Sizing for Buderus GB142?

Steven_4

We are a family of 4. Myself and my wife, 2 very small kids. I'm not too sure on the controls, we have trv's for the buderus panel rads but nothing right now for the baseboard. Can we get TRV's for each of the seperate pieces of baseboard?

Steven_4

Would the bigger boiler be better?

My plumber had a heat loss done for our house which is 3300 sq ft of conditioned space and a heat loss of 45,000btu (on design day). We think that he should use the smallest GB but the company selling it to him specked the GB142/30. This is a fairly tight house and has panel rads, staple up radiant, and baseboards. Any help would be appreciated.

J.C.A._3

What....

Are you doing for hot water? This could be the swing vote. A high demand (say 2 daughters about 12-19 years of age) would make me think twice if you are going to use the boiler for domestic water heating.

If you are only using it for heating, the 24 would be my choice, but I don't know all the particulars. You've got at least 2 different temps for mixing and the water consideration would be just the beginning of the deciding factor. TRV's? What kind of control/sensing will you be using?
Placement of the temperature sensing device will also play a part.

The system will only work as well as the sum of the design and you've just teased us by not giving more details

Not such an easy choice eh? JMHO. Chris

hr

Isn't

the smallest #24 rated at 75K output at high temperature? this should be plenty to drive heat and an indirect for your family. Upsize to a 60 gallon tank for down the road when the kids grow in size and shower duration

hot rod

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Brian

GB142

I just fired up an Aerosa 50 with a 24 at my contractors house.I was leary about the combination but I filled a 72x34 whirlpool twice with no problem.The valve was a Delta 2715 with no restricter.In the future I'll have no problem recommending the 24 with the Aerosa.Don't forget you have DHW priority.

Good Luck
Dobber

Joe@buderus

GB142 and indirect

Which ever GB142 you decide, please keep in mind to size the circulator to handle the pressure drop of the tank and GB142. The DHW sensor that comes with the GB142 must be used in the tank for DHW priority and full output temperature of the GB142. Thanks,

Darin Cook_3

Central VT

The GB 142 can be derated by turning a dial on the heater. This will match the unit to the calculated heatloss of your home for the coldest day (calculated) of the year. A GB142/24 is more than adequate to run a 40 or 50 gallon indirect as log as you stay within the continuous rating draw and what the required btu input is. If you want to get more hot water out of your indirect have a thermostatic mixing valve installed on the tank. This will allow you to run the tank at a higher temp (decreasing the risk of legionella bacteria) and you can adjust the mixing valve to let out say 115' water. Long before you could feel any change in water temp the boiler will be firing at full btu input and satisfying your domestic hot water demand. There is no benefit dollar wise or other to simply put in a bigger heater just because the supply house wants to. That also brings forth a question of why the installing contractor does not figure any of this out on his own. Sounds like it is someone who is just "hooking pipes up". Remember there is no opinion involved here it is only science. You just have to use a contractor who is willing to obey the laws of physics. Hope this helps.








Darin

Steven_4

Decided to go with the smaller boiler.

Darin,
Thanks for the help. I was speaking with your partner Mark, about our job but he could only do the heating end. No one else from the wall in our location. I'm happy with our contractor in that he has a good reputation and is an honest guy but he just doesn't have a lot of experience with SIP houses and this boiler. He felt that the distributor had specked the 30 and that if anything went wrong he could always lean on them. After speking with mark, we told our guy we wanted to go smaller and switch to the Phase III Smart 40 water heater (another item he has never used). He still has a hard time doing it but we'll just sign off on it and call it a day. Thanks for all the help.
Steve