Tankless water heater and butane use

[Wild Turkey]

We're looking at building a new house.

We can go with a tankless powered by either electricity or butane from a 100 gal tank.

It's just us except when we get visitors and don't expect a lot of them.

So how long will a 100 gallon tank last a tankless?

What's the expected service life of them?

Any advice from experienced users?

[Stwood_]

Butane?  Huh. I haven't heard of butane being used for heating in ages.

[fredhargis]

Yeah, I wasn't aware you could get butane for that application. Sure you don't mean propane?

[David G]

91600 Btu per gal propane.  So a 100 gal propane tank with a 100,000 BTU/hr tankless heater would operate about 100 hours.  That is a lot of showers.

[JosephP]

We're looking at building a new house.

We can go with a tankless powered by either electricity or butane from a 100 gal tank.

It's just us except when we get visitors and don't expect a lot of them.

So how long will a 100 gallon tank last a tankless?

What's the expected service life of them?

Any advice from experienced users?

1 bedroom, no basement? 


Is butane easily available through delivery services in your area (and at what cost)?  Why not propane...and why not a slightly larger tank?  If the above "100 hours" is correct that means getting it filled about every 2-3 months? for 2 people...and you haven't washed laundry or dishes yet.  I would think the service charge of bi-monthly visits will eat into savings.

What fuel will you be using to heat the house?  That would be my first choice for water heater too in most cases - but I'm no expert, by any means.

[blackhat]

91600 Btu per gal propane.  So a 100 gal propane tank with a 100,000 BTU/hr tankless heater would operate about 100 hours.  That is a lot of showers.

Times .9 for combustion efficiency, times .7 for useable tank volume, times .8 for actual firing rate. Not quite as attractive. What's the home heating fuel?  Not sure I would choose free butane.

[Robert Adams]

Same here. Haven't seen butane available in many decades but there is always always a little in propane. 

      If going propane I would definitely not go with a tank as small as  a 100 gallon. You don't want to run out in a short period of time especially if weather is bad. Also 100 gallons is not enough to get the propane guy to come out and fill your tank in most places. Here they won't come out unless you need at least a $300 delivery.  

              So i would be looking at a 300 gallon o so tank and be prepared for a big bill when you need to get propane as that's how it works cause they don't like to deliver small amounts. 

              When we  used to voulnteer at the community assistance/food bank one of the items was a limited amount of utility assistance and LOML took care of that stuff. Propane would not get assistance because it was always a $300 min delivery and the clients had to come up with a big chunk of cash at once and the food bank only covered part of it. Unfortunately those in need of those services are the ones with propane tanks and they are the ones that can least afford those big payments when needed.

[fredhargis]

Couple of things. LP (if that's what we are talking about) will almost certainly be cheaper then electric in a tankless or tank heater. But it can be approximated.  the info above gets you most the stuff you need for the LP. When you divide the cost (it was $1.05 for me this year) per gallon  by the 91,600 you get your cost per BTU (.0115¢ per 1000/btu). The heaters probably are 80-85% efficient, so the cost per recovered 1K/BTUs becomes .0135¢. Now the electric will deliver 3412 BTUs per KWH. For that KWH will cost about 12¢, so the cost per 1K/BTUs runs .035¢. But the electric is a lot more efficient in usage, you don't have flue loss and other stuff. It's probably not 100%, but call it that. So each 1K/BTU of LP will run .0135¢, and electric will be a little over 2.5 times as much (with my local costs plugged in, and assuming I didn't screw something up royally in the math). Some of the other things about LP: my supplier delivers when the tanks is at 25% (any size tank) but it varies by outfit. Some of them don't want to install a tank unless you have a minimum annual usage, without that you pay a "underutilized tank" fee (rent). Tanks (if you buy one) have a very long life. At our last house we used the same tank for over 20 years, and the supplier painted it once in that time. If you let the supplier provide the tank, he's the only one who can/will fill it. If you buy one, you can buy your gas from any supplier (in theory). There is usually a discount for customer owned tanks in the LP price. But all of this varies so much by region, it pays to check with suppliers in the area and see what they offer.  Anyway, for what's it worth......

[Cooler]

Two blocks away from my house they have natural gas piped in.  In our neighborhood it is propane, oil or electric only.

I have oil heat and hot water and electric stove (induction).  I never heard of tank-less using oil though.

Note:  A quick Google search shows that there are such animals.  Never heard of this manufacturer though:  Toyotomi (about $2,000.00 + install)


http://www.houseneeds.com/heating/tankle...er-heating

[EightFingers]

I have a tankless w.h., gas dryer and gas stove. 100 gallons of propane lasts us (wife and me) about 19 to 20 months