Testing 1000 gallon pressurized storage tank

[goosegunner]

Finally testing my storage tank today. A few things that I have noticed.

1. Takes a while to bring 1000 gallons of 62 degree water up to temp.

2. The top did heat fast but 5 hours later the return is still pulling 62 degree water off the bottom of the tank.

3. Danfoss is working as it should but at times the boiler will idle for a few minutes because the Danfoss is pretty much closed with 62 degree water on one side.

I have 162 degrees on the top and about 140 half way down 62 degrees near the bottom.

I used the Simple pressurized method with connections on opposite ends. Hot top/ closest to boiler and return bottom far end of tank.

Now that I see first hand how the tank heats and works down it is apparent that I could have connected to one end top and bottom as others from the site had told me.

gg

 

[bigburner]

explain further - why you think it should be hooked different and why you think the boiler is idling. ??

 

[goosegunner]

explain further - why you think it should be hooked different and why you think the boiler is idling. ??

I know the boiler was idling because it would hit set point and the fan would shut off. I think I had the danfoss bypass closed too far so I was not moving enough gpm in any direction. flow was throttled by the Danfoss cold return and the Hot port with bypass.

I am not saying that my tank should be hooked differently, what I am saying is, I could have hooked top and bottom on one end and I believe the results would have been the same.

When you feel the tank at different levels the heat difference is quite remarkable. Being new at this the concepts are hard for me to understand at times until I see it and think about it more.

If I was hooked on one end of the tank, as hot as the top water is there is no way the system could do anything other than pull cool water off the bottom. Now when the temperatures become closer together it may be a little different but I doubt it.

In the long run It cost me $200 more for copper pipe to go to the far end of the tank to pull the return. Not that I want to spend $200 needlessly but compared to the what else I have spent so far it is a drop in the bucket.

gg

 

[taxidermist]

You need to adjust your ball valve on your boiler loop. Your boiler should never idle when your return temp is 62*


Rob

 

[goosegunner]

You need to adjust your ball valve on your boiler loop. Your boiler should never idle when your return temp is 62*


Rob

I just wonder if I am not moving enough water for the boiler output. If I close the bypass more the Boiler temp gauge rises even faster. Right now I only have the push in thermometers in boiler supply, return before and after Danfoss.

I am getting about a 10 degree increase from boiler supply vs return, so it seems I am moving water at a decent rate. But the boiler with a good load of red oak will still climb to 5 degrees below the set point and drop to low fan for a few minutes.

I completed the clean, flush, refill and addition of boiler treatment so I will be testing again tomorrow.

Can someone tell me where a good pump head calculator can be found so I can look at my numbers?

gg

 

[Hunderliggur]

Agree you should not idle with 62F return. I do get states when starting where the circulator shuts off while the boiler heats up again. I have the circulator start set at 170F and stop at 165F. The Danfoss is 140F. When starting, the boiler will cycle the circulator when the return is 140 or less. When return gets higher, the circulator runs constantly [BTW - I have not measured the Danfoss output temp - guess I should!). What is the set point temp setting on your control [mine is 195F]? Sounds like you cannot get the BTU's out of the boiler fast enough which is why it hits the set point even though the return temp is 140F. Does your circulator have variable speed? I originally set mine too low but when I stepped it up a notch the system runs much better.

 

[taxidermist]

Also look for trapped air. I have a taco air scoop and i always leave my bleed screw open.


Rob

 

[goosegunner]

Also look for trapped air. I have a taco air scoop and i always leave my bleed screw open.


Rob

I have a Taco 4900 series air separator and it works pretty well. I think I might need to replace the 90 that turns down to my tank. If I put a T there I can put a vent in the top to catch any air that might rise from the tank. I also have a vent in the center of the tank on a riser.


I might try and slow the water down again, I can hear it gurgling in supply near the tank so I would guess its air or water moving too fast?

My boiler is raising temp 10 degrees, Shouldn't the rise be more? Maybe water is moving too fast to absorb heat?



gg

 

[Hunderliggur]

Can't move too fast to absorb heat, but can move too fast for best efficiency. Gurgling mean air and speed. I doubt you move it so fast you get cavitation. Try a slower speed, I think most shoot for a 20F rise through the boiler. Air in the system will cause lots of problems.

 

[goosegunner]

Ok it seems to be running a little better now. Things I changed and have noticed.

1.I set the pump on low instead of High.

2. Gurgling in supply to tank has stopped.

3. I set the Danfoss to 155 on the mixed port.

4. With the pump on low I am getting just under 20 degree increase from return to supply.

One thing that appears to be causing some of the issues was the digital boiler temp gauge reads 10 degrees higher than the gauge in my supply pipe. I have increased boiler set point to 195. Boiler temp gauge is hovering around 185 and the gauge in the supply right after boiler says about 175.

The difference may have contributed to dropping to low speed. Only time will tell.

gg

 

[Gasifier]

Goosegunner, that sounds good. Hope all goes well. I am curious what your house heat demand is at night now. Do you have much? And how often are you burning to keep the 1000 gallons up to the temp you want? Have you insulated that tank yet?

Now you will have to change your signature to reflect 1000 gallons on-line!

 

[goosegunner]

Goosegunner, that sounds good. Hope all goes well. I am curious what your house heat demand is at night now. Do you have much? And how often are you burning to keep the 1000 gallons up to the temp you want? Have you insulated that tank yet?

Now you will have to change your signature to reflect 1000 gallons on-line!

Heat demand on house is 0 right now. I has been 80+ here in Wisconsin the last few days. I just put it on line and am still doing test burns, no insulation yet.


I did have to turn the circ up to medium. I loaded with some pine and red oak and it hit 5 degrees below the set point. I had a 30 degree increase on return vs Supply. I think it is the Danfoss that will cause me trouble. As the Cold return creeps up the Mixed rises and causes the Boiler to increase in Temp.

I think a loading unit would work much better if you could actually set your target return temp.

gg

 

[taxidermist]

As th return temp increases you need to close your ball valve on your bypass. All you are doing is allowing heated water to mix with cooler water to keep your danfoss open and prevent shock to boiler. When I start my fire my ball valve is about 3 open as my return temps come up I shut my ball valve so i am not circulating hot water around my boiler and causing it to idle.

Rob

 

[ewdudley]

I did have to turn the circ up to medium. I loaded with some pine and red oak and it hit 5 degrees below the set point. I had a 30 degree increase on return vs Supply. I think it is the Danfoss that will cause me trouble. As the Cold return creeps up the Mixed rises and causes the Boiler to increase in Temp.

In other older threads I believe it was confirmed there is such a thing as a Danfoss 'from the factory' with its guts bass-ackward some how or another.

Also if your Danfoss is flipped with the mix port towards the tank and the cold port towards the boiler I think that might explain what you're seeing.

--ewd

 

[goosegunner]

I did have to turn the circ up to medium. I loaded with some pine and red oak and it hit 5 degrees below the set point. I had a 30 degree increase on return vs Supply. I think it is the Danfoss that will cause me trouble. As the Cold return creeps up the Mixed rises and causes the Boiler to increase in Temp.

In other older threads I believe it was confirmed there is such a thing as a Danfoss 'from the factory' with its guts bass-ackward some how or another.

Also if your Danfoss is flipped with the mix port towards the tank and the cold port towards the boiler I think that might explain what you're seeing.

--ewd

I checked and flipped mine at install. It was indeed backwards from the attached sticker.

As far as the Danfoss, I believe that once I get the tank to temp and keep it there on a daily basis the ball valve setting will be much closer through out the burn.

When I had 62 degree return I obviously needed the ball valve open further than if I never let the tank below 130.

gg

 

[Hunderliggur]

Set and forget I say. I never mess with my bypass valve. If you find your sweet spot with at 10 to 20 rise and no idling, you are there. Sounds like you are pretty close anyway. One question though - how do you set a Danfoss to 155F? Mine is 140F pieces of metal, not a settable valve. I guess I could buy some 155F guts if I want to (I don't).

 

[goosegunner]

Set and forget I say. I never mess with my bypass valve. If you find your sweet spot with at 10 to 20 rise and no idling, you are there. Sounds like you are pretty close anyway. One question though - how do you set a Danfoss to 155F? Mine is 140F pieces of metal, not a settable valve. I guess I could buy some 155F guts if I want to (I don't).

My bypass valve was set so to allow enough water through the hot port on the danfoss to set the return temp at the mixed port to read 155. That is the problem as the return water rises the boiler return rises reducing the delta t. It then will hit the set point easier. Hopefully once I am up and running for the season my return temp will not be that low again so I should be able to find the sweet spot for my operating range. When I got near the end the bypass valve was almost fully closed.

I heated the tank yesterday from 98 top/ 72 bottom, to 182 top/ 172 bottom. It took 12 hours but I was gone for 4 hours mid day and the boiler was out of wood. The top of the tank only has a piece of r19 laying on it now with no other insulation on the tank.

gg

 

[Fred61]

Hunderliggur is correct. You should be able to find the sweet spot and set it and forget it. It's actually the flow through the bypass that actuates the automotive type thermostat. When the flow meets or exceeds 140 degrees the thermostat will start opening and start allowing flow through the unit As it cools the sensor bulb on the thermostat from the colder return water it will either close or reduce the opening which allows circulation. I can imagine it may be actually pulsating when the return temperatures are cold. Remember, the sensing bulb on the auto type thermostat must be on the bypass side of the unit. That is what actuates the unit.
Anyone installing a Danfoss should check to see if the thermostat is oriented correctly as mine was assembled backwards but you must understand what is happening there before you assume it is actually backwards and change it. Sometimes the graphics will confuse people. Mine came with about four different stick on graphics in a plastic bag and I had a choice as to which one I wanted to use.
Starting out with cold storage and cold boiler, my circulators cycle numerous times until the water temperature rises high enough to have them run continuously, since my set temperature (circulator on) is set at 178 degrees.

 

[goosegunner]

Hunderliggur is correct. You should be able to find the sweet spot and set it and forget it. It's actually the flow through the bypass that actuates the automotive type thermostat. When the flow meets or exceeds 140 degrees the thermostat will start opening and start allowing flow through the unit As it cools the sensor bulb on the thermostat from the colder return water it will either close or reduce the opening which allows circulation. I can imagine it may be actually pulsating when the return temperatures are cold. Remember, the sensing bulb on the auto type thermostat must be on the bypass side of the unit. That is what actuates the unit.
Anyone installing a Danfoss should check to see if the thermostat is oriented correctly as mine was assembled backwards but you must understand what is happening there before you assume it is actually backwards and change it. Sometimes the graphics will confuse people. Mine came with about four different stick on graphics in a plastic bag and I had a choice as to which one I wanted to use.
Starting out with cold storage and cold boiler, my circulators cycle numerous times until the water temperature rises high enough to have them run continuously, since my set temperature (circulator on) is set at 178 degrees.

The circulator on temp is one thing that I need to change on my econoburn. They come set at 150 from the factory. It will run until boiler drops to 150 after fire is out. that is a long time with tank temps at 180 and no fire in the boiler.

gg

 

[Hunderliggur]

I have my circulator on set to 170F, off at 165F. I have been wondering what other owners use. I might try a higher temp when I get some time to experiment, but 170 makes a good burn right now. 150 did not get the firebox hot enough for good heating in the upper chamber.

 

[goosegunner]

I have my circulator on set to 170F, off at 165F. I have been wondering what other owners use. I might try a higher temp when I get some time to experiment, but 170 makes a good burn right now. 150 did not get the firebox hot enough for good heating in the upper chamber.

As far as I know my econoburn does not have a differential, on or off at the same temp.

gg

 

[rkusek]

I have my circulator on set to 170F, off at 165F. I have been wondering what other owners use. I might try a higher temp when I get some time to experiment, but 170 makes a good burn right now. 150 did not get the firebox hot enough for good heating in the upper chamber.

I think I ran on at 165 off at 160 last winter and that worked great. About 20* warmer than the initial setting I used. Boiler ran great.

 

[maple1]

I have my circulator on set to 170F, off at 165F. I have been wondering what other owners use. I might try a higher temp when I get some time to experiment, but 170 makes a good burn right now. 150 did not get the firebox hot enough for good heating in the upper chamber.

As far as I know my econoburn does not have a differential, on or off at the same temp.

gg

That doesn't sound quite right - to me anyway. Wouldn't no differential lead to constant start/stop?

 

[goosegunner]

I have my circulator on set to 170F, off at 165F. I have been wondering what other owners use. I might try a higher temp when I get some time to experiment, but 170 makes a good burn right now. 150 did not get the firebox hot enough for good heating in the upper chamber.

As far as I know my econoburn does not have a differential, on or off at the same temp.

gg

That doesn't sound quite right - to me anyway. Wouldn't no differential lead to constant start/stop?

It hasn't to this point at 150 anything over and the pump runs, under and it stops. The boiler once lit doesn't drop below that unless it is out of wood. It may change if the temp is set higher.

gg

 

[Gasifier]

Gentlemen, and I use that term loosely, :lol: this is interesting to me for a few reasons.

1. Do you see any advantage to having the circulator set to a lower temperature when it is warm like this to keep the boiler from going so cold. For instance, right now I am just keeping my tank warm by charging it once a day in order to heat my DHW. I shut the boiler off when I go to bed and boiler and tank are 175 degrees rounghly. Right now the tank keeps the boiler warm for a while longer because of that. The morning temp is around 150 or so. And this way when I come home the next day around 4pm the boiler is still at 125-130 degrees. The tank is a little warmer because of the better insulation of course. This way I am not having to warm my boiler from a colder temperature all the way back up to 175 again. I don't know, like I said. I am a rookie at these systems. I will set the circ pump at a higher temp to come on and off at when the colder weather comes. Just curious. With the temperatures the way they are, and the circulator set higher the circ. pump would be off a lot quicker and the boiler would go a lot colder by the next day.

2. What do you guys use to know the temperature of your return water after you Danfoss or whatever protection valve it is that you use. I need to get a couple of sensors and digital readouts so I have a better idea of what that is. Anything simple and inexpensive you can suggest? Thanks in advance. I appreciate any info you can give me.