Automating Water Heater?

[az1324]

I have a normal gas water heater. I'd like to automate it so that it can be taken offline when no one is home. I know the best idea is to replace it with a tankless but I'm not quite ready to do that.

So are there any electronic thermostats for gas water heaters that can be controlled externally?

The only one I have been able to find is this Sears/Honeywell combination but I can't find any information on the control unit itself.

It might not be possible to retrofit something like that onto a standard water heater depending on how it is deigned.

The other idea I had was to put an electronic valve on the line from the control to the burner so that the pilot would remain lit but the burner would never fire unless the valve was open. But I am not sure if this would somehow cause damage to the thermostat/control unit.

If anyone has experiences doing this let me know.

Thanks.

 

[Frunple]

I have a normal gas water heater. I'd like to automate it so that it can be taken offline when no one is home. I know the best idea is to replace it with a tankless but I'm not quite ready to do that.

So are there any electronic thermostats for gas water heaters that can be controlled externally?

The only one I have been able to find is this Sears/Honeywell combination but I can't find any information on the control unit itself.

It might not be possible to retrofit something like that onto a standard water heater depending on how it is deigned.

The other idea I had was to put an electronic valve on the line from the control to the burner so that the pilot would remain lit but the burner would never fire unless the valve was open. But I am not sure if this would somehow cause damage to the thermostat/control unit.

If anyone has experiences doing this let me know.

Thanks.

Before you do this, why not take a look at Legionnaires' disease and you'll see that a good way to catch it is by heating and cooling the same water over and over again.

 

[Techvet]

I was on the hot water heater quest about a year ago while we were finishing our new home and sort of looked for a similar item, albeit one with an IP addressable thermostat. In the end, I could not find one. Seems that IP addressability is not high on the 'must have list' for water heater manufacturers. However, I did get a power vent LP gas model whose thermostat is AC powered. I inserted a UPB controlled receptacle in the mix and and now I have easy HW Heater control. However, I cannot adjust the thermostat beyond simply turning it on or off. Oh, and there is no standing pilot on this particular model, so loosing power is no big deal.

 

[SteveQ]

I assume you are trying to save a few bucks by not using gas to heat the water while you are not home. Although this is a very "green" idea. The amount of gas saved is far overshadowed by the risk you are creating by trying to modify the gas line to your water heater. This could be very dangerous!

If you want to save gas, turn the valve off when you go on vacation. Otherwise leave it on.

Steve Q

 

[BrettS]

I assume you are trying to save a few bucks by not using gas to heat the water while you are not home. Although this is a very "green" idea. The amount of gas saved is far overshadowed by the risk you are creating by trying to modify the gas line to your water heater. This could be very dangerous!

If you want to save gas, turn the valve off when you go on vacation. Otherwise leave it on.

Steve Q

I think that's pretty good advice. As long as you're not leaving to go away very frequently I think you might be better off with the manual option.

I have an electric water heater, which is much easier to automate, and I've been going back and forth about whether or not to automate it. Everything I've read seems to indicate that turning off the water heater during the day and then turning it on shortly before you shower in the morning may save some energy, but not very much. The energy you save probably won't offset the cost of automating it to begin with. Modern water heaters are pretty well insulated and don't loose much heat during the day anyway. With a gas water heater it would probably be more expensive to automate... and more dangerous if you need to do it yourself.

Brett

 

[az1324]

Hmm. Yes good points on working with gas lines. The house is often left unoccupied for weeks/months at a time and I don't always remember to turn off the water heater so I thought it would be nice to have a way to do it automatically.

 

[znelbok]

That makes all the difference. If you are going for long periods I think the justification is there.

All you need to do is put a solenoid valve on the gas line. Sounds simple, but get a gas fitter to do it so its done right with the right valve.

A small leak around the valve and the operation of the valve could spell disaster as a spark ignites the cloud of gas.

Re-lighting the heater will probably be manual though - depends on how you light it now and what flame out protection it has.

You will want a valve that you dont need to keep power on for either position, otherwise you will be powering it for weeks to keep it shut. A pulse to close it and a pulse to open it.

Mick

 

[BrettS]

In that case I think it may make sense to automate it. Like Mick said, you could probably get a valve that would just cut the gas to the water heater. That would be safe and could be done remotely, but it would be inconvenient in that you would have to manually relight the pilot every time. Of course, it would be convenient to be able to restart the water heater when you're on your way to the house so you'll have nice hot water when you get there.

Techvet's water heater with the AC powered thermostat might be the best option. You could turn it on and off with a simple appliance module that way, and frankly, the cost might not be that much more than a valve. I haven't looked at gas valves, but I have been looking at water shut off valves and they seem to be in the $300+ range... I imagine that a gas shutoff valve would be at least that much and maybe even more because they'd want to try to do something to keep it from generating sparks.

$300+ is a good chunk of a new water heater and you wouldn't have to worry about retrofitting a gas line too... plus if your existing one is older you'd have the peace of mind (and energy effeciency) of a new one. Someone recently told me that most insurance companies won't pay claims on floods caused by water heaters that are more than 10 years old.

Brett

 

[az1324]

I don't want to cut off the gas completely because it is not always me that is returning to the house first and I don't want to make relighting the pilot a necessity. But if I did it might be easier just to switch the thermocouple connection rather than dealing with a gas valve. Killing the thermocouple would shut down all gas flow.

The water heater is only 2 years old.

If the cost is too high, I would just wait until I'm ready to put in a tankless. I think there are some tax credits for them also.

I might just have to keep manually turning it off (keeping the pilot) until then.

 

[Techvet]

I don't want to cut off the gas completely because it is not always me that is returning to the house first and I don't want to make relighting the pilot a necessity. But if I did it might be easier just to switch the thermocouple connection rather than dealing with a gas valve. Killing the thermocouple would shut down all gas flow.

The water heater is only 2 years old.

If the cost is too high, I would just wait until I'm ready to put in a tankless. I think there are some tax credits for them also.

I might just have to keep manually turning it off (keeping the pilot) until then.

FWIW, my new water LP gas water heater with the electric t-stat ran about $850-900 last year for a 50 gal tank - probably be a bit more now. It'd be hard to justify ditching a 2 year old heater, but with propane prices nearing $2.75-$3.00/gal this past winter it might be easier to justify. By the way, the same heater is available as a natural gas model. So far the UPB set-up I have works great for cycling the heater and it certainly avoids messing with the gas line. I should add that this heater vents through plastic pipe verses a conventional metal vent, which allows for horizontal venting.

 

[jeffw_00]

how about the fact that if you are turning it off only for hours, it takes more energy to get it back to temp than to maintain it at temp?

 

[politics123]

I assume you are trying to save a few bucks by not using gas to heat the water while you are not home. Although this is a very "green" idea. The amount of gas saved is far overshadowed by the risk you are creating by trying to modify the gas line to your water heater. This could be very dangerous!

If you want to save gas, turn the valve off when you go on vacation. Otherwise leave it on.

Steve Q

I think that's pretty good advice. As long as you're not leaving to go away very frequently I think you might be better off with the manual option.

I have an electric water heater, which is much easier to automate, and I've been going back and forth about whether or not to automate it. Everything I've read seems to indicate that turning off the water heater during the day and then turning it on shortly before you shower in the morning may save some energy, but not very much. The energy you save probably won't offset the cost of automating it to begin with. Modern water heaters are pretty well insulated and don't loose much heat during the day anyway. With a gas water heater it would probably be more expensive to automate... and more dangerous if you need to do it yourself.

Brett

Brett --

Unless you specifically purchase a well-insulated HW (I've never seen such at Lowes or HD), they can always be better insulated. Once I put a radiant barrier around my 1-year old model, I was surprised at how warm it got inside the barrier (I have flaps for the warning labels and thermostats... they're usually covered, but I can lift them up and touch the skin of the HW heater)

For a water-heater timer, remember that you'll always need X amount of HW. All you save with the timer is the passive heat loss for that X amount of water. You should measure your heat loss (disable the heater, measure the temperature at the top of the tank, and then measure the temperature 8-24hrs later do determine temperature loss) to determine whether it makes sense.

Passive heat loss within an 8hr window is going to be pretty minimal.

In general, there will be a far better return for your investment by reducing HW consumption. This is because you tend to be in your house more than you tend to be away for extended periods of time! The easiest ways to do that:
-Install low-fall faucets and shower heads
-Install energy efficient (front-load) washing machines
-Install energy efficient dishwaster --> don't do dishes by hand

 

[Techvet]

My observations have been that the water holds its heat pretty well for up to 24 hours. Getting it back up to temp takes no time and probably uses a bit less gas than just letting it run all day. But... mine doesn't run that much anyway, so I don't bother shutting it down during the day. If I'm planning to be out of the house for 2 or more days, then that is altogether different.

Depending on where propane prices go this next year, I'm toying with the idea of adding an electric tankless HWH to the mix. A propane version wouldn't be a bad idea aside from the fact that it really sucks the propane when it fires. Adding an electric tankless model would give me the benefit of being dual fuel, so I could pick the power source that is the cheapest. I've sourced an electric tankless unit that would serve the whole house, but it alone requires a 125 amp, 220V breaker (the manufacturer says that 200A incoming service is sufficient, but but I have 400A service coming to my home so I've room to spare.) Its technology actually modulates the current, so you only pull what you need, plus it activates with .25-.5 gal/min, so it'll get along nicely with low flow shower heads, etc.

 

[SteveQ]

I have an electric water heater. I have installed a monitor on it that tells Homeseer when it is ON. I am collecting data to measure the impact of reducing our hot water useage. I took a look at how often the water heater is ON when we are gone for 2-3 days. Although I dont have a lot of data, my water heater is ON for .43 hours per day when no hot water is being used. My water heater uses 3300 Watts when ON, so I use about 1.4 KWhrs to keep the water hot. My power cost is approximately $.15 per KWH. So my cost is roughly $6.00 per month.

On the other hand, on peak days we use about 3 hrs of water heater time which equates to - $1.50 per day or $45 per month. So if we could cut down our hot water usage by 10-15% we would save much more than the by turning OFF the water heater when we are not home.

That said, I am more interested in using my home automation system to help me conserve hot water useage: things like running the dishwasher every other day instead of daily.

Steve Q

 

[WayneW]

I have an electric water heater. I have installed a monitor on it that tells Homeseer when it is ON.

I monitor my water heater also, using a 220VAC relay. May I suggest you add rules to look for the water heater not turning on often enough (circuit breaker trip, bad thermostat) or staying on too long (bad thermostat, broken hot water pipe). It will take some trial and error, based upon your family & needs, but I think mine notifies me if the WH doesn't turn on for 10 hours or stays on for 50 minutes.