Tempering tank for hot water system

Page 1 of 3  
Ok guys, pick this one apart..... I have a wood stove in my basement. I just replaced my old 52 gal electric hot water tank with a new 40 gal model. I am planning to use my old stripped down tank as a tempering tank ahead of my new heater and place it as close to my wood stove as possible (about 6 inches or so away). I plan to remove the upper and lower elements on the old tank and replace them with a 1" copper line from the top element threaded opening to the bottom threaded opening and extend the copper line over my wood stove so that it will pick up heat from the stove / flue pipe. I am thinking cool water from the bottom will naturally be drawn up the copper line as it is being heated by the wood stove and will circulate back to the top and will constantly be looping around to warm the water inside the tempering tank. I am thinking that possibly overnight, the water in the tank will eventually warm up to around 100 degrees F. And the new electric heater will only need to heat that water up to 120 degrees F. There are only two people in the house and no automatic dishwasher, warm water usage for the wash cycle only of the clothes washer @ 2 loads per week, and maybe two short showers per day. Do you think this is a feasable plan? I am not any kind of engineer, but just a practical tinkerer trying to save a few bucks on my electrical bill......... Thanks for any comments on this! Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

its a interesting idea, but i doubt large gains:( I woul;d of stuck with the larger tank since its a long life purchase and more gallons cost little more.
plus to be effective you will have to constantly be turning the electric water heater off and on, or gain very little
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I kept a tank that was not leaking and use it as a tempering tank from air temp, just that alone saves a bit, just a tank next to a heat source will help alot, try it and figure out and put in bypass valves so when something leaks you still have HW. My electric 40gal tank cost about 35 a month to run, my present NG Tankless costs $9 in summer with all gas cooking and clothes dryer and using the electric as a tempering tank might be saving me a few $ a month. Be inventive all things help.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Thanks for the comments! I plan to have shut off valves so I can always go back to the standard setup. I do plan to go back to the standard setup for summer as there will be no heat from the woodstove at that time anyway. I guess I thought the 40 gal capacity for the new heater would be sufficient for two people in the house and it was about $30 less to buy than the 50 gal model. To begin with, I don't plan to be shutting the new electric one off and on. It is well insulated and has heat sinks in the inlet and outlet so it should not be cycling on too much during the night. It's probably going to be alot of work and probably about $40 to $50 for materials to get it set up and probably at best it might save $15 a month during the heating season (6 to 7 months in our area) so about $100 / year possibly? At least I don't have to pay anybody to do the installation work. Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

think about what you said, other than passive gain from the tank the recirle line will be a loser.
tempered but still cold water enters, heater turns on, water gets to 120 and heater shuts off.
now some water recirls from the heat loop. if its not at least 120 it will be cooling your tank and costing more money for electric.
as to tankless, electric tankless capable of running a home will likely take 200 amps just to heat water. even ifd its just a 100 you would still need a main service upgrade 200 amps for home, 200 amps for heating water.......
new lines service power drop:( not worth the cost
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Like I said I am not an engineer and can't do the thermodynamic equations and btu loss or gain or heat transfer calculations. All I can do is try it and see what happens. You could be right about the heat loop not working out.... But its not quite like going to the moon and not coming back is it (rocket science)? But seriously, I do appreciate your comments as I am willing to learn and appreciate others opinions. All comments are very welcome and appreciated! Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The proposed recirculation line originates and terminates at the tempering tank. So no water from the electric water heater tank is displaced from the recirculation line. The recirc line is just a way to increase the heat gain of the tempering tank from the wood stove.
Cheers, Wayne
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Even if its 70 from the stove it will be a winner, his incomming will be likely 55 or less in winter, mine goes to 35-36f, if basement air is above water temp he wins. Above a stove will be maybe 300f, and tank is also next to wood stove.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Go ahead and use the tempering rtank in the summer. You'll at least bring the water temp up from ground temp, which could be ~55F or so to air temp, which could be ~70F or however hot it gets in the summertime.
Ken
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Your new 40-gallon tank will be more than sufficient for the two of you plus any guests you might have. We have a 40-gallon gas Bradford White water heater for our 2,500 sf house (full bsmt, 1st, 2nd, and 3rd floors), and we've not had any water shortages even with as many as 7 people in the house, and we use a dishwasher plus washing machine. Obviously all the hot water demand can't be in the same moment, so we just make sure to run the dishwasher and washer at times when people are not likely to be showering, and all is good.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Steve wrote:

The more you preheat the water the more you save. It's money in your pocket.
--
<<//--------------------\>>
Van Chocstraw
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
i'm thinking this will work fine. BUT i wonder why you are retiring the tank if it is still sound enough to be a tempering tank? I doubt if you get the water to 100, but it'll be a damn site warmer than the incoming water.
s

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Good question! One of the thermostats went out on my old heater. It was 30 + years old and I figured it was as good of a time as any to try this tempering tank idea which I have been thinking of trying for a long time. It just might be a dissapointment but I am willing to try it. Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I didn't read all the details in the original message, but have you considered the total energy flows?
If the tempering tank is inside the building thermal envelope, the energy needed to bring the water up to room temperature has to come from somewhere - most likely your space heater. So, it isn't free.
If the tempering tank is outdoors, you have to consider that you have an unheated space that will be chilling the water for at least part of the year...
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

He has a wood stove in winter, and warm summer air in summer. It works for my set up. His problem is to not forget a pan and hose under the tank, in a hot summer it could be a dripping mess.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I've already considered this and the tank does not sit very far away from the floor drain. Thanks, Steve
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

after being agains this originally i believe its a good idea, my concern would be legionaires disease
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Has anyone actualy got legionares from a HW tank. Doesnt it need open air to establish and breed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

yes it was in the sealed and pressurized water system in that hotel. it grows in warm water.
they used repeated pure bleach to kill the bacteria
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

What hotel, the only hotel I heard of it was in stagnant water from AC chillers or other AC equipment. I can understand non chlorinated, warm pooled water growing anything, but chlorinated, sealed, moving, pressurised systems, no I have not heard that as fact.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.