Triggering Demand Hot water recirculation loop pump

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tnakelski
Posts: 74
Joined: Tue Sep 11, 2012 1:27 pm

Re: Triggering Demand Hot water recirculation loop pump

Post by tnakelski » Fri May 08, 2015 2:03 pm

One other option would, use Mi Casa Verdelite Z wave controller and use Geo fencing which is included with the Verdelite, This would trigger the HW pump when you're home via a z wave outlet. You just need a Smartphone(s). Oops just saw your post that you are normally home so this really isn't an option for you. You stated that "Maintaining a constant hot loop when not in use is expensive" did you actually see a lot higher cost per day when the HW Circulator pump is used. These pumps usually shutdown when the water temp gets to 90 F. I have one and the pump is located about 50 feet from the hot water heater. I really didn't see a jump in cost when using it. During the day since both of you are home hot water is used on and off during the day which actually helps the HW Circulator pump do its job. At night when sleeping it would be wasteful having it run, use the timer. Since you have the GEM try a day or two without the HW Circulator pump and see how much the hot water heater is costing you. Then track it with the HW Circulator pump on and see what the difference is. I'm assuming your hot water heater is electric. One other side note in a traditional setup domestic hot water actually accounts for about 20% of total energy usage.
nbarnard
Posts: 57
Joined: Mon Apr 20, 2015 3:37 pm
Location: New Brunswick

Re: Triggering Demand Hot water recirculation loop pump

Post by nbarnard » Sat May 09, 2015 9:41 pm

tnakelski wrote:One other option would, use Mi Casa Verdelite Z wave controller and use Geo fencing which is included with the Verdelite, This would trigger the HW pump when you're home via a z wave outlet. You just need a Smartphone(s). Oops just saw your post that you are normally home so this really isn't an option for you. You stated that "Maintaining a constant hot loop when not in use is expensive" did you actually see a lot higher cost per day when the HW Circulator pump is used. These pumps usually shutdown when the water temp gets to 90 F. I have one and the pump is located about 50 feet from the hot water heater. I really didn't see a jump in cost when using it. During the day since both of you are home hot water is used on and off during the day which actually helps the HW Circulator pump do its job. At night when sleeping it would be wasteful having it run, use the timer. Since you have the GEM try a day or two without the HW Circulator pump and see how much the hot water heater is costing you. Then track it with the HW Circulator pump on and see what the difference is. I'm assuming your hot water heater is electric. One other side note in a traditional setup domestic hot water actually accounts for about 20% of total energy usage.
Yeah the pump itself doesn't use much electricity (30w). I am starting to think the hot loop may not be the problem. I just installed the GEM and don't have enough historic data to be jumping to conclusions. Seems even with the recirc off and us away from the house it is still using nearly 400w to maintain temp instead of the 78w standby heat loss it is rated for. Using 0.4 Wh per hour.

Heater is only three or four years old too. Not sure if they loose efficiency over time or need to be drained periodically etc.
Teken
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Location: The Bad Lands

Re: Triggering Demand Hot water recirculation loop pump

Post by Teken » Sun May 10, 2015 10:09 am

The HWT should be drained based on the type of water quality you have on site. By default your HWT should be fully drained and flushed once a year. This ensures sediments are removed and the Anode / Cathode is free of floating particles.
Teken . . .

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tnakelski
Posts: 74
Joined: Tue Sep 11, 2012 1:27 pm

Re: Triggering Demand Hot water recirculation loop pump

Post by tnakelski » Mon May 11, 2015 6:53 am

Maybe check the settings on the CT's , 400 watts sounds like a lot. During the period of standby (no water draw) do you see a spike as if the element is firing up? My feeling is either the element is on or off.
nbarnard
Posts: 57
Joined: Mon Apr 20, 2015 3:37 pm
Location: New Brunswick

Re: Triggering Demand Hot water recirculation loop pump

Post by nbarnard » Mon Jun 08, 2015 6:56 pm

Teken wrote:The HWT should be drained based on the type of water quality you have on site. By default your HWT should be fully drained and flushed once a year. This ensures sediments are removed and the Anode / Cathode is free of floating particles.
Just a followup on what I found. Drained tank and checked elements, minimal buildup/sediment. Turns out my DHW loop was circulating on its own even with pump off, just with convection. After closing the ball valve on end of loop heater dropped down to 80ish watts on standby. I ended up purchasing a WebPowerSwitch and adding an electric ball valve to the loop. Now I have loop pump and valve controlled via script running on web switch. Works great!
penguinshockey
Posts: 25
Joined: Sun Apr 12, 2015 8:47 pm

Re: Triggering Demand Hot water recirculation loop pump

Post by penguinshockey » Mon Nov 02, 2015 1:54 pm

Hi Nathan -

Now that you have been monitoring your new setup for nearly six months - I was wondering if you determined it to be a cost effective convenience? I have a hot water recirc loop which circulates the hot water from the water heater to the farthest faucet then back thru the cold water line. There is a temperature control valve located between the hot and cold water lines at the farthest faucet. Can't remember what it is set for but it maintains a given temperature at that faucet. Though the pump may be running, there may be no flow. I have a temperature probe at the cold water inlet and hot water outlet of the water heater so I can monitor the hot water temp. One of the benefits is that I can see when the recirc loop is active. I'm currently testing to determine costs.

Jim
nbarnard
Posts: 57
Joined: Mon Apr 20, 2015 3:37 pm
Location: New Brunswick

Re: Triggering Demand Hot water recirculation loop pump

Post by nbarnard » Mon Nov 02, 2015 2:26 pm

Hi Jim, if I recall, it was costing me about 300-400$ annually to run the hw recirc pump (based on usage of hot water heater). This would be offset somewhat due to losses in the line each time you turned on fixture to get hot without a dhw.

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nbarnard
Posts: 57
Joined: Mon Apr 20, 2015 3:37 pm
Location: New Brunswick

Re: Triggering Demand Hot water recirculation loop pump

Post by nbarnard » Mon Nov 02, 2015 2:30 pm

A big problem for me was even when I shut recirc pump off the system continued to cycle due to heat rising and cold falling. I had to install an electronic ball valve to act with pump. Now I have system set to run total of 3-4hrs daily based on timer. I figure $300 annual savings. Next time I would super insulate hot water loop, and not with the 3/8 foam- which I did already.

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