Pros and Cons of Tankless water heaters in RV
Thank you for your replies if any.
Forum Discussion
To explain the all hot or all cold.
Flow rate turns on the unit, you have to meet the minimum flow rate through the heater or it does not come on. In most cases that is around .6 gpm in small units, but in the first gas home model I got it was 1.4 gpm.
.6 gpm to a showerhead is less than half the flow rate of most showerheads. RV showerheads can be lower flow to conserve water, but Girard, the biggest brand of RV tankless heaters warns that rv users with low flow showerheads will need to remove any restrictors from the showerhead.
At .6 gpm the water comes out with no force, but because the flow is low, the water has more time in the small heating chamber to be warmed. The faster that water flows through the chamber, the less heat it can absorb.
So if the flow rate allows a 50 degree rise in temp that makes a comfortable shower or sink temp IF the water entering the unit is about 50 degrees, if the incoming water is 70 degrees it will exit at 120, if it enters at 40 degrees it will exit at 90.
The RV units try to regulate the temp by modulating the flame from the propane, in an attempt to control how much heat is applied to the water to allow more variation in the final warm water. How successful they are is a matter of opinion.
sample flow chart of tankless water heat flow vs temp rise this is for a single point of use home electric unit, but sized similar to the rv units,
elec unit.
Note usage is listed for region where it is to be used, rv cant specify that, it moves around.
Look at amount of heating, flow at that temp change, and then decide if you will be able to live with those parameters.
Flow rate turns on the unit, you have to meet the minimum flow rate through the heater or it does not come on. In most cases that is around .6 gpm in small units, but in the first gas home model I got it was 1.4 gpm.
.6 gpm to a showerhead is less than half the flow rate of most showerheads. RV showerheads can be lower flow to conserve water, but Girard, the biggest brand of RV tankless heaters warns that rv users with low flow showerheads will need to remove any restrictors from the showerhead.
At .6 gpm the water comes out with no force, but because the flow is low, the water has more time in the small heating chamber to be warmed. The faster that water flows through the chamber, the less heat it can absorb.
So if the flow rate allows a 50 degree rise in temp that makes a comfortable shower or sink temp IF the water entering the unit is about 50 degrees, if the incoming water is 70 degrees it will exit at 120, if it enters at 40 degrees it will exit at 90.
The RV units try to regulate the temp by modulating the flame from the propane, in an attempt to control how much heat is applied to the water to allow more variation in the final warm water. How successful they are is a matter of opinion.
sample flow chart of tankless water heat flow vs temp rise this is for a single point of use home electric unit, but sized similar to the rv units,
elec unit.
Note usage is listed for region where it is to be used, rv cant specify that, it moves around.
Look at amount of heating, flow at that temp change, and then decide if you will be able to live with those parameters.
