Hot Water Heater Low Morning Temps

[CommanderDave]

Recently had a new Rheem 50gal Marathon electric hot water heater installed. It was also connected to my geothermal heat pump's desuperheater - a direct connection to the bottom of the tank, not to a "buffer" tank. I have the water temp set to 130deg, but I only get 114deg in the morning hours. I don't have a daily routine so there are days I don't use much hot water in the mornings. My concern is I don't like the water temp going down that low due to the possibility of bacteria growth. I was told by the heater installer not to change the temp setting on the lower tank's panel where the desuperheater line comes in, but to leave it at 120deg. My question is, is there a way to have hotter water in the mornings? Would a recirculation pump solve the problem? Should I increase the temp on the tank's lower/desuperheater inlet? Is there some other type of configuration that would automatically increase water temp to maintain it's set temperature? Is installing a "buffer" tank the only solution, and if so would it maintain hot water if the geo unit is not running consistently in mild weather? What about a mixing valve/tank booster?

 

[Fitter30]

Recently had a new Rheem 50gal Marathon electric hot water heater installed. It was also connected to my geothermal heat pump's desuperheater - a direct connection to the bottom of the tank, not to a "buffer" tank. I have the water temp set to 130deg, but I only get 114deg in the morning hours. I don't have a daily routine so there are days I don't use much hot water in the mornings. My concern is I don't like the water temp going down that low due to the possibility of bacteria growth. I was told by the heater installer not to change the temp setting on the lower tank's panel where the desuperheater line comes in, but to leave it at 120deg. My question is, is there a way to have hotter water in the mornings? Would a recirculation pump solve the problem? Should I increase the temp on the tank's lower/desuperheater inlet? Is there some other type of configuration that would automatically increase water temp to maintain it's set temperature? Is installing a "buffer" tank the only solution, and if so would it maintain hot water if the geo unit is not running consistently in mild weather? What about a mixing valve/tank booster?

Normal electric heater wiring the top element gets power till thermostat satisfy
then sends power down to the bottom thermostat till it satisfy and sends power back to the top. Top thermostat calls powers the element satisfy then to the lower. Like to see a pic of the heater with piping and a wiring diagram usually in the manual or under the element covers ( turn power off before removing them).

 

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[CommanderDave]

Attached photos showing desuperheater connections and wiring diagram.

 

[Fitter30]

Attached photos showing desuperheater connections and wiring diagram.

Heater is wired like my post 2. Heater 1 pic the swing check valve looks to have the flow going down. A swing check can't be used in any vertical position especially down. Needs to be a spring check or the swing check has to be in a horizontal line. The existing check has a small 1/4" hex bolt head towards the top of of it which is the pivot point of the swing. Guess the pump for the line is at the geo unit?

 

[CommanderDave]

The desuperheater is built into the geo. It's my understanding a swing check valve can be used in in a vertical position if in an upward flow. Do you have any solutions to my issues or questions?

 

[Fitter30]

The desuperheater is built into the geo. It's my understanding a swing check valve can be used in in a vertical position if in an upward flow. Do you have any solutions to my issues or questions?

No it can stay in the open position in the right condition. Looks like it's feeding in the bottom.

1. Feature/CriteriaLift check valvesSwing check valvesSpring-loaded check valvesOperationDisc lifted by fluid flow, closes by gravity or back pressureHinged disc swings open with flow, closes when flow reversesSpring mechanism compresses to open, expands to closeAdvantagesGood sealing for high-pressure applicationsLow pressure drop
   
   Suitable for fluids with suspended solids
   Fast response to flow changes
   
   Can be installed in any orientation
   LimitationsLift check valve pressure drop is higher due to disc lifting
   
   Limited to horizontal installation
   Sensitive to debris, which can obstruct disc movement
   Generally limited to horizontal installation
   
   Slower response, allowing potential backflow before sealing
   Higher cost due to spring mechanism
   
   Potential for spring wear in high-cycling applications
   Ideal applicationsClean fluid systems with consistent flowWater and wastewater systems with large volumes and suspended solidsSystems requiring quick response and versatile installationInstallation flexibilityLimited (horizontal only)Limited (primarily horizontal)
2. Technical Information Center
3. Product Information

Swing Check Valve - Types and Features​

July 30, 2022 by Charles Kolstad

Check valve comparison table​

Table 1: Lift check valve vs swing check valve vs spring-loaded check valve

Feature/Criteria	Lift check valves	Swing check valves	Spring-loaded check valves
Operation	Disc lifted by fluid flow, closes by gravity or back pressure	Hinged disc swings open with flow, closes when flow reverses	Spring mechanism compresses to open, expands to close
Advantages	Good sealing for high-pressure applications	Low pressure drop Suitable for fluids with suspended solids	Fast response to flow changes Can be installed in any orientation
Limitations	Lift check valve pressure drop is higher due to disc lifting Limited to horizontal installation Sensitive to debris, which can obstruct disc movement	Generally limited to horizontal installation Slower response, allowing potential backflow before sealing	Higher cost due to spring mechanism Potential for spring wear in high-cycling applications
Ideal app
Installation flexibility	Limited (horizontal only)	Limited (primarily horizontal)	High (any orientation)
Cost	Moderate	Low	Higher

 

[CommanderDave]

I turned off the geothermal desuperheater and closed the inlet/outlet valves (Rheem recommended I do this). Set the upper and bottom temp settings on the Rheem electric water heater to 125deg. Now I'm getting hot water whenever I want it. I plan on turning the geo desuperheater back on during summer/AC months as I understand that is when it can be most effective/helpful.

 

[Fitter30]

I turned off the geothermal desuperheater and closed the inlet/outlet valves (Rheem recommended I do this). Set the upper and bottom temp settings on the Rheem electric water heater to 125deg. Now I'm getting hot water whenever I want it. I plan on turning the geo desuperheater back on during summer/AC months as I understand that is when it can be most effective/helpful.

Desuperheater should work on any mode. With plastic pipe can't set up proper flow without having a way (drain valves) in and out Dhw lines from the desuperheater to get good temp readings. Having temp reading at start up would give good comparison. The heat exchanger could also be fouled. Page 13 has some startup info.

https://www.waterfurnace.com/literature/premier/im1555.pdf