Water heater questions

[tkappeler]

When we built our home, I fretted about water heating options. We considered tankless but dismissed that for many reasons (cold water slugs, no PVC venting options, low flow based on temp rise in winter, etc). We considered high efficiency propane but the venting options were limited as we would have to route the vents 50' or so to meet codes for window clearances. We were also unsure of the propane use.

In the end, we went with electric due to time considerations ease of installation. I know. Worst possible energy efficiency. We have an 80 gallon and my thinking was that if we use 30 for a bath, then the resulting required temp rise would be far less than using 30 in a conventional 40 gallon. Was my thinking off?

To compound things, we have no historical experience as it is our first year. With energy prices (electric and propane) spiking all winter, we do not know how much of our electric bill is solely due to the water heater and how much is related to spiking energy prices. Our only other major electric use in winter is the high efficiency, 2 stage air handler on the furnace.

I am thinking that we can better check how much is related to the heater and how much is related to the water heater in a month or so when the heat use drops way off but A/C not yet on.

In the meantime, I am reconsidering the water heater decision. Stay with electric or switch to high efficiency direct vent propane with 50' vent run, especially with how propane drastically spiked this winter.

Any empirical data for comparisons would be great too.

 

[zzvyb6]

I'd add a high efficiency direct vent water heater (like the one I already have) but keep the electric with solar or windmill driven 12 v elements.

 

[murphy1244]

80gal is usually for two bathrooms.

 

[dave1949]

Tom, the only empirical data I have is that we use ~115 kWh per month for our 50 gal. electric water heater. That is how much our monthly electric usage increased when we switched from propane. Two retired people don't use as much hot water as two working people with family. With the super insulated modern water heaters, I think the 80 gal. capacity is costing you something, but not as much as it would have in the past. The new heaters just don't cycle very much when not in use.

In 2013, 88% of our total electric usage was provided by our grid-tied solar electric system. I replaced propane with sunshine--at some upfront cost to be sure.

The old water heater was indirect-fired, a dedicated zone on the propane boiler. That consumed ~245 gal. of propane per year for the same hot water load.

 

[doxford jim]

Not quite what you are asking, but this meter is a handy item for checking all sorts of electrical loads. I have one installed and was shocked at the electrical load of different household equipment. Electric water heaters and electric clothes driers are the two main energy culprits. We have a geothermal heating/cooling system which uses a lot, but we don't have any other bills.
Here is a link to the meter I am using if you are really interested. It sure helps you monitor what you are using.

Welcome To MTP Instruments

Hope it is some use to you.

 

[DoubleL]

GE GeoSpring 50 Gal. 10-Year Hybrid-Electric Heat Pump Water Heater

Got one of these when they first came out and it's worked flawlessly. It has a 10 year warranty.

Sears.com

 

[dave1949]

GE GeoSpring 50 Gal. 10-Year Hybrid-Electric Heat Pump Water Heater

Got one of these when they first came out and it's worked flawlessly. It has a 10 year warranty.

Sears.com

I've only read about those. Do you notice the heat removed from the room/area that the heat pump takes for heating the water?

I'm a little conflicted on the concept. The heat it captures cost something to produce. Maybe I don't understand it.

 

[Rustyiron]

GE GeoSpring 50 Gal. 10-Year Hybrid-Electric Heat Pump Water Heater

Got one of these when they first came out and it's worked flawlessly. It has a 10 year warranty.

Sears.com

I was hoping that someone would reply that had one of these new heat pump HWH. Any more out there? I hear that a nice "by product" of these units is they also dehumidify pretty well also, handy in the summer.

 

[JD 4520]

Have you ever considered using a wood boiler to heat your water and supply heat to your house through your furnace? There are several out there and after spending considerable time in tease arch, I have gone with the Frontier model by Greenwood USA. Www.greenwoodusa.com. Mine is in my garage fairly close to my furnace and hot water tank supplying heat to both. If you don't have access to wood then it isn't a solution but if you do it is super efficient.

 

[Looking4new]

Thanks for the link d j.

 

[tkappeler]

Have you ever considered using a wood boiler to heat your water and supply heat to your house through your furnace? There are several out there and after spending considerable time in tease arch, I have gone with the Frontier model by Greenwood USA. Wood Boiler | Wood Furnaces And Biomass Boilers For Home Heating. Mine is in my garage fairly close to my furnace and hot water tank supplying heat to both. If you don't have access to wood then it isn't a solution but if you do it is super efficient.

Thanks. That looks interesting if I had hot water baseboard or radiant heat. But for domestic hot water only, that seems like an expensive way to go.

I'd love to do geothermal but the quotes are $6500 for the three vertical wells and $7000 for the lines, manifolds, heat exchanger and that is using my existing coil.

 

[JoeL4330]

You didn't say how you heat your house. for example, if by resistance electric, then your electric water heater is 100% efficient in the winter.
If you air condition in the summer, your heat-pump hot water heater is similarly very efficient ...You have to consider more than hot water heating ...as was hinted at in aking how the heat was produced for the HW heatpump ...

Wasn't quite sure about your 50' run for propane HW ...that's PVC, right, if you power vent ...and, if it runs through conditioned space, then in the winter--as above--you recapture all the heat ...but not so good in the summer, of course. And, I understand the window-code issue, but that's for windows that "open" ...if you can live with one or two that are glass but not open-able, then you might find a better vent location.

Just guessing that, too, if you air condition in the summer, that will be your big electricity cost, anyway.

 

[Scooby074]

Some good info in this thread.

Gas tankless heaters can be pretty sweet and can generate a ton of hot water. There is the issue of upfront cost and propane useage however.

I have an electric heater and right now Im averaging about $40/mth for my 60 gal.

I highly suggest you get a power monitor like the MTP as Jim suggests, or the Owl, or the TED. That will allow you to select a specific circuit and monitor it. Avoid the monitors that just read the wheel on your power meter.

The idea about a gassifier or other boiler is a good one. Its what I plan on doing for my next house.

 

[grsthegreat]

Actually electric water heaters are 100% efficient (no energy loss) and their main drawbacks are slow recovery. I got rid of my 40 gal electric waterheater about 7 years ago cause we were always running out of hot water. I could have installed an 80 gallon unit, but we descided to install 95% efficient direct vent propane units instead. I liked the idea of two 40 gal water heaters set in parallel. One unit basically acts as a large insulated storage unit for the hot water while the other unit is used to heat the water. We never run out of hot water.

I had one of the units fail a few years back and ran out of hot water. The sensor failed. I simple turned on the 2nd unit, and we had hot water again. It took about 1 week to get the replacement part under warranty, so the added unit was a god send.

As far as utility costs go, for us it was a tossup. Our elect bill dropped as much as the propane went up. It did free up some amperage to run my hottub, (which i really needed) .

I guess the geo thermal is a nice unit, but the installation costs are HUGE. For me it would take too long to recoup the costs. Govt subsidies would help...but i dont want anything they have to offer. I wish i could live my entire life without ever having to deal with any one in the govt.

call me pig headed.

We have these huge wind farms up here in White pass (Wash) that are a govt subsidy boondoggle. Hundreds if not thousands of wind towers installed on the govt dole. Ive yet to see more than 10-12 of them ever running.....ever. Ive driven by them soo many times...never running. Ive been told that most arnt even connected to the grid. that wouldnt surprise me one bit.

But i digress...as usual... If you go with electric pick a minimum 80 gal unit. Go with the super insulated units. According to my local utility, due to slow recovery of elect units, an 80 gal electric provides as much hot water as a 40-50 gal gas water heater.

 

[PapaPerk]

Actually electric water heaters are 100% efficient (no energy loss) and their main drawbacks are slow recovery. I got rid of my 40 gal electric waterheater about 7 years ago cause we were always running out of hot water. I could have installed an 80 gallon unit, but we descided to install 95% efficient direct vent propane units instead. I liked the idea of two 40 gal water heaters set in parallel. One unit basically acts as a large insulated storage unit for the hot water while the other unit is used to heat the water. We never run out of hot water.

I had one of the units fail a few years back and ran out of hot water. The sensor failed. I simple turned on the 2nd unit, and we had hot water again. It took about 1 week to get the replacement part under warranty, so the added unit was a god send.

As far as utility costs go, for us it was a tossup. Our elect bill dropped as much as the propane went up. It did free up some amperage to run my hottub, (which i really needed) .

I guess the geo thermal is a nice unit, but the installation costs are HUGE. For me it would take too long to recoup the costs. Govt subsidies would help...but i dont want anything they have to offer. I wish i could live my entire life without ever having to deal with any one in the govt.

call me pig headed.

We have these huge wind farms up here in White pass (Wash) that are a govt subsidy boondoggle. Hundreds if not thousands of wind towers installed on the govt dole. Ive yet to see more than 10-12 of them ever running.....ever. Ive driven by them soo many times...never running. Ive been told that most arnt even connected to the grid. that wouldnt surprise me one bit.

But i digress...as usual... If you go with electric pick a minimum 80 gal unit. Go with the super insulated units. According to my local utility, due to slow recovery of elect units, an 80 gal electric provides as much hot water as a 40-50 gal gas water heater.

Electric water heaters loose energy through convection and conduction. They are not 100% efficient unfortunately.

 

[grsthegreat]

heres an interesting site

ACEEE | Water Heating

they have compaired operating cost for every kind of units

 

[grsthegreat]

Electric water heaters loose energy through convection and conduction. They are not 100% efficient unfortunately.

true, but they are rated at 99% efficient. Meaning 99% of the electricity you purchase is turned into heat. For me thats 100%... or close enough.

 

[jel1988]

The only 80 gallon residential tank I ever installed was in a household with 6 teenagers and 3 showers. The owner was sick of cold showers after a hard day of work. Are you sure you really need 80 gallons? Tankless should work in your local (they don't where I live and people are installing them like crazy) but I have never seen a 50ft. vent extension kit.

 

[tkappeler]

The only 80 gallon residential tank I ever installed was in a household with 6 teenagers and 3 showers. The owner was sick of cold showers after a hard day of work. Are you sure you really need 80 gallons? Tankless should work in your local (they don't where I live and people are installing them like crazy) but I have never seen a 50ft. vent extension kit.

The 50' run would be 3" pvc on a condensing unit. Two runs, intake and exhaust. We do not need the 80 gallons but I felt that using 40 out of 80 for a bath still left a large portion of warm water in the tank and therefore smaller heat rise (temp differential) than simply bringing the full 40 to temp if I used the smaller unit. Seems logical but I am not sure.

heres an interesting site

ACEEE | Water Heating

they have compaired operating cost for every kind of units

Thanks!! That is what I was hoping for. I have to look further to see what per unit fuel costs they used give the price spikes of late.

 

[soilsailor]

Whether you have to heat the 30 gallons in a 80 gallon tank or in a 40 gallon tank, you still need to supply the energy required to raise 30 gallons of cold water to your heater 's set point. Either way it is the same amount of energy.

Certainly there is a difference in the usability as adding 30 gallons cold to 50 hot will cause a smaller temperature drop than adding 30 to 10, but the energy required to raise will not differ significantly between the two all else being equal.