Reno Zone 5A: repair/replace hydronic baseboards or switch to underfloor radiant?
First, thank you for all of the knowledge shared on this forum; it’s been very useful as we’ve improved our home’s efficiency and comfort!
After struggling to find a definitive answer through research, my questions are:
1. Does underfloor radiant provide efficiency gains over hydronic baseboards?
2. Is there a noticeable improvement in comfort?
3. What else I should consider?
Climate Zone 5A: Southern NH
1989 contemporary with large first floor and primarily cathedral ceilings (see photo)
– 2×6 walls with R19 fiberglass batts and exterior R5 XPS
– R38 fiberglass batts in cathedral ceilings –inadequate given ice dam issues.
– Small accessible attic upgraded to R50 cellulose fill and air sealed
– Finished basement (drop ceiling), below grade only exterior R5 XPS. (Planning to upgrade with interior XPS where possible)
1989 oil boiler (109k BTU/hr) with two zones + indirect hot water HTP tank
– Fin baseboards with polybutylene tubing that is beginning to leak in spots
2020 Mitsubishi Hyper Heat Mini Splits:
– 36k BTU/hr multi head for 1st floor Master BR and 2 2nd floor units
– 18k BTU/hr head in the basement
2021 Mendota propane fireplace (To be installed) rated to 41k BTU/hr output
– The next project on the list is replacing flooring throughout the first floor giving us the best opportunity to do this project.
– Mini-splits have been great (My room by room Manual J seems to have been adequate) but as the monthly average temp drops to 30F they are approaching the cost of oil. I hypothesize that this is due to their placement high on the wall (in rooms with high ceilings); we set them above 75F to get the room to be ~69F. My hope was the heat from the basement unit would rise to heat the first floor, but even with the basement door open, not enough heat transfer is occurring. A contributing factor is the heat loss through the under insulated below grade walls.
– I had considered removing the baseboards and boiler, but given the recent cold snap I think that is unwise. Given the infrastructure in place I like the redundancy of two heat sources. I’m also unconvinced there is a better solution for our home’s hot water supply than the indirect hot water. I don’t think a HPHW will keep up with our demand–I would prioritize keeping our hot water supply capability over more efficient options.
– Given the drafts in the house, when it’s really cold I prefer the baseboard heat from a comfort standpoint, although we have waited a long time to turn them on.
– I plan to upgrade the boiler in either case and may downsize to better match the load.
TLDR: Should I replace my leaking hydronic baseboards with underfloor radiant heat or repair the baseboards and use the money saved somewhere else? If you were me, what else would you consider? Thank you in advance!
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