Heat exchanger setup on stove pipe ?

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Manly said:
I feel your pain and understand your search to cut cost. Some years ago I looked into the possibility of using the wood stove to preheat water. Just isn’t practical. About 6 years ago I installed a Toyotomi oil fired on demand water heater. It gives me use of the oil tank since we never use the oil furnace. We love the Toyotomi water heater. It has been reliable and only draws 85 watts while running. Never run out of hot water. We use a lot of hot water, about 1/2 tank of oil per year. I installed the unit myself and do my own service. The cost of the unit has increased almost $1,000 from the time I purchased mine. If you had to pay for installation and annual service it probably isn’t worth it for most folks. Then again since you live in CT like myself, you’re going to pay through the nose whatever way you go.
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Not being from CT originally, this was all a huge shock to me. I knew it was expensive but this is insane.

Have you had any scale issues with your tankless oil fired setup?
 
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During the summer months I heat ALL the water I need in a couple of gallon jugs left on the porch in the sun.

In the winter, I heat ALL the water I need in a pan or two left on my wood stove.

In the shoulder months, I heat ALL the water i need in a pan on my gas range --- the only time I pay cash for heating water.

You really don't need an investment in elaborate technology to heat water if you are willing to be a little creative and not insist on having floods of hot water on tap.
 
wooduser said:
During the summer months I heat ALL the water I need in a couple of gallon jugs left on the porch in the sun.

In the winter, I heat ALL the water I need in a pan or two left on my wood stove.

In the shoulder months, I heat ALL the water i need in a pan on my gas range --- the only time I pay cash for heating water.

You really don't need an investment in elaborate technology to heat water if you are willing to be a little creative and not insist on having floods of hot water on tap.
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No thanks to that.

Are you married? Lol.
 
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sr73087 said:
The upfront cost difference in this case is substantial. For an 80 gallon hybrid it was roughly $1,900 uninstalled. The 50 is on sale from 1,200 to 800 and then they are offering a $350 rebate on top of that. Originally I figured go the “safe” route with an 80, I can’t end up any worse off. However, it’s around 1/4 of the price, which is what made me consider the 50 in the first place.

I think the difference in operational cost is probably a lot less now than in the past since insulation is much better today and much less heat loss occurs.

I guess one other thing to consider is will it cost more to replenish 20 gallons from a 50 or 20 gallons from the 80. Assuming your use was the same, would having to lower reserve cause the unit to throw on the electric elements sooner, thus defeating the purpose of going hybrid sort-of.
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Some overthinking going on here.

A 50 will likely do you as well as an 80. In either case, they still have electric elements in them for the odd time the heat pump can't keep up. I'd stop right there & go with that, if I was going heat pump. No idea how much DHW you use (do you know accurately what it costs you now?), but if it's more than the 50 can supply using the heat pump and you wanted to absolutely prevent the elements from coming on, you could always increase your stand by capacity by adding on an ordinary tank heater, with the elements not wired up, and a little recirc pump between them. From the figures you say, that's like a $1400 difference? If I read right? That would buy a lot of years of very infrequent element heating. Like, more than a decades worth, I bet.
 
sr73087 said:
That is true, I think you guys have killed this idea going forward. Which is good, too many projects as it is.



From what I have found Connecticut has the highest cost in the lower 48 for electricity (among other things). Our generation rates can be quite good, as we can pick out supplier. However, I get killed on the delivery charges. I compared my bill (UI) with my brother's in Pa (Peco) by dividing the Bill Total/Kwh and found that per Kilowatt we were paying over 74% more overall per Kw. I never realized that there was such a big difference in utility rates. So from simply an operational cost perspective, maybe it depends where you are and what the current rates are in your area.

For what it is worth, if you look at the energy guide numbers ( I think it was calculated at .12/Kw) a standard AO Smith 50 gallon electric water heater should cost in the upper $400 range per year. They are stating the hybrid should use $114 per year, which if it is correct, should be a 74% reduction in yearly electric cost (assuming 450/year for the electric). 9.5/month vs. 37.50/month. I would also be downsizing from the 80 to the 50 which should save as well, not having to maintain an additional 40% of water. Not sure if those figures were calculated under ideal conditions though and what the usage was either. There are so many factors that play into this and I am not married to the idea. Just tired of a $200+ electric bill in the winter with gas heat. Looking for others thoughts to make the best decision. Thanks everyone for your input so far.
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We have the same issue in Maine, high delivery costs. My electric bill this winter has been between $200-300 per month and that's including the delivery charges. We use a few hours per day of electric heat when I don't feel like getting up to load the stove. Out DHW heater is also 45 years old and needs to go after we repair our mechanical room. A HPWH and a wood cook stove with DHW capacity are planned, along with a solar water heater eventually. The plumbing is there, but the previous owners bypassed the solar water heater on the roof for some reason. We would like to do minisplits at some point, but the cost to install is very high. This is the same with the hybrid water heaters, but the incentive is higher on the water heater vs the minisplits.
 
I investigated solar DHW when doing my system over. Didn't pencil out for me, at all - the payback just wasn't there if we can heat it for half the year for $25/mo otherwise.

If you have some of the gear in place for it now, that might change things some.
 
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sr73087 said:
electrathon, how does your setup handle this issue? I know I’ve seen setups that bleed the pressure off, but wouldn’t the tempature continue to climb?
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How do I control temperature or pressure?

Pressure is controlled with an expansion tank, just like you do with a standard hot water heater (on a 50 gallon water heater there is about a gallon of expansion between the cold fill and the resting hot period). My pressure gauge only moves a few pounds, and some of that comes from the city side of the system variations. There is also a blow off valve on the system, it has never even dripped.

As for temperature, I have a 50 gallon tank in the basement. There is a solar controller that pumps the heated water in the stove down to the tank. it runs about once in 4-5 minutes, depending on the size of the fire in the stove. Each cycle heats about a quart of so of water. If the tank is fully cold it will take hours for it to recover. It settles in at about 125 degrees in the tank. Rarely gets much over that. With hot fires and great wood, maybe a little more. Cooler fires and poor wood, a little less. I did add 6' of baseboard heater into the basement last summer to help keep the water temp below the point of turn on for my instant hot water heater. Your hot water stays a more consistent heat if the water heater adds just a little bit of heat to the water being used.
 
SpaceBus said:
We have the same issue in Maine, high delivery costs. My electric bill this winter has been between $200-300 per month and that's including the delivery charges. We use a few hours per day of electric heat when I don't feel like getting up to load the stove. Out DHW heater is also 45 years old and needs to go after we repair our mechanical room. A HPWH and a wood cook stove with DHW capacity are planned, along with a solar water heater eventually. The plumbing is there, but the previous owners bypassed the solar water heater on the roof for some reason. We would like to do minisplits at some point, but the cost to install is very high. This is the same with the hybrid water heaters, but the incentive is higher on the water heater vs the minisplits.
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Egads. We run around $80-$100 . . . when we're not running the hot tub. Figure on maybe another $20 with the hot tub. No electric heat other than a few space heaters used occasionally. Also, no hot water heater run off electric or stove . . . use propane for both of those.
 
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