Buderus 115 3 Section vs 4 section and heat loss

ChrisP

Hi everyone,



First let me say this board has been very helpful and I'm now down to final choice on contractor.



Contractor #1 came in and measured my home room to room and came back with a 62,203 BTU heat loss. He recommended a Buderus 115/3 Section with Superstor 45



Contractor #2 came in and sized my baseboards and came to about 145ft of hydronic baseboard and recommended a Buderus 115/4 section boiler with Superstor 45.



Baseline was heat at 70 degrees and 0 temp as the low with a 180 degree temp.



Home was built in 1988 and is about 2200 square feet. We are located not far from Worcester, MA and face direct west with pretty much no trees in front of us. Get's pretty windy where we are in the winter.



To complicate things a family member works for FW Webb and told me I should use the Net IBR as a better number than the DOE and he's been doing this for close to 15 years.



Who is right and what do you recommend. If I oversize on the Buderus and go with the 4 section over 3 section how much would I be losing?



Never thought things would get so complicated.

Robert O'Brien

# 1 is correct

The amount of baseboard is useless information in selecting a boiler size,the heat loss is the only thing that matters. The 62K figure is right in line with what I would expect with that size home and design temp. A bigger boiler does nothing except use more fuel. Why do you disbelieve the calculation and give credence to rules of thumb? NO offense to your family member, but would you take medical advice from a medical supply salesman ?

CMadatMe

Net

A boilers net btu rating is used when a boiler is installed in an unconditioned space such as a crawl space or garage. The DOE rating is used when a boiler is installed in a conditioned space such as a basement or if the boiler piping is insulated.



As Rob said the guy that did the heat loss is the guy I'd go with.



Sincerely, the medical salesman.

Robert O'Brien

Chris

I've met two guys in my life who the "medical supplies" wisecrack doesn't apply to. You're one of them,please accept my apologies!

CMadatMe

No Worry

Rob no need to apologize. I know where your coming from. Appreciate the gesture.

R Mannino

With That Amount of Baseboard

you more than likely couldn't get all the heat that the 4 section could produce out of it. I had a G115/3 out run (limited out at 190) the radiation on a house larger than that (about 3000 sq. ft.) on a cold day and it was about 50 some odd degrees in the house (old boiler was down). The house wasn't under radiated either and it was a cold day.

ChrisP

Follow-up and thanks

Thanks everyone for the sizing confirmation. This helps me trust my instinct to go with the contractor who took the time to measure the system out.



A couple add on questions. Any issue with using a Superstor 45 over the Buderus Indirects?



Should I look at the G125 or GB125.? Is it worth it or am I better off to go with a more traditional burner like the Riello due to parts and techs that are used to it?

CMadatMe

Baseboard

145 ft of board at a 1 gpm flow rate with 180 degree water has a capable output of 81,000 btu's. Seems like this application needs the control to go with the boiler. Doing youself a dis service by not utilizing the outdoor reset control avail for this boiler.

Mac_R

Buderus 115

I love the Buderus G115.  Go with the guy who did the building heat loss calculation.  That is most accurate.  It is not a bad idea to measure the baseboard.  By looking at the baseboard you can get an idea of how the house is heated.  Think of it.  Way back when the house was built the contractor lined every outside wall with baseboards.  Chances are the home is way over radiated.  But with a Buderus boiler along with the 2107 control that is a good thing.  If the room only needs 4 feet of baseboard and it has eight.  You can run much cooler water through the system and still heat the house.  So instead of running 180 degree water you can now run 140.  It dont sound like much.  When you are talking around 100 gallons of water in the system it adds up. 



The most important thing about the Buderus no matter what modal you go with is that Logamatic 2107.  I use it on every install and have seen over 70% savings.  tanking people who are using 1,000 gallons a year of oil down to less than a tank is a wonderful thing.  make sure they use the 2107 and the BFU room temp sensor.  Put the main living space on constant circulation and if the bedrooms are zoned keep them on a zone valve.  They will just open and close with the thermostat.  Also you might want to think about upgrading your circulator to the new TACO delta T pump.  Or water flow is determined by the heating requirements of the house.   GPM= BTU/(delta T*500)  The BTU requirements change on indoor and outdoor conditions.  So there fore your flow rates need to change as well.  The TACO delta T pump uses sensors on the supply and return lines to slow down and speed up as required by the heating load.  Oh and don't use an off brand indirect with the 2107.  You will have problems.  The Buderus tanks are good.  You will have an anode rod you will need to have changed every couple of years.  However it is worth it because of the nightmare of a time you will have getting the tank to hold at the right temp.  Also make sure to have a mixing valve installed on the DMHW side of the indirect.  The Buderus can have a 14 degree temp swing.  You can easily get scalding hot water out of the tank.  The little bit of money they cost is will worth protecting your family.  Good luck and congradualtions of picking Buderus.

ChrisP

Logomatic 2107

Very much wanted to add that this round but it looks like I'm going to have to hold off one year. Unfortunately, the cost of the Buderus 115 plus Indirect had to be added to as also have to install a 35' Chimney Liner so I don't cause issues with condensation.



Wanted to hold off on that but my chimney is on the outside of my house and is only clay tile lined. Everything I've read says you'll need the liner.



Can the 2107 be added later and does it have problems with non-Buderus Indirects?

Mac_R

G115

Yes and no about the Logamatic.  If you are going to use the Logamatic you should really take advantage of the constant circ with the BFU.  Yes the Logamatic has problems with non Buderus tanks.  As far as lining the chimney.  You dont need to do it with the G115.  The stack temps on that boiler are above the 350 needed.  If they are not you can adjust the rods in the heat exchanger or remove them all together.  That will save you some money and buy you the Logamatic.  Just do your self a favor and Go with the S-120 indirect.  For the price it is a really good indirect.  I have not had a customer call me because they ran out of hot water.  All the information on the Buderus systems are on their web site.  www.Buderus.us