Water Heaters - Which energy is more efficient for tankless?
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dpslusser
09-17-09, 07:17 PM
Which energy source for tankless water heaters is the most efficient?
ZL700
09-17-09, 08:16 PM
Natural Gas
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furd
09-17-09, 09:11 PM
More efficient than what?
If you are asking what source of heat will give you the most hot water at the lowest cost then you first need to specify the cost of the various fuels (natural gas, propane and electricity) in your area. Then you need to apply the conversion factor for a specific heater.
Electricity is the highest efficiency if you do not look at the source of the electricity but generally speaking electricity is the poorest choice for a tankless heater.
If you are asking what source of heat will give you the most hot water at the lowest cost then you first need to specify the cost of the various fuels (natural gas, propane and electricity) in your area. Then you need to apply the conversion factor for a specific heater.
Electricity is the highest efficiency if you do not look at the source of the electricity but generally speaking electricity is the poorest choice for a tankless heater.
dpslusser
09-17-09, 09:35 PM
Lets say all energy sources are of equal cost. Which one is the most efficient?
nap
09-17-09, 09:42 PM
Lets say all energy sources are of equal cost. Which one is the most efficient?
electrical resistance heaters are just about 100% efficient. That means that all power consumed is used to produce heat and there is no "waste heat" that is expelled outside like in a gas unit.
that does not mean they are the most cost efficient to run. You have to look at the power consumed X cost per Btu to determine which cost the least to run
electrical resistance heaters are just about 100% efficient. That means that all power consumed is used to produce heat and there is no "waste heat" that is expelled outside like in a gas unit.
that does not mean they are the most cost efficient to run. You have to look at the power consumed X cost per Btu to determine which cost the least to run
ray2047
09-17-09, 09:56 PM
Lets say all energy sources are of equal cost. Which one is the most efficient? If you aren't worried about over paying for BTUs then installation cost is a big factor. If you have a 100a or in some cases even a 200a electric panel you may need a service upgrade just to supply electric to an instant water heater so you are looking at $1500+ for the service upgrade plus the cost of running from one to as many as three separate 60a electric circuits to the heater.
On gas your existing gas line to your water heater will have to be replaced with larger pipe. Existing venting can't be used. You need expensive high temperature stainless steel double wall vent piping alone could run $150 based on Bigbox prices for a vent kit.
Add in that electric instant WHs are a lot cheaper but may cost more to install. Will you ever get your money back. Maybe not. Will you have all the hot water you want maybe.
Final consideration is that in many parts of the country electric per BTU costs 2-3 times as much as gas.
Edited: To delete the incorrect, poorly thought out comments I originally made..
On gas your existing gas line to your water heater will have to be replaced with larger pipe. Existing venting can't be used. You need expensive high temperature stainless steel double wall vent piping alone could run $150 based on Bigbox prices for a vent kit.
Add in that electric instant WHs are a lot cheaper but may cost more to install. Will you ever get your money back. Maybe not. Will you have all the hot water you want maybe.
Final consideration is that in many parts of the country electric per BTU costs 2-3 times as much as gas.
Edited: To delete the incorrect, poorly thought out comments I originally made..
nap
09-17-09, 10:23 PM
. But really both use the energy source about as eficently and that isn't a major consideration in my opinion.
if the gas was as efficient as the electric, you wouldn't need that special stainless steel double wall flue pipe to carry all that wasted heat out of the house. All that heat is waste which equals poor efficiency.
if one would notice, by comparison, the extremely high efficiency gas furnaces use PVC pipe for an exhaust pipe and the expelled air is barely warm. Almost all the heat is kept inside and used to heat the building.
Efficiency? Well in my part of the country at least 30% of the electric is made with gas so with an electric one if you go back to the beginning gas is burned to make steam with some thermal loss the steam is piped to turbans with some thermal loss of energy, the turbine turns with some mechanical loss of energy due to friction and... . well you get the idea. With gas you just burn it and make heat directly. But really both use the energy source about as eficently and that isn't a major consideration in my opinion.that has nothing to do with appliance efficiency. This is a cost factor (energy costs).
if the gas was as efficient as the electric, you wouldn't need that special stainless steel double wall flue pipe to carry all that wasted heat out of the house. All that heat is waste which equals poor efficiency.
if one would notice, by comparison, the extremely high efficiency gas furnaces use PVC pipe for an exhaust pipe and the expelled air is barely warm. Almost all the heat is kept inside and used to heat the building.
Efficiency? Well in my part of the country at least 30% of the electric is made with gas so with an electric one if you go back to the beginning gas is burned to make steam with some thermal loss the steam is piped to turbans with some thermal loss of energy, the turbine turns with some mechanical loss of energy due to friction and... . well you get the idea. With gas you just burn it and make heat directly. But really both use the energy source about as eficently and that isn't a major consideration in my opinion.that has nothing to do with appliance efficiency. This is a cost factor (energy costs).
ray2047
09-17-09, 11:07 PM
Excellent points Nap. Thanks for the corrections.
dpslusser
09-19-09, 01:43 PM
I have an old 100a service....and know gas lines to the house. So i will be having to upgrade something. The service does need upgraded. but ive had other people tell me NG/LP tankless is the best way to go as is cost/energy. I have to call the gas company to see how much it would be to get gas lines installed.
594tough
09-20-09, 12:24 PM
In absoulut efficiency terms, electric will usually come out on top, although power vented gas is pretty good. But in terms of $$$$$, many parts of the country,,,,gas has a distinct edge over electric on dollars to heat the water.
nap
09-20-09, 04:57 PM
In absoulut efficiency terms, electric will usually come out on top, although power vented gas is pretty good. But in terms of $$$$$, many parts of the country,,,,gas has a distinct edge over electric on dollars to heat the water.
absolutely. I did not mean to infer anything otherwise. We were getting into what was more efficient and electricity is inherently more efficient simply because there is no waste heat that leaves the appliance.
electricity can be much more expensive to run though depending on the costs of electricity and natural or LP gas in your area.
absolutely. I did not mean to infer anything otherwise. We were getting into what was more efficient and electricity is inherently more efficient simply because there is no waste heat that leaves the appliance.
electricity can be much more expensive to run though depending on the costs of electricity and natural or LP gas in your area.