New GE Hybrid Hot Water Heater in Series

Hi,

I currently have a Boch oil fired Hot Water heater that is close to 20 years old. Last year I replaced the anode rods and the retention head was replaced 3 years ago. The tank seems to be in good shape but it's hard to tell.

With the price of oil I was thinking of buying a new GE Hybrid water heater (1,130 with discounts and I can install it myself).

I live in NY so electric rates are about 18 cents a KW and no discount for off peak unless you're a business. Oil is about 3.80 a gallon. Anyway, I have a coal stove that heats most of my house. I also run the boiler water to a coil in the fire box of the coal stove. This does around 70% of the heat needed. My old Utica boiler is kept at 120 - 150 and doesn't run much. My boiler room stays around 80 degrees in the winter and about the same in the summer (on average). The Hybrid heater takes the heat from the air to heat the water so a warm boiler room will make the heater run more efficient.

We have 3 adults on the house and 1 teenager in H.S. The teenager takes 20 minute showers and then my wife follows (10 minute shower) after her and I shower about an hour after my wife (10 minutes).

I'm concerned that we will be running out of hot water and that the traditional elements will kick in to heat the water which will cost us a lot of money and worse we will have luke warm -cold showers. With 3 ladies in the house - cold showers wouldn't fly.

I was thinking of keeping my oil fired heater and installing the new GE Hybrid electric unit in series. The oil fired unit would be first in line and I'll turn it off to see if the GE unit can keep up with demand. However, if the GE unit has trouble with demand in the winter or for back to back showers I can turn the aqua stat down on the oil fired unit to around 90 - this would pre-heat the water for the GE unit.
The scenario I don't want is that the GE unit can't keep up and must use the 4500 watt heating elements to keep up with demand. With electric rates at 18 cents a KW I would be spending way more than my oil fired unit. If I see that the GE unit is working great after a year I can either close the valves and by pass the oil fired unit or completely or remove the tank. I like this idea. Any comments. Here is a pic: http://tinyurl.com/5uv64o6
Also, would I see an appreciative drop in water pressure. Right now I have good pressure.

Info on this new technology:

http://tamargrow.com/7861/

These would be great sitting in a garage in Florida or if you were a small family of 2 maybe.
This is not a work horse...it is merely a small window air conditioner unit dumping it's heat into the tank below. And very high priced too.

The idea of "Saving Money" is a Great Marketing Tool.

To avoid costly mistake I'd look around and compare OUTPUTS...but if the HEAT isn't there to start with in the surrounding area it doesn't matter what the output is. This will be a giant drain on HEAT in the space...is there a source for the heat to be replenished?
Do some math to see how many BTUs will be draining in a day, in a week, in a month...it has to come from somewhere.

I didn't see how the GE stacked up to this one.
Here's the specs for an add-on to existing tank unit: Nyle "Geyser R"

Unit Specifications:
[I have annotated some in red]
* 6,000 BTU/hr
* Default tank setting is 120°F (49° C) in accordance with Department of Energy Guidelines
* Adjustable from 90-140° F (32-60° C)
* 12.5 gal/hr recovery @ 120°F tank temperature and at 60°F water supply ONLY 12.5 gal. RAISING 60* in an hour.
* 62.5 gallon first hour rating**Depends on tank capacity...but it still take 5 hours of zero use to get that replaced again.
* Heats water up to 140°F
* 115 Volt/60hz
* 5-10 Amp draw (suitable for any 110 volt household outlet)
* Dimensions: 16” (40.6 cm) width x 15” (38.1 cm) height x 20” (50.8 cm) depth
* Durable powder coated steel cabinet for years of trouble free service
* QPS/SGS Listed (UL-1995 / CSA C22.2 No. 236)
USTC Logo PS Certified Electrical Safety Logo

Does it source from outside air? Heat pumps are effective until outside air reaches about freezing. If it's sourcing from inside air in the winter as McGeiver suggested your heating bills will be higher.

No big deal in the summer if it's sourcing from inside and actually preferable because it's effectively an air conditioner.

Assuming it can provide enough heat the big question is whether you can justify the cost, $1K is a lot of electricity.

They pull the heat from the room they are in. It still has traditional coils and the heat pump. If you are expecting alot of usage I think you can have both run. I don't know if your heating bills would go up, if this thing absorbs heat in a basement from beside a coal stove it is doubtful the btus it will absorb are even noticiable. One other side note that would add to the savings is the heat pump acts like a dehumidifire. So if you have a mild moisture problem in you basement this may alliveate it. That would free up a ittle money for me not having to run a dehu. in the summer.

But they are to new and I don't want to be the test bed. wait 5 years and hopefully they will be down to $800





Eric

The boiler room stays unusually hot in the winter from the heat coming off the flue from my boiler and heating pipes. This heat isn't really used so it would be good to harness this heat and make hot water from it. When the heat pump runs it only uses 600w vs 4500 in a traditional HW heater. However, it does have several modes and will run like a traditional HW heater if you put it in that mode. The heater does 63 gallons the first hour so I may have enough hot water for back to back showers. Not sure until I get it installed. I read the reviews and people who switched to this unit from a traditional HW heater are saving about 30.00 a month. Not too bad. I use about 20 gallons a month for HW at 4.00 a gallon that is 80.00. I'm thinking this HW heater should cost me around 40.00 a month to run. I can afford 40.00 but I really want to get off oil. My only concern is if the pressure will drop much running two tanks in series.

Caution here on savings - The heater has several modes and the specifications do not indicate what energy is used for each mode. I suspect that the 63 gallons for the first hour rating is using the straight electric element to recover with. The whole premise on the savings here is a slow recovery rate using the heat pump only. Note that the savings indicated may be verses straight electric water heaters.

Look at your energy rates. Oil at 3.80 per gallon and 78% combustion is still about 2/3 the cost of 0.18 $/kwh electric at 100%. If you can get by with using the heat pump only, I suspect the COP of the heat pump will be arround a 4.0. I did not see anything in the water heater literature that gave this efficiency. This means you get 4 btu's for every 1 btu of electric used. (3 btu's sucked from surrounding air). This would be the equivelant of 4.5 cent electric using straight resistance.
At this rate the heat pump water heater would be less than 1/2 of oil. So cutting you bill in half is a reasonable assumption only if you turn off the oil. Note that a large portion of water heating costs is standby losses. Having the oil fired heater on and warm will cost considerably.

Putting the water heaters in series will not cause considerable pressure drop as these are tank type water heaters.

If you save $40.00 per month, that will be about a 30 month payback which is reasonable.

Great post. The effeciency rate is 2.5 Good point about the recovery rate which could be in high demand mode. If I can spread out my showers to give the heat pump a chance to make hot water I should see savings.

Be wary of the effiency rating as this is a unit-less number. According to the website a straight electric water heater has an efficiency rating of .88. Probably due to standby losses. These ratings are like mileage ratings for cars. Calculated under certain conditions. Fall outside of those conditions and they are not accurate.

Typical shower should be 2.5 gpm. Twenty minutes of shower will about deplete the tank. Don't forget dishwashers and washing machines. They are big hot water users also.

Okay, let's assume you have no shortage of available heat in the surrounding location...

And, with all else that has been said, do not overlook the RECOVERY TIME...5 Hours to get back to fully heated tank w/ Zero use during that 5 Hours.

The issue here really isn't if it is an energy savings...it's will you have enough hot water every time you need it...it's not a work horse, IMO.

Where do you get the estimate of 5 hours for recovery?

Let's do a little math:

You have 50 gallon tank, which gives you 62.5 gallon first hr. delivery rate divided by 12.5 gal/hr recovery rate = 5 hrs. to recover again.

If there's addition HW drawn it will be even that much longer to recover.

While we're throwing numbers around...@ the 6000 btu/hr rate of heat produced by this HP/HWH...it is the equivalent of 1758 watts of energy (not what your meter reads) or less than 1 quart of heating oil...or even less energy than 1/2 lb. of ant. coal. Again, this is not a work horse.

See, you're avoiding 4500 watt electric elements...but trying to do the same job w/ 1758 watts of energy...results will be poor.

This HWH will change the way you use hot water...or the HP will need an assist from the resistance wattage to make up the difference.

Hope this helps

On the back of a bar napkin (thanks Sting),
I came up w/ 11% savings compared to heating oil, based on $3.80 a gal.and .18/kWH @150% efficiency.
I came up w/ 48% savings compared to heating oil, based on $3.80 a gal.and .18/kWH @200% efficiency.

BTW:@ $6.00 a bag, Coal beats the .18/kWH @200% efficiency electric by 41%

As the percentage of electric efficiency comes up, then the savings would go up.

YMMV...what's the payback?

How do I know what my efficency is? Where are you getting 150% and 200%? A 48% savings would be great but at 11% I'm wasting my time. Also, from what you posted it sounds like I'm not going to be happy with the heat pump mode so I'll be using a hybrid mode which will make the larger (two 4500 heating elements) work which will cost me a fortune. Not sure what to do. I just got a call that the heater is in too. Any advice is appreciated.

McGiever wrote:On the back of a bar napkin (thanks Sting),
I came up w/ 11% savings compared to heating oil, based on $3.80 a gal.and .18/kWH @150% efficiency.
I came up w/ 48% savings compared to heating oil, based on $3.80 a gal.and .18/kWH @200% efficiency.

As the percentage of electric efficiency comes up, then the savings would go up.

YMMV...what's the payback?

Those percentages are "what Ifs" variables. Heat pumps advantage is to achieve well above 100%...COP 3 = 300% but if it can't keep-up...assistance will come @4500 watts=100%.

Real life experiences will tell what it is...there are a lot of variables.

The post before the 150-200% one should be interpreted as to what to expect for performance.