Basic Piping and Storage Design...Planning Phase please help!

maple1

Minister of Fire
Sep 15, 2011
10,657
Nova Scotia
In my case the heating system draws out of the hottest part of the tank. At the beginning of a burn my tank temperature may be 100° to 110°. However, at the end of a burn my tank my tank temperature may be 150° to 165°, but never as hot as the 175-185° water produced by the boiler.
This has me curious. My boiler output goes right to top of storage. So whenever I'm burning, the two temps are the same. How does your boiler put out 175-185 but storage is only 150-160? Also does your boiler also pull from coldest part of storage? (I think also recommended). If so that sounds like a very big boiler dT?
 

HardDrinkin'Lincoln

New Member
Nov 2, 2019
42
WA
Here's how my storage temperatures typically look after a 2 hour burn. These temps were from last night and the starting temp of the tank was 90°.
1590240932323.png
 

salecker

Minister of Fire
Aug 22, 2010
1,265
Northern Canada
My house draws from the top of the tanks when the boiler is resting.I pull the hot from the top and don't mix it.I bring my water to around 185 before the boiler hits the shutdown.
Then the house draws from storage for the next 19 hours or so.
I don't mix my water,it gets used at whatever temp shows up.Cast Iron Rads throughout the top floors,one unit heater in the basement.
 

JJSHELLEY

Member
Jan 18, 2018
21
Ny
I have a Triangle Tube propane boiler that uses outdoor reset to determine the radiant water temperature. Water temp is 80° when outside temp is 55° and increases as the outside temp drops, to 115° at 0°.

The Vedolux 350 and 500 gal. tank is a good match for my house built in 2013, 1,875 sq. ft. single story with insulated concrete slab and 1/2" PEX in 3 zones. I sized them based on the actual heat loss calculation for the house. What is the total BTUs lost by the house over a 24 hour period on the coldest design day? Then given BTU generating capacity of the boiler you can figure out how many times per day you would have to burn a load of wood. This is really the first step in determining the size of the boiler. Once the boiler size is known then most boiler manufacturers will recommend a minimum storage tank volume. A larger tank can always be used to store more hot water and then release the energy over a longer period of time before having to relight the boiler.

In my case there was no room, in the garage or my budget, for any tank larger than 500 gallons.
I have a Triangle Tube propane boiler that uses outdoor reset to determine the radiant water temperature. Water temp is 80° when outside temp is 55° and increases as the outside temp drops, to 115° at 0°.

The Vedolux 350 and 500 gal. tank is a good match for my house built in 2013, 1,875 sq. ft. single story with insulated concrete slab and 1/2" PEX in 3 zones. I sized them based on the actual heat loss calculation for the house. What is the total BTUs lost by the house over a 24 hour period on the coldest design day? Then given BTU generating capacity of the boiler you can figure out how many times per day you would have to burn a load of wood. This is really the first step in determining the size of the boiler. Once the boiler size is known then most boiler manufacturers will recommend a minimum storage tank volume. A larger tank can always be used to store more hot water and then release the energy over a longer period of time before having to relight the boiler.

In my case there was no room, in the garage or my budget, for any tank larger than 500 gallons.
Question about injection pump from storage to closely spaced T's. I plan on going with the pump below. Some of the reviews talked about when using Delta T the pump would ramp up and ramp down and short cycle all the time. Did you have any problems? I plan on running 1" from storage to house manifold T's.

 

HardDrinkin'Lincoln

New Member
Nov 2, 2019
42
WA
That Taco pump should work fine. Use the set-point mode and install the temperature sensor down stream from the closely spaced Ts. The pump's speed will vary to maintain the target temperature at that point. I've never had short-cycling with the set point modes.

I noticed that there appears to be a swing check valve located between the closely-spaced Ts.
1601385697922.png


That will need to be removed because there can be conditions where the flow rate from the storage tank exceeds the flow rate of the heating zones. At such times the excess flow from storage will need to flow to the right directly from supply to return. To do that the check valve should be removed.
 

JJSHELLEY

Member
Jan 18, 2018
21
Ny
That Taco pump should work fine. Use the set-point mode and install the temperature sensor down stream from the closely spaced Ts. The pump's speed will vary to maintain the target temperature at that point. I've never had short-cycling with the set point modes.

I noticed that there appears to be a swing check valve located between the closely-spaced Ts.
View attachment 263913

That will need to be removed because there can be conditions where the flow rate from the storage tank exceeds the flow rate of the heating zones. At such times the excess flow from storage will need to flow to the right directly from supply to return. To do that the check valve should be removed.
Good to hear about the pump! Not so good to hear about check valve. I am glade you caught that. I wonder why that check valve was installed their. My brother has the same set up and they put the check valve before the 2 T's.

If I remove check valve will it have any negative effects on my current set up?


1601386720488.png
 

JJSHELLEY

Member
Jan 18, 2018
21
Ny
Is it okay to open the swing valve up from the top and remove the arm/plate?

Simple fix?
 
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HardDrinkin'Lincoln

New Member
Nov 2, 2019
42
WA
Regarding your storage and piping question:

I initially had the supply and return for the heating/DHW loads connected to top and bottom. But I found that with the way the tank was connected, the pump to the plate HX was returning water to the bottom that was as hot as when it left the tank when no DHW was being used. What this did was to feed the hot return water into the boiler return line, preventing the boiler from getting the coolest water from the bottom of the tank. Returning already hot water to the boiler made it difficult to remove heat from the boiler. So I moved the heating/DHW return line to the top of the tank.

The boiler will always be getting to coolest water from the bottom of the tank now. As cool water is removed from the bottom of the tank the hot water entering the top is pushed down toward the bottom. At the end of a full burn the top of the tank can be a 175° and the bottom at 155°.
 

JJSHELLEY

Member
Jan 18, 2018
21
Ny
Okay, that makes sense. I'm going on my 4th week with the my new set up and everything is going better than planned. Thank you again for all your help! Especially with spotting the check valve in-between the 2 T's!!!!

The TACO Delta T Circulator is also working great. Initially when the in-floor heat clicks on and the return temp from the floor is low the Taco will ramp up and shut down a few times before the return temp warms up. Then it is more of constant flow with the Taco. Just at first there is that delay in the sensor, and the Taco short cycles a few times. So at fist it reads cold water and goes high flow. Then it shuts down a little after 120. As it shuts down the return temp from floor is still cold and the pattern repeats until return gets up to 100F and then it runs smooth. So it runs on and off for the first 5 min depending on how cold the return temp is for the floor. After that it runs pretty much at it's lowest GPM to maintain a 120F setpoint

I don't think it is hurting the circulator?

Everything else in the words of Tarm Biomass is "Happy Wood Burning"
 

HardDrinkin'Lincoln

New Member
Nov 2, 2019
42
WA
That startup behavior occurs because the temperature of the pipe is changing faster than the sensor's ability to track it. But, as you observed, the water temp, sensor temp and pump speed reach equilibrium in a few minutes and run smoothly at the desired target temp.
 
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