Heating Systems

Silky

New member
May 5, 2015
2
Lake Orion, MI
I purchased a home with an inground pool in September of 2014. I had use of the pool for 2 weeks before I had to close it for the winter. So I'm new to pool ownership and I am new to TFP. I would like to install a heating system and would like to get some inputs on gas vs. electric. Of course, I have a host of questions I'd like to submit, but thought I'd start out simple. My pool is Grunit, 20000 gal, 21' X 34'. Any suggestions would be greatly appreciated.
 

BoDarville

TFP Expert
LifeTime Supporter
Jun 5, 2012
3,844
DFW, Texas
Welcome to TFP!

When it comes to heating, it will take a given number of BTU's to heat a volume of water to a target temperature. If your goal is to heat the water the quickest way possible, I would suggest a natural gas heater and get the largest one that will work with your existing gas line. If there is no existing gas line and you need to have a new one installed, then you can specify a properly sized line to work with the heater you are considering. Talk to your gas pipe fitter to see if there are any other restrictions with regard to your existing gas setup.

Many people think they will save on their gas bill if they install a smaller heater, but this is a fallacy. For example, if you wanted to heat your pool by 10°F, it will take a given amount of BTU's to do that. A 400K BTU heater will do the job in about half the time compared to a 200K BTU. Either way, you are still using the same amount of BTU's (and thus the same amount of gas) to heat the water to your target temperature. One factor to look into is the efficiency rating of the heater. A higher efficiency rating means that more of the heat will go into heating the pool vs. being lost into the atmosphere. For example, a 400K BTU heater with a 90% efficiency rating means that 360K BTU will go towards heating the water whereas the same heater with an efficiency rating of 80% would only contribute 320K BTU's of heat to the pool.

I must say, using the term "quick" in the context of heating a pool is a relative term. Even with a 400K BTU natural gas heater like I have, you can expect about a 2°F rise in water temperature per hour. And, although natural gas is usually the least expensive source to use for heating (compared to electric or propane), you will notice a slight bump in your gas bill whenever you use the heater for any length of time. Heating pool water is expensive!

I have attached a spreadsheet that I created that will give you some idea of the cost and time needed to heat a pool to a target temperature using a natural gas heater. It takes the above-mentioned considerations into effect as well as others (wind, ground temperature, sunlight, ambient outdoor temperature). Several members have used this calculator and have reported back that it has been pretty accurate.


View attachment HeaterCalculator.zip
 

Defgufman

LifeTime Supporter
Mar 13, 2015
584
Savannah GA
Welcome to TFP!

When it comes to heating, it will take a given number of BTU's to heat a volume of water to a target temperature. If your goal is to heat the water the quickest way possible, I would suggest a natural gas heater and get the largest one that will work with your existing gas line. If there is no existing gas line and you need to have a new one installed, then you can specify a properly sized line to work with the heater you are considering. Talk to your gas pipe fitter to see if there are any other restrictions with regard to your existing gas setup.

Many people think they will save on their gas bill if they install a smaller heater, but this is a fallacy. For example, if you wanted to heat your pool by 10°F, it will take a given amount of BTU's to do that. A 400K BTU heater will do the job in about half the time compared to a 200K BTU. Either way, you are still using the same amount of BTU's (and thus the same amount of gas) to heat the water to your target temperature. One factor to look into is the efficiency rating of the heater. A higher efficiency rating means that more of the heat will go into heating the pool vs. being lost into the atmosphere. For example, a 400K BTU heater with a 90% efficiency rating means that 360K BTU will go towards heating the water whereas the same heater with an efficiency rating of 80% would only contribute 320K BTU's of heat to the pool.

I must say, using the term "quick" in the context of heating a pool is a relative term. Even with a 400K BTU natural gas heater like I have, you can expect about a 2°F rise in water temperature per hour. And, although natural gas is usually the least expensive source to use for heating (compared to electric or propane), you will notice a slight bump in your gas bill whenever you use the heater for any length of time. Heating pool water is expensive!

I have attached a spreadsheet that I created that will give you some idea of the cost and time needed to heat a pool to a target temperature using a natural gas heater. It takes the above-mentioned considerations into effect as well as others (wind, ground temperature, sunlight, ambient outdoor temperature). Several members have used this calculator and have reported back that it has been pretty accurate.


View attachment 36099
Great information, thank you BoDarville