gb142 question

clammy

After reading through the instruction of the gb i noticed the programer allows you to adjust heating output down while maintaning full output for domestics water production but i was wondering does the adjust of the heating out effects the staging or modultion of the heating output .Have a job coming up with a small heating load but a larger domestic water neds .My though was to oversize the unit so to take advantage of the heat output adjustment but still have enough btus for domestic water production still working out alot on this job in the layout and planning thanks for any input peace clammy

Jamie_6

Clammy,

I just got back from Buderus this week and they where discussing this point. I really don't think it's the best angel to take but it can be done.

Let’s say you have a 54,000 BTU load on a house. This would fit the GB 142-24 perfectly. It modulates between 22,000 BTU's and 75,000 BTU's, and you have FULL modulation there. This boiler will only provide the maximum efficiency for the first 50% of the maximum boiler rated output! Because all we need is 53,000 BTU's. Although, we have full modulation for that first 50% starting at 22,000 BTU's.

Well, let’s say, the job you are working on needs such a large hot-water load you must use a GB 142-45. 42,000 BTU's to 142,000 BTU's of full modulation! This boiler starts at a minimum output of 42,000 BTU's. Now we are fully modulating between 42,000 BTU's to 53,000 BTU's. That's only 11,000 BTU's of modulation as opposed to 31,000 BTU's of full modulation. Seems like we are losing a lot of savings there!

It would almost seem to me like using a reset control on a conventional boiler (not Buderus w/ a Tekmar) and a conventional boiler that is Buderus (w/ the Logamatic)! With that Logimatic control on a Buderus you can gain an additional 10 to 15% additional savings. (Since they are not worried about that cold water back to the boiler)

Hope this helps and I was not just rambling!!!!!!!!

It looks like pretty soon we are all going to have to start bidding strictly domestic Hot- Water systems.

Jamie


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dconnors

not quite..................

When you reset the modulation rate to a specific level; the output in BTU's is limited to that setting. Example: 142,000 boiler set at heat output of 50% will now only provide 71,000 BTU at max firing. domestically it will still give you 142,000 BTU. Hope this helps.

Jamie_6

Dave,

Yeah, but won't the bottom of the performance still only be at 42,000 BTU's? The load on the house would still only be 52,000 BTU's at design and you would lose alot of modulation on the lower end? Or am I not understanding this correctly?

Jamie

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clammy

thanks

Thanks for the infromation i had figured that that would be the set up i'll just do a little more figuring out still have plenty of time thanks to all peace clammy

dconnors

hope this helps

Based on what you told me; you dont need alot of modulation. You always want to keep the boiler at the lowest modulation as is possible to achieve the greatest eff. Modulation rate and return water temp are what drives the eff. of all condensing heaters.