Propane tankless water heater?
Question:I'm building a new house and was thinking about putting a tankless propane water heater in the house. My question is, I'm wondering if I can use a 100lb tank to fuel the heater and how long would it last under normal use? Like for a 117,00 btu heater.
Answers:
A 100 pound tank I believe is only ten gallons of fuel if I'm right. This isn't very much. I would go to a "pig" or a 350 gallon small tank and go to a "keep fill" basis.
You have to do a lot of figuring for this. Let the propane company decide all that. They have all the standards you'll need.
Ask a propane supplier. They probably have all the stats that you are seeking.
they work well but it all depends how much your going to use it ,it will probably last 2 months per tank load. and i'm talking for domestic hotwater for showering,not for heating the house .. if your going to use it for both then you going to be filling up every 2 weeks during the cold season almost pointless to have ...do you have natural gas in the area ,probably a much better selection... at least for the hydronic side...
ok listen maybe this numbers can help you.
Weight per gallon 4.24 pounds.
Heat value per gallon of liquid gas 91,547 Btu
Heat value per pound of liquid gas 21,591 Btu
now you do the maths.
First of all, I would double check the BTU rating of the tankless heater. That number sounds low to me. Most I have seen are around 300,000 -450,000 BTU's. Also, check on the type of flue pipe required. Most gas fired tankless heaters require a special, triple wall flue pipe, that could easily cost more than the heater itself. Another point to consider: NO PLASTIC PIPE IS ALLOWED DOWNSTREAM OF A TANKLESS WATER HEATER! This is straight from the manufacturers, and they will not warranty any damage caused by a ruptured pipe, nor will the plastic pipe manufacturers either. Last but not least, the water supply has to be sized properly. If the pipe is too big, too much water will flow across the heat exchanger, and not get hot enough. Too small, and the water will get too hot, and possibly set off the T&P valve, so do your homework, or better yet, have a plumber who has experience in tankless heaters examine your installation, as most plumbers don't know enough about tankless heaters yet. Good luck!
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