ChuckS
New Member
I recently had this full house tankless water heater installed and it was taking just over a minute to get hot water out of the facets. I installed this recirculation system which helped a little but I think it can be improved.
This design uses a flow switch in series with an aquastat to turn the pump on as soon as any hot facet is turned on and does not turn off until the water in the pipes get hot. The advantage of this recirc system is I can quickly turn on then off a facet when I go to use the restroom and the water is hot by the time I go to wash my hands. The bad part is it didn't really reduce my initial time to get hot water as much as I hoped.
Studying this as I have, I know the length of time it takes me to get hot water is a product of all the water sitting in the pipes plus about 6 seconds for the heater to begin kicking out hot water. Because I have mostly ¾ pipes, according to this calculator which is just about dead on it was initially taking just over a minute to get hot water.
The recalculating system cut the time down to about 45 seconds but I think it can be improved. According to the calculator, 45 seconds over 35 feet means my flow is about 1.5 gpm. I measured the output from the facet by timing how long it takes to fill an empty 1 gallon jug and it comes to exactly 1 minute. I believe this means I gained exactly .5 gpm flow rate by adding the loop.
Since my pump is rated up to 6 GPM, the loop is completely ¾ pipes and I have ½ pipes to the facets I know I should be able to get this loop to move more water. I believe the problem with my recirculation loop is that the water has no where to go. Yes it circles water back around and through the heater but it competes with the city water which by my guess means I am getting .5 GPM city water and .5 gpm from the loop which equals my 1 gpm out the facet.
What I think will work is some kind of tank about 2.5 gallons in size which will quickly suck in the water from the pipes when I first turn on the water then slowly release it to the input side of the water heater as the water is being used. I was hoping the expansion tank would do this but either I don't have the air pressure just right, it needs to be relocated or I am not getting an increase in pressure when the pump turns on.
Can someone suggest some kind of tank, it can be mechanical, electric (30 second timer for example), float valve or anything that can be rigged to take in about 2 gallons of water from the loop then via a pump or whatever, release that water back into the system as we shower etc¦
I hope this makes sense but if not please ask questions because I desperately need your help!
PS... The way I adjusted the expansion tank was I took it to grease monkey and had it filled to the max pressure of 80 psi. I installed it in the loop and make sure no water was going in the tank. I then slowly started releasing air until I could feel a little water in the tank. I figured I was right on the edge and that any increase should put more water in the tank. I am a DIY layman so don't laugh too much...
This design uses a flow switch in series with an aquastat to turn the pump on as soon as any hot facet is turned on and does not turn off until the water in the pipes get hot. The advantage of this recirc system is I can quickly turn on then off a facet when I go to use the restroom and the water is hot by the time I go to wash my hands. The bad part is it didn't really reduce my initial time to get hot water as much as I hoped.
Studying this as I have, I know the length of time it takes me to get hot water is a product of all the water sitting in the pipes plus about 6 seconds for the heater to begin kicking out hot water. Because I have mostly ¾ pipes, according to this calculator which is just about dead on it was initially taking just over a minute to get hot water.
The recalculating system cut the time down to about 45 seconds but I think it can be improved. According to the calculator, 45 seconds over 35 feet means my flow is about 1.5 gpm. I measured the output from the facet by timing how long it takes to fill an empty 1 gallon jug and it comes to exactly 1 minute. I believe this means I gained exactly .5 gpm flow rate by adding the loop.
Since my pump is rated up to 6 GPM, the loop is completely ¾ pipes and I have ½ pipes to the facets I know I should be able to get this loop to move more water. I believe the problem with my recirculation loop is that the water has no where to go. Yes it circles water back around and through the heater but it competes with the city water which by my guess means I am getting .5 GPM city water and .5 gpm from the loop which equals my 1 gpm out the facet.
What I think will work is some kind of tank about 2.5 gallons in size which will quickly suck in the water from the pipes when I first turn on the water then slowly release it to the input side of the water heater as the water is being used. I was hoping the expansion tank would do this but either I don't have the air pressure just right, it needs to be relocated or I am not getting an increase in pressure when the pump turns on.
Can someone suggest some kind of tank, it can be mechanical, electric (30 second timer for example), float valve or anything that can be rigged to take in about 2 gallons of water from the loop then via a pump or whatever, release that water back into the system as we shower etc¦
I hope this makes sense but if not please ask questions because I desperately need your help!
PS... The way I adjusted the expansion tank was I took it to grease monkey and had it filled to the max pressure of 80 psi. I installed it in the loop and make sure no water was going in the tank. I then slowly started releasing air until I could feel a little water in the tank. I figured I was right on the edge and that any increase should put more water in the tank. I am a DIY layman so don't laugh too much...
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