Tarm 4th Week of Use:Notes and Questions

[Birdman]

1.The Tarm 40 no longer has an issue with condensation. The issue seems to have cleared itself up.
2. I am getting good burns with gasification.
3. I adjujsted a valve and I am getting hotter water to my baseboards and more heat. Still... at times.. I have 3 or 4 zones calling for heat which lowers my temp on the hot water circulating at that time. I have to then turn down one thermostat and let that zone heat up the room first. Then when the room is up to temp... I can let the other 2 or 3 zones get to work with a higher water temp.
4. The Tarm is awesome... so much heat from so little wood. I am calculating heating the whole house up to 70 and all the hot water( 5 people) using 4 cord of hardwood and maybe a cord of pine. This is an estimate.. but I think it will be close. From December to mid March. My house has a high heat loss as well... and 2000 sq ft.
5. Smoke is not an issue. I have learned how to load and clean properly.
Questions:

1. The temps here are crazy lately. Sometimes it is 40 during the day and 20 at night. This is tough for me to gauge how much wood to use and when to load. I am learning how to use small fires to have less idle time.... but I think storage would be the ideal solution. How do others without storage deal with the issue of temp swings and burn times? Are there other things i should try besides just judging the size of the fire?
2. Storage. I want pressurized. My question. Hot can I get this storage? Can I get it up to 180-190? And if so.. I am curious to find out how much storage I would need and at what temp to get me by for teh amount of hours I may need ( tons of variables here i know). What is typical of those with storage? Can someone describe how there typical day goes with using storage?

 

[Nofossil]

1.The Tarm 40 no longer has an issue with condensation. The issue seems to have cleared itself up.
2. I am getting good burns with gasification.
3. I adjujsted a valve and I am getting hotter water to my baseboards and more heat. Still... at times.. I have 3 or 4 zones calling for heat which lowers my temp on the hot water circulating at that time. I have to then turn down one thermostat and let that zone heat up the room first. Then when the room is up to temp... I can let the other 2 or 3 zones get to work with a higher water temp.
4. The Tarm is awesome... so much heat from so little wood. I am calculating heating the whole house up to 70 and all the hot water( 5 people) using 4 cord of hardwood and maybe a cord of pine. This is an estimate.. but I think it will be close. From December to mid March. My house has a high heat loss as well... and 2000 sq ft.
5. Smoke is not an issue. I have learned how to load and clean properly.
Questions:

1. The temps here are crazy lately. Sometimes it is 40 during the day and 20 at night. This is tough for me to gauge how much wood to use and when to load. I am learning how to use small fires to have less idle time.... but I think storage would be the ideal solution. How do others without storage deal with the issue of temp swings and burn times? Are there other things i should try besides just judging the size of the fire?
2. Storage. I want pressurized. My question. Hot can I get this storage? Can I get it up to 180-190? And if so.. I am curious to find out how much storage I would need and at what temp to get me by for teh amount of hours I may need ( tons of variables here i know). What is typical of those with storage? Can someone describe how there typical day goes with using storage?

Great questions. One of the things that happens with storage is that you have more latitude about when to build a fire. It can be more at your convenience as opposed to when the natives start getting cold. Pressurized storage can be heated to pretty much your boiler's outlet temperature, although if you get mixing that messes up your stratification you may not be able to get the whole tank that hot.

Do you have some form of boiler input temperature protection such as a Danfoss valve or recirculating pump / valve? I ask because that might be part of the reason that you're not getting hot enough water to your zones. That will be MUCH more pronounced when you start trying to heat a giant load such as a storage tank.

A good rule of thumb is that you want storage that's big enough to carry you through whatever portion of a 24 hour period is left after your fire goes out. In my case, I need to run the boiler about 7 hours on a typical winter day. That means I have 17 hours left before I want to start the next fire. My house needs about 15,000 BTU per hour on a typical day, so that means I need to be able to store about 255,000 usable BTUs of heat to get through the day.

I have an unpressurized tank with a heat exchanger between the tank and the boiler. This limits the maximum tank temperature that I can efficiently reach - about 160 average storage temp is reasonable. My minimum useful temp is 120 degrees. With a 40 degree swing, that means I need 6375 pounds of water in my storage (1 pound by 1 degree is 1 BTU). Water is 8.3 pounds per gallon, so my storage would need to be 768 gallons. I actually have 880 gallons.

To do the calculations you have to know your house's heat loss. For most people, 500 gallons is a minimum useful size, and 1000 gallons is nice if you can do it. Pressurized is more efficient than unpressurized because you don't have the intervening heat exchanger.

Note that the larger your wood boiler, the more storage you need. That's because it burns fewer hours per day to provide the heat that you need, so you're using storage more hours out of the day.

 

[Birdman]

I do have some sort of boiler protection.... I think. I am definately guessing here.. is it the termovar? I had to increase my temp so i shut a valve a little bit... I am assuming this was to limit the mixing? When i heat with storage... describe to me how this works? When a zone calls... does it take the hot water right from the storage and then deposit the cooler water right back into the storage from that zone?

I am finding that my water temp really needs to be about 160 or higher to the zones in order for me to get effective heat to that room. If all 4 zones are calling... my temps are at 130... and this does not give off much heat. Therefore.. I am hoping to have pressurized storage.. but it will only help me if the water in the storage will be 160 and if there is enough it. It is hard for me to watch my Tarm idle... when the house is heated and there is not much of a need for the heat... because all the zones are not calling and the temp has gone up outside to 40. It feels like I have wasted heat and energy. I can only try to adjust the wood amount when i fire and hope the temp will be what i predict outside. If I had 500 gallons of pressurized storage... can I heat it up to 160 and above?

 

[Nofossil]

I do have some sort of boiler protection.... I think. I am definately guessing here.. is it the termovar? I had to increase my temp so i shut a valve a little bit... I am assuming this was to limit the mixing? When i heat with storage... describe to me how this works? When a zone calls... does it take the hot water right from the storage and then deposit the cooler water right back into the storage from that zone?

I am finding that my water temp really needs to be about 160 or higher to the zones in order for me to get effective heat to that room. If all 4 zones are calling... my temps are at 130... and this does not give off much heat. Therefore.. I am hoping to have pressurized storage.. but it will only help me if the water in the storage will be 160 and if there is enough it. It is hard for me to watch my Tarm idle... when the house is heated and there is not much of a need for the heat... because all the zones are not calling and the temp has gone up outside to 40. It feels like I have wasted heat and energy. I can only try to adjust the wood amount when i fire and hope the temp will be what i predict outside. If I had 500 gallons of pressurized storage... can I heat it up to 160 and above?

So it sounds like there is some problem. No way should you see temperatures anywhere near 130 at the boiler outlet when it's running. My EKO 25 runs 165 to 175 at the outlet over the course of the fire. The Termovar should provide inlet temperature protection.

We need some data - at a minimum, inlet and outlet temperatures for the TARM when you're having this problem. Storage will not solve this - there has to be something odd going on. Do you have a plumbing schematic that you could post?

 

[Birdman]

The 130 temp is at the oil boiler... and i am not sure if this is return temp or supply temp. This is the only temp gauge i have.. except for the one on the Tarm panel. I do not have a schematic. It is set up as the parallell in the tarm manual. I am assuming the oil boiler gauge is the return? temp after the hot water has gone through all the zones and comes back colder? I know it goes out hot... when there are only 2 zones calling... that gauge reads alot higher.. like 160-180.

 

[Birdman]

One other question I had.... does the fan ever shut off by itself when the fire goes out? I mean.. If the temp keeps going down in the boiler.. below 140... and then keeps going down... does the fan shut off eventually? If not... how does one deal with htis issue? Makes no sense to have the fan keep running in this situation?

 

[chuck172]

Birdman, you have a low limit control. The probe should be inserted into the firebox and the knob inside the boiler set at 190*. That should shut down the fan.

 

[Bad Wolf]

I have the Excel 2000 and the fan goes off when the stack temp drops below 250, or doesn't reach 250 within 15 minutes of start up. I'm only building one or two fires a day so its usally shut down. One day I couldn't keep the fire going because the fan kept shutting off. Then I found I had pulled the probe most of the way out when I was doing my weekly cleaning, pushed it back in and all was good.

Storage should solve a lot of your issues.

 

[kevindauch]

Check the low limit temp, it is in Celsius on the boiler control.

 

[jebatty]

I'll chime in on a couple of points related to the Tarm.

Fan low limit: If you have no storage, the fan low limit probe (as stated in my manual) is placed under the boiler top insulation and on top of the firebox. The low limit thermostat dial is set at 60C (140F). If you have storage, the probe is inserted into the hole on the vertical wall of the smokebox, front right, just to the right of the wing nut, and the low limit thermostat dial is set at 90C (194F). This setting kills the draft fan as boiler temp drops after the wood load is burned out.

Boiler temps: go to a kitchen supply store and buy at least 3 of the meat probe thermometers, smaller dial ones are less expensive than larger dial ones. Let them stabilize and check the temps on all three. If needed, you can turn the dials a bit so they all read the same (rough calibration). These are not super accurate, but they will provide enough information to be useful. You may want more than 3 thermometers just to put them in other places for the "fun" of it. Wrap insulation around the probes of each thermometer so as to get a more accurate reading of actual temp.

Use cable ties and bind the sensor ends to piping at the following locations: (A) boiler output to system, (B) return to boiler from Termovar, (C) return from system to Termovar. Wrap insulation around the probes of each thermometer so as to get a more accurate reading of actual temp.

Fire the boiler. Shut down all zones but one (for simplicity). Open the balancing valve only enough to let a little of the boiler output water input to the Termovar (more below on adjusting the balancing valve). As the boiler heats, one zone calling for heat: (A) should rise steadily and roughly match boiler thermometer on instrument panel. (B) also will rise steadily as boiler heats from a cold start, because the Termovar is shunting all water to the boiler return. (C) will show the system return water temp and initially will be much less than (A), as the Termovar is letting very little heated water into the system, even though the water it is letting into the system is hot. As the boiler comes up to temp, (A) should be in the 160-190 range, depending on system heat demand, (B) should stay at about 160 or a little less, and will be more than 160 only if system is not using full boiler output. (C) differential from (A) will show how much of the boiler output is being used by the system.

Adjusting the balancing valve, based on my experience. You want this valve open just enough to insure water from the Termovar return to boiler is at about 160 or a little less when the boiler is in full operation. If this valve is closed too much, boiler return water can be considerably less than 160, maybe 120-140 range or so, depending on temp of water being returned from the system. If this valve is opened too much, boiler return water can be greater than 160, but essentially you will be recycling more hot boiler water back to the boiler than needed, the system will be shorted otherwise available hot water, and boiler heating efficiency to system will drop. Even if properly set, if system return water is very cold (80-110 or so), boiler return water may be 140 +/-. But as system return temp water rises, you should find boiler return a pretty constant 160, unless system return is above 160.

If your system regularly operates so as to return water quite cool, the balancing valve needs to be opened a little more so that boiler return always stays at about 160. As mentioned above, the goal, when the boiler and system is in full operation, is to have boiler return temp (B) at about 160.

 

[NHFarmer]

Jim,excellent description of the balancing valve adjustment.I just set it about halfway and left it.The meat thermometers are a great idea,I will see if I can optimise my system.I do notice that without reloading I can only go about 4 to 5 hours max on a burn,my wood is all 16"long but I was hoping for a bit longer burn times.Other than that the system is working great