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LP choices...

Foxbarry1 Member Posts: 3
Need advice... I currently have two LP traditional 50 gallon tank water heaters (fairly new State Select, high efficiency). They are zoned out...one supplies water for the master bath and guest bath; the other is for the kitchen, laundry room and guest bath. The gas valve/thermostat needs to be replaced on one, so I was considering replacing the two LP tank heaters with one high capacity LP tankless.

My wife and I are expecting our fist child in October and are planning for a total of 3 kids in the future. We occasionally have guests utilizing the guest baths.

I've been reading pros and cons for the last two days. Ultimately, I want to decrease my LP usage and can't decide if the way to do that is to keep what I have or go for the tankless. Will one tankless use less propane than two high efficiency tank heaters...especially considering we my be a family of 4 or 5 with occasional guests? All opinions welcome! Thanks.


  • SpeyFitter
    SpeyFitter Member Posts: 422
    edited July 2011

    You said yourself that you have 2 "fairly new" high efficiency hot water tanks. I"d suspect fairly new falls within 2-3 years old max, and you said one needs a thermostat/gas valve.

    Now most hot water tanks carry some sort of warranty on parts at the very least. Why is replacing the gas valve/thermostat and keeping the tanks not an option? You have essentially 100 gallons x high efficieny tank of output - that should be plenty for your future requirements. High efficiency hot water tanks are, assuming few to no repairs, probably the cheapest ways to heat hot water, or right up there at least, as far as life cycle cost goes.

    Personally, I am NOT fond of tankless. You will require an annual service/maintenance at a minimum to flush lime out of the heat exchanger if you want to take advantage of their efficiency and the fact they do not require a tank, you will require major venting alterations in the strong majority of tankless retrofits (aka cutting drywall and/or roofs open, might need a drywaller and roofer to do the patch up for the flashings/penetrations, etc.), potential upsizing of the gas line or bumping up the gas line pressure which is more $$ depending on the position of the gas line relative to the gas meter/utility, parts are more expensive, harder to come by unless you got a really good guy who stocks parts and takes pride in what he/she sells, and worst of all, if the power goes out, you ain't got no hot water!  

    I would bark up a few trees here - I would keep what you have, and fix it for the time being and it will do you proud for the next 3-7 years meeting your families demands until you suspect failure may be imminent, consider installing a thermostatic tempuring valve to tempur the hot water temperature down to a safer temperature for your future babies & curious toddliers (keep the tanks in the 135-140 range to kill legionairres, bump the supply line temperature down with a thermostatic tempuring valve to say 115-120), and then over the next few years you can really ponder where you want to go. You might also want to consider installing a potable expansion tank on each tank which will help absorb pressure due to thermal expansion on the tanks and contribute to them having longer lives.

    The way I see it, your options would be to consider replacing your existing set up (in 3-7 years) with a stainless high efficiency tank. There are presently only a few companies that make them, I think heat transfer products is one. This tank will last a lot longer, have more hygienic hot water production than your standard glass lined steel tank, and you can ponder upping the size of it at this time to something bigger if you find it doesn't suit your families requirements for some reason, although 100 gallons of 135-140 degree water with reasonable recovery should be plenty unless you're having 5 showers at the exact same time.

    Another option is to consider how your house is heated - do you have a furnace, or a boiler? If you have hydronic heat emitters (baseboards, or radiant floors, or panel rads, etc.) with a boiler, you may want to install an indirect using the boiler to heat an integral coil built into the tank that heats the hot water- this would be a very reliable, effective, and inexpensive way to heat water very comparable to heating it with high efficiency tanks, but it would last quite a long time, and you could have a higher output modulating boiler that would give you excellent output, and if you get a stainless indirect, a very long life cycle.

    Keep in mind that most hot water tanks right now have excellent insulation - typically 1.5 to 2+" of sprayed on insulation that really minimizes standby losses so the argument by tankless manufacturers that you're heating water in a tank all day long is pointless in my opinion.

    The other option is explore electricity rates in your area on an apples to apples basis with propane and you might want to consider looking at one of those newer heat pump hot water heaters, however, consider life cycle costs, and warranty; these tanks are typically made out of steel so I suspect by the time the higher efficiency of the built in heat pump pays for itself, it may be time to replace the tank in comparison to a standard 100% efficiency, simple, electric element tank. (the heat pump hot water tanks often have elements to help with some recovery, or different settings that may use the elements at time, but you get the just I think).


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  • Foxbarry1
    Foxbarry1 Member Posts: 3
    Re: options

    Good comments, thanks. Yes, the parts are under warranty, but the labor is not. Rather than put the $200 into labor for repairs, I was thinking about putting that money into tankless, but you bring up some good points. Obviously this will cost considerably more up front. I know my current configuration will provide plenty of hot water... My biggest concern is that I may be spending major bucks on propane for two tank heaters when one tankless might help reduce that cost. I'm in the country and rely on propane for central heat, fireplace and stove top. I have a 500 gallon LP tank. Both water heaters are located in the attic as well as both ac heaters. Last time I filled up, propane was going for about $2.50/gallon. Ouch. I do not, however, want to be disappointed in my water temperature, even during the busiest of holiday get togethers. I think I'm leaning towards keeping what I've got, claim warranty for the part, pay for the labor, and maybe adding those tank insulating covers to increase efficiency even more. Thanks for your input.
  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    My question

    What is wrong with the control on your water heater?. It should not need replaced if only two or three years old.

    When we find out the problem there then you may not need to spend all that money.Is this a standing pilot water heater with a thermocouple? Is it an FVIR version of water heater?
  • Foxbarry1
    Foxbarry1 Member Posts: 3
    Re: my question

    Yes, pilot with thermocouple. The burner stays lit, 24/7, regardless if the dial is set to vacation or pilot light levels, super hot, or anywhere in-between. The only way to turn the burner off is to shut off the line valve. Recently had the pilot assembly replaced because the pilot wouldn't stay lit. Ever since then, the burner has been stuck on. Plumber that replaced pilot assembly says it's a coincidence. I'm just tired of dealing with this heater, tired of sinking money into labor, but am willing to keep it if this is the last issue for awhile.
  • hot_rod
    hot_rod Member Posts: 22,259
    could you

    combine both systems into one. Then you could fire the second tank only when the demand goes up, visitor , etc.

    Consider adding solar. One tank would be the solar pre-heat with electric backup for high demand options. In most areas solar can provide 50- 60% of your DHW. Check at www.dsireusa.org to see what incentives might be available to go solar.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tim McElwain
    Tim McElwain Member Posts: 4,628
    What make is this

    water heater? Something is not making sense here. You say it will not shut off when set to pilot that rteally baffles me. Give some more information and maybe we can fix this without spending a lot more money. A few pictures of the control on this unit would help.
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