Domestic Hot Water.

  • Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.

    We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.

    We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
Status
Not open for further replies.

Enzo's Dad

Feeling the Heat
Dec 16, 2013
340
Canton, CT
Ok now that i am using a stove to heat the house, I am beginning to realize how much a hot shower costs me. Between the baseboard heat, and domestic hot water if figure I am going through 15-20 gallons of oil a week. Id say 50% of the oil consumption is for hot water. I"m in the camp that home heating oil will continue to go up and I have propane for a gas cooktop. Will I save money by switching to a propane hot water heater, or do i have spend several $1000's and switch to a rennai system to save money in the long run?

Im sure this idea has been discussed but i am looking for ideas.
 
A tankless is not for everybody. There is a lot more to consider than operating costs with them, although you won't ever hear that from a salesperson. I know 3 families here who have put them in, not a one says they would do it again. Among other things, we have really hard water, and they scale up just like any other water heater. Oil, electricity, or propane, you are captive to a supplier.

Which, historically is the cheapest and/or most reliable in your area? That is about all the criteria I can think of to base the decision on. Can you reduce the amount of baseboard heat the house is calling for? Electric WH's can be put on timers so they don't maintain hot water all day when nobody is home, can that be done with oil, and/or would it work for your lifestyle?
 
A tankless is not for everybody. There is a lot more to consider than operating costs with them, although you won't ever hear that from a salesperson. I know 3 families here who have put them in, not a one says they would do it again. Among other things, we have really hard water, and they scale up just like any other water heater. Oil, electricity, or propane, you are captive to a supplier.

Which, historically is the cheapest and/or most reliable in your area? That is about all the criteria I can think of to base the decision on. Can you reduce the amount of baseboard heat the house is calling for? Electric WH's can be put on timers so they don't maintain hot water all day when nobody is home, can that be done with oil, and/or would it work for your lifestyle?

Would love if you could elaborate some more on the tankless hot water heaters DD . . . we are going through maybe 3 gallons each week of propane which is only used for cooking and hot water (conventional heating tank with power vent). I've thought some about switching to a wall mounted on-demand unit to save on propane usage/expense.

I should mention that we do have hard water, but so far that doesn't seem to be a real issue with the conventional heating system.
 
We put in an inexpensive electric water heater instead of the oil indirect. If you're using an indirect and heating with oil during the winter, it might pay to run the indirect in winter and electric in summer.
 
3 gallons of propane sounds good to me! Im thinking about having a second heating system for hot water.
And for the record we are in a household of 3
 
If I were doing it all over, I would put in a very small (5 gallon) electric WH in th ebathroom and one supplying the kitchen/washing machine. Most clothes can now be cleaned in cold water but there are many people saying you need to clean underwear, etc, in hot water because soap alone will not clean the germs in underwear. If you are using a brief shower instead of a bath tub, 5 gal. is plenty. I know that we waste a lot of hot water because the WH is farther from the kitchen than it should be.
 
I have had a tankless for about 6 years and I love it. Before I preheated my water with my heat pump I was using 180 gallons of propane per year. Now I am using about 120 gallons of propane per year. That being said if this thing stops working I will turn the breaker on for my electric backup. An electric hot water tank is $350. A tankless setup is $1400 but about 1/3 less to operate than an electric.

The propane company charged me $3.59 for 80 gallons last fall because I don't use enough propane. Because of this I will probably switch to electric next time around
 
When I had an oil boiler that I was just using for DHW I was burning ~1 gal/day of HHO ($1000/yr), but >75% was standby losses ! In fact, I was paying twice in the summer, b/c half my AC load was the parasitic losses from the boiler.

Bottom line, any fuel in a DHW system with lower losses will be cheaper to run. A conventional electric tank will be cheap to install, have maybe 5-10% parasitic losses, and would cost $500-$700 a year to run, with no 'maintenance'. I would get (and in fact I did) get a Heat Pump Water Heater, HPWH. which costs me ~$200/yr to operate with a fam of 4, you might be $300/yr with more expensive elec. Upfront is a little higher, but many utilities have rebates. The fed rebate for HPWH (I think) expired in 2013, but you might check to see if it was renewed.

Lots of threads in here about switching from oil DHW to HPWH, pretty much free money, if you search. One issue is to check that you can shut down the oil boiler in the summer and leave it cold. Prob 90% of old boiler are aok with this, 10% might have small leaks. IF you can't shut it down in the summer, you are stuck, and no new DHW heater will get the oil monkey off your back.
 
  • Like
Reactions: chance135
If they could only make the HPWH quiet. From teh specs, it is much louder than the refrigerators.
 
Mine is a 7' tall monster, and it is louder than a refrig, but quieter than an AC window unit. In bedroom, not ok, in garage, aok.
 
Garage? These things seem better suited to the warmer climates.

attached garage tucked under....insulated, seldom goes below 50°F.
 
A reminder: a regular resistance electric hw heater, super insulated, pipes insulated, and effective heat traps on both the cold and hot water ports, can be very efficient. By super insulation I mean at least 6" of fiberglass or similar, sealed for air leaks, on the top, around the sides, and underneath, plus the hw htr raised off the cold floor. I did this for our electric hw heater years ago, hw heater on a separate meter, and electric usage dropped 50%. Our electric bill for hot water is about $4.00/month, maybe $5.00 if we have lots of family visiting during a month.

And I second
If I were doing it all over, I would put in a very small (5 gallon) electric WH in the bathroom and one supplying the kitchen/washing machine.
Our kitchen is a long way from our main electric hot water heater, and I disconnected the supply to the kitchen and dishwasher from the main supply and put in a separate 5 gallon heater just for the kitchen, super insulated as above. Now immediate hot water, and no longer does anyone let the hot water run continuously while washing/rinsing dishes. Turn it on and turn it off. No waste, plenty of hot water.
 
Might as well talk both ends of the specturm - tankless coil in an oil boiler has to be the absolute worst.

Thats what I have, I hate it this summer I am going to change. Leaning twoard a propane 60 gallon. I was just seeing what others had done.
 
Thats what I have, I hate it this summer I am going to change. Leaning twoard a propane 60 gallon. I was just seeing what others had done.

NG and Propane tank heaters are also low eff due to flue losses, and propane can be higher $/BTU than oil. Might want to compute a cost of operation using your local cost for propane and kWh. My guess is that HPWH will be cheaper to operate than propane in your area...if you have a basement spot for it.
 
I'm not suggesting solar but thought someone should mention it.

For five years I've had a 80 sq. ft hydronic solar collector, siphon feed, tank/exchanger, propylene glycol system that supplies all my hot water for 9 months a year. The roof that the collector is mounted to is too shallow for reliable hot water from Dec through Feb so it feeds 80 or 90 degree water to a electric water heater. The rest of the year the electric water heater is turned off and stores excess hot water from the solar tank/exchanger.
Glad I built my system but it could be a royal pain if you don't know what your doing.

As to which type, LP or Electric, is best. For low consumption electric is best because of low standby loses. For high consumption gas is best because of lower fuel cost.
 
I have an old resitance tank heater buried in a built in cabinet that surely is half full of mud from our well. I plan to replace it for several reasons and will most likely use a marathon tank heater. This company does all of the super insulation for you plus the tanks are plastic so they are supposed to last forever or at least until the market allows technology to produce a heat pump water heater that does not pollute my home with noise or cold air.

The super insulated tank heater simply eliminates the stand by loss. You still need to pay for the electrons to raise the temp from 50-120 at least once.
 
. For high consumption gas is best because of lower fuel cost.

This is certainly not true in my location. Propane at 2$ per gallon doesn't beat electric at 10 cents per kwh. Perhaps you meant piped natural gas like in the city?.
 
I hate my boiler running in the summer, however i started reading about Indirect water heaters tied to the boiler, This may be the best use of money.
Electricity is expensive in ct Right now we are at 18 cents per kilowatt.
 
I hate my boiler running in the summer, however i started reading about Indirect water heaters tied to the boiler, This may be the best use of money.
Electricity is expensive in ct Right now we are at 18 cents per kilowatt.

Unless you have a cold-start, low mass boiler (unlikely if you have a DHW coil), then an indirect will do little to reduce your bill. And I was figuring you for 18 cents/kWh on the HPWH heater expense.
 
+1 on solar domestic hotwater.
I heat the house with a woodstove.
We get all our hotwater from the solar panel ('Thermodynamic') for ~7 months a year, and a substantial boost for 2-3 more.
In Connecticut you would do even better.
We put the water tank in the basement so the waste heat warms the basement, which is beneficial all year in my climate.
 
Many experts are shifting away from recommending solar hot water panels. The current consensus is to install a heat pump hot water heater and some solar panels set up with net metering. If you do want to look at SHW, you need to look at evacuated tubes versus conventional flat plate. Flat plates at best raise the water temp 70 degrees which if you have well water at 40 degrees yields 110 deg hot water. Evac tubes are far more expensive but they can boost water 140 degrees so 40 degree well water yields 180 degree water so they can cover you in the winter unless you get a stretch of cloudy weather.
 
Status
Not open for further replies.