Monitoring water heater?

I have a water heater heating the shop floor. It's a propane
natural vent model with a pilot light. How can I monitor and log
the running time of something like this? Mainly just want to
know how many hours a day it runs not so much as when it
runs.

That is not a very efficient way to heat water, and if it has no electrical components it will be kind of hard to time it. You could put an air conditioner thermostat on it somehow that would start and stop a clock when ever it is burning.

find somebody with a gas meter for propane then you will be able to figure how many btus you are using per hour

Preferably use a logging counter with probe similar to a thermocouple. Probably never use it again so here's a relative safe dependable suggestion that might spark an idea of your own. All older and many newer gas furnaces have a switch in the heat exchanger that closes on heat rise and turns the blower on. Place the switch in the flue bonnet and wire to an electric clock that doesn't reset and start blnking every time it's disconnected. Hit up a hvac technician to pull the switch from a furnace that is being replaced.

Don't you have a pump that turns on and off?

Or get a simple solar cell, mount it where it can see the flame. Use the current to kick on a relay and send that to a timer or clock or ??

(quoted from post at 19:35:10 01/22/13) That is not a very efficient way to heat water, and if it has no electrical components it will be kind of hard to time it. You could put an air conditioner thermostat on it somehow that would start and stop a clock when ever it is burning.

Click to expand...

This is what I would do. Or if it is LP, you know all the fuel from that tank is going to heating the floor.

If your heater ha a 110 volt circuit that runs the pump or anoter part of the system, put an ordinary clock on that circuit and monitor the clock. If yoy set the clock at 12:00 when you start , say at 07:00 in the morning and then read the clock at 17:00 in the evening and the clock says it is 05:00 you will know that the heater ran 5 hours. I did that with my home oil burner one winter. Interesting!

Fred

This is what I have in the chicken house, might be to pricey for your setup. The heat has been running for 545 hrs. Three 400K btu boilers

Nate

I'd think that monitoring the pump would be fairly close. The heater should seldom come on while the pump is stopped, and will run pretty much constantly when the pump is running.

The best way would be to meter the gas running into the heater, but meters for natural gas and propane aren't cheap.

Another alternative would be to put a thermostatic switch on the chimney. A furnace limit switch should work for this purpose. Or you could install an optical flame sensor (like those used in torpedo heaters) in the bottom of the heater.

How do those optical flame sensors work? Applying voltage to it and changing resistance when it sees a flame or does it produce voltage when it sees a flame. I like the idea but don't know how to work it into a useful circuit.

The water heater is in tandem with a woodburner so the pump operation is independent of the burner on the waterheater. The water heater is to take up the slack when I am not home or its really cold out. Would like to get an idea of how much it runs in a day.

Bill, you made me do some homework.

It seems that the most common variant is a cadmium sulfide photoresistor. I found a spec sheet for one that's commonly used in oil furnaces, the Honeywell C554A. According to the spec sheet, it has a resistance of over 20,000 ohms in the dark, which drops to less than 1600 ohms in the presence of a flame. How you would use this device depends a lot on what sort of meter you intend to use. A problem with this particular device is it's only rated for 60 volts peak or about 40 Vrms (clearly intended only for 24 volt controls). But I suspect the ones used in torpedo heaters can handle 115 volts, if that's what you need to do.

You also need to find an hourmeter. Hobbs makes a 115V, 60 Hz hourmeter that draws 3 watts, which works out to be 26 milliamps. Put a CdS sensor similar to the C554A in series with a Hobbs meter, I think it will work. However, a solid-state meter with a higher input impedance would be a better choice, you could use a potentiometer to adjust the sensitivity of the sensor.

Obviously the exact components you use depend on what power you have available. Many systems like yours have 115 volt controls, while others use 24 volts. Of course you can always add a transformer to drop the voltage.

(quoted from post at 10:51:24 01/23/13) How do those optical flame sensors work? Applying voltage to it and changing resistance when it sees a flame or does it produce voltage when it sees a flame. I like the idea but don't know how to work it into a useful circuit.

The water heater is in tandem with a woodburner so the pump operation is independent of the burner on the waterheater. The water heater is to take up the slack when I am not home or its really cold out. Would like to get an idea of how much it runs in a day.

Click to expand...

ot a Remington-150 torpedo heater. The flame sensor (looks like cadimum sulfide photo type) in it does not switch the fan/pump & ignitor directly, but ties to a "controller" which seems to operate as a relay (with a time delay to allow flame to build enough to allow flame sensor to detect it) which powers fan/pump & ignitor. If flame sensor does not respond within ~5 -10 seconds, the relay opens & shuts it down. So, flame sensor is not switching much current. PP216 (HA3019) sensor was bought from DESA International for $15. P.O. Box 719, 2701 Industrial Dr,, Bowlingreen, KY, 42101 to replace the sensor in my heater. Works now!

Hey Bill, I just had another idea. I figured something like this device must exist; a quick google search found it. Just stick it somewhere where it can detect the operation of your heater, then whenever you want to you can download the history to your PC.

The nice thing about this approach is you can easily get the data into a spreadsheet and do all kinds of analyses. For example, you should be able to figure out how many Btus you used each day of the month.

The only drawback I see is that you need to use their proprietary software to configure the logger and download the data. If your PC runs Windows, that won't be a problem.
USB temperature data logger