Draw from the TOP or BOTTOM

[bulldogbones]

Hey guys I think I know the answer but I wanted to double check and after reading about 20 other threads I wasnt able to find the answer.


Do I draw from the top or bottom of my Hot water storage tank to heat my radiators???

If I remember right I pump in the new hot water from the boiler into the bottom of the tank and suck from the top of the tank for my heat. And the returning cooled water goes into the bottom of the tank and the return to the boiler draws from the bottom of the tank, right???

 

[Donl]

Pump hot water from the boiler into the top of the tank when charging, and draw hot water from the top of the tank when when discharging. The idea is to help maintain stratification in the storage tank by keeping cooler water on the bottom and hotter at the top.

 

[Singed Eyebrows]

If I'm not mistaken, you want your hottest water(boiler output) in the uppermost fitting & just below this you take off system hot water(basically as Don said). It would seem there would be some turbulance if done opposite this & you don't want the tank to mix, Randy

 

[jimdeq]

Randy, I have seen numerous pictures of pressurized storage tanks with only one set of pipeing to the top of the tanks. I would assume that this pipeing is water going in from boiler and water going out to the zones through the same pipe? Would two pipes in the top be more beneficial for flow reasons because the zones could be supplied while the tanks are charging?

 

[Singed Eyebrows]

Randy, I have seen numerous pictures of pressurized storage tanks with only one set of pipeing to the top of the tanks. I would assume that this pipeing is water going in from boiler and water going out to the zones through the same pipe? Would two pipes in the top be more beneficial for flow reasons because the zones could be supplied while the tanks are charging?

I don't know how water would go in and out the same pipe without some flow problems. I would & did run 2 pipes to the top & 2 to the bottom. With my vertical tank less than 3 feet from the boiler there are no problems at all. I can load a pic of my tank tomorrow, Randy

 

[Hunderliggur]

Hot from the boiler goes IN to the top, hot to the radiator goes out from the top. Cold to the boiler goes out from the bottom, cold from the radiator goes in to the bottom.

You could use the same fitting on the top - if the boiler is producing heat it will go to the radiator not storage, same for the bottom. I have seperate fittings so I don't mess with that. Some tanks have dip tubes on the top which have a pipe inside the tank to go to the bottom.

 

[kabbott]

Hot from the boiler goes IN to the top, hot to the radiator goes out from the top. Cold to the boiler goes out from the bottom, cold from the radiator goes in to the bottom.

You could use the same fitting on the top - if the boiler is producing heat it will go to the radiator not storage, same for the bottom. I have seperate fittings so I don't mess with that. Some tanks have dip tubes on the top which have a pipe inside the tank to go to the bottom.

And the correct answer is post #5....
Depending on the rest of the system(as always) 1 connection on top and 1 on bottom would mean you could heat the house with the tank
totaly cold..... If you have seperate connections for boiler and load it MAY require some heat in the tank to deliver any heat to the load...
In real world conditions this may not be an issue though..

If the connections are far apart it MAY take some time for heat to arive at the load port if the tank is cold...

Kris

 

[bulldogbones]

Ok great thanks everyone. Thats how I have the tank setup now (post #5 ) it already had a draw straw in it. So like (post #6) said the first time I use the boiler I will be heating my house before I heat the tank which is fine. I also got a circ pump with a check valve so if and when the boiler stops producing heat I wont circ water through a cold boiler therefore defeating the purpose of the stored hot water.

 

[Donl]

And the correct answer is post #5....
Depending on the rest of the system(as always) 1 connection on top and 1 on bottom would mean you could heat the house with the tank
totaly cold..... If you have seperate connections for boiler and load it MAY require some heat in the tank to deliver any heat to the load...
In real world conditions this may not be an issue though..

If the connections are far apart it MAY take some time for heat to arive at the load port if the tank is cold...

Kris

Maybe I am missing something here! My answer above assumed that there are two states, one state for charging the tank and the other state for discharging the tank. During the charge state the storage tank only stores heat energy. The heat energy stored is surplus to the heating needs of the load. During discharge state there is no heat energy available from the boiler and the storage provides the stored energy back to the load.

In my setup I use a 4way valve to change direction of flow to and from storage. I have also seen systems shown on this site to use two opposing pumps to do this.

Maybe you are talking hydronic separation?

 

[rkusek]

It also depends on your piping arrangement. I have a primary loop that everthing else connects to (boiler, shed heater, UG line to house, and storage tanks). I think my best choice will be to go with one set of pipes and two circs pointed towards each other (w/o check valves). Basically, when boiler circ runs so does storage charging circ. When boiler circ is off and call for heat exists, then storage discharge circ would run using a relay to make sure both storage circ can't run at same time. I believe someone suggested this on Hearth some time ago, will try to find it again before I do mine.

 

[bulldogbones]

Here is what it looks like. Does that make more sense?? Does it look like it will work ok?

 

[Donl]

Here is what it looks like. Does that make more sense?? Does it look like it will work ok?

My first impression is that this will work, but not well.

The pump closest to the boiler when operating will always cause some flow through the storage tank and the manifolds to the radiators. Basically, the tank and loads are always in parallel. I don't think that is desirable.

Also, how is this design addressing cold return protection?

 

[Singed Eyebrows]

When I had my tank built I copied the ones that were professionally made & engineered out. These were on Kotly.com. They used 2 fittings at the top & 2 at the bottom. Non had one pipe top & one pipe bottom. As others mentioned, the top of my tank needs to heat before I have system heat & for me this isn't a problem. If you have a situation where you just can't wait for heat then my setup won't be correct for you, Randy

 

[bulldogbones]

Here is what it looks like. Does that make more sense?? Does it look like it will work ok?

My first impression is that this will work, but not well.

The pump closest to the boiler when operating will always cause some flow through the storage tank and the manifolds to the radiators. Basically, the tank and loads are always in parallel. I don't think that is desirable.

Also, how is this design addressing cold return protection?

What do I need to protect from? There will never be a time when the boiler is screamin hot and cold water gets piped into it. If I go away for say a week and everything goes cold say 50deg. And during that time I will be using my forced air for heat. When I come home I will turn my thermostat on and that will kick on the first circ and the second circ will be going because the aquastate will tell it to run. Then I will build a fire water will be continually moving through it there for the ALL the water will come up to temp evenly........right??? Or am I missing something?

 

[Singed Eyebrows]

Here is what it looks like. Does that make more sense?? Does it look like it will work ok?

My first impression is that this will work, but not well.

The pump closest to the boiler when operating will always cause some flow through the storage tank and the manifolds to the radiators. Basically, the tank and loads are always in parallel. I don't think that is desirable.

Also, how is this design addressing cold return protection?

What do I need to protect from? There will never be a time when the boiler is screamin hot and cold water gets piped into it. If I go away for say a week and everything goes cold say 50deg. And during that time I will be using my forced air for heat. When I come home I will turn my thermostat on and that will kick on the first circ and the second circ will be going because the aquastate will tell it to run. Then I will build a fire water will be continually moving through it there for the ALL the water will come up to temp evenly........right??? Or am I missing something?

Thermal shock is not all you want to protect from. If your system keeps inlet temps above about 70C you will be fine, if not you risk acid corrosion, Randy PS, you do not want to bring your boiler temp up slowly as it seems you are saying. This needs to heat fast & stay there, Randy

 

[Donl]

What do I need to protect from? There will never be a time when the boiler is screamin hot and cold water gets piped into it. If I go away for say a week and everything goes cold say 50deg. And during that time I will be using my forced air for heat. When I come home I will turn my thermostat on and that will kick on the first circ and the second circ will be going because the aquastate will tell it to run. Then I will build a fire water will be continually moving through it there for the ALL the water will come up to temp evenly........right??? Or am I missing something?

Cold water protection is used to prevent cooler water from being returned to an operating boiler. From my understanding returning water should be maintained above 140 degrees F. Lower temps may cause condensation which will eventually harm the boiler. I would suspect there will be times when the return from your radiators and the bottom of your storage tank will be cool enough to warrant protection.

On another note, I have found it worth while to monitor water temperatures going to storage. In my case there are times when the storage tank is warmer than the output of the boiler. In that case I control the flow to storage in order not to cool it down.

 

[bulldogbones]

What do I need to protect from? There will never be a time when the boiler is screamin hot and cold water gets piped into it. If I go away for say a week and everything goes cold say 50deg. And during that time I will be using my forced air for heat. When I come home I will turn my thermostat on and that will kick on the first circ and the second circ will be going because the aquastate will tell it to run. Then I will build a fire water will be continually moving through it there for the ALL the water will come up to temp evenly........right??? Or am I missing something?

Cold water protection is used to prevent cooler water from being returned to an operating boiler. From my understanding returning water should be maintained above 140 degrees F. Lower temps may cause condensation which will eventually harm the boiler. I would suspect there will be times when the return from your radiators and the bottom of your storage tank will be cool enough to warrant protection.

On another note, I have found it worth while to monitor water temperatures going to storage. In my case there are times when the storage tank is warmer than the output of the boiler. In that case I control the flow to storage in order not to cool it down.

Right now the circ pump that is on the boiler loop is hooked to an aquastate and if the boiler water drops below a certian temp then that circ pump shuts of and I will be drawing from just the storage.



Now on to the cold water return protection....... Where do I add in a cold water protector??? and what are they?

 

[Singed Eyebrows]

I would put a thermometer on your boiler inlet. You say your short boiler loop temp is protected by the aquastat & if it is probably nothing more needs to be done. Understand though that a Thermic valve will not fluctuate much, your aquastat has a differential & I don't know how this is set. If you look at thermometer you can tell exactly what is happening, Randy PS, If & when you install this setup you can look at a thermometer, pretty hard to now!

 

[kabbott]

And the correct answer is post #5....
Depending on the rest of the system(as always) 1 connection on top and 1 on bottom would mean you could heat the house with the tank
totaly cold..... If you have seperate connections for boiler and load it MAY require some heat in the tank to deliver any heat to the load...
In real world conditions this may not be an issue though..

If the connections are far apart it MAY take some time for heat to arive at the load port if the tank is cold...

Kris

Maybe I am missing something here! My answer above assumed that there are two states, one state for charging the tank and the other state for discharging the tank. During the charge state the storage tank only stores heat energy. The heat energy stored is surplus to the heating needs of the load. During discharge state there is no heat energy available from the boiler and the storage provides the stored energy back to the load.

In my setup I use a 4way valve to change direction of flow to and from storage. I have also seen systems shown on this site to use two opposing pumps to do this.

Maybe you are talking hydronic separation?

Yes Don, I was thinking of the tank being the separator. I assumed(possibly wrongly) this was what the OP had in mind.

That is what I would do with pressurized storage. With 1 inlet/1 outlet to the tank the storage could be isolated in case of
a problem. Also if the storage was cold for whatever reason you would get heat as soon as the boiler is warm, and not have
to wait for the top of the tank to get hot.