First year using both my boiler and storage tank. Here is my question to anyone with any experience with these tanks, I have my recently built gasifier heating water for the tank and pumping from it to heat radiators in the house. I have been using the original cooling plates to heat the domestic, but it seems to be doing just as good a job of cooling the tank as heating the water. Anyone ever try this before?
Zero Dairy storage tanks
- Thread starter Dogshark
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Karl_northwind
Minister of Fire
one would hope it would do as much to heat the water as cool the tank. physics and all that....
maybe explain a bit further what doesn't seem to be working as you expected?
karl
maybe explain a bit further what doesn't seem to be working as you expected?
karl
maple1
Minister of Fire
Yes, further explanation might help.
But taking a stab at it - you could either be over-pumping, which would not lose heat but would mix the tank & eliminate any stratification. Or, you also would need good insulation on all the piping & the exchanger - you can lose a lot of heat with no insulation.
Not sure exactly what you are seeing.
But taking a stab at it - you could either be over-pumping, which would not lose heat but would mix the tank & eliminate any stratification. Or, you also would need good insulation on all the piping & the exchanger - you can lose a lot of heat with no insulation.
Not sure exactly what you are seeing.
I have the boiler heating the water stored in the tank, and draw from there with a different pump to the heating zones. Cycle temp is set at 170' and during normal heating I can maintain 168' circulation with the blower at 80%, thus getting an efficient burn. The boiler draws from the bottom of the tank which is set horizontally, and returns to the actual center of the tank (top to bottom and end to end). For the domestic hot water I feed the input from the well line into the original internal cooling plates that were intended to chill milk. The water entering the cooling plates is 52-54 degrees and I get about 145' out to the electric water heater, so I don't have any flow control on that process. What I see when the boiler is circulating during a burn cycle is that after a couple of showers there is a noticeable drop in tank temperature, example last night I saw a 10 degree drop after 2 10 minute showers. I guess the root of my question is this seems to effectively heat the water for domestic but maybe not be the most efficient way to use the stored heat in the tank. Is there a more efficient way of doing both?
maple1
Minister of Fire
That sounds like a very capable heat exchanger in there. How much water is in the tank?
I don't think, aside from putting lots of insulation to all your DWH piping, that you can change things much. It's not like you are losing heat - it is being used in the shower. Is all the piping insulated? Any idea what hot water was costing you in electricity before?
You might be able to even out the draw (spread it out over more time) by recirculating between the tank & the electric water heater, and keeping the electric water heater hotter all the time. Then you wouldn't see a big drop all at once. That works better with larger water heaters - more storage room. But overall you should be spending the same amount of BTUs. Also more time spent circulating is more potential for heat loss, but as long as everything is insulated good, you can minimize that.
I don't think, aside from putting lots of insulation to all your DWH piping, that you can change things much. It's not like you are losing heat - it is being used in the shower. Is all the piping insulated? Any idea what hot water was costing you in electricity before?
You might be able to even out the draw (spread it out over more time) by recirculating between the tank & the electric water heater, and keeping the electric water heater hotter all the time. Then you wouldn't see a big drop all at once. That works better with larger water heaters - more storage room. But overall you should be spending the same amount of BTUs. Also more time spent circulating is more potential for heat loss, but as long as everything is insulated good, you can minimize that.
There about 400 gallons in the tank with a float valve from the same line feeding the DHW used for make-up water and another 100 in the boiler, the heat transfer to DHW is good, just looking to minimize temp lose in the tank. Winter has been mild thus far, so not good test of the system. Don't have an accurate cost on the water heater yet, I am purely guessing at about $30 a month. As the winter progresses will have a more accurate cost differential on the heating.
velvetfoot
Minister of Fire
A diagram would be interesting. Where are you measuring your "tank temperature"? Where are the heat exchanger plates in the tank? Where do the heating manifolds tap into the tank-at the top and bottom of the tank, or does the supply use the same pipe as the boiler? I know with my setup, I could conceivably have the boiler running, both zone pumps pumping off the boiler manifold, and a shower using heat from the tank. If the zones continue to run, the tank could continue to cool, because the zone pumps are using all the boiler's heat. I have no "priority" on dhw.
bubmiller
Member
When an agitator quits on a tank of milk, ice will form on the bottom of the tank, but the top milk will spoil. I'd wonder if your dhw is pulling the heat from the bottom and the water isn't circulating much in the tank. Might want to make a drop tube to return water from the boiler to the bottom of the tank, then pull off near the top for heat and to the boiler. That would use natural convectional currents to help prevent temperature stratification.
maple1
Minister of Fire
If I could find a diagram of the plates/cooling coils I would gladly provide them. The inlet and outlet are at the 9:00 position on one end of the tank, aside from that I have not been able to find anything on this tank, except for folks trying to sell them on Ebay.
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