I did a major edit after I answered one of my own questions, so it's no longer two questions...
Purchased this house with existing propane fired hot water tank with a circulation pump and dedicated return line. It works great, but is just too wasteful of propane to run the way it's set up. I'm on a well and septic, so I understand the rationale for having it, but I want to minimize the cost of running it. It looks like, originally (20 years ago when the house was built), the circ. pump was wired into a timer. Somewhere along the way, the pump was disconnected from the timer and wired to an on/off switch in the kitchen. So, when we bought the house, the procedure was to go to the kitchen and turn the pump on whenever you needed hot water. Not especially convenient if the object was to wash your hands in the upstairs master bath. At the time, I had a lot of other things occupying my time, so I just added another switch upstairs (i.e., three-way switch) so it was a bit more convenient, but we still have the issue of forgetting to turn the pump off, especially if we are running the dishwasher after everyone has gone to bed, for instance. Also, from upstairs, it's impossible to tell if the pump is running if the house is noisy, so the 3-way switch is problematic because you never know if you're turning the pump on or off. So, I'd like to change the set up.
I would like to add some sort of control. Timers, temperature sensors and on-demand switches all have drawbacks in my situation. Programmable timers seem inefficient because you're simply running the pump for larger blocks of time, a little better then 24/7, but not much better. Using a temperature sensor to keep the water at a pre-determined temp. also seems too wasteful. I wouldn't mind an on-demand set up, but I'm not sure it would work for the dishwasher example above, since they appear to only heat for one cycle after you push the button before shutting the pump off (our dishwasher runs for two hours). I think this push button, on demand set up would work for a shower, because it sort of primes the hot water which keeps coming after the pump shuts off, but the dishwasher is intermittent, as is the laundry machine. So, without someone to keep pushing the button, the dishwasher or laundry would receive cold later in it's cycles. I understand that I could also add a timer, but I'd like to keep it simple, as convenient as possible, and I'd like to run the pump as little as possible for efficiency. The electricity cost to run the pump isn't the issue. It's the cost of the propane to keep re-heating the water as it cools in the pipes.
So, I found a product that may work, and I would like to ask if anyone can see drawbacks. Basically, you get a flow sensor switch and a control unit. The flow switch is placed at the cold water inlet to the hw tank, and my existing pump is plugged into the control unit. The control unit is then plugged into the wall. Wires run from the flow sensor switch to the control unit, and whenever it senses a flow of water into the hw tank, it turns on the pump. When the flow stops, the pump turns off. I think this would be ideal for my situation. Currently, if I turn on the hw in the distant, upstairs bath, and then walk over and flip the switch to turn on the pump, I get hot water within a few seconds, almost instantly. I understand that this slightly defeats the reason some people install these circulating pumps. That is, some people install them for the convenience of instant hot water. And having to wait even a few seconds goes against the whole idea of having the pump. However, in my case, without the pump, the wait for hot water would be a few minutes, so this seems like a good compromise.
Am I missing a fatal flaw in the set up?
Thanks in advance,
Colin
p.s. The return pipe is not insulated, which I plan to correct in any case.
Purchased this house with existing propane fired hot water tank with a circulation pump and dedicated return line. It works great, but is just too wasteful of propane to run the way it's set up. I'm on a well and septic, so I understand the rationale for having it, but I want to minimize the cost of running it. It looks like, originally (20 years ago when the house was built), the circ. pump was wired into a timer. Somewhere along the way, the pump was disconnected from the timer and wired to an on/off switch in the kitchen. So, when we bought the house, the procedure was to go to the kitchen and turn the pump on whenever you needed hot water. Not especially convenient if the object was to wash your hands in the upstairs master bath. At the time, I had a lot of other things occupying my time, so I just added another switch upstairs (i.e., three-way switch) so it was a bit more convenient, but we still have the issue of forgetting to turn the pump off, especially if we are running the dishwasher after everyone has gone to bed, for instance. Also, from upstairs, it's impossible to tell if the pump is running if the house is noisy, so the 3-way switch is problematic because you never know if you're turning the pump on or off. So, I'd like to change the set up.
I would like to add some sort of control. Timers, temperature sensors and on-demand switches all have drawbacks in my situation. Programmable timers seem inefficient because you're simply running the pump for larger blocks of time, a little better then 24/7, but not much better. Using a temperature sensor to keep the water at a pre-determined temp. also seems too wasteful. I wouldn't mind an on-demand set up, but I'm not sure it would work for the dishwasher example above, since they appear to only heat for one cycle after you push the button before shutting the pump off (our dishwasher runs for two hours). I think this push button, on demand set up would work for a shower, because it sort of primes the hot water which keeps coming after the pump shuts off, but the dishwasher is intermittent, as is the laundry machine. So, without someone to keep pushing the button, the dishwasher or laundry would receive cold later in it's cycles. I understand that I could also add a timer, but I'd like to keep it simple, as convenient as possible, and I'd like to run the pump as little as possible for efficiency. The electricity cost to run the pump isn't the issue. It's the cost of the propane to keep re-heating the water as it cools in the pipes.
So, I found a product that may work, and I would like to ask if anyone can see drawbacks. Basically, you get a flow sensor switch and a control unit. The flow switch is placed at the cold water inlet to the hw tank, and my existing pump is plugged into the control unit. The control unit is then plugged into the wall. Wires run from the flow sensor switch to the control unit, and whenever it senses a flow of water into the hw tank, it turns on the pump. When the flow stops, the pump turns off. I think this would be ideal for my situation. Currently, if I turn on the hw in the distant, upstairs bath, and then walk over and flip the switch to turn on the pump, I get hot water within a few seconds, almost instantly. I understand that this slightly defeats the reason some people install these circulating pumps. That is, some people install them for the convenience of instant hot water. And having to wait even a few seconds goes against the whole idea of having the pump. However, in my case, without the pump, the wait for hot water would be a few minutes, so this seems like a good compromise.
Am I missing a fatal flaw in the set up?
Thanks in advance,
Colin
p.s. The return pipe is not insulated, which I plan to correct in any case.
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