aquastat install


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Old 12-27-12, 11:02 AM
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aquastat install

I need advice with re-connecting a water heater to the oil-fired boiler. The previous owner had the system connected in this fashion, but disconnected some things before we bought the place. The water piping is still in place, but the electrical/control has all been disconnected. I would like to reinstall the missing pieces and have the option to make/supplement hot water via the furnace during winter months or during an emergency situation (e.i. when running off the generator).
The circulator pump is disconnected, but has wire/conduit that runs to the lower heating element. There is an unused 120V two-wire connection right above the water heater that is on the same circuit as the furnace. This would be available while running the generator; the 240V line to the water heater would not be available.
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My initial plans are to remove the wire/conduit leading to the lower heating element, install a clip-on aquastat (such as*Grundfos 595444 3/4-Inch Clip-On Aquastat Control - Amazon.com), install a switch on the unused 120V line, and power the aquastat/pump via the switch.*Thoughts? Suggestions?*Thanks in advance!
 
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Old 12-27-12, 11:18 AM
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Are you trying to heat an electric hot water heater with your boiler or do you have a coil in the boiler for DHW what you want to use as a back up?
 
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Old 12-27-12, 11:37 AM
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There is a coil in the boiler.
 
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Old 12-27-12, 12:16 PM
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I'm confused... by the tilt of his head, I think your chicken is too!

It appears that someone tried using the electric water heater in an 'aqua-booster' fashion.

Take a look at Figure 3 in this PDF

http://www.htproducts.com/literature/lp-32.pdf

What I don't get is why the wires for the pump are going into the water heater... it would appear that the guy was powering the pump from the internal thermostat.

Are the electric elements in that water heater still in use? That's your current source of domestic hot?
 
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Old 12-27-12, 01:01 PM
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I don't understand the connection to the water heater either.
The lower heating element is still in use. The circulating pump is not connected.
 
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Old 12-27-12, 01:59 PM
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I'm sure it's a 120VAC pump motor... I wonder if the OO did something very silly... which I'm not even going to mention what I'm thinking so as not to give ppl bad ideas...

But I think he was running the pump from the thermostat that also ran the heating element. Probably only running the pump in conjunction with the electric element... or maybe he did something else very silly.

But yeah, you could use an aquastat to run that pump. Problem would be getting it to where it sensed the temp inside the tank.

How would you position the clip-on so that it didn't come on when the pipe simply cooled off during times of no hot water use? It really needs to sense the temp inside the tank.
 
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Old 12-27-12, 03:18 PM
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I didn't really think about the pipe cooling down...

The pipe between the boiler and the hot water tank is currently warm, 120F according to the multimeter.

The piping between the pump and boiler and also the pump and tank are both cool to the touch.

Placing the aquastate in either position seems like it would cause problems...

Are there any alternatives?
 
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Old 12-27-12, 03:48 PM
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Are there any alternatives?
I suppose that if you could SAFELY (without shorting out the 240 to the thermostats and the elements) get a probe up under the insulation in the tank that would work...

I recently saw a setup ( Geyser heat pump add on )

Geyser-R | Nyle Systems – Energy Saving Heat Pump Solutions

http://www.nyle.com/downloads/GeyserR_Manual.pdf

Where they have the probe stuck under the insulation down by the drain valve...

Might be an option?

Instead of an electromechanical a'stat, perhaps one of the Ranco ETC or Johnson A419 with a thermistor probe on a wire would work?

What might not be a bad idea for starters, just to see if the pump even works, and to get an idea of how efficient...:

Wire a line cord to the pump, shut off the electric to the WH , run the hot water in the tank down below setpoint and plug the pump in to see how fast it recovers.
 
 

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