We bought this house three years ago. Although it is 200 years old, it had modern systems installed in the 70's. The house has two water heaters. One is an oil-fired heater that is a few years old and a stone-lined electric water heater that was probably installed in the early 80's.
My question is.... what is the best way to connect the water heaters? They are currently installed in parallel, meaning that when you turn on the hot water, water is drawn from both heaters in approximately equal amounts. This seems pretty inefficient. I am wondering if it makes more sense to connect them in series... meaning the electric is plumbed into the hot water pipes and the oil-fired is plumbed into the electric.
Any plumbers out there? Does it really make any difference how they are plumbed?
Bruce, I'm not a plumber, and being from Texas, no experience at all with oil fired water heaters, but the plumbing you described certainly sounds unusual to me. I would think with two water heaters, the first question would be where are they located in relation to the faucets they serve.
Just as one example: When we built my brother's house, the "main" gas fired water heater was in the garage and the kitchen was on the other side of that wall, so hot water got to the kitchen sink and dishwasher almost immediately. However, the master bath and laundry facilities were at the opposite end of the house. So, under the house, right under the master bath, in fact, he installed a smaller electric water heater. Then the hot water for the master bath and laundry came from the gas water heater to the electric water heater, then up into the bath and laundry. That gave him almost instant hot water in the master bath and laundry from the electric heater and before it could run that small heater out of water, the cold water in the lines between the two heater had mixed with the hot water and he now had hot water coming from the big gas heater.
That system worked beautifully, and in fact, he had previously done the same thing with a big mobile home except that both water heaters were electric and he installed the small heater under the lavatory in the bath at the far end of the house from the main water heater.
Makes me wonder if something similar wasn't the original plan with what you have.
Are one of the water heaters used as a boiler for radiant floor or baseboard heater? Could be a reason for the second one. My guess would be to have them plumbed like Bird described, whichever is cheaper to run make it the primary heater that feeds the other one. How do you like the Oil fired heater? I think one would be more cost effective than going with a propane unit, BUT a Oil fired unit is about twice to three times as expensive as a gas unit.
Thanks for the input guys..... the two water heaters are 6 feet apart in the utility room, along with the oil-fired hot air (and A/C) system, the washer/dryer pair, and a pair of 275 gallon oil tanks. Two bathrooms are directly above the utility room and another directly adjacent. The kitchen and another bath are at the other end of the house in an ell. I had heard that the old man hated the electric company (he installed a 35KVA generator running on propane) and that is why he installed the oil-fired heater. When we bought the place, I found the valve on the electric heater about 3/4 closed.
So... neither water heater has a proximity advantage over the other. The oil-fired is a much higher recovery rate than the electric, but the stone-lined electric provides low-cost hot water storage. That's why I thought of connecting the oil-fired to the input of the electric and feeding the system from the electric. The only advantage that I can see from having them in parallel is that you have twice as much hot water on-line before you need to reheat. But the oil-fired recovers pretty quickly.
As for the efficiency difference between oil and gas... up here in Maine, we don't have natural gas out here in the boonies. My last tank of propane cost well over $2 a gallon. The oil that I bought about the same time was almost half the price. Gas might be more efficient, but it ain't twice as efficient.
For that matter, I have over 120 cord of oak firewood waiting to be cut and split... [img]/forums/images/icons/grin.gif[/img] Just finished a timber harvest.
</font><blockquote><font class="small">In reply to:</font><hr />
That's why I thought of connecting the oil-fired to the input of the electric and feeding the system from the electric.
[/ QUOTE ]
That sounds more logical to me than the current arrangement.
We are thinking alike, I won't have natural gas where I will be and farm diesel/fuel oil is cheaper than propane, It hasn't been quite as much of a spread in price as your $2.00/ gal propane, OUCH... Plus more btu's per gallon in diesel.
I agree, I would feed the electric one from the oil water heater.
If they are not serving different areas of the home, and you do not need the capacity of 2 water heaters, I'd consider removing one of them. Why pay to keep 100 gallons (assuming 2 50 gallon heaters) of hot water around if you don't need it.
I've considered taking one off-line. But we have three grown daughters and regularly have quite a few overnight guests. On those occaisions, it is nice to have the extra capacity. The stone-lined heater is a pretty efficient hot water storage facility. So I don't imagine it costs that much to run.... especially if the oil-fired unit does the heating work.
Reply With Quote
