Setback for hot water tank?

Yeah Ano, you don't have a heating problem, you have a cooling problem. So lets talk about how much you have to spend for cooling? J/K. :)
 
dgage said:
Yeah Ano, you don't have a heating problem, you have a cooling problem. So lets talk about how much you have to spend for cooling? J/K. :)
 
This is where heat pump hot water heaters really are nice.  Put them inside your house, and they double as an AC unit.  They pull heat from the room and dump it in the water.  Then when you use the water the heat goes down the drain and out of the house (at least a lot of it does).  
 
I have one in the attic of my office.  The attic is inside the insulation envelope (spray foam on the roof deck).  It helps keep the attic cool and dehumidified which of course helps keep it cooler in the rooms below since there is no insulation between the attic and the rooms below.
 
SteveQ said:
'Lou Apo' timestamp='1365125428' post='193756']How about this. Put a "T" fitting on your hot water tank outlet. Thread the T fitting in with the long axis up and down so you have a straight shot into the tank from the top. Use the side port for your water to the house. Use the top port to thread that thermometer. A solar powered manual gauge is not quite what I was looking for. I wanted something that I could connect to my home automation system. I can manually measure the water temperature by opening the sillcock about 3feet from the water heater and sticking a thermometer in the outflow. Installing a tee fitting on the top of my water heater is a major issue; a lot of soldering would be required. I don't really need to know the temperature, do I? Steve Q
 
 
Here you go.  An RTD sensor.  Plug this into a CAI webcontrol and have it post values to your server.
 
http://www.automationdirect.com/adc/Shopping/Catalog/Process_Control_-a-_Measurement/Temperature_Sensors_-a-_Transmitters/RTD_(PT100)_Sensors/Probes_(with_Hex_Nipple)
 
or 
 
http://www.ebay.com/itm/RTD-Pt100-ohm-Probe-Sensor-L-300mm-long-type-PT-NPT-1-2-Thread-with-Lead-Wire-/321048857761?pt=LH_DefaultDomain_0&hash=item4ac000cca1
 
This is cool, thanks for finding it. Still requires a lot of changes to my water heater connections but would fit nicely into my current temperature monitoring setup.

I'm not sure there would be much benefit for me to try to regulate the hot water temperature. I think my faucets and shower valves do that already. The dishwasher has a built in water heater so no need there. Perhaps the washing machine might benefit but we never use the "hot" cycle. If the water was hotter, we could take longer showers but we are trying harder to do just the opposite. So, I think I will leave things just the way they are now. I'm happy!

Steve Q
 
dgage said:
Yeah Ano, you don't have a heating problem, you have a cooling problem. So lets talk about how much you have to spend for cooling? J/K. :)
 
AC is another story. :blush:  Wonder if they make a hot water cooler? 
 
SteveQ said:
This is cool, thanks for finding it. Still requires a lot of changes to my water heater connections but would fit nicely into my current temperature monitoring setup. I'm not sure there would be much benefit for me to try to regulate the hot water temperature. I think my faucets and shower valves do that already. The dishwasher has a built in water heater so no need there. Perhaps the washing machine might benefit but we never use the "hot" cycle. If the water was hotter, we could take longer showers but we are trying harder to do just the opposite. So, I think I will leave things just the way they are now. I'm happy! Steve Q
 
I think it is more about being crazy HA than about actually saving money.  But if you were pretty consistent in your water usage, you could have it heat the water just hot enough at each stage of the day.  Like before your morning showers it would kick up just hot enough to complete the showers and shut off.  After you finish your shower, the tank would be cooled down, but you wouldn't have it heat the water at that time since you would be going to work.  Then a couple hours before you come home from work you could have it kick up good and hot to carry you through your high priced electricity hours.
 
ano said:
AC is another story. :blush:  Wonder if they make a hot water cooler? 
 
They have those for pools.  Summertime around here gets them well into the 90's.  Not very refreshing, almost like a hot tub.
 
jdale said:
We've had some long power outages here. You can still take a hot shower 24 hours after the power has gone out. Just not a really long one.
We had work done on our gas lines last year and the gas was turned off.  It was the 3rd night before I noticed that the pilot light had to be relit, and that was after my wife and I showering each day and the kids' bath each night.
 
dgage said:
Yeah Ano, you don't have a heating problem, you have a cooling problem. So lets talk about how much you have to spend for cooling? J/K. :)
I'm all for more efficient cooling - we're about to enter the time of year when my electric bill jumps up to $800-$900/month trying to cool a 6yr old 4K sq ft home...  The Whole House Fan paid for itself in 2 months but when it never gets under 74° outside, it's worthless; and we're hole all day so we really have no choice but to run the AC!
 
The problem with heating and cooling is that we always heat and cool more than what is really needed. For example, I have a 50 gallon water heater but I hardly ever use 50 gallons of hot water per day (only when we have guests). But I specifically installed a bigger water heater so I could have enough extra capacity to handle extra showers. It would probably have been better to have installed 2 smaller tanks and just turn on the second tank when guests are coming.

I've done quite a bit of bathroom remodeling over the years and for one I designed a shower that included full body sprays. When I did the calculations on water requirements, it turned out the shower would have used 50 gallons of hot water in 8 minutes. The manufacturer recommended 2 - 80 gal water heaters! So we changed the design from 6 body sprays to 2.

Central air conditioning is a similar issue. We want to cool our entire house but we we only live in a small part of it. Open floor plans and vaulted ceilings make the problem worse. Again, it would be better to have multiple smaller AC units to cool only the living space we really need. As much as I hate window AC units, I installed one last year in our upstairs bedroom. It was the only affordable/ practical way to get more cooling upstairs. We don't have to use it much and I was able to integrate it into my home automation system so I can turn it on remotely when needed.

Steve Q
 
SteveQ said:
The problem with heating and cooling is that we always heat and cool more than what is really needed. For example, I have a 50 gallon water heater but I hardly ever use 50 gallons of hot water per day (only when we have guests). But I specifically installed a bigger water heater so I could have enough extra capacity to handle extra showers. It would probably have been better to have installed 2 smaller tanks and just turn on the second tank when guests are coming. I've done quite a bit of bathroom remodeling over the years and for one I designed a shower that included full body sprays. When I did the calculations on water requirements, it turned out the shower would have used 50 gallons of hot water in 8 minutes. The manufacturer recommended 2 - 80 gal water heaters! So we changed the design from 6 body sprays to 2. Central air conditioning is a similar issue. We want to cool our entire house but we we only live in a small part of it. Open floor plans and vaulted ceilings make the problem worse. Again, it would be better to have multiple smaller AC units to cool only the living space we really need. As much as I hate window AC units, I installed one last year in our upstairs bedroom. It was the only affordable/ practical way to get more cooling upstairs. We don't have to use it much and I was able to integrate it into my home automation system so I can turn it on remotely when needed. Steve Q
 
 
It really shouldn't be an issue have a bigger hot water tank than you typically need.  The solution to having "too much" hot water is to simply turn the temp down.  And by keeping the hot water at a cooler temp, you have a lower delta and thus less heat loss from that respect.  But you do have more surface area to lose heat, but less surface area per gallon.  My bet would be that keeping 50 gallons at 120 has less heat loss than 30 gallons at 140, but I don't have any data to back that up. The only caveat to that is the risk of growing legionella in your tank by failing to keep it hot.  Someone would need to do more research on the legionella thing, it may be that you can "shock" your tank every x days by cranking the temp up for a brief period of time, or maybe you can't.  It would just depend on the legionella life cycle.
 
I have made an attempt to automate our water heater some years back, but when I have learned that the reason to keep the water at 130F is to control Legionella, I started following published research on the subject. So far I have seen conflicting opinions on the best way to combine energy efficiency and bacteria control. What most research agree on is that Legionella will die at or above 140F and will become dormant below 68F. Anything in between can have potentially devastating consequences, considering that this bacteria is gram-negative, resistant to common treatments and can cause instant lethal shock. So I have decided that the health of my family is more important than saving a few bucks and discontinued the daily heater automation.
 
We still turn the heater off when go away for a week or longer, but program to turn the heater back on for at least a day at 140F before our return and then recirculate the water a few times to address any "spill-away" in the pipes. To do that, we set the water thermostat to 140F before leaving and use the relay connected to OP2 to disconnect the wire between the thermostat an the heater. The thermostat will be calling for heat, but the heater will not receive the call. Then simply turn the relay off a day before scheduled return, and the heater will begin heating the water. After return home, we would set the thermostat back to 130F.
 
You can read a few publications on the subject here:
 
http://www.who.int/water_sanitation_health/emerging/legionella.pdf
http://www.touchbriefings.com/pdf/13/Hosp031_t_Armstron.pdf
 
On the flip side of legionella is scalding.  120 is the recommended temp to avoid that.  So if you have kids, what is one to do?
 
And good luck with 68.  I'm not sure the water is even that cold in the winter around here.  "cold" water here is around 80 in the summer.
 
In my last two homes I installed thermostatic faucets - that puts the temp limit at point of use. So you can choose the water heater temp based on other factors.
 
Thermostatic faucets is my preferred type also, they are great especially if you have kids. We actually have installed a shut-off valve and water meter at the tub, and it turns the water off after exact number of gallons, so you don't have to watch it and still get perfect temperature with the thermostatic valve.
 
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