GB 142 Applications manual (system designs)

S Davis

Sounds like a design problem to me, we have installed a lot of condencing boilers with pannel rads and fin tube and we just size them for 140 degree supply at design, with a 20 degree delta you are in condencing mode even at design temps.


S Davis

Apex Radiant Heating

central VT

Why do they have diagrams of a system that will not be efficient

Let me begin by saying that we are the homeowner that has been posting most of the CO and GB questions over the past few days. I don't mean to waste anyones time but am just trying to get an efficient system. We value everyones opinion and have found alot of useful information on this website.
A pro (from the web) has seen pictures of our installation, whick looks exactly like the pictures in the buderus applications manual on page 28 or 29. 5 zone system with bb, staple up and in slab radiant, circulator pumps on all the radiant zones with mixing valves. With this sytem we have a supply temp of 190 deg, to feed the bb and mixing valves to deal with the radiant. We have been advised that our system does nothing to help with overshooting and also will never allow our boiler to condence. We should have our installer rebuild part of the system with a mixing station and tc62 controller.
Our installer points to the fact that he built it exactly as shown in the book.
Why do they show the diagram of a system that will not utalize all of the features of the boiler? I know that unless you are looking at this book or pictures of our install, that its hard to comment on our system but we just feel like we are stuck.

Dave_22

Was your baseboard system existing already or new? If new, it could be designed with more footage of baseboard which you would let you run at lower design temps. The Buderus manual might assume this. What temps does the staple up and slab run at? Does each zone have a thermostat? You could try to lower the 190 setpoint down if your house still stays up to temp. I have "fooled" a system by using a relay which makes the high temp baseboard zone "think it's a DHW call. What this does is make the boiler run to high fire for the baseboard zone, but fire down with the other zones. The minus is the baseboard zone gets priority over the others and if it calls for heat a lot, the others could suffer-hard to say if it would work well with your system. The other option like I stated in one of the last posts was to keep your ears open for the "outdoor reset" function that will be available in the near future. Fact is, you got your self a great boiler no matter which way it is used, in my opinion.

Joe@buderus_2

Diagram

The idea behind the drawing is to show a large radiant system with a small baseboard loop. The large radiant return water temperature would mix with the higher return baseboard loop and temper the return water. As stated in our phone conversation, let's try the system and see what temperatures it runs at. We have seen applications just as what is shown that work quite well. SYSTEM DESIGN is important when installing a boiler and choosing the system layout. Most of the pro's who post here don't "install" a boiler - they design and install a "heating system". That is why heating systems are not "do-it-yourself" projects. Please post the findings on the supply and return temperatures. Thanks

Ted_9

GB142

Well said Joe.

Mr. Homeowner, why is the baseboard set at 190 anyway? Is the re enough fin tube? Most were designed at 180, and you install should be thinking about lower temps.I would try anything from 140 to 170 and not set back the t-stat much in those zones.

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