Froling pump short cycling

[Caiden]

Hello,
I have a question for fellow Froling users. I have a Froling S3 Turbo 50 with two 300 gallon storage tanks. I have been running it for about 3 months and love the system. I do have a concern that has been addressed with the supplier. When the boiler is in "Off" mode and the boiler is 4 degrees higher than the top buffer tank temp the circ pump starts. When the tank temp is 3 degrees lower than the boiler the pumps turns off. This temperature fluctuates often boiler up or tank down 1 degree causing the pump to continually cycle on and off sometimes several time per minute. This does not seem to be good for the pump. Shouldn't there be a buffer when the pump cycles on it should remain on for a certain amount of time? Has anyone experienced this issue? If so is there a fix? If not a fix does anyone agree with the supplier that this is "the nature of the beast". Any comments or suggestions would be greatly appreciated. Thanks

 

[maple1]

Hello,
I have a question for fellow Froling users. I have a Froling S3 Turbo 50 with two 300 gallon storage tanks. I have been running it for about 3 months and love the system. I do have a concern that has been addressed with the supplier. When the boiler is in "Off" mode and the boiler is 4 degrees higher than the top buffer tank temp the circ pump starts. When the tank temp is 3 degrees lower than the boiler the pumps turns off. This temperature fluctuates often boiler up or tank down 1 degree causing the pump to continually cycle on and off sometimes several time per minute. This does not seem to be good for the pump. Shouldn't there be a buffer when the pump cycles on it should remain on for a certain amount of time? Has anyone experienced this issue? If so is there a fix? If not a fix does anyone agree with the supplier that this is "the nature of the beast". Any comments or suggestions would be greatly appreciated. Thanks

Not familiar with the Froling, but there isn't anything in the manual about being able to change settings? Or if there is an adjustable differential involved? Usually even if not possible to change, the manual would say something about that.

 

[Caiden]

Not familiar with the Froling, but there isn't anything in the manual about being able to change settings? Or if there is an adjustable differential involved? Usually even if not possible to change, the manual would say something about that.

The manual supplied to the installer does not even address any adjustable differentials for this. The installer talked to the distributor about this concern and was told that I just how it runs. I understand the logic to recover the heat from the boiler while it is not firing but I would rather it recovered it in bigger steps rather than a little at a time. It just doesn't seem normal to me. Thanks for the reply.

 

[salecker]

Unless you have check valves in the system
any recoverable heay will get to storage via the laws of thermodynamics anyway.

 

[Caiden]

There are no check valves between the boiler output and the piping going to the top of the tanks but there is an LK 821 diverter valve between the heating zone return and the piping going to the bottom of the tanks. I'm not real clear on how this all works. This really has me thinking. Thanks for the reply.

 

[Smoothride]

Cadien, I have the exact same issue. I installed a new Froling S3 Turbo 50 with 880 gallons of storage this summer and it has that annoying cycling issue, also. I have been in contact with my supplier and he is talking to Froling. I do not have any answers yet but the only thing I have seen is the top tank sensor shows a 1 degree drop when the pump starts and it jumps up when pump stops. Several times in 1 minute. My tanks are set up in a 2 pipe system with the system draws going off the manifold before water reaches the tank.

 

[Caiden]

Smoothride,

I'm glad to hear that I'm not the only one with this issue. Sounds like the systems may be piped the same way. I will post again if I can get a solution to the issue. I am worried this may cause premature failure of the circulator pump or circuit board. Thank you for the pos, I have the exact same issue. I installed a new Froling S3 Turbo 50 with 880 gallons of storage this summer and it has that annoying cycling issue, also. I have been in contact with my supplier and he is talking to Froling. I do not have any answers yet but the only thing I have seen is the top tank sensor shows a 1 degree drop when the pump starts and it jumps up when pump stops. Several times in 1 minute. My tanks are set up in a 2 pipe system with the system draws going off the manifold before water reaches the tank.
Smoothride,
I am glad to hear that I am not the only one with this issue. It sounds like it is the same problem. Sounds like the systems may be piped similar. I am worried it may cause premature failure of the circulator pump or circuit board. I will post if I can get a solution to the issue. Please post if you find a solution. Thank you for the response.

 

[Newfiestang]

I have the S3 Turbo connected to two 250 gal tanks. I have seen this also but mine definitely does not cycle on and off many times per minute. It does cycle on/off maybe once every 5 mins or so. IMO its normal for my system. Have you checked your min/max pump speeds.

My min pump speed is set to 25% and with no wood burning it will usually only run at 25% to keep boiler and buffer at same temperature. If your min pump speed is set high, say like 80 to 100% i expect you will get short cycling in this situation.

 

[Caiden]

I have the S3 Turbo connected to two 250 gal tanks. I have seen this also but mine definitely does not cycle on and off many times per minute. It does cycle on/off maybe once every 5 mins or so. IMO its normal for my system. Have you checked your min/max pump speeds.































































My min pump speed is set to 25% and with no wood burning it will usually only run at 25% to keep boiler and buffer at same temperature. If your min pump speed is set high, say like 80 to 100% i expect you will get short cycling in this situation.



































































I have the S3 Turbo connected to two 250 gal tanks. I have seen this also but mine definitely does not cycle on and off many times per minute. It does cycle on/off maybe once every 5 mins or so. IMO its normal for my system. Have you checked your min/max pump speeds.



My min pump speed is set to 25% and with no wood burning it will usually only run at 25% to keep boiler and buffer at same temperature. If your min pump speed is set high, say like 80 to 100% i expect you will get short cycling in this situation.





 

[Caiden]

That is a great suggestion. I am following the set up procedure from the supplier which says to set it at 80%. I have not even thought about trying to change this but seems like it makes perfect sense to me. I have a Grundfos 26-99 which is a 3 speed manually adjustable pump. the installer set the pump speed to high. I changed the minimum pump speed to 25% but when the pump starts it shows running at 100%. Do you have a pump that the boiler is able to control the output of the pump? Thanks for the input.

 

[Newfiestang]

That is a great suggestion. I am following the set up procedure from the supplier which says to set it at 80%. I have not even thought about trying to change this but seems like it makes perfect sense to me. I have a Grundfos 26-99 which is a 3 speed manually adjustable pump. the installer set the pump speed to high. I changed the minimum pump speed to 25% but when the pump starts it shows running at 100%. Do you have a pump that the boiler is able to control the output of the pump? Thanks for the input.

Are you going into service mode to make the change. I have a 3 speed pump as well and mine is controlled by the hydraulic module, not the core module. My pump is also set on speed three but during first lightening of the boiler it will run at the lowest speed 25% and adjust accordingly as boiler temp rises. This works perfect in getting the boiler temp up to setpoint quickest. If i set mine to 80 or 100% it takes much longer for the boiler to come up to temperature.

Also as boiler burns out of wood it automatically starts reducing pump speed to keep the boiler warm as long as possible.

 

[Caiden]

I am going into service mode. The system selected is Hydraulic System 4. I have noticed the pump speed ramping up starting at 25%. Your suggestion is working on the "heating" mode. After the fire has died down the boiler goes into "Off" mode. Then when the buffer tank temperature is 4 degrees lower than the boiler temperature the pump comes on at 100%. I will keep monitoring when the tank temperature and boiler are dropping to see if there is a change. Do you have the S3 Turbo 30 or 50? I am wondering if there is something going on with the Turbo 50 to cause this. Thank you again. Your input is greatly appreciated. I am always interested in hearing how others are succeeding in operations of these units.

 

[Smoothride]

I tried turning the min pump speed down to 25% and I still have the cycling issue. When the boiler is off, the temp was 174 on the boiler and in the top of the buffer tank, the pump would come on at 100% and quickly shut off (0%) and do that back and forth several times in 1 minute.... wait a little...3 to 5 min, and then do it again.

 

[Caiden]

Smoothride, I generally see a 4 degree higher temp on the top tank sensor than the boiler temperature when the pump comes on. Have you noticed a pattern of the temperature differentials when the pump is activated?

 

[Newfiestang]

I am going into service mode. The system selected is Hydraulic System 4. I have noticed the pump speed ramping up starting at 25%. Your suggestion is working on the "heating" mode. After the fire has died down the boiler goes into "Off" mode. Then when the buffer tank temperature is 4 degrees lower than the boiler temperature the pump comes on at 100%. I will keep monitoring when the tank temperature and boiler are dropping to see if there is a change. Do you have the S3 Turbo 30 or 50? I am wondering if there is something going on with the Turbo 50 to cause this. Thank you again. Your input is greatly appreciated. I am always interested in hearing how others are succeeding in operations of these units.

I have the S3 30.

My system is set to Hydraulic system 2, that is very close to Hyd system 4 from what i can see. I am away at work now but i will monitor my system closer once back home.

I dont really have any other suggestions but ill review manual again. I designed and installed my system from scratch like most on here so im pretty familiar how the S3 software works now.

 

[Caiden]

Newfiestang, I am using Hydraulic system 4 as directed by the supplier. I don't understand the different systems at all.
I noticed this morning that when the pump starts it runs at 100%. It only ran for more than a few seconds one time and when it did the pump went to 25% after about 12 seconds and continued to run at 25% for several minutes. I will observe again and try to catch it in this cycle. Thanks again for your input.

 

[Smoothride]

Smoothride, I generally see a 4 degree higher temp on the top tank sensor than the boiler temperature when the pump comes on. Have you noticed a pattern of the temperature differentials when the pump is activated?

I have the 50, also. I am seeing anywhere from 2 to 7 degree difference between boiler and the top tank sensor. When the pump comes on, the boiler temp simultaneously jumps up 1 or 2 degrees and when the pump shuts off, drops to the pre pump start temp. Pump comes on for 1 to 3 seconds and then shuts off. This will happen 2 to 5 times in a minute, then may not happen for 3 minutes or so or not at all. I did catch it doing it while I was looking at the pump output and that read 100%.

 

[Newfiestang]

This is a table for the different systems.

 

[Newfiestang]

Newfiestang, I am using Hydraulic system 4 as directed by the supplier. I don't understand the different systems at all.
I noticed this morning that when the pump starts it runs at 100%. It only ran for more than a few seconds one time and when it did the pump went to 25% after about 12 seconds and continued to run at 25% for several minutes. I will observe again and try to catch it in this cycle. Thanks again for your input.

This seems similar to how mine runs. I would say its normal. The reason IMO is to keep the boiler warm so it will be in the best condition (warm) for the next fire. This will both help with reducing boiler condensation plus be in a position to get the chimney up to temperature quickly.

 

[chew72]

A quick question on storage tank sensor location. Is the top buffer tank sensor located a little way inside of the tank? I'm thinking between the top 5 - 10% of the tank. That's where mine is located and I have no issue. I'm thinking if it's located on the inlet pipe you may have greater heat loss and the temperature in the pipe is dropping a little lower than the buffer tank if there is no flow. Triggering the pump to come on.

I don't have a manual in front of me but if you wanted to increase the differential between turning on and turning off it would probably be referred to as a "hysteresis" value.

 

[Newfiestang]

A quick question on storage tank sensor location. Is the top buffer tank sensor located a little way inside of the tank? I'm thinking between the top 5 - 10% of the tank. That's where mine is located and I have no issue. I'm thinking if it's located on the inlet pipe you may have greater heat loss and the temperature in the pipe is dropping a little lower than the buffer tank if there is no flow. Triggering the pump to come on.

I don't have a manual in front of me but if you wanted to increase the differential between turning on and turning off it would probably be referred to as a "hysteresis" value.

All my sensors are in thermowells in the the tank....or tanks in my case as i have two.

And i have 4 sensors, 2 in each tank. These are located apprx 12" from top and 12" from bottom in each tank.

Yes if the sensors are just strapped on to an uninsulated pipe they will definitely see lower temperatures and not accurately measure the internal tank temperature. The sensors will also see a delay in this configuration.

 

[Mila70]

Caiden, we're looking at installing a Froeling S3 Turbo with two 300 gallon tanks, but we're having some trouble figuring out how much it would cost us installed. Would you, by any chance, be willing to share a breakdown of your costs for the various components and materials, as well as the installation costs billed by your installer? I know that every system is different, but I think I'll be able to extrapolate since I have some sense (a list) of the various controls, valves, fittings, etc. planned. I'm just having a really hard time getting a straight answer, and the current estimate for the fully installed boiler and storage tanks and DHW with pump sensors, controls, fittings, valves, and piping is substantially higher than any estimates I've found online for a P4 installation with two 300 or even larger tanks and DHW and close to double what I've found for comparable systems with an S3 Turbo. I can't quite figure out why the numbers are so much higher except that the labor is a lump sum, and I have no sense of how much actual installation should cost. I would be incredibly grateful for any information!

 

[Newfiestang]

Mila70,

might not be much help because im in Canada but my complete system with S3 Turbo 30Kw, two 250 gal tanks, Turbomax DHW tank, 62 gal expansion tank, three circulators, all fittings, pipe & valves was right around $25000 CDN. I installed it myself so that didnt include any labor cost. Its not cheap venture but well worth it IMO. Its the ultimate wood burning package and again IMO its the best boiler out there. I was 4 years researching before i decided on Froling. No regrets at all yet.

 

[Smoothride]

Mila70,

might not be much help because im in Canada but my complete system with S3 Turbo 30Kw, two 250 gal tanks, Turbomax DHW tank, 62 gal expansion tank, three circulators, all fittings, pipe & valves was right around $25000 CDN. I installed it myself so that didnt include any labor cost. Its not cheap venture but well worth it IMO. Its the ultimate wood burning package and again IMO its the best boiler out there. I was 4 years researching before i decided on Froling. No regrets at all yet.

I agree... same money... but over my Orlan Eko, hands down...way better.

 

[Smoothride]

This is a table for the different systems.

View attachment 291336

I saw that earlier...but with the buffer tank system, I do not see how anything other than #4 is an option.