Storage Question

[wood thing]

What if the top ot the storage is at -- say -- 175* and there has been demand in the house, the burn is about finished.
Demand goes off, the boiler temp is now 160* and going to storage. What happens when you put 160 water on top of 175 water ? Does the tank remain stradified or will it mix ? Will the output of the tank at this time be less than 175* ? Does anyone control storage input temp ? Thanks for any comments.

 

[ChiefChicken]

It all depends on how your system is wired. My Tarm will stop circulating water through the boiler (it will also shut off the draft fan) as soon as the stack temp drops below 250° for 15 minutes. The lack of stack temp signals that there is no more wood to burn, thus no need to run the draft fan or pump cooler water through your storage tank.

 

[RobC]

My situation is the boiler temp is just a few degrees below or the same as storage when boiler fan shuts off. Boiler circulator shuts off with fan.The blower off, with storage, is a function of exhaust temperature not boiler temperature. Even though the fire has died out the refractory is still hot.
Is your question hypothetical or are you experiencing this ?

 

[wood thing]

My situation is the boiler temp is just a few degrees below or the same as storage when boiler fan shuts off. Boiler circulator shuts off with fan.The blower off, with storage, is a function of exhaust temperature not boiler temperature. Even though the fire has died out the refractory is still hot.
Is your question hypothetical or are you experiencing this ?

The econcoburn does not have any stack temp sensors or anything else. I have been using a simple timer and estimating the length of burn.

 

[Singed Eyebrows]

Thats what I like about the tank chargers, Laddomatt Termovar. The Lado is controlled with both the pump thermostat & a wax pellet(auto type) thermostat so that when the boiler temp drops the output flow gets shut off. Randy

 

[RobC]

Have you read the owners manual thoroughly ? Tarm tucks in a second set of instructions " for use with storage " one of the changes is the positioning of the thermo-sensor. "Move sensor from boiler jacket well to fire box".

 

[woodsmaster]

It's going to mix, but as long as your pulling cooler water off the bottom your stll adding btus to the tank.

 

[woodsmaster]

I have my circulator set to turn on at 170. Can you raise the temp on yours?

 

[Rory]

I have two sensors in the tank (3 if you count the Johnson controlling the oil backup, but two for the purposes of this discussion), and it won't circulate unless the boiler is at least 10 degrees hotter than the lower tank temp. That still doesn't answer your question, but my guess is that there would be some mixing.

 

[wood thing]

Thank you for the replies. I think I will play with some controls but some what concerned about the boiler setting there doing nothing when there is some left over fire. I am understanding that there would be no flow. I also agree with woodmaster that as long as I return cooler water to the boiler I would be adding btu to the tank. 14* here this morning

 

[Hunderliggur]

What is your use temp? I have radiant floors that work well as low as 100F, and a mixing valve on the tank output limiting the max output to 130F. If you have baseboards you may need higher temps. I would be just as happy with a tank of 160F 100% as a stratified tank with an average temp of 160F. Your needs may vary. I also set my pump launch to 170 and 5 hysteresis and it is burning better thanbefore when it was 160 + 10.

 

[wood thing]

What is your use temp? I have radiant floors that work well as low as 100F, and a mixing valve on the tank output limiting the max output to 130F. If you have baseboards you may need higher temps. I would be just as happy with a tank of 160F 100% as a stratified tank with an average temp of 160F. Your needs may vary. I also set my pump launch to 170 and 5 hysteresis and it is burning better thanbefore when it was 160 + 10.

I have mostly baseboard and two small radiant zones. I run higher temp water for the baseboard and indirect, then mix down for the radiant. 160 does a good job but if I run much lower I have longer demand periods, thus more wood. This is mostly a problem when it is really cold. I find that if I can keep my storage at 160 or above, the boiler runs much better. It will go into idle on mild days.

 

[Rory]

I have radiant floors that work well as low as 100F, and a mixing valve on the tank output limiting the max output to 130F. If you have baseboards you may need higher temps.

Where does the mix water come from? I have a similar setup for my DHW, but we are drawing water into the system to exit at a faucet.

 

[Hunderliggur]

Radiant mix is the return floor water which is 20F lower than the floor supply. You split the return with one part going to the HX/storage ad the other going to the "cold" input to the mixing valve. The HX/storga supply goes to the "hot" of the mixing valve. The mixed output goes to the floor supply.

 

[wood thing]

I have radiant floors that work well as low as 100F, and a mixing valve on the tank output limiting the max output to 130F. If you have baseboards you may need higher temps.

Where does the mix water come from? I have a similar setup for my DHW, but we are drawing water into the system to exit at a f
aucet.

My mix valve (taco) is at my supply / return manifold in the house. It is used for the radiant zones and not the indirect.

 

[RobC]

For water quality talk to WoodBoilerSolutions.com