anything being fine. It's all needs to be calculated based on distance and BTU and is spelled out in the International Fuel Gas Code (https://codes.iccsafe.org/content/IFGC2018/chapter-4-gas-piping-installations).
OK! I stand corrected. Thanks for the info. I know that my Main is that yellow plastic stuff that is 3/4" and it does work for my unit, but you are totally correct.
There is a 1/4" line that comes out of the 250 gal tank and feeds a regulator which has 1/2" coming out of it and is buried under ground for 50-60'. That is connected to another regulator on the side of the house and has 3/4 galvanized running the length of the house with each appliance tapped off it along the way with 1/2" gal into a valve. 1/2" copper from there to the appliance. It works and thats all I know!
I your case you're coming right off the gas source instead of a meter/main & regulating it so it probably is fine. In your case not only is it a very simple calculation but you have the luxury of being able to up the pressure to whatever the limit is of the HW heater. My understanding, and I'm admittedly no expert, it that stuff will work but if starved for gas you get an increase in CO which most ppl probably wouldn't even realize unless it rose to the level of getting headaches, etc. There's virtually no research on the effects of long term exposure to low levels of CO. Int'l Gas code I ref'd assumes worst case scenario of running everything in the system simultaneously which in the calcs for what I hope to do is oven/stove, water heater, clothes dryer, furnace, garage heat, pool heater, and potentially 1 or 2 other small (10k BTU) space heaters. Very small chance all that would ever run simultaneously but on the big stuff (furnace, HW, pool) there is a reasonable chance. As it is even right now, if I ran everything at once (I never run the garage on full) the system is probably undesized but I've never gotten a CO alarm.
Is there maintenace involved with an outside tankless natural gas water heater. If so what is involved, how often, can it be done by a homeowner, if not what is the cost say here in Central FL?
Thanks guys for the PM's with the reasons not to go with the outside natural gas tankless unit. Never knew of the issues and additional cost. Good I held off a bit!
One more thought. Think about where the vent comes out from the unit and try to locate it somewhere where people aren't. When the unit comes on, there is a brief odor of gas. This is normal and not really a problem, but you wouldn't want it venting into your front yard, were you have a picnic table. Ask me how I know.
I've been running my electric heater for 24 yrs now mad by AO Smith. I'm not sure what can go wrong with it other than a thermostat or heating element. And that being said, I hope there is hot water in the AM. Gas is not an option and when the electricity goes out, neither is water. I have been known to get water out of the creek to flush. The chainsaws and log splitter and tractor don't know the difference.
Update: I did purchase an A. O. Smith 50-gallon hybrid water heater. It has been installed and is running. It has four operating modes - two are relevant for all practical purposes. The default mode is labelled "hybrid" and uses the heat pump unless the temperature recovery can't maintain a specific temperature. If the air pump needs help the two electrical elements kick in. The other mode is "efficiency" and uses the heat pump only. I have the heater set on efficiency, and so far no hot water issues. The next couple of days will be the real test, as it is supposed to be in the 40s at night and low 60s during the day. The forecast is for Christmas day to be the coldest December 25 here in 27 years.
Last week, I replaced my 40 gallon (u.s.) Rheem water heater power vent, circa 1992, with a 50 gallon Rheem power vent. I thought it best to replace a nearly 30 year old unit eventhough it was functioning ok. My insurance company questioned me about my old water heater a year ago and I told the agent that I was replacing it. My payback is less than 5 years as opposed to paying $36 monthly renting from gas company.
Update on post #38 - The hybrid water heater got us through the cold snap just fine. Three showers, two loads of laundry and two runs of the dishwasher and no hot water issues. The only concern now is how well will it hold up. So far I'm a happy camper.