Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Get some Sense... [sense monitoring solution]

This site may earn commission on affiliate links.
D58B667F-58E0-4149-B8D8-4896B0158D91.png

Sense does report on my Model S’s power consumption. Check it out...
 
I don't have Sense, I'm trying to make sense myself ;)

I've identified most large energy sinks in my house, but I'm looking for suggestions on what people think this might be -- drawing about 2kW roughly every 20 minutes. We have gas heat and hot water, so that's not it. It could be the refrigerator, but I didn't think they pull 2kW.

upload_2018-3-12_9-4-10.png
 
I don't have Sense, I'm trying to make sense myself ;)

I've identified most large energy sinks in my house, but I'm looking for suggestions on what people think this might be -- drawing about 2kW roughly every 20 minutes. We have gas heat and hot water, so that's not it. It could be the refrigerator, but I didn't think they pull 2kW.

View attachment 285892
My post double posted then disappeared. You sure it's not the power surge of the fridge compressor starting up every 20 minutes? The initial power surge is large, and then the continuous draw is low.

I'd unplug the fridge for 1/2 an hour to verify.

Do you have other motors? ACs running? generators?
 
I don't have Sense, I'm trying to make sense myself ;)

I've identified most large energy sinks in my house, but I'm looking for suggestions on what people think this might be -- drawing about 2kW roughly every 20 minutes. We have gas heat and hot water, so that's not it. It could be the refrigerator, but I didn't think they pull 2kW.

View attachment 285892

Sump pump? ( 1HP should only be 750 W, but with startup...)
 
I think I found it. It's a 10 gallon aux hot water heater tank that's on a 130 degree thermostat.

The thing is, it's connected to a circulator pump which I only run (on a timer, see below) in the morning and evenings. Without the timer, the aux heater tank was running 24x7 and consuming $250 of power every month! (We have a tankless hot water heater so the aux tank is needed to avoid the cold water slug problem). I put the timer on the circ pump to prevent the heater from running when we didn't need it. I didn't realize it would continue to heat the water three times an hour when not needed.

Anyway, I'm going to put the aux tank heater (2000 watts) on a relay to turn on/off with the circulator pump timer switch (TP-Link
HS210 Smart Wi-Fi smart switch). The smart switch can only handle up to 600w so I'll need a relay to turn off the water heater along with the circulator pump.

Do you think this will do the trick as a 120V 15A relay? SSR-25AA FOTEK Soild State Relay AC-AC 25A 80-280VAC 24-380VAC GSE W | eBay

Or maybe this: https://www.amazon.com/Functional-Devices-RIB2401B-Enclosed-Relay/dp/B000LEUJU6/ref=pd_bxgy_60_2

Or does anyone know of better 120V household relays to use?
 
  • Informative
Reactions: dhanson865
I think I found it. It's a 10 gallon aux hot water heater tank that's on a 130 degree thermostat.

The thing is, it's connected to a circulator pump which I only run (on a timer, see below) in the morning and evenings. Without the timer, the aux heater tank was running 24x7 and consuming $250 of power every month! (We have a tankless hot water heater so the aux tank is needed to avoid the cold water slug problem). I put the timer on the circ pump to prevent the heater from running when we didn't need it. I didn't realize it would continue to heat the water three times an hour when not needed.

Anyway, I'm going to put the aux tank heater (2000 watts) on a relay to turn on/off with the circulator pump timer switch (TP-Link
HS210 Smart Wi-Fi smart switch). The smart switch can only handle up to 600w so I'll need a relay to turn off the water heater along with the circulator pump.

Do you think this will do the trick as a 120V 15A relay? SSR-25AA FOTEK Soild State Relay AC-AC 25A 80-280VAC 24-380VAC GSE W | eBay

Or maybe this: https://www.amazon.com/Functional-Devices-RIB2401B-Enclosed-Relay/dp/B000LEUJU6/ref=pd_bxgy_60_2

Or does anyone know of better 120V household relays to use?

Hi,

The HS210 is coming up as a 3 way light switch for me. Is that triggering a timer?

How often does the circ pump run? If the tank is only on when the the circ pump is running, the water may cool off more than you would like, and then you will need to wait for the pump to move enough water to mix the new hot supply into the 10 gallon tank defeating the purpose. You might be better off wrapping insulation around the tank to reduce the standby loss.

I would skip the SSR for this application. The outputs leak a little and it will dissipate 27W @ 17A (may need heat sink) when on vs 2.5 W for the relay coil + 14.5W for worst case contacts: 17W total, relay may be more fail safe also.
If the pump is 120V (based on the SSR) go with something like this G7L-1A-BUBJ-CB AC100/120.
If there is switched 12V available, you could use something like this G7L-1A-BUB-J-CB-DC12.
Both sub $20 at Digi-Key
 
How often does the circ pump run? If the tank is only on when the the circ pump is running, the water may cool off more than you would like, and then you will need to wait for the pump to move enough water to mix the new hot supply into the 10 gallon tank defeating the purpose. You might be better off wrapping insulation around the tank to reduce the standby loss.

I think he would just need two timers, one to get the 10-gallon tank up to temperature and a separate one to turn on the circulation pump 10-15 minutes later. (Or however long it takes to get the tank up to temperature after it has been off.)

But yes, insulating the tank, and plumbing should be a high priority.
 
The HS210 is coming up as a 3 way light switch for me. Is that triggering a timer?

Oops.. it's HS200. A SPST timer smart switch. Works great for my application (cycling the circ pump on a timer as well as on-demand via mobile app).

How often does the circ pump run? If the tank is only on when the the circ pump is running, the water may cool off more than you would like,

Right now, the circ pump only runs in the morning and evenings. The tank is "on" 24x7 which is the source of the spikes I was seeing. But when the circ pump runs, the heater for the aux tank is always on -- constantly warming the water circulating to the upper floors. This was driving up my energy consumption more than $250/month until I put a power meter on the lines to figure out what was causing the huge drain. Once I put a switch on the circ pump, the huge energy sink went away. I didn't realize it was going to leave behind this periodic heating every 20 minutes to keep the tank at temperature (kinda obvious now that I think about it).

If the pump is 120V (based on the SSR) go with something like this G7L-1A-BUBJ-CB AC100/120.

Thanks. No switched 12v is available, just the switched output (120v) that turns on the circ pump via the timer. I just want to make sure the SSR can handle 120v@15amps of the heater (which it looks like it does). Found it on Amazon for $20: https://www.amazon.com/Enclosed-Power-Relay-120VAC-SPST-NO/dp/B000LEST4E/

I think he would just need two timers, one to get the 10-gallon tank up to temperature and a separate one to turn on the circulation pump 10-15 minutes later.

Just one timer is enough for both. The circ pump uses very little energy, so turning both on at the same time won't really slow down the heating of the 10 gallon tank (it's small) plus whatever is in the pipes.
 
Oops.. it's HS200. A SPST timer smart switch. Works great for my application (cycling the circ pump on a timer as well as on-demand via mobile app).



Right now, the circ pump only runs in the morning and evenings. The tank is "on" 24x7 which is the source of the spikes I was seeing. But when the circ pump runs, the heater for the aux tank is always on -- constantly warming the water circulating to the upper floors. This was driving up my energy consumption more than $250/month until I put a power meter on the lines to figure out what was causing the huge drain. Once I put a switch on the circ pump, the huge energy sink went away. I didn't realize it was going to leave behind this periodic heating every 20 minutes to keep the tank at temperature (kinda obvious now that I think about it).



Thanks. No switched 12v is available, just the switched output (120v) that turns on the circ pump via the timer. I just want to make sure the SSR can handle 120v@15amps of the heater (which it looks like it does). Found it on Amazon for $20: https://www.amazon.com/Enclosed-Power-Relay-120VAC-SPST-NO/dp/B000LEST4E/



Just one timer is enough for both. The circ pump uses very little energy, so turning both on at the same time won't really slow down the heating of the 10 gallon tank (it's small) plus whatever is in the pipes.

That's a nice switch. If the heater is only a 15A unit, they make an outlet that is only $24 from Amazon .

If I can be a little nosey on the system: Do you have the circ pump for when you will have large water demands, and the small tank for the rest of the time? If so, the new setup will only have the small heater on part of the time and the water will get colder in the intervening periods, more so as hit water is pulled from the tank.
If you only need hot water at that location at those times, then the water heater is superfluous.
My thinking:
With a 15A 120V heater and a 10 gallon tank at 100F, you only get 15×120/1000×3412/60 = 102 BTU/min which is (8.29×10)=1.23 degree F per minute temperature rise.
If your on demand water heater is set to 130 and the recirc pump runs at 2 GPM (for example), it is supplying 2×8.28×(130-100) = 496 BTU/minute to the tank. Or almost 5x what the tank element provides. It is also driving the tank water out, so in 10 minutes it would have replaced the entire volume twice getting it close to the on-demand temp.
Long story short, if your small tank only runs when the pump is on, the element isn't going to gain you much. The volume in the tank will provide warmer water in the intervening periods.

Geek mode off
https://www.amazon.com/TP-Link-Heavy-duty-certified-Assistant-HS100/dp/B0178IC734
 
@HankLloydRight

And I forgot my point. If you get the controlled outlet, you can stage the water heater and pump in the future if it is helpful. About the same cost as a relay. Possibly: circ in morning, heater enabled during the day, circ in evening.

Also: unless there are large temp swings in the tank water temp, disabling the element and then heating the tank up to the same level using the element is not going to change power usage much.