Residential heating hot water distribution and biomass boiler

smadanairb

Here's the rundown:
House: 2,000 SF, two story New Englander built around 1900. Fully weatherized (air sealed, walls dense packed with cellulose, attic blown with same, triple pane replacement windows...megh). Basement tight and dry. Occupants use about 50kBtu for heating. Last five years heated with a wood pellet stove.

1. Removing 15 yr. old oil boiler serving two floors and four zones and having qualified plumber install an OkoFEN PES20 wood pellet boiler with 4 ton hopper.
2. Existing distribution is poorly designed. 100' of 5/8" copper in the basement and 42' of 5/8" copper return. All insulated, but the runs are too long with too many bends, angles and distribution losses.
3. Existing baseboard for the two first floor zones adds up to 58'. Second floor not to be changed.
4. Before the pellet boiler is installed, I want to remove the first floor supply/return distribution from the basement and re-design with straight lines directly to the existing/new baseboard copper drops with 5/8" Whirsbo hePEX. This is the same PEX used when two zones were added to the second floor two years ago.

Questions:
1. To me (a building commissioning guy) this seems easy. Cut out the copper. Install new baseboard in the zone. Connect new baseboard to existing baseboard as necessary. Connect PEX to existing/new copper drops from baseboards. Connect PEX to supply/return header. Is this harder than it seems?
2. The headers at the boiler are currently to remain unchanged (the plumber quoted $3400 to re-design with the pellet boiler installation. still thinking about that...). There are iso valves to isolate the boiler on the supply/return sides. Do I need iso valves at the supply return for the baseboards?
3. Can I run the return lines off the new baseboard (kitchen and bath only) inside the baseboard, running over the top of the finned tube, and drop the return into the basement? Benefit: residual heat from the PEX return would be in the house and not in the basement. The zones on the second floor were installed in this manner - two soldered copper elbows, one end soldered to the copper in the finned tube and the other fitted to the PEX return, with the PEX return laying on top of the aluminum fins and running back to a chase down to the basement.
4. Can I design/connect the zone 1 returns as I draw them on page 3?
5. Page 2 of in the link below describes the existing design. I want to change zone 2 supply to the 31' length of baseboard into a return line. See page 3 of the redesign. This would reduce the length of supply in the basement and keep the heating hot water in the baseboard.

I have drawings. See link below.
https://cornerstonecx.egnyte.com/dl/TCANDnUM4b

Thanks!
Brian

njtommy

If your going through All the trouble to do that. Why don't you just install manifolds and pull a home run ( supply and return) to each baseboard? The you can also balance the flow to each section to get the proper amount of btus to each section.

smadanairb

Hi Tommy. Do you mean to install a manifolds for each zone? Currently, each zone has a zone valve. All served by a Taco pump.

hot_rod

There are a number of ways to pipe that system, manifold piping would be one good choice.




http://www.caleffi.com/sites/default/files/coll_attach_file/idronics_4.pdf

njtommy

Yes a manifold for each zone Basically what Hot Rod has posted above.

hot_rod

A load calc might be a good first step. Determine how much baseboard is required room by room.

Then determine how many zones you really need.

Is there a buffer tank with the pellet boiler? A backup boiler?