Thread: Two 50 gal Parallel water heaters

I did an inspection the other day and found something I'd never seen before. This house has two water heaters side by side. They are plumbed so that one feeds into the other. Above the second water heater is what appears to be a pump. The pump is plumbed but the electrical wire was never connected. The seller was unsure what it was and was hoping I could explain it's purpose. Well I couldn't but I told them I would find out. So please help. The house is on a private well and septic. The pump says Cartridge Taco Circulator. Any ideas? I have some photos but I'm having trouble getting them uploaded.

Similar Threads:

• Two Attic Water Heaters (GAS)
• electric water heaters
• Re: Publications for ages of Water Heaters
• Laars Heating Systems Recalls Gas Boilers and Water Heaters
• Laars Heating Systems Recalls Gas Boilers and Water Heaters

Sounds like the heaters are plumbed in SERIES, not parallel.
The pump (from your description) is a circulator pump to keep hot water at all points in the circulation loop. Usually there will be a return line at the farthest fixture. Some will have thermostats, some will have timers, some will just run continuously.

Hot Water Recirculating Pumps

Originally Posted by Jim Luttrall

Sounds like the heaters are plumbed in SERIES, not parallel.
The pump (from your description) is a circulator pump to keep hot water at all points in the circulation loop. Usually there will be a return line at the farthest fixture. Some will have thermostats, some will have timers, some will just run continuously.

Hot Water Recirculating Pumps

Yep.

Sounds like what that is.

Thanks Jerry, I will let my client know.

Originally Posted by Bill Anglin

Thanks Jerry, I will let my client know.

Bill,

Jim gave the information first, I just seconded his post.

Could be parallel with a recirc pump, here's an example from last week:

Also, take a look here:

http://www.hotwater.com/bulletin/bulletin64.pdf

Also check for check valves -- without them that pump can easily push warm water back up the cold water line, and if the pump is ever off, cool water can be pushed back up the return line creating lukewarm water at the faucets.

Originally Posted by Michael Thomas

Could be parallel with a recirc pump, here's an example from last week:

Also, take a look here:

http://www.hotwater.com/bulletin/bulletin64.pdf

That there looks like a great install. One of the better ones I seen in a long time.

Originally Posted by Michael Thomas

Could be parallel with a recirc pump, here's an example from last week:

Also, take a look here:

http://www.hotwater.com/bulletin/bulletin64.pdf

Originally Posted by Ron Hasil

That there looks like a great install. One of the better ones I seen in a long time.

I still prefer series connection as there is a larger supply of hot water available and the cost of replacing an element in the first tank is not much, and, over the life of the first heater (no different than if only one heater was connected) the cost is not objectionable (otherwise the cost to replace a single heater would also be objectionable), and, if the cost IS objectionable (say such as this economy as it stands now), the second heater can take over the entire function as though there were only one heater installed - then replace the first heater (if the entire water heater needs replacement) later.

To me, the life of the first water heater will be no different than the life of a single water heater and that should not be the deciding factor.

Besides, one could adjust the first water heater thermostats down to their lowest setting to serve only to 'pre-warm' the water going into the second water heater which is set to heat the water to the desired temperature.

There are several ways to avoid that concern with the first water heater.

I think the idea of having two 50's side by side is to increase capacity and save money. The hundred gallon units are very expensive. I'm thinking they should be plumbed in parallel to provide more hot water capacity in storage. Plumbed in series only makes one a pre-heater for the other and does not provide additional usable hot water. It may reduce the rise time though and in effect, end up with the same usable supply.

Originally Posted by Dana Bostick

I think the idea of having two 50's side by side is to increase capacity and save money. The hundred gallon units are very expensive. I'm thinking they should be plumbed in parallel to provide more hot water capacity in storage. Plumbed in series only makes one a pre-heater for the other and does not provide additional usable hot water.

Actually, when in series you get one complete tank of hot water and the first tank acting as a pre-heater allows the second tank to virtually keep supplying hot water as it now only has to heat its supply water up much less to keep it hot. In series one water heater heats COLD water to be WARM, the second water heater only has to heat WARM water to make it HOT.

With the tanks plumbed in parallel you get a similar initial large supply, but then BOTH tanks are now having to heat COLD water to get it WARM after the initial hot water is drawn off the tanks.

Originally Posted by Jerry Peck

but then BOTH tanks are now having to heat COLD water to get it WARM after the initial hot water is drawn off the tanks.

(You're not trying to say it uses more electricity in parallel are you?)

Originally Posted by Kyle Smith

(You're not trying to say it uses more electricity in parallel are you?)

Nope.

Uses the same, most likely.

Especially with a circulating pump.

given the amazing recovery rate of Gas Fired Water Heaters me thinks that connecting them in series would provide more than adequate supply of hot water as well as saving energy costs since the second tank would heat the water up to desired tempreratureeon ly on demand with the first tank ''tempering' the incoming water.

why anyone would need that much hot water unless these tanks feed a radiant hot water heating system i do not know.

How many showers do these people take anyways?

cheers

The possibility also exists that water tanks could be installed in series and have a diverter valve installed so that one tank serves as a hot water reserve or storage tank in cases where hot water demand is uneven, causing the main tank's hot water to be used up. This kind of installation is more common in commercial or institutional settings. For example, in retirement communities using common water heating, many residents might take showers at around the same time each day. This kind of situation could result in a heavy hot water demand only during certain times of the day. Maintaining a large volume of hot water just to have hot water on hand all of the time would be energy wasteful. The problem arises when hot water tanks sit around too long without being flushed. In one case, nursing home residents developed Legionnella-related diseases because a storage hot water tank was not flushed often enough. To prevent scalding, the institution had lowered the hot water temperature rather than using anti-scalding valves or faucets. This meant that the tanks were heating water to temperatures favorable to Legionella growth (most favorable temperature being around 104 degrees F) rather than to a killing temperature. So, the tank incubated Legionella during the off hours and then when hot water demand went up, the incubated Legionella was pumped into the showers, where it exposed the residents. They discovered the source when one resident who was not so fond of bathing did not come down with Legionella-related disease despite being similar health-wise to the ones who did. I have not seen such a system in any homes in our area--yet. But, I have observed that energy-saving methods used in institutions have been making their way into the residential market. I can see a system such as a storage water tank system ending up in a residence.

Originally Posted by Joe Laurieri

How many showers do these people take anyways?

The house served by the hot water heaters in the pictures was 5 1/2 baths.

I have a near perfect plumbing setup at my house, 7yrs now and it works great.

Two series electric water heaters.

The first one is on a switch so it just serves as a holding tank unless we have company. It gains some free heat sitting there in the garage (the well water is really cold).

The second one has a recirc loop with a timer, only run the timer during the am hours and around dinner time. The loop is installed under the slab.

The two distant fixtures have small 2.5 gallon water heaters under the sink for instant hot water when the loop is not running. When the loop is running they are idle

When they get old I can replace all 4 myself just for the cost of new electric units which are much cheaper than gas ones.

Power bills are low for several reasons, house on a slab (thermal mass), very little hot water wasted, R38 in attic, Seer 14 variable speed heat pump units and power company discount for being all electric.