Powered Damper Bradford White water heater

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NWCherokee

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I am in the process of replacing 23 yr old gas furnace and AC and was thinking about just replacing 23 yr old gas water heater tank around the same time (both in garage.) The existing is a typical 50 gallon / 40k btu tank and I can say that we always have the hot water we need when we need it. So I plan to replace with a Bradford White tank with same specs but was curious about savings or other advantages/disadvantages in going with a powered damper? I have a free outlet on the wall near the tank. Water heater is located in an unconditioned garage with insulated walls and insulated garage doors, so temps don't get too crazy either way.
 

Bannerman

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A powered damper cannot be simply added to a WH not equipped for that capability. For such capability, there are interconnects required to prevent the WH burner from igniting unless the damper is first verified to be fully open.

While there will be some standby heat loss occuring through the insulated shell into the unconditioned garage space, the larger area of heat loss will be from the exhaust vent tube running through the center of the water tank. With a naturally drafted unit, the largest volume of heat rising and exiting the chimney or 'B' vent will be while the burner is operating, but heat will continue to be transferred to the exhaust vent by the hot water in storage even while the burner is not operating. You are correct in wanting to stop that heat loss, but there are other methods that are in compliance to code.

Many gas appliances no longer utilize natural drafting and so must rely on a forced draft exhaust fan to eliminate products of combustion. Those devices are often vented horizontally through an exterior wall, thereby eliminating the need for a natural draft vertical chimney. Because tank type water heaters have not changed much in technology, modifications were needed so they could be utilized in homes without a chimney. Many WHs are now equipped with an electric forced draft fan so they maybe exhausted horizontally through an exterior wall.

Because the fan will move a larger volume of air than needed to eliminate the exhaust gases, that additional air will dilute the exhaust gases, lowering the temperature of the exhaust, usually permitting small diameter plastic piping to be utilized for exhaust venting.

A power vented WH will require electricity to operate the exhaust fan. Because the WH cannot heat water unless the exhaust fan is verified to be running, the gas valve will be interconnected with pressure and air flow switches which must be satisfied before the gas valve will initiate the sequence to ignite the burner so as to heat water.

Exhausting the WH horizontally will reduce the amount of standby heat loss exiting the exhaust vent while the burner is not operating. Whether the savings will be noticable for your specific application, I can't answer.

One disadvantage to a power vent WH, during power loss, no further water will be heated so once the hot water in storage has been depleted, that's all you get. I anticipate your current naturally drafted WH utilizes a standing pilot light and does not require external power and so will continue to heat water even during an extended period without electrical power.
 
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Terry

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A powered damper, unlike a direct vent, has no fan.

The Bradford White damper model RG2D50S6N has an energy factor of 0.68
The Bradford White atmospheric RG250T6N has an energy factor of 0.63

bw_gas_atomspheric_vent_damper_energy_star_1120.jpg



flue-damper-01.jpg
 

Bannerman

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Terry, it appears the diagram contains errors.

I anticipate the label 'Hot Water Outlet to Fixtures' on the far left, should rightly be labelled 'Cold Water Supply to Mixing Valve' since the arrow is pointing right to supply the mixing valve.

(I fixed the photo today, thanks for noticing, Terry Love)

Also, any hot water which is not to be tempered, would need to be obtained prior to the mixing valve.

That diagram would also be clearer if it showed the interconnect wiring between the motorized damper and the gas control valve.
 
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NWCherokee

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A powered damper, unlike a direct vent, has no fan.

The Bradford White damper model RG2D50S6N has an energy factor of 0.68
The Bradford White atmospheric RG250T6N has an energy factor of 0.63

bw_gas_atomspheric_vent_damper_energy_star_1120.jpg



flue-damper-01.jpg
Terry,

So I guess my question would be what is your opinion on going with the power damper version vs the atmospheric model (beyond the, what is it, 5% energy savings?) I have no desire to go tankless or hybrid for various reasons so I am not trying to pursue the lowest energy consumption at all costs. I just have an open outlet nearby so these two models are my direct replacement choices. I have not been able to find much real world information online for powered damper water tanks vs atmospheric. Usually the searches return results for atmospheric vs powered vent or tankless instead.
 

Clog

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Necroposting a bit, but, the choice is sometimes dictated by location of water heater.

I chose a powered damper, as opposed to a powered vent, because the interior location of the water heater was not adjacent to any exterior walls, and the cost to breach a new hole in the ceiling, through the attic, and open a roof penetration in a valley was not worth whatever dubiously marketed efficiency ratings hoped for in a powered vent, all costs considered.

A powered damper utilized the same venting system as the traditional atmospheric venting system that was combined with the furnace flue, and, the powered damper provided the advantage of a built in signaling logic to automatically shut off the gas valve, which I leveraged with a leak detection system and automatic water shut off valve, so that both water and gas supplies will shut off in the vent of a leak or a problem.

The powered damper provided a convenient step up in efficiency from a traditional tank, without the additional construction and rework required to incorporate a powered vent or tankless water heater system. After a couple of years with it, I've been happy thus far. It will take a couple of decades of service for me to say that it is "proven".
 
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