Froling FHG-L 50 Install

[mustash29]

higher than expected/desired return temps - turns out the loading unit pump was moving water too QUICKLY. So what was happening was that a well defined stream developed in the tank where water was flowing from the supply straight to the return which was screwing up stratification and not doing much mixing either

That would be considered "channeling".....yes?

As in when you have high flow through a resin filtration bed (demineralizer, charcoal media, etc) you can cause a channelling / tunneling effect where the flow takes the path of least resistance and moves through the filter media and does not get cleaned / purified correctly. At my work we have anion / cation resin beds that turn city water into grade A pure water for boiler makeup. Exccessive flow will cause them to die with low throughput. They usually break through on high silica before they hit the high conductivity set point. We now have an RO unit and run the demin beds as polishers. 300 Kgal instead of 30 Kgal throughput before needing a re-generation.

Back to boilers & storage.....besides pumping capacity, what about using a flow diffuser on the tank tappings? Say you have a 1" pipe from the boiler to the tank. Why not insert that pipe into the tank, drill that pipe full of holes and "shower" the top of the tank with little jets instead of a 1" stream. The same could be done with the cold "suction" from the tank to the boiler.

Simple diffuser manifold. My boilers at work:

- Dearating feed water tank is 12 psi and roughly 290 deg F
- The boiler economizer pre heats that to about 400 - ish
- So 400 ish feedwater at 130 gpm is injected to the bottom of a horizontal steam drum via a 4" by 12 foot long diffuser pipe with lots of 1/2" holes
- Steam drum temps are running about 550 and 1000 psi, this is a saturated system 1/2 water, 1/2 steam with cyclonic and chevron moisture separators on the steam outlet. That steam is then superheated to 830 deg F.

 

[jebatty]

I doubt "channeling" is occurring. Data 4a and Data 5 graphs show that boiler return water is nearly the same temperature as bottom of tank water. It also seems that if any "channeling" is occurring, it most likely would channel from boiler supply to system supply, and it does not appear that this is occurring due to the difference in temperature between boiler supply and system supply.

The graphs show pretty good stratification on tank charging although some mixing is occurring because hot boiler supply is greater than hot system supply, and as tank charging progresses bottom of tank temperature is closing to tank top temperature even when tank top temperature is dropping. I still will try slowing down the loading unit circ and data log to see the results. My intuition tells me that the solution will be 1) more care in not overloading the Froling as bottom of tank temperature rises towards the temperature of system return water and 2) working to adjust flows to achieve lower system return temperatures.

 

[jebatty]

More flow tuning to do, but in the meantime I finished and installed the monitoring panel for the Froling. The temps for SS (system supply) and SR (system return) will make it easy to finish the flow tuning.

We will be using the M (middle) of storage temperature as the guide to reload and fire the Froling. Simply stated, for starters, if M is at or below 130F, load to bottom of firebox door opening. This will be about 50-80 lbs of wood (aspen/oak), or 65 lbs average, based on the wood mix; or about 390,000 btu's for the average mix of wood. Instructions will be to load only when low coals or fire out, and always a full load to the bottom of the firebox door.

Both the reload temp and the amount of the wood load will be revised based on demand experience and outdoor weather temp, may add reset later. This will allow the most inexperienced staff to load the Froling and allow it to burn with maximum output with no idling to end of burn because there always will be sufficient storage capacity to take the output, even if there is little system demand. The storage tank is 1650 gallons.

I'm just about at the point of shutting down the system and operating only the Froling to charge storage to better measure actual output and efficiency based on 6050 btu/lb of wood, assumed 20% MC. The storage tank is pretty well insulated, but there still is quite a bit of heat loss to the Froling/storage tank building, so an efficiency determination will be skewed downward by ambient heat loss.

 

[maple1]

Wondering on your temp guages - those look like the same Ebay ones from the far east that I have, but I think I see a bunch of Cat5 running into the box? Did you adapt/modify the 'stock' probe wiring to Cat5?

And do you have a link for your stage guage/probe? I'd still like to have digital probes in my stack & my secondary chamber - but I still haven't gotten around to finishing up all the other probes I have yet to put in.

 

[jebatty]

The temp gauges use DS18b20 sensors. Each gauge needs it own direct wire to the gauge. I used Cat5e: orange/ow to one gauge; brown/bw to another gauge, blue/bw to a 3rd gauge; and combined green/gw for a common ground. More cable for more gauges.

On eBay search for "ds18b20 temperature meter" for the temp gauges. Most if not all of these come with the sensor. Different colors are available.

The stack gauge is K-type with probe:
http://stores.ebay.com/Procon-Products?_trksid=p4340.l2563
http://www.ebay.com/bhp/type-k-thermocouple-high-temperature

You can see a silver cable for the K-type, not modified for Cat5e.

For a power supply I used a 12vdc walwart, but I am going to replace it with about an 18vdc supply. The ds18b20 gauges are plenty bright on 12vdc, but my K-type gauge is rated at 24vdc, works on 12vdc but it is not very bright.

 

[muncybob]

I'm considering an led display for my basement boiler...is there a way to have this info wirelessly sent to a monitor of some sort in a different part of the building? I'm not talking to a phone or pc but to a dedicated wireless display.

 

[maple1]

The temp gauges use DS18b20 sensors. Each gauge needs it own direct wire to the gauge. I used Cat5e: orange/ow to one gauge; brown/bw to another gauge, blue/bw to a 3rd gauge; and combined green/gw for a common ground. More cable for more gauges.

On eBay search for "ds18b20 temperature meter" for the temp gauges. Most if not all of these come with the sensor. Different colors are available.

Sounds & looks like we've got the same guages & sensors. So you needed to splice the Cat5 into the sensor leads, between the sensor tip & the plug on the other end? Is there a limit as to how long you could make the leads? Not sure I'm up to splicing that tiny stuff.

Thanks for the other info - I don't know if I will ever be 'finished'.

 

[jebatty]

Yes, have to cut the sensor cable, strip and splice. Tedious and I soldered all splices, then shrink wrap for insulation. There is a limit I'm sure, but I have had success up to about 30 feet. What does "finished" mean? ha ha.

 

[jebatty]

Learned something yesterday about the Froling. Although the control appears to be programmable for different output levels, that is only functional with an adjustable loading unit which I have not seen to be available in the US. Short answer is that output is at the maximum 170,000 Btuh rate regardless of the control setting. I wanted to make sure that the Froling was set for maximum output before proceeding further. This is a good result for DP because the building being served needs full output, and because DP has adequate storage, there is no need for a reduced output setting anyway.

Also good news on staff reports during our recent cold spell when temps got down to -29F at night and didn't rise above 0F during the day. The Froling met all heat and dhw needs without any need to switch to LP to meet demand or comfort levels. Supply water to the system during the highest demand periods at this time fell to a little over 130F, but no complaints about the building not being warm enough or insufficient dhw. I noticed middle of tank temp at 108F, and bottom of tank was about the same, so boiler supply to top of tank was remaining stratified to provide hotter water to the system.

With bottom of tank return to boiler at about 108F during this cold spell, the loading unit was mixing supply with return to provide required return hot water protection, so full boiler output was not available to the system. Output to the tank was in the 160-165F range, but flow from the tank to system was at higher gpm than boiler supply gpm to the tank, cooler water in the tank was being mixed with hot boiler supply to provide demand gpm, and therefore supply temperature to system was lower than boiler output to the tank. EDIT

And yesterday when daytime temp stayed at a nearly constant 0F, I observed that the Froling not only was meeting demand but storage tank temperatures were rising.

I didn't have time during the cold spell to spend a night with the Froling to do weighed wood burns, data log, and make any determinations of output, efficiency, etc. I want to be able to do that soon if the weather cooperates with my schedule. Regardless, it appears to me that the Froling is now operating as its design permits, and importantly DP also is getting the heat it needs. The data and analysis will be an add-on benefit for educational and informational purposes.

 

[flyingcow]

jebatty, how ,any different brands of wood burners have you operated/owned/oversee? seems to me a few more brands for you to play with and you're the consumer reports of gasser's? BTW, a good part of your post here has been a bit over my head, but interesting and good reading. You've got me wanting to put my Innova down in my truck garage and replace with a Froling at the house.

 

[ewdudley]

With bottom of tank return to boiler at about 108F during this cold spell, the loading unit was mixing supply with return to provide required return hot water protection, so full boiler output was not available to the system.

I don't see where any of the heat produced by the boiler could go except to the system.

Boiler not getting hotter or cooler, so zero heat flow to boiler.

Storage not getting hotter, so zero positive heat flow to storage.

All heat generated by boiler must be going to system.

170,000 btu per hour of heat generated by boiler.

5.96 gpm of 108 degF water coming in from storage, 5.96 gpm of 165 degF going out to storage.

No less than 15.45 gpm of 130 degF going out to system, no less than 15.45 gpm of 108 degF returning from system.

 

[jebatty]

Four brands: Tarm Solo Plus 40 - 2007, the Froling now in its 3rd heating season, and a Garn WHS3200 and Wood Gun E500 starting in 2009 if I remember correctly. If I had to replace my Tarm, I would consider a Froling or similar based on info then available. On the other hand, my Tarm is very simple to operate, the control system is simple and easily modified/supplemented, and it has been trouble free since installed, once I learned how to operate it. When the time comes, the choice will be challenging, that is if simple, quality boilers then are available.

Thanks for the compliment. I had no prior experience in HVAC, and only personal domestic water/drain plumbing experience before 2007. I've been given the title of "engineer" at DP, not really merited, but the educational and learning journey has been a ball. I still make mistakes and/or fail to analyze things correctly, but that's been my learning curve.

 

[jebatty]

I don't see where any of the heat produced by the boiler could go except to the system.

I am glad that you take the time to review my posts. I think you are correct. My example, which really is the same as yours, which leads me to the conclusion that you are correct: The Froling/loading unit with a single 15-58 specs 12 gpm maximum. If boiler output is 165F, if system return water is 108F, then delta-T = 57, and if boiler is producing rated output of 170,000 Btuh, then it follows that 170,000 / 57 / 500 = 5.96 gpm flow rate to the tank/system; which then also means that about 6 gpm is being recirculated through the boiler. Do I have it right?

You have stated in the past that all "heat produced by the boiler must go to the system" and I need to indelibly etch this in my brain. Thanks.

Your edit also is very helpful, and that's where I was going next in this reply, but no longer need to do so. Thanks again. I am editing my prior post to delete the erroneous statement.

 

[jebatty]

ewd -- I don't think I ever will be able to reach the point where storage temp is in equilibrium so that i can calculate exactly what the flow is to the system, especially because 5 - 15-58 draw from the system in various series/parallel configurations, and none to one or more may be "on" at any point in time.

 

[ewdudley]

The Froling/loading unit with a single 15-58 specs 12 gpm maximum. If boiler output is 165F, if system return water is 108F, then delta-T = 57, and if boiler is producing rated output of 170,000 Btuh, then it follows that 170,000 / 57 / 500 = 5.96 gpm flow rate to the tank/system; which then also means that about 6 gpm is being recirculated through the boiler. Do I have it right?

We've got two unknowns, actual boiler btu per hour, and actual 15-58 gpm.
Assuming BTU per hour of 170000 we get one answer:

Calc GPM:
7.64 GPMRecirc
5.96 GPMStorageNet
13.60 GPM1558
170000.00 BTU


And assuming 15-58 gpm of 12 we get another:

Calc BTU:
6.74 GPMRecirc
5.26 GPMStorageNet
12.00 GPM1558
150000.00 BTU

use strict;

my $TBoilerSup;
my $TBoilerRet;
my $TStorageRet;
my $BTU;
my $GPM1558;
my $TBoilerDelta;
my $TStorageDelta;
my $TMixDelta;
my $GPMStorageNet;
my $GPMRecirc;

sub calc_gpm {
   $GPMStorageNet = $BTU / ($TStorageDelta * 500);
   $GPMRecirc = ($GPMStorageNet * $TMixDelta) / ($TBoilerDelta);
   $GPM1558 = $GPMStorageNet + $GPMRecirc;
}

sub calc_btu {
   $GPMRecirc = ($GPM1558 * $TMixDelta) / $TStorageDelta;
   $GPMStorageNet = $GPM1558 - $GPMRecirc;
   $BTU = $GPMStorageNet * $TStorageDelta * 500;
}

sub pr {
   printf("%9.2f GPMRecirc\n", $GPMRecirc);
   printf("%9.2f GPMStorageNet\n", $GPMStorageNet);
   printf("%9.2f GPM1558\n", $GPM1558);
   printf("%9.2f BTU\n", $BTU);
   printf("\n");
}

$TBoilerSup = 165;
$TBoilerRet = 140;
$TStorageRet = 108;
$TBoilerDelta = $TBoilerSup - $TBoilerRet;
$TStorageDelta = $TBoilerSup - $TStorageRet;
$TMixDelta = $TBoilerRet - $TStorageRet;

$BTU = 170000;
calc_gpm();
printf("Calc GPM:\n");
pr();

$GPM1558 = 12;
calc_btu();
printf("Calc BTU:\n");
pr();

 

[jebatty]

I think the more objective variable is the gpm. I have used 12 gpm but the spec is not exactly 12 and an adjustment can be made for the actual spec. I also can do a head calc on the plumbing to estimate actual gpm.

Btuh output may be a constantly moving variable, depending on the stage of the burn, moisture content, etc., although the Froling appears to seek a maximum available output through the lamda control, varying the speed of the draft inducer, and varying the air mixture in the firebox and gasification chamber.

 

[ewdudley]

I think the more objective variable is the gpm.

So with boiler operating conditions not really out of the ordinary and a reasonably conservative 15-58 flow estimate of 12 gpm, the unit is supplying a solid 150,000 btu per hour net for real. Around here, that's about $4.50 an hour in heating oil not burned, not bad!

 

[jebatty]

Really appreciate the input. Thanks!

 

[jebatty]

Getting close to a full report on the Froling. Spent the night with her last night, low of -27F, calm wind. Although the goal was not to determine whether the Froling could satisfy the full demand of the 6000 sq ft Interpretive Center building that it is heating, plus dhw, the Froling in fact did that, and it also slowly added to storage btu's.

I want to do one more night after the Froling has been fully cleaned, which should provide maximum output results. The burn last night was after a number of days of full-time, full output, 24-7 operation, and I'm guessing that flue temp probably was somewhat high and available output was somewhat low as a result. Anyway, a 2nd burn will determine that. We're headed for another very cold spell this weekend, and I hope that can be another night out with a sweet, hot friend.