Buffer Tank Question

Uni R_2

My fairly new 40 gallon electric water heater will soon be without a job (woohoo) and I'd like to know if it could be used to help minimize cycling with a new Prestige Solo 110. My heatloss is 58K and dropping (i.e. the utility room still needs to be insulated) and the Prestige only modulates down to 30K gross. Based on the heatloss calculation, on a typical winter day here (30-35F), the heatloss will be right around minimum modulation for the Prestige at 28-32K, even less for the shoulder seasons.

Could you use a Monoflo fitting to divert return water through a buffer tank and then allow gravity flow to release the stored BTUs back into the primary heating circuit (there's constant circ on the heating circuit) once the boiler shuts off and the pump shuts down?

Instead of dropping the return straight down off the main heating circuit, the tee would go lateral towards the tank and then another tee would allow the return to drop down and head to the boiler. Unfortunately the tank and the main heating circuit are roughly the same height. I'd prefer to use the standard 3/4" tappings. The bottom leg across to the buffer would be 3/4" and probably copper to help the gravity flow down. The lateral and the main are 1.50" and the boiler piping is 1.25".

Uni R_2

Simon & Garfunkel

And the vision that was planted in my brain
Still remains
Within the sound of silence.

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No opinions?

hr

I don't

have an answer for that. Pumps and forced flows I can wrap my brain around. Gravity has a mind of it's own

Why not just put the tank in series and turn the boiler into a 48 gallon capacity?

hot rod

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Uni R_2

Rationale...

Thanks Hot Rod for your other response, I'll put here what I emailed to you earlier today when there were glitches with posting.

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OK... so here was my rationale.

There were two reasons for this. The first was what I felt to be the limitation of the tank. It has 3/4" tappings that I can totally trust. I really wouldn't feel comfortable using the element tappings, and I'd prefer to give the tank a new job rather than just adding to the landfill.

Given that, I was thinking that if the buffer could get filled at a slower rate (and also release heat back at a slower rate) it would actually be an even better buffer. Say the boiler's secondary circuit flow is 8gpm - that buffer tank would be about the same temperature as the primary heating circuit in just 5 minutes, and that is also when the return water is also at its coolest. I was thinking that if this only had a fraction of the flow when the boiler pump is running, say 2 or 3 gpm, then it would moderate return temps downs for 15 or 20 minutes and that this could be tuned.