My Tarm doesn't have the pump switch hooked to anything, which seems to be the way they are installed these days. I have a Siebel controller which monitors temperatures at the Tarm, and at the top and bottom of storage. I have it set to come on when the Tarm is at least 140 and 4 degrees warmer than storage, and shut off when the differential drops to 8 degrees. After a fire, the top and bottom of the tank can be 30 degrees apart, and the pump continues to circulate and mix for a long time. For some reason, the Tarm stays warmer than the bottom of the tank for a long time, keeping the pump going for hours after the fire has gone out. Is this normal, or do I perhaps have a parameter wrong, or should I look into hooking up a defeat switch for the pump?
Defeating the pump
- Thread starter Rory
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Is that a Resol control with the Steibel name on it? Depending on the model most can be used as a setpoint (thermostat function), or differential control.
Used as a setpoint make sure you have the on/ off paramaters adjusted properly. Also used as a setpoint function the pump will run to try to meet the programed temperature. Fire goes out but the control wants to meet it's setpoint regardless.
Differential function may be a better choice. Sensor 1 should always be the source sensor.
Does the control have a priority function? If so make sure it is in priority 1.
An easy way to check this or any temperature control is to pull the sensors out and cool or warm them to activate the control. A glass of ice water and a match works great to simulate operating conditions
hr
Used as a setpoint make sure you have the on/ off paramaters adjusted properly. Also used as a setpoint function the pump will run to try to meet the programed temperature. Fire goes out but the control wants to meet it's setpoint regardless.
Differential function may be a better choice. Sensor 1 should always be the source sensor.
Does the control have a priority function? If so make sure it is in priority 1.
An easy way to check this or any temperature control is to pull the sensors out and cool or warm them to activate the control. A glass of ice water and a match works great to simulate operating conditions
hr
Aa I said, the pump comes on when the Tarm ("Collector" on he display) reaches 140 and is at lest 4 degrees warmer than the tank, and shuts off once when it detects cooling to within 8 degrees of the tank. The problem is when I have extreme stratification at the end of the burn and the bottom of my storage tank is 30 degrees or so cooler than the top and the Tarm. It wants to circulate until the difference between the Tarm and the bottom of the tank drops to 8 degrees, and that seems to take forever. I guess I question the efficiency of the loop as much as the control system. I would expect the Tarm to cool to the bottom temp of the tank fairly quickly, but I guess the Termovar is helping to prevent that.
Post a diagram showing where your sensors are located. Might be that relocating them will help with the problem. Other comments:
1) "on" at 140 at 4 warmer than the tank with the Termovar -- my Termovar starts to open at 160 and provides minimum return water protection of 140. I would set the "on" at 160 minimum, as even at 160, with cooler return water, the Termovar likely is returning water to the boiler to maintain return water protection. Your "on" sensor may be reading at a point that maintains a high temp by reason of the Termovar. I also would set 10 warmer rather than 4 warmer than the tank, and set "off" at less than 8, maybe 4 or 5, reason being a) at 4 warmer you are not moving many btu's, and b) at high tank temp, the 8 "off" setting will prevent the tank from reaching a high temp closer to the Tarm.
2) Tarm will not cool to bottom of tank quickly both by reason of the Termovar and by residual coals and heat retention in the thermal mass of the Tarm. The work-around is to shut down tank charging when the Tarm shuts down the draft fan following the end of the burn. This is the lo-limit control on the Tarm, which I set at 90C (194F). I wired a 110vac relay in series from lug #11 on the Tarm Strip, to the aquastat that controls the circulator. The low limit shuts off the circ as the fire dies out. I played with the settings and found 90* works well enough. This will greatly reduce the storage tank discharging back into the boiler.
1) "on" at 140 at 4 warmer than the tank with the Termovar -- my Termovar starts to open at 160 and provides minimum return water protection of 140. I would set the "on" at 160 minimum, as even at 160, with cooler return water, the Termovar likely is returning water to the boiler to maintain return water protection. Your "on" sensor may be reading at a point that maintains a high temp by reason of the Termovar. I also would set 10 warmer rather than 4 warmer than the tank, and set "off" at less than 8, maybe 4 or 5, reason being a) at 4 warmer you are not moving many btu's, and b) at high tank temp, the 8 "off" setting will prevent the tank from reaching a high temp closer to the Tarm.
2) Tarm will not cool to bottom of tank quickly both by reason of the Termovar and by residual coals and heat retention in the thermal mass of the Tarm. The work-around is to shut down tank charging when the Tarm shuts down the draft fan following the end of the burn. This is the lo-limit control on the Tarm, which I set at 90C (194F). I wired a 110vac relay in series from lug #11 on the Tarm Strip, to the aquastat that controls the circulator. The low limit shuts off the circ as the fire dies out. I played with the settings and found 90* works well enough. This will greatly reduce the storage tank discharging back into the boiler.
I'm going to jump in because I'm having same problem. The solutions above sound good but here's some more info in the hope to optimize our systems. They sound very similar. Rory are you using pressurized or non pressurized ?
My system is a Tarm 60 with 1000G pressurized storage.
My controller is a SOM 7 which seems to be a Resol / Delta Sol BS Plus. Nine system configurations with 4 sensors and 2 120v relays.
I bought my Tarm with near boiler piping and electrical done. To complete system as provided ( SOM System design #3 ) S1 goes to Tarm immersion well. S2 to bottom 1/3 of tank. S3 to top 1/3 of tank. That leaves 1 available sensor or S4. R1 (relay) goes to Tarm pump and that leaves R2 available. R2 in non-pressurized would be used for storage tank over heat dump, for example.
I have read that in some cases a return circulator from storage can be benifical. I had a extra 007 and a longer pipe run from Tarm to Storage so when I did my piping at storage I included the 007 - R2.
Any thoughts on including R2 at different points during the tank charging ? When I plug R2 in manually it definitely helps get the whole 1000G up in temp but you don't see really hot - hot on top tank mixes. I was think that towards the end of the burn you would want to have R2 shut off and just have R1 run to pack heat on top only.
Any input on reprogramming the Resol / SOM to accommodate this arrangement.
It seems that if I switched to System Design #2 and included MX3O and MX3F values that might do it. However while unloading tank and the temp would drop and pump would kick back on. Not good.
Thanks Rob
My system is a Tarm 60 with 1000G pressurized storage.
My controller is a SOM 7 which seems to be a Resol / Delta Sol BS Plus. Nine system configurations with 4 sensors and 2 120v relays.
I bought my Tarm with near boiler piping and electrical done. To complete system as provided ( SOM System design #3 ) S1 goes to Tarm immersion well. S2 to bottom 1/3 of tank. S3 to top 1/3 of tank. That leaves 1 available sensor or S4. R1 (relay) goes to Tarm pump and that leaves R2 available. R2 in non-pressurized would be used for storage tank over heat dump, for example.
I have read that in some cases a return circulator from storage can be benifical. I had a extra 007 and a longer pipe run from Tarm to Storage so when I did my piping at storage I included the 007 - R2.
Any thoughts on including R2 at different points during the tank charging ? When I plug R2 in manually it definitely helps get the whole 1000G up in temp but you don't see really hot - hot on top tank mixes. I was think that towards the end of the burn you would want to have R2 shut off and just have R1 run to pack heat on top only.
Any input on reprogramming the Resol / SOM to accommodate this arrangement.
It seems that if I switched to System Design #2 and included MX3O and MX3F values that might do it. However while unloading tank and the temp would drop and pump would kick back on. Not good.
Thanks Rob
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I have the same controller as ROBC and the sensors are set up in the same arrangement with my 670 gallons of unpressurized storage. I'm not really a plumbing and electrical kind of guy, so building my storage was the extent of my involvement in the project, but I did end up learning a bit about the controller, as my installer didn't really seem to have a clue. I don't find the STIEBEL manual to be the most user-friendly document I've ever read. Per jebatty's advice, I bumped my CMN up from 140 to 180 It was originally set at the factory default (105, I think), and I used to hear the loop running to the Termovar through the boiler at start up. Bub from revision energy straightened that out for me and bumped it up to 140, but I'll try 180. I usually takes me a long time to hit that temp, but maybe holding it back will solve that. I can always bump it back to 160 or so if 180 seems to be too much. I had knocked my DTF from 4 to 8 thinking that I'd shut down sooner, but upon jebatty's advice I've turned it back to 4 again. I really like his idea of the really to shut the circulator off with the combustion fan on cooldown, that seems like the logical course of action to me.
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