Recirculation pump (without return line) + thermostatic mixing valve = No Aquastat needed?

[DIYinATX]

I'm running an Watts 500800 recirculating pump (consumer level).
And a Honeywell AMX300 mixing valve.
There is NO RETURN LINE. No recirculation line.
The pump dumps the unused recirculating hot water into the cold water line via a "comfort valve" mounted at the furthest sink.
Actually, I'm running two comfort valves. One in my kitchen and another at the furthest hand sink.

I've had it hooked up for more than a day now.
Without an Aquastat.
And there are no issues.

38 gallon electric water tank (consumer level) set to highest temp possible.
The mixing valve is adjusted so that I'm getting 118-120 degrees coming out of the faucet.

If I were going to have a problem, would it have happened by now?
Or do I still need to worry about a surprise someday?

A laser thermometer aimed at the cold water intake copper pipe going to my water heater tank ranges from 59* to 69*.

 

[John Gayewski]

Whatever is controlling the pump seems to be working. I guess it depends how your pump is controlled and how you'd like it to be controlled. Meaning if you want to change the perimeters of when your pump runs adding a control can get you there. An aquastat is just a control.

 

[Sponsor]

 

[Tuttles Revenge]

That system uses both a timer on the pump and a thermostatically controlled sensor valve. So the pump is turned on by the timer, it runs hot water to the valve located under the sink until the thermistatic valve senses it has reached temperature and stops the flow of water through or slows it down. then the timer turns the pump off.

 

[Fitter30]

Pump running on a timer or 24/7. 24/7 cold will get warmer why run the pump if its not needed

 

[DIYinATX]

I've got the pump timer configured to turn off from 1AM till 7AM.
It's running for the rest of the day.
No idea if that's saving me any money (not likely) but I don't care because I love the convenience!

In a year or two when I get into my remodel, I'd like to run a dedicated return line.
And I also want to run a new line to my dishwasher and washing machine which would bypass the tempering valve and get unregulated hot water.

I love that plumbing has so many cool options I never knew about!

 

[cbx4evr]

That system uses both a timer on the pump and a thermostatically controlled sensor valve. So the pump is turned on by the timer, it runs hot water to the valve located under the sink until the thermistatic valve senses it has reached temperature and stops the flow of water through or slows it down. then the timer turns the pump off.

Realize I’m waking up an old thread but it’s talking about exactly what I want to install in my cabin so I can get some hot water in the kitchen without filling up my septic tank. I understand the system. My question is more about the pump itself. Basically I’m wanting to know if the pump senses flow and shuts down, even if it’s in the On or Timer mode, when the valve under the sink closes??? i suspect it isn’t that sophisticated but thought I would ask.

 

[Fitter30]

Realize I’m waking up an old thread but it’s talking about exactly what I want to install in my cabin so I can get some hot water in the kitchen without filling up my septic tank. I understand the system. My question is more about the pump itself. Basically I’m wanting to know if the pump senses flow and shuts down, even if it’s in the On or Timer mode, when the valve under the sink closes??? i suspect it isn’t that sophisticated but thought I would ask.

No the pump doesn't shut off they only draw about 25 watts.

https://www.amazon.com/Grundfos-595916-Horsepower-Comfort-Recirculator/dp/B07LGQZRFV/ref=asc_df_B07LGQZRFV/?tag=hyprod-20&linkCode=df0&hvadid=475789406344&hvpos=&hvnetw=g&hvrand=13688353330522695580&hvpone=&hvptwo=&hvqmt=&hvdev=t&hvdvcmdl=&hvlocint=&hvlocphy=9023792&hvtargid=pla-1183839092791&psc=1&mcid=9079274f326a3172821af879670804cb&gclid=EAIaIQobChMIrqW26fjNgwMVXF9HAR3g5AGDEAQYAiABEgL-D_D_BwE

 

[John Gayewski]

Realize I’m waking up an old thread but it’s talking about exactly what I want to install in my cabin so I can get some hot water in the kitchen without filling up my septic tank. I understand the system. My question is more about the pump itself. Basically I’m wanting to know if the pump senses flow and shuts down, even if it’s in the On or Timer mode, when the valve under the sink closes??? i suspect it isn’t that sophisticated but thought I would ask.

According to my fuzzy understanding the pump turns off of it senses too much resistance. Or if the temp is satisfied.

 

[Tuttles Revenge]

Here is one manufacture that we use for this style of recirc system. lots of options available.

AquaMotionHVAC.com » The Comfort and Savings of Instant Hot Water with Recirculation

aquamotionhvac.com

 

[cbx4evr]

I'd love to get the AquaMotion unit but it's basically not available up here in Canada. The Watts Premier 500800 or the Grundfos is about my only option with the Watts being cheaper.

My utility room access requires me to go outside to access it. My inclination is to set the pump to run continuous but connect it to a wi-fi outlet which we would activate 15 minutes before we need hot water. Not that the power consumption is a concern, but, I'm not keen on the pump running "dead headed" when the valve closes, however, maybe that isn't a concern.?

 

[John Gayewski]

I'd love to get the AquaMotion unit but it's basically not available up here in Canada. The Watts Premier 500800 or the Grundfos is about my only option with the Watts being cheaper.

My utility room access requires me to go outside to access it. My inclination is to set the pump to run continuous but connect it to a wi-fi outlet which we would activate 15 minutes before we need hot water. Not that the power consumption is a concern, but, I'm not keen on the pump running "dead headed" when the valve closes, however, maybe that isn't a concern.?

The pumps for these systems are supposedly designed to run dead headed. If the pump is made for the system it should be good.

 

[DIYinATX]

A year later and I'm still loving this setup.
I turned it off during the summer and then just turned it back on again a month ago.

Added bonus - my butt doesn't get shocked with freezing water when I use my bidet.

For my next house or next remodel, I'm adding a dedicated return line.
And a power outlet & hot water line next to the toilet.