George Day
New Member
First off let me thank you for opening and reading this post. Any advice will be appreciated.
I currently have a 1948 3500sqft (3700sqft with walk in attic storage-currently unheated) house heated by 19 wall convectors and a Burnham series II boiler. Last winter 2-3 of the radiators towards the end of the loop were weak, this year 5 are weak or give off no heat. I am pretty confident I have bled all of the air out of them, by going around the house a couple of times with solid stream outcome. I also replaced the circulator pump. A plumber friend of mine believes the diverter tees in the loop are worn out at those units. In my area it will cost an arm and a leg to get the tees replaced only to be putting them in 70 year old pipes, so that is a not a preferred option.
Additionally, I am about to rehab the utility/laundry room and would like to relocate the boiler from there to the garage where the water heater is. With that in mind, I am looking at replacing both the boiler and water heater in favor of a Navien NCB 240 combi unit. I am looking at changing all the boiler pipes under the house from steel to PEX. Running the system as a home run design with 2 zones. Zone 1-13 convectors on first floor (568" of convectors) and zone 2 will have 6 convectors up stairs (280" of convectors). I could split these out differently if needed.
Another option is to keep the boiler I have and pipe the loop using pex, and tees as designed. That is to fix what is here and see what needs upgraded at a later date.
In my research I have performed a heat loss calculation through the SLANT/FIN app which provided me a 84,487 BTU/hr, I have also double checked this with utility bills using Dana's blog "Out With The Old, In With The New" found at http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new#ixzz4boKywBNi That calculation put me at 84,935 BTU/HR. My water heater is also gas and I have gas logs, so my estimations could be high.
The Navien NCB 240 comes in at 120K BTU/HR max with a min at 18K.
More details:
Downstairs heat loss- 54,763 BTU/Hr
Upstairs-29,724 BTU/Hr (may want to add 2 more convectors for walk in attics adding nearly 19BTU/hr)
Boiler-164,000BTU/hr input 136,000 output and 118,000 net (82% eff)
Watched the boiler cycle today and measured the temp at 163F out and 136F in, while checking the 8th or 9th convector in the loop at 155F in and 140F out.
Need the ability to run 1 shower, 1 dishwasher, and 1 clothes washer at time.
Goal is to design a system that will last 10-20 years and pay for itself in energy effieciency.
Concerns: navien/combi reviews online, using convectors at a low temp, house has hard water (which may increase maintenance on any boiler), also concerned with have the additional cost of removing convectors and putting in wall rad panels if convectors are not up to the new boiler at lower temps. Domestic HW not enough flow when my kids get a little older an start the Hollywood showers of teenagers.
All comments welcome. George
I currently have a 1948 3500sqft (3700sqft with walk in attic storage-currently unheated) house heated by 19 wall convectors and a Burnham series II boiler. Last winter 2-3 of the radiators towards the end of the loop were weak, this year 5 are weak or give off no heat. I am pretty confident I have bled all of the air out of them, by going around the house a couple of times with solid stream outcome. I also replaced the circulator pump. A plumber friend of mine believes the diverter tees in the loop are worn out at those units. In my area it will cost an arm and a leg to get the tees replaced only to be putting them in 70 year old pipes, so that is a not a preferred option.
Additionally, I am about to rehab the utility/laundry room and would like to relocate the boiler from there to the garage where the water heater is. With that in mind, I am looking at replacing both the boiler and water heater in favor of a Navien NCB 240 combi unit. I am looking at changing all the boiler pipes under the house from steel to PEX. Running the system as a home run design with 2 zones. Zone 1-13 convectors on first floor (568" of convectors) and zone 2 will have 6 convectors up stairs (280" of convectors). I could split these out differently if needed.
Another option is to keep the boiler I have and pipe the loop using pex, and tees as designed. That is to fix what is here and see what needs upgraded at a later date.
In my research I have performed a heat loss calculation through the SLANT/FIN app which provided me a 84,487 BTU/hr, I have also double checked this with utility bills using Dana's blog "Out With The Old, In With The New" found at http://www.greenbuildingadvisor.com/blogs/dept/guest-blogs/out-old-new#ixzz4boKywBNi That calculation put me at 84,935 BTU/HR. My water heater is also gas and I have gas logs, so my estimations could be high.
The Navien NCB 240 comes in at 120K BTU/HR max with a min at 18K.
More details:
Downstairs heat loss- 54,763 BTU/Hr
Upstairs-29,724 BTU/Hr (may want to add 2 more convectors for walk in attics adding nearly 19BTU/hr)
Boiler-164,000BTU/hr input 136,000 output and 118,000 net (82% eff)
Watched the boiler cycle today and measured the temp at 163F out and 136F in, while checking the 8th or 9th convector in the loop at 155F in and 140F out.
Need the ability to run 1 shower, 1 dishwasher, and 1 clothes washer at time.
Goal is to design a system that will last 10-20 years and pay for itself in energy effieciency.
Concerns: navien/combi reviews online, using convectors at a low temp, house has hard water (which may increase maintenance on any boiler), also concerned with have the additional cost of removing convectors and putting in wall rad panels if convectors are not up to the new boiler at lower temps. Domestic HW not enough flow when my kids get a little older an start the Hollywood showers of teenagers.
All comments welcome. George