Using electric water heater as storage for tankless (Steamhead)

Steamhead

I seem to recall someone posting a diagram showing how to use a standard electric water heater as a storage tank fed by a tankless coil. I have a couple of places where this setup would be ideal.... could whoever has the diagram please post it again?

Thanks in advance.

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Unknown

I don't have a diagram , but

I can tell you how we pipe them . Bronze circulator pumping away from the bottom of the tank to the inlet of the coil . Tee in the cold of the house between these 2 . The outlet of the coil goes directly to the cold side of the tank , and the hot side of the tank goes to the hot of the house .

Sometimes you see a check valve on the pipe right after the circulator to force all the water through the coil , but someone mentioned that it can overheat what you set the tank for , and that sounds right .

Steamhead

How do you control it?

Is there a way to put an aquastat on the tank, or do you use a transfer switch with the existing tank thermostat so it can get heat from the tankless or the elements as desired? This way if the boiler quits you still have hot water.....

And- will a standard bronze circ like a Taco 007 pump enough water thru the usual 1/2" coil or do we need something bigger?

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techheat_2

I use the existing surface aquastat to control the circulator. 006B is fine.

techheat_2

This diagram is similar

http://www.htproducts.com/literature/lp-24.pdf

Steamhead

Thanks

That diagram looks just like what Ron was describing except that the SuperStor has some extra tappings to hook up the coil. But I'm still looking for an easy way to switch the tank from the coil to the elements, so they will still have hot water as for example if they run out of oil........

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hr

A dual stat

this is similar to how I control a tank from an outdoor wood boiler. The standard, installed electric water heater stat is set about 10 degrees lower than the stat you use to control the tankless.

Should the boiler fail the WH tank stat could bring on the elements. There are probably two stage setpoint or aquastats out their that could control both from a control mounted in a tank well, maybe Bill "Honeywell" has a part number.

It would function just like a two stage wall thermostat.

Would a boiler triple aquastat have all these functions and a punp relay to boot? I would have to look one over.

Another nice feature is to install a tempering/cald valve on the outlet, should the tank over geat. I use the simple Honeywell/ Sparco for this. A nice protection feature and extends the hot water supply if you run over 130 temperatures.

hot rod

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Unknown

We buy the electric tanks

and use the lower surface mount aquastat to control a 006 circulator . I am not too sure about recovery times , but we recently installed a steamer and reconnected the existing aquabooster that was cold for days , and it seemed like it heated up in minutes . Its a good idea to have the elements hooked in as a backup , but we don't do it .

To have it switchable to use the elements for a backup gets a little tricky . One way is to use just the upper element for emergency heating , or maybe find a tank with a good side tapping for a relief valve and use that for an aquastat , while keeping both elements connected . Bradford - White has a 220 V. electric tank that uses one element in the lower part of the tank , so the upper part is empty - pretty easy to mount your own surface mount there .