GB Confusion????????

Mad Dog_2

we have a really nice "45" going in on a special job. Thanks Joe. Mad Dog

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Jamie_6

O.K. This one has me confused across the board. (Not like that would be too hard though!)

This is the same job I posted last week and my local rep. from Buderus "kind of tackled" today. Apparently, since we have so many circulators pushing around so much water in this system our flow rates are to much and to drastic for the boiler to operate how it is suppose to. The only way we could get the boiler to fire on its highest output was to decrease flow to all of our circuits by throttling down the outlet sides of the pumps on all of our connected radiation.

I don't understand how the other pumps are affecting our boiler though? This is a P/S piped boiler and should this not be affected by any other flow rates because it is isolated by the closely spaced tees? Or, is the manifold below the GB supposed to operate like the top drawing?

From what my rep. states I will have to change all the Grudfos 15-58 I have (that are on speed #1) to smaller pumps on my entire board.

Boy am I glad I am SOOOOOO rich that I could spend over 16 hours out of the last week playing with this boiler and then have to go out and spend $$$$$ on a bunch of new cirs. If this is my price of tuition on learning a new product I need to go into the manufacturing business so everyone else can take a loss and I still get to move product!





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[Deleted User]

Either too much flow...

or not enough load, and consequently no delta T.

Qwestchuns for you.

Is it able to acheive and maintain the required outlet temperature?

If not, what is your required temperature?

What is the Delta T across the system? How about across the boiler?

What I suspect is happening is that the differential in temp across the system is inadequate for the Joiman logic to decide to ramp up its burners. That the way the Joimans do things. If you raise the set point, it will increase the output, but still at a much lower temperature than we Amelicans can adjust to. They don't believe in overshooting ANYTHING. They'd rather crawl up to it slowly rather than ZOOM up on the load and overshoot it significantly, thereby creating waste.

If you can slow the flow of the system to generate a larger delta T, the logic will "see" the load and should adjust its firing rate upward. But again, as it starts to approach the demand, and delta T drops off again, it will cycle back in temp and burn rate. I sometimes think their controls are too smart. But then again, I marvel at the way their systems "coast up" to the set point of the DHW tank and not onver shoot and not waste ANYTHING.

Us Amelicans use WAY too much pumping power according to them. And we do, because we can! Just like the big dog.

If you follow their logic, you will experience Mike T's Eurocave conditions, but you will use significantly less energy and the system will work as designed.

We Amelicans are SUCH energy hogs. And comparitively speaking we are. It's, because we can...

Here's some drawings to hopefully explain why your DT is so low. Remember, the DT the boiler sees is connected to the throttle:-) No delta T, no throttle, BIG delta T BIG throttle. (Boy, wait till the boiler police sees this one...)

Anywho, hope this helps.

ME

Jamie_6

Mark,

You are 100% correct! The larger we made the Delta tee across the system the more output we got out of the boiler. To achieve this we had to put a 35 degree differential on the air-handlers and 20 degree differential on the slab radiant. This gave us a 38 degree differential @ the boiler.

My questions:

1. This boiler is not true P/S then is it. Because the flow of the system affects the flow of the boiler.

2. Do they make smaller pumps then 15-58 and are there spreads between flanges the same. (Or am going to be dumping even more money on repiping this thing)

3. By throttling down the flow so much am I still going to be able to achieve my set points in design conditions. The valves on the iso-flanges are almost all the way shut.


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[Deleted User]

Jamie..

No, it is in fact P/S piping,it just that your heat source bases its firing rate ont eh differential in TEMPERATURE between its tees, which is influenced by FLOW on the system. I wouldn't go out and purchase new pumps, I'd just choke back what you've got so long as it can meet your pressure drop requirements.

You still need to answer my orginal questions....

Is it able to acheive and maintain the required outlet temperature?

If not, what is your required temperature?

What is the Delta T across the system?

How about the Delta T across the boiler?

I think you're being fiddle faddled by the fickle finger of fate, or possibly dibbled by the dirty digit of destiny due to Buderus' Beautifully Bodacious control logic.

I answered #'s 1 and 2. The answer to number 3 is, "It Depends..." If you a re no where near design conditions, then that's the reason the boiler is not going to high fire. It's waiting for the load to "show up".

As long as it is generating water temperatures at or near what you currently need, then when design conditiosn DO show up, if everything in the puzzle is properly designed and sized, then evything should work just fine. That said, you may NOT want to chole back the flow on those circulators UNTIL you ar e at design condition. Its hard to simulate design condition. About the only way you can even get close, is to do what you did, which is choke the living crap out of the secondary flow, and at that, its still a false scenario because you're decreasing flow.

All things considered, when you get to design condition, you will most probablly see a 30 degree delta T, and everything else will work just fine.

Remember, you're dealing with a fairly intelligent heat source. Not just some blonde bimbo boiler (No offense to any blondes out there...)

The drawing you depicted would be true of if the load flow is less than the source flow. You will see or feel water flowing backwards through the common tees.

Conversely, if you are flowing more in the main than you are the input branch as depicted, then you end up with a higher flow rate occuring between the common tees than you have in the boiler loop secondary, but the direction is still forward.

If your main flow is the same as your branch boiler flow, then the flow through the common tees is ZERO, as depicted.

At any given point in time, you could be anywhere in between these two scenarios.

One thing for sure, the system primary flow is NOT influencing the boiler secondary flow, just the DT it's going to "see".

If you open all the doors and windows on this house and "create" load, everything should fire up and do its thang.

ME

Jamie_6

Mark,

I will get all the temps. and design perameters today and post tonight.

We are not at design today but of coarse I was below design all last week. I can completly grasp the flow issues I am having. (Thanks for making it technician friendly!)

Would you recommend placing some sort of glob valve on the supply side of each circulator? I'm just affraid that if someone touches the iso-flange we are back to square one.

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singh

Your not alone

I've been following Jamie's scenario.
I have the same situation.
Except I don;t have all my seccondary circs on, just two for the air hadlers.
And at first I could not get to dialed in setpoint,then, after following Buderus advice,we began to throttle back the pump and set to #1 speed.
I get up to limit ,but it quickly drops down to lower temp.And won't go back up until fans cycle off.
I don';t have my radiant circ on yet and I'm curious as to what will happen, then the HW coils will be supplemental. My guess it will always be at low fire, until all circs are running at design conditions.
However it was -5* last week for two nights and the two temporary AH circs were still at a lower temp, you'd think the heater will be at high fire with just two zones trying to warm up the place. (dialed in @ 165 but 135* to AH)
Its funny to see the logic work great when the DHW comes on. 194* no problem . But then again all three circs are off, heater and two zones.
And its not pri/sec any longer.
As for lots of pumps,the same should occur (in theory) when you have one big pump and lots of ZV's. One zone on and all that pumping power going thru the heater and its pump.
I guess this is not a concern in the Netherlands, Maybe thats why Nefit designed it to be a water heater and not a boiler with our American multiple and numerous pumping and piping stratedgy.

Joe@buderus_2

GB issue

Many great points posted here! At first we thought the "KIM" needed to be re-programmed, but that didn't resolve the issue. One of our reps (Steve Grady) stopped at a job in Albany last Thursday with a few test instruments and has provided a lot of information which we will use. Delta T seems to be the issue. From my understanding in Holland (land where the GB142 are made) they have not been able to simulate the issue. They are coming over next week to visit a couple of sites to see first hand. I request a little time for us to check this out. We have sold over 3000 units and see this in only about ten installs.
We are also looking at the RC10. The other day I posted that the GB142 programming has a high limit of 194 degrees and have been assured of that from Holland. The RC10 control comes from Germany and may have the limit of 167 degrees programmed in it. That is being checked into. We wish to provide accurate, informative, corrective action for these issues, but it takes time. I fully understand Jamie's fustration and appreciate his efforts. Hopefully we can have accurate answers next week.

Joel_3

Vitodens

we have had a similar problem on one Vitodens install and haven't had it any where else . I found the vitodens running much hotter than it's curve set point . It was trying to maintane a lower temp in the low loss header but couldn't do it because of the massive flow rate we had through the header . several 15-58s with AH's and some small zones . we had very little delta across the zones . Slowed the pumps down , increased the delta and everything was much happier. the other snafu making it worse was in night set back the factory default internal pump speed is very slow . we ussually change that but somehow missed it on this one . we where getting an intermitant high limit fault . the boiler would be artificailly at high fire the zone would shut off and it would spike to 194 and shut it down.

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[Deleted User]

You'll need something...

MAYBE.

Lets look at the paramters first. Forgot to ask one obvious question. Is the place warming up?

If it is, then this all may be for naught. If it's not, then it's not for naught.

I know that the urge to "Open this baby up and see what it'll do" sometimes exceeds the urge for sex. But if it isn't necessary, then why do it...

Get back to me. In lieu of a globe valve, you could use a Thrift balance cock, which is made for that purpose, and cost around $10.00 each.

ME

singh

Joe

With the few problematic GB's out there, is the recurring culprit hydro-air?

Joe@buderus_2

We have seen the issue with Hydro Air applications, all radiant and applications with the RC10.

S Davis

Boiler Loop

What I have started doing on our installs is making a boiler loop and using that to inject heat into the radiant main loop, this way I can control the flow going by the boiler and set the delta better.
You can't see it but there is a globe valve behind the post after the pump.


S Davis

Apex Radiant Heating

Jamie_6

Mark

That is one of the major problems here; the home is not heating up.

I took some readings today and came up with the following information.

I found some really bizarre stuff! For some reason my flat plate is not transferring heat well at all. We will check the glycol mix on Monday. I have to run the boiler @ 180 degrees to get anything out of the air-handlers. And only want to run it at 140 degrees for stage 2.

One problem we thought we may have had was we had too much load on our boiler.

A 2 ton Unico Air-Handler @ 4 GPM with 140 degree water gives us 27,000 BTU’s.

A 3 ½ ton Unico Air-Handler @ 4 GPM with 140 degree water gives us 45,000 BTU’s.

Then you add the basement slab & garage and we are over!!!!!!!!!

But (Behold the Ultimate Truth) we started removing load and nothing would work that way either.

So apparently flow is the issue. THEN WHY do all the other GB installs we have in with multiple pumps work? We just completed a home that has a Buderus mixing station and a Buderus pumping station. Both with Grundfos 15-58. The pumping station is connected to R-22 panels and the mixing station attached to 9 radiant zones (zv).


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[Deleted User]

Bummer...

Uncomfortable humans is not good... You WILL resolve the situation I'm sure.

Lets look at the thermagram.

The FPHX appears to be working, but may be undersized. One way I've found to confirm flow is to quiclky close off a ball valve in the subject circuit. If you hear the hydraulic rush, kind of a HISSSsss as you close the valve, it indicates decent flow. If there were poor flow, but the circuit were fully purged, you'd not hear the hiss, and the delta T across the HXer would be BIG. Other than a low discharge temp, the HXer looks to be active. Possibly a stuck check valve in a pump??

The primary loop across the boiler input tees is also seeing a decent delta T, well within what the Deutch would like to see. Not knowing for sure what the actual flow rates are, it's hard to say but the fact that your boiler discharge temperature matches the post boiler primary loop temperatures indicates to me that either the loop flow is low, or the boiler loop flow is too high. I suspect the former (loop flow too low) If the loop flow were higher, the discharge temperature of the primary loop would always be somewhat lower than boilers discharge due to mixing.

This is also an indication of too high a flow within the boiler circuit, because its only seeing a 15 degree delta T, but due to the nature of a modulating burner, that assesment may not be valid. If the burner were running full out at the time you got these numbers, then it would be an indication that the boiler flow rate is too high, or as previously discussed, the load loop flow too low. This is confirmed by the temperature at the tweener tees. If the load loop flow were greater than the source loop flow, the temp between the source tees would be the same as the EWT to the righ hand side of the drawing, and the discharge temperature would be somewhere between the tweener tee temp and the boiler discharge temp.

Now that I've said all that and countered myself about a hundred times, lets boil it down. I suspect a lack of flow, and possibly a lack of heat transfer at the FPHXer. If you had exhausted the capacity of the heat source, you would NOT be seeing 180 degree F discharge temps, and you would be seeing a LARGE delta T across the boilers in/out tappings. In other words, the boiler burner would be running wide out, but the discharge temperatures would be realtively low (140 or less).

There may be some other underlying problems, but I suspect a flow issue. Once you've addressed the flow issues, we can move forward and address the others as they raise their ugly heads.

I concur with you that the heat source may be somewhat undersized. The numbers don't add up. Actually, they add up to more demand than you have in the way of capacity, but I'm making some pretty broad assumptions here.

Remember also, that it has been my experience that most heating systems are oversized by a factor of 2.

In your case, if you started from a cold start, you may still be "charging the thermal battery". Once charged, the flywheel of thermal mass kicks in to help carry the load and buffer temperature swings. In other words, once you get everything up to snuff, everything else will fall into line.

As for the FPHX, you can oversize it to allow it to work with a low water temperature, but I guess you'd need to double check your AHU fan coils to make sure they are capable of delivering the needed comfort with the available LOW supply temps.


Hang in there dude. We WILL get your customers warm again.

You're just being fiddle faddled by the fickle finger of fate:-)

Say hey to your Pa, and hug him.

ME

Mike T., Swampeast MO

Something is not adding up here:

7.1 gpm of flow through the radiant loops:

Supply 100° - return 75° = 25° delta-t

7.1 gpm @ 25° delta-t = 88.75 mbh -- more than the output of the boiler when running flat out! If those flow estimates are anywhere near correct then it's no wonder you're getting little from the FPHX--there's almost no heat left and I suspect that the flow to it is VERY low as your 3-way mixing valve is hogging nearly everything to meet the radiant demand.

Are the slabs not yet up to temp? Perhaps a SEVERE problem in the garage with infiltration and/or slab losses? Water under the slab(s)?

Have you tried shutting down the radiant portion to see if the AHs are now satisfied? If the AHs are satisfied you might try running one and then the other radiant zone to see if something strange is going on with one (or both) of them.

JC-TRX250R

With the small loop are you getting the 142 to downfire automatically. We tried that loop on our first install (big old radiators) and the 142 always stay on high fire and would not throttle back. We took the loop out and now the 142 down fires correctly. That was Steve Grady's recommendation and it worked. There theory was that we were fooling the 142 into thinking that we needed more heat then we actually did and it was firing to try and maintain the correct delta T.

S Ebels

You're right Mike

The numbers don't add up. Taken as they are, there is much more heat being transfered than is available from the GB. I would guess the flow rates are incorrect as temp should be fairly easy to observe.

Jamie, the temp drops on the HX look to large to me. What physical size is the HX and how many plates?

Jamie_6

Mike


I'm still in the process of truly understanding flow rates and GPM.

The funny thing about this job is that all of the radiant is throttled back ALOT. We created the 25 degree delta so the boiler would go into high fire. We where running a 10 degree Delta but the boiler was only producing 110 degrees and our target was 120 degrees. The room where only a few degrees off at that point. By choking the radiant so much we are not able to keep up with the demand it has on it?

I did try letting just the radiant run or just the A/H run, but was not successful on either side.

All of the flow rates I have posted are off of Wirsbos Radiant Design report. In the Report it states that:

Water Source 1: 11 USGPM @ 24.8 ft(H2O)

Water Source 2: 3 USGPM @ 8.9 ft(H2O)

Total Load: 68,274 Btu/hr

Now the heat loss report with hydro was 69,737 Btu/hr. This is why I choose the smaller GB. The Hydro is 2nd stage only which is not required in any one room. I figured this would be most applicable in the fall and spring when the load on the house is much smaller and the HO will have faster reaction times to the swings in our weird PA weather. BUT like I said, if I try and run the hydro only I still do not get heat.

Now the FPHXer does not seem to operating up to snuff. It is sized for 80,000 Btu/hr but I do not thing it is performing properly. I agree with Mark and I think I will up size that Flat Plate.

As far as the slab they are both insulated the same just the basement is 9 feet below it! Maybe more thermal protection down there?

Thanks for the help!

Jamie

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Jamie_6

Hey Joe,

We still do not have any heat! What is going on?

Jamie

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Mike T., Swampeast MO

Jamie:

When I played with the numbers a bit more it seems that the output of your radiant zones, wide-open with 10° delta-t was very close to your estimate. Seems reasonable for a slab getting up to temp.

When you throttled the flow to the radiant slabs you obviously reduced flow. By increasing the boiler temp you just got more mixing through the three-way.

It REALLY looks like your problem is in the flat plate heat exchanger circuit. It has it's own dedicated circulator, right? Even using water/glycol the FPHX sizing sounds reasonable. The temp drop on the air-handler side looks good--it just appears that you have NOWHERE near enough heat available on the other side of the HX.

Possible problems in the FPHX circuit:

Bad circulator.

Circulator FPHX mis-match (e.g. way too much head loss in the FPHX for the pump).

Obstruction in the FPHX.

Reversed or defective flow-check type devices.

Again, it truly looks like a problem in that FPHX circuit. I would exhaust every possibility there before suspecting other things.

----------------------------------

Can't determine from the thread. Are you using the RC-10? If so, am I correct that you've disabled in an attempt to solve the problem?

Have you ever used this boiler and control system with a FPHX before?

Jamie_5

flow rates

I am not a professional heating contractor.

But I believe Mike T. is right about the flat plate heat exchanger circuit.

The flow in the primary loop (except between the tees for the boiler secondary circuit) is produced by your three parallel circuit circulators. My calculations indicate that you are pushing less than 0.75 GPM through the primary circuit from the two radiant circulators because only that amount of 178F water is necessary to produce the 2.48 GPM of 100F water you have circulating through the radiant circuits in total, at a 25F drop. In fact, if the radiant circuits are using less heat than design, the total flow in those circuits is even lower than I have calculated, thereby reducing the amount of water coming in from and going out to the primary loop. Thus, if the flate plate heat exchanger pump is producing low flow for any of the reasons Mike T. suggested, there will be little *total* primary circuit flow (the sum of 0.75 GPM and the heat exchanger circuit flow), with the result that most of the boiler circuit flow will be "backwards" in the common piping between the tees for the boiler circuit, thereby producing a small temperature drop to the boiler, which responds by remaining on low fire.

At least that's my reasoning.

Joe@buderus_2

Jamie, I spoke with our rep Jim Marmer and he advised that after the site visit, the thought is "Flow" might be an issue. From my understanding the rep is planning on going to the site on Wednesday for further investigation. Thanks,

Jamie_6

Wednesday!

Joe,

The rep. is coming out today but I am really not sure what he is going to do! I was told that flow is the issue.

Roy throttled down the system severely the last time he was here and we did not get any output out of anything. (Actually, the air-handlers started to produce heat and we found a bad FPHXer) The radiant was not even heating the space. I finally just let the boiler & system get full flow which allowed the radiant to get full flow and the two slabs heated up within 5 hours. Although, now that I turned on the entire house I now have even cooler water coming out of this boiler.

I have tried running every possible combination of slabs with each other and by themselves to try and get this thing running with no avail.

Would you please tell me the firing ratio of the boiler so I can use my manometer and see if this boiler is even coming out of low fire? Which I think it is not. No matter how high I make the boiler outlet temperature, by throttling valves, the inlet temperature is 10 to 15 degrees behind. From what I understood it was suppose to be a much larger gap.

Would you please contact me today, I have an extremely angry homeowner / builder on my shoulders who has me bidding many similar jobs. Not to mention all the other jobs I can not make it to because I am stuck on this one.

I also started and picked up another GB yesterday for a similar system and I need to know what we did wrong in installing this thing so it does not happen again.

Jamie

1-610-960-6163

singh

I'm confused?

The more I read this thread.
Can someone explain to me how a flow issue will
keep the GB in low fire.
Too much flow you say? I have another install, with multi circs, this is not
an issue.
Last week I to observed when all zones are off I reached my dial in temp,
when I had just one zone on the GB , temp drops, and stays there for a long time
,but it will eventually make its way back up to high temps,very brief though,then
right back down for another long spell.
Perhaps this is the way the GB thinks, I'm use to the bang on-off boiler trying to maintain limit, with a 20* delta.
Unlike Jamie, I have heat, but it would be nice to have the AH not cycle off so much,becuause of low supply temps. I had the L6006 strap on set at everything from 140* to 110* with 20* diff. I did not install the AC/HW coils, but the 4 ton unit is way oversized in my opinion 180* @ 4gpm will give me 90,000 output. 140* around 46,000 and my GB 30 may be undersized a little when I have all zones on.
I'm just giving more scenarios for Buderus, Joe if Steve Grady wants to look at this install and test also contact me. But for now I'm ok , just would like to know what to do for the next one.

Mike T., Swampeast MO

If the problem is low flow to the flat plate heat exchanger then the boiler is not seeing the full load--when a modulating boiler doesn't see the full load it doesn't fire to full power.

S Ebels

Contol ??

Can the control on that boiler be operated via a setpoint demand or some other kind of external demand. Like an aux. input? If so, wire it up and set it at 160*, see if it will reach the target temp that way. On the Viessmann board there is an input for an external call for heat that you can wire up to basically any kind of control. If you can do that, it may help establish what's going on.

Mike T., Swampeast MO

Or does the Buderus have a "test" mode or switch like the Vitodens? With the Vito this does result in 100% burner output. If there's not enough load it will kick out on high limit.

Am pretty certain that the "external call" will still modulate the burner--just at a fixed supply temp instead of weather compensated.

S Ebels

Exactly

If this can be done, you could tell whether it's a boiler sizing problem or a flow issue. IE; if the boiler reaches set point and all your emitters are "on" you know you have enough output. If it doesn't get there you have sizing issue or you can start isolating your loads to see if any are not delivering heat.

Joe@buderus_2

Jamie, I called the rep Jim Marmer and asked him to call you. I am out of the office (home with a sick child) and I know there are people from Holland looking at a couple of installs. Thanks,

JC-TRX250R

Yeah you can go into the chimney sweep mode and that will fire the boiler at 100% for 30 mins if I remember correctly.

Joe@buderus_2

Update

Spoke with our rep today who visited the site and here is what he found:
The ball valves that he had throttled down earlier in the week on the zone supply's where in the full open positon and when the valves where closed slightly the delta T started to climb. After the valves where throttled down, the slab temperature was 35 degrees with a 90 degree supply and 50 degree return temperature. The boiler was firing up to 180 degrees. The rep then put the cover on the GB142 and the burner started modulating down. As soon as the cover was removed the burner would ramp up. Upon checking the exhaust pipe and air intake pipes outside, it was discovered that the elbows to seperate the two had not been installed yet and the exhaust was seen being pulled into the fresh air intake - cross containimation. For now the cover is being left off the GB142. Once the slab is up to temperature, the exhaust and air intake termination completed and the house closed up a bit to be closer to the sized load the flow issue will be looked at again.
Thanks,

S Ebels

Good info Joe

It never pays to overlook the basics of the install but in our haste sometimes the most rudimentary item get neglected. Merry Christmas to all of you at Buderus and thanks for hanging out here on the Wall. Keep up the good work!

Darin Cook_3

I am actually glad

that it was a simple overlooked issue. I am REAL TIRED of dealing with manufacturer issues we did not cause but have to run on. I would seriously hope that Buderus will keep us fully advised of any issues or product updates so that we can handle them accordingly. We have used the Buderus line for many years now and would like to keep a great working relationship with them. When the GB line was released in the states that completed the missing link in their boiler line for us. We look forward to a great relationship with Buderus for many years to come and saving a huge amount of energy for our customers.







Darin

John McArthur_2

Glad it was something simple. Our company is about to begin installation of about a dozen of the GB's, so I have followed this thread closely. We specify Buderus almost exculsively, with a few Laars now and then, and it makes me feel good that there is good tech support.

We got burned by the Endurance boilers a few years ago and have been quite shy about going to C/M boilers.

leo g_13

I haven't experienced this

myself, as here in Vancouver, we do not generally need anti freeze in our systems. But talking to a contractor who works in Whistler, they had a similiar sounding problem with some hydro-coils. They solved their problem by replacing the FPHE with tube and shell. It appeared that the glycol laden water was too "thick" for the minute passageways of the Flat Plate.

Also, on any job where we supply pool/hot tub heat from our boiler, every pool company has requested tube/shell, as there has been problems on the pool side of the FP's from the chemicals in the water plugging up the passage ways.

Hope this is helpful.

Leo G

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Mark Hunt

Jamie


How are things going now?

Mark H

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rob

Jamie....

I just realized where I saw your name recently. Did we meet at our favorite uncle's classroom?? Uncle Wayne and his Carrier/Bryant 80% Troubleshooting Class. Best wishes for a great Holiday Season to you and your dad.

Jamie_6

Hey Guys!

Thanks for following this thread and helping me out with all of your answers and questions. As you can see I made a foolish mistake and did not cross all my (t)'s and dot all of my (i)'s. The funny thing is that this mistake has taught me a lot about the GB that I did not find in the directions. Not to mention some of the piping issues that has developed with the GB and flow-rates. I'm sure Buderus will be addressing these issues in there piping directions in the instillation manual.

Lessons Learned!!!!!!!!

1. Follow ALL of the instructions. Especially putting on the termination 90’s outside.

2. The GB has an operating limit of 167 degrees (This effects the hydro on the project)

3. The GB has a self protection in its logic to protect the boiler from to drastic of a temperature drop across the boiler. If the boiler sees a differential of greater then 45 degrees it will slow down its firing rate to protect it from cracking the block. (We are on day #4 of heating the mass up to temp.)

The combination of all three of these factors affected this project greatly and stumped everyone equally.

This experience has strengthened my trust and dedication to the Buderus line and technical support division.

Joe@buderus_2

high limit

The high limt of 167 is in the RC10 programming, not in the GB142. We are correcting the RC10 high limit as we speak.

Mike T., Swampeast MO

So, is it safe to say that the 167°F (75°C) limit is related to German laws?