Cost to heat DHW with oil (tankless)... update 1 month later..

Thanks. I'm thinking my best bet right now is to do nothing as well and see what develops. Our boiler is only 4 years old and in great shape.

Also, this may be interesting should it pan out and depending on the cost:

http://www.geappliances.com/products/water/heat-pump-water-heater/

I looked up the Stiebel Eltron unit - it retails for $4,500 and I saw $2,799 as the best price, and only has a 5 year warranty. At that price, even if it cut my DHW costs by 75% (which is doubtful - 50% is more realistic) it would still be a 4-5 year payback to just break even.

The GE unit looks interesting, though unless it has a polybutylene tank like my Marathon hot water heater (i.e. will last forever with no leaks), then I'd probably buy one of the add-on units instead.

Figures that the Stiebel unit would be expensive, but $3k is a joke.

Hi Newstove,

This might be just the thing to eke a little more DHW efficiency out of your oil burner:
http://www.hearth.com/econtent/index.php/forums/viewthread/27508/

Has anyone in the north-east ever used this for DHW?

http://www.tanklesswaterheater.com/product3.php

I would like to turn off the oil furnace all together except for the winter. Seems like it would be good enough for the warmer months.

I'm sure it would work well if you actually have the power needed to feed one... most average homes don't.

All that is required is at least a 200 amp service to connect the 50amp disconnects

That's a lot of power, most homes don't have this kind of surplus sitting in reserve. If yours does, and electricity is cheap in your area, this looks like it might be a great fit for you.

See attached image for electric rates - I live in TAXachusettes

Those are just the energy rates. You failed to post the other charges National Grid has too.

The total cost per KWh is actually $0.147 right now when you add in the rest of the charges (distribution, transmission, etc.)

True enough - MA has high rates for EVERYTHING. Makes me want to move.

I am not an expert in this area but from what I have read, and seen firsthand with my electric water heater I don't see how a tank less water heater is cost effective. I think we can agree that any savings for a tankless is due to eliminating standby loss. The same amount of energy is needed to heat the water. The water heater I just installed is an older one with R16 insulation, I added an additional 4 " of fiberglass to increase it to about R28. My heater will go for over 15 hr without heating (No hot water being used).
It runs about 15 min/24 hr to maintain heat. I think that's about .15 cents worth of electricity. It would probably be more that 25 years to see a payback.

You may be better off with a good quality tank water heater.

If you push the numbers on the listed specs for electric tankless and a well insulated elec tank, the tankless looks like it will never pay back.

WES is right.

NG tankless vs tank might be better--the flue leads to inevitable standby loss, but hey, NG is cheap.

Today anyway, who knows what tomorrow will bring...

WAY off the topic area, and if I see a lot of further discussion on it, I will dump the offending posts (or move them to the ashcan) but Carla Howell and friends will be working to put a referendum question on the 2010 ballot to roll the sales tax back to 3%.... http://www.centerforsmallgov.com for details... I figure it can't hurt, even if the legislature does try to ignore it like they have done w/ other measures in the past...

Gooserider

I'm doing the hour meter thing right now. I changed from a tankless to a cold start boiler with an indirect. My conclusion: A BTU is A BTU Is a BTU. There may be stack losses from a poorly insulated boiler compared to a tank, but its not worth the $700 it cost for the tank or the $1500 it would have cost for installation had I not done it myself. I'm a little disappointed at how fast I'm buring through the liquid. I'm using about 2.5 gal/day right now, with mean outside temps right now about 45 degrees F. I use 200 gallons of hot water a day, and I'm guessing I'm burning between 1.2 and 1.5 gallons just for hot water. From May to October I burned about 200 gallons. That puts my system efficiency at about 75-80%, which I would call optimistic, because I'm not counting the 5 minutes someone runs the water before the shower warms up.