Buderus GB142/Tn4 problem

Unknown

hey devan,

tn4 properly connected to a mod/con boiler that is compatible (like these) will control the modulation of the boiler in order to hit the target water temps it desires in the heating system.

You are correct that coming out of setback, the boiler will want high fire typically if there is a drop in water temperature below setpoint. But that IS synced with the tekmar; the tekmar is reading the water temperatures and telling the boiler what it needs to do. Under no circumstance should the buderus be doing anything with modulation or water temp the tN4 system didn't tell it to do. If the supply temp isn't dropping, higher modulation is not necessary.

Unknown

problem!

has anyone seen this?

tn4 system controlling two buderus GB142 boilers with the correct modules installed to allow tn4 to directly modulate the boiler.

signal from the tn4 system seems appropriate (goes up and down in strength as the output demanded changes).

Yet, the boilers, once ignited, continue to run up to high fire until they trip on high limit, every time.

Buderus rep wants to use the 'buderus cascading control' which, I believe, would wreck the whole tn4 integration, and tn4 does not seem to be the problem.

is this a unique problem? anyone seen it before?

crazy, man, crazy.. thanks in advance.

Josh M.

Rob, we have seen this before. The TN4 system for some reason runs the boilers straight to high fire. I wish they would allow us to adjust the PID. I don't like their algorithm at all!

Steve Eayrs_2

Haven't had this problem

Did you use the EM-10 to connect the TN4 to the 142?
Or at least I think thats the right model number.
Steve

Unknown

I have a gb running off a tn4 that seems to be working beautifully. Initially I was a bit dissatisfied with the behavior of the boilers modulation. My observation was that the control seemed to fail to throttle back sufficiently as supply temperatures approached target. Seemed to me that the control was not being very smart about finding it's proper modulation, it seemed to fail to slow down in anticipation of target sufficiently. I called tekmar about this and they took my version numbers and said that improvements had been made in the software, sent me a new board and this issue was resolved. But this was a nit picking performance issue, not a "real" problem like you are describing.

Perhaps your em-10 is wired wrong. There are two ways to wire it( as I recall ) one is x voltage = x temp, the other way, voltage is proportional to modulation, this is the was it should be wired.

Oops missed the two boiler thing,that changes things.

Unknown

Well, I don't think it's the tN4... the signal to the boilers is dropping off just as we would want it to.. the boiler just seems to be ignoring that and running up to high fire only... that is, it's not responsive to the variable signal the tekmar is sending.

we do have other GB142s working beautifully as well.

Josh M.

Scott, that is good to know! I will have to upgrade our controls too. It would be nice to have a low fire hold option in the future.

Rob, It defiantly sounds like you have a wiring issue goin on.

Unknown

does the buderus have a "boost" option like the ultra does? i.e., the longer a demand lasts, the higher it raises its temp?

I'm wondering if it's in the boiler setup at this point.

Gary Jansen_4

gb142 problem

Have you checked for proper polarity? Shorted wire to the gb? Have you checked the output voltage at both the tn4 terminals and at the boiler input terminals?

NRT.Shawn

Buderus GB142/Tn4 problem

The system is Tn4 with two Buderus GB142's. Tekmar 423 Reset Module using the 0-10VDC output to the Buderus GB142 EM-10 module (Tekmar terminals 54/55 go to U1/U2 on EM-10 1, Tekmar terminals 56/57 go to U1/U2 on EM-10 2) . The EM-10 module is then wired to the GB142 panel. Wire polarity between the Tekmar and the EM-10 module has been verified. The Tekmar signal is varying in strength (as the Tekmar attempts to modulate the boilers) at the Tekmar, however the boiler still runs up to high fire (no modulation). Technician is going to be checking the signal strength at the boiler.
All other wiring seems to be correct (per technician on site). Still unable to get the boilers to modulate.

singh

No boost.

It does have a Manual Mode, which goes to High fire, so one can perform tests. etc.



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

singh

Side Question

What are the benefits of using the Tn4 with EM10 over using , the AM10 and BC10 that is furnished with boiler. They modulate off delta from supply and return sensors , and ODR?

Vs. CM10



To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Unknown

Tn4 is sort of like AM10 and RC10 combined. It's odr with indoor feedback so that swift recovery from setback is possible. Plus it works with multiple zones. it will calculate circulating temp for zone with highest demand and basically establish constant circ. for this zone. zones with lower loads will then operate in a calculated pulsed on off fashion, not in response to room temp overshoot as with a conventional system or a zoned AM10 but in anticipation based on it's "understanding" of these zones relative needs. It also synchronizes these on off zones attempting to keep a zone calling as opposed to letting these cycles run independent of each other. Good description of all this in the essay section of the Tekmar web site.

Tn4 is great in radiant applications because it's gives good performance where zone loads are different, without requiring separate water temps. I'm not saying slab and staple up can go on the same mix, but there is fairly wide range made possible by the nature of this control logic.

NRT.Shawn

The EM10 module allows the Tekmar to handle the modulation of the boiler. By using the Tekmar to handle the modulation it provides Outdoor Reset, Indoor Feedback, and zone synchronization. This helps to minimize water temperatures (while still maintaining space heating) Tn4 it will also increase water temperatures when the system comes out of a setback state (providing a more rapid response to a heating demand).

Mike T., Swampeast MO

Given the results you describe, I suspect that the problem lies in the multiple-boiler interface controller.

It sure sounds as if, regardless of the 0-10V signal from the TN4, that the lead boiler is acting as if it were a non-modulating first stage. In other words, the lead boiler fires to the max regardless of load with only the lag boiler capable of providing modulation in the event that the lead boiler proves inadequate.

I do not know the full details of the control equipment involved, but unless the multiple boiler controller is capable of and properly set to modulate one or both boilers via the very same 0-10V signal, this is exactly the problem I would suspect.

The slickest multiple mod-con controllers I've heard of are actually capable of determining if it's more efficient to drive more than one boiler at relatively low output compared to one boiler at higher output (presuming of course that the boilers are properly piped and installed in parallel).

singh

Good description.

Thanks.




To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

singh

Thanks

Shawn,



""Tn4 it will also increase water temperatures when the system comes out of a setback state (providing a more rapid response to a heating demand)""

Q:Does the Tn4 only increases supply water temperature to zones coming out of setback, but not boiler output.? So if coming out of setback , especially slab zones boiler sensors reads large delta, it still wants high fire, rather than sync with Tekmar??

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"